#LyX 2.0 created this file. For more info see http://www.lyx.org/
\lyxformat 413
\begin_document
\begin_header
\textclass book
\begin_preamble
\usepackage{wrapfig}
 \setlength{\intextsep}{0cm plus1cm minus1cm}
\newcommand{\menuitem}[1]{\textbf{\emph{#1}}}
\end_preamble
\use_default_options false
\maintain_unincluded_children false
\language american
\language_package default
\inputencoding auto
\fontencoding global
\font_roman default
\font_sans default
\font_typewriter default
\font_default_family default
\use_non_tex_fonts false
\font_sc false
\font_osf false
\font_sf_scale 100
\font_tt_scale 100

\graphics default
\default_output_format default
\output_sync 1
\bibtex_command default
\index_command default
\paperfontsize default
\spacing single
\use_hyperref false
\papersize a4paper
\use_geometry false
\use_amsmath 1
\use_esint 0
\use_mhchem 1
\use_mathdots 1
\cite_engine basic
\use_bibtopic false
\use_indices false
\paperorientation portrait
\suppress_date false
\use_refstyle 0
\index Index
\shortcut idx
\color #008000
\end_index
\paperwidth 21cm
\paperheight 29.5cm
\leftmargin 1cm
\topmargin 1cm
\rightmargin 1cm
\bottommargin 1cm
\secnumdepth 2
\tocdepth 3
\paragraph_separation indent
\paragraph_indentation default
\quotes_language english
\papercolumns 1
\papersides 2
\paperpagestyle plain
\tracking_changes false
\output_changes false
\html_math_output 0
\html_css_as_file 0
\html_be_strict false
\end_header

\begin_body

\begin_layout Standard
\align left
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
thispagestyle{empty}
\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset VSpace 0.2in
\end_inset


\end_layout

\begin_layout Standard
\align center

\size giant
expEYES 
\size larger
Junior
\end_layout

\begin_layout Standard
\align center
\begin_inset Graphics
	filename pics/ej-with-netbook-hr.jpg
	lyxscale 10
	width 5cm

\end_inset


\end_layout

\begin_layout Standard
\align center

\size large
User's Manual 
\end_layout

\begin_layout Standard
\align center

\size largest
Experiments for
\begin_inset Newline newline
\end_inset

 Young Engineers and Scientists
\end_layout

\begin_layout Standard
\align center
http://expeyes.in
\end_layout

\begin_layout Standard
\align center
from
\end_layout

\begin_layout Standard
\align center
PHOENIX Project
\begin_inset Newline newline
\end_inset

Inter-University Accelerator Centre 
\begin_inset Newline newline
\end_inset

(A Research Centre of UGC)
\begin_inset Newline newline
\end_inset

New Delhi 110 067
\begin_inset Newline newline
\end_inset

www.iuac.res.in
\end_layout

\begin_layout Standard
\begin_inset Newpage newpage
\end_inset


\end_layout

\begin_layout Standard
Preface
\end_layout

\begin_layout Standard
The PHOENIX (Physics with Home-made Equipment & Innovative Experiments)
 project was started in 2004 by Inter-University Accelerator Centre with
 the objective of improving the science education at Indian Universities.
 Development of low cost laboratory equipment and training teachers are
 the two major activities under this project.
 
\end_layout

\begin_layout Standard
expEYES Junior is a modified version of expEYES released earlier.
 It is meant to be a tool for learning by exploration, suitable for high
 school classes and above.
 We have tried optimizing the design to be simple, flexible, rugged and
 low cost.
 The low price makes it affordable to individuals and we hope to see students
 performing experiments outside the four walls of the laboratory, that closes
 when the bell rings.
\end_layout

\begin_layout Standard
Hardware design is open and royalty-free.
 The software is released under GNU General Public License.
 The project has progressed due to the active participation and contributions
 from the user community and many other persons outside IUAC.
 We are thankful to S Venkataramanan and Prof.
 R Nagarajan for correcting this document by carrying out the experiments
 described independently.
 
\end_layout

\begin_layout Standard
expEYES Junior user's manual is distributed under GNU Free Documentation
 License.
 For more details about the project visit the website 
\shape italic
expeyes.in
\end_layout

\begin_layout Standard
\begin_inset space ~
\end_inset


\end_layout

\begin_layout Standard
Ajith Kumar B.P.
 
\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset


\begin_inset space ~
\end_inset

(ajith@iuac.res.in)
\end_layout

\begin_layout Standard
V V V Satyanarayana
\end_layout

\begin_layout Standard
Jimson Sacharias
\end_layout

\begin_layout Standard
\begin_inset Newpage newpage
\end_inset


\end_layout

\begin_layout Standard
\begin_inset CommandInset toc
LatexCommand tableofcontents

\end_inset


\end_layout

\begin_layout Chapter
Getting Started
\end_layout

\begin_layout Section
Introduction 
\end_layout

\begin_layout Standard
Science is the study of the physical world by systematic observations and
 experiments.
 Proper science education is essential for cultivating a society where reasoning
 and logical thinking prevails and not superstition and irrational beliefs.
 Science education is also essential for training enough technicians, engineers
 and scientists for the economy of the modern world.
 It is widely accepted that personal experience in the form of experiments
 and observations, either carried out by students or performed as demonstrations
 by teachers, are essential to the pedagogy of science.
 However, almost everywhere science is mostly taught from the text books
 without giving importance to experiments, partly due to lack of equipment.
 As a result, most of the students fail to correlate their classroom experience
 to problems encountered in daily life.
 To some extent this can be corrected by learning science based on exploration
 and experimenting.
 
\end_layout

\begin_layout Standard
The advent of personal computers and their easy availability has opened
 up a new path for making laboratory equipment.
 Addition of some hardware to an ordinary computer can convert it in to
 a science laboratory.
 Performing quick measurements with good accuracy enables one to study a
 wide range of phenomena.
 Science experiments generally involve measuring/controlling physical parameters
 like temperature, pressure, velocity, acceleration, force, voltage, current
 etc.
 If the measured physical property is changing rapidly, the measurements
 need to be automated and a computer becomes a useful tool.
 For example, understanding the variation of AC mains voltage with time
 requires measuring it after every millisecond.
\end_layout

\begin_layout Standard
The ability to perform experiments with reasonable accuracy also opens up
 the possibility of research oriented science education.
 Students can compare the experimental data with mathematical models and
 examine the fundamental laws governing various phenomena.
 Something similar to what research scientists do but with less sophisticated
 equipment.
 The expEYES ( expEriments for Young Engineers & Scientists) kit is designed
 to support a wide range of experiments, from school to post graduate level.
 It also acts as a test equipment for electronics engineers and hobbyists.
 The simple and open architecture of expEYES allows the users to 
\shape italic
develop new experiments, without getting into the details of electronics
 or computer programming
\shape default
.
 This User's manual describes 
\shape italic
expEYES
\shape default
 Junior along with several experiments, there is also a Programmer's manual
 available.
\end_layout

\begin_layout Section
The equipment
\end_layout

\begin_layout Standard
ExpEYES Junior is interfaced and powered by the USB port of the computer.
 For connecting external signals, it has several Input/Output terminals,
 arranged on both sides, as shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-ExpEYES-toppanel"

\end_inset

.
 It can monitor and control the voltages at these terminals.
 In order to measure other parameters (like temperature, pressure etc.),
 we need to convert them in to electrical signals by using appropriate sensor
 elements.
 
\end_layout

\begin_layout Standard
Even though our primary objective is to do experiments, you are advised
 to read through the brief description of the equipment given below.
 The device can be also used as a test equipment for electrical and electronics
 engineering experiments.
\end_layout

\begin_layout Paragraph*

\shape italic
IMPORTANT : 
\end_layout

\begin_layout Standard

\shape italic
The external voltages connected to expEYES must be within the allowed limits.
 Inputs A1 and A2 must be within 
\begin_inset Formula $\pm5$
\end_inset

 volts range and Inputs IN1 and IN2 must be in 0 to 5V range.
 Exceeding these limits slightly will flash an error message.
 If the program stops responding, exit and re-connect the USB to reset the
 device.
 Larger voltages will result in permanent damage.
 To measure higher voltages, scale them down using resistive potential divider
 networks.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/top-panel.png
	lyxscale 50
	height 9cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
The ExpEYES Junior top panel showing the external connections on both sides.The
 channel numbers shown against some terminals are meant for those who write
 software to access them.
 The arrows indicates the direction of the signals, for example arrow from
 
\begin_inset Formula $A1\Rightarrow1$
\end_inset

 means the signal from terminal A1 goes to channel number 1.
\begin_inset CommandInset label
LatexCommand label
name "fig:The-ExpEYES-toppanel"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection
External connections
\end_layout

\begin_layout Standard
The functions of the external Input/Outputs terminals are briefly explained
 below.
\end_layout

\begin_layout Paragraph*
Programmable Voltage Source (PVS) :
\end_layout

\begin_layout Standard
Can be set, from software, to any value in the 0 to +5V range.
 The resolution is 12 bits, implies a minimum voltage step of around 1.25
 millivolts.
 There is a read-back to verify PVS.
\end_layout

\begin_layout Paragraph*
\begin_inset Formula $\pm5V$
\end_inset

 Analog Inputs (A1 & A2) : 
\end_layout

\begin_layout Standard
Can measure voltage within the 
\begin_inset Formula $\pm5$
\end_inset

 volts range.
 The resolution of ADC used is 12 bits.
 Voltage at these terminals can be displayed as a function of time, giving
 the functionality of a low frequency oscilloscope.
 The maximum sampling rate is 250,000 per second.
 Both have an input impedance of 
\begin_inset Formula $10M\Omega$
\end_inset

 .
\end_layout

\begin_layout Paragraph*
\begin_inset Formula $0-5V$
\end_inset

 Analog Inputs (IN1 & IN2):
\end_layout

\begin_layout Standard
These terminals can measure voltages in the 0 to 5V range.
 
\end_layout

\begin_layout Paragraph*
Resistive Sensor Input (SEN):
\end_layout

\begin_layout Standard
This is mainly meant for sensors like Light Dependent Resistor, Thermistor,
 Photo-transistor etc..
 SEN is connected to 5 volts through a 
\begin_inset Formula $5.1k\Omega$
\end_inset

 resistor.
 It also has a built-in analog comparator.
\end_layout

\begin_layout Paragraph*
Digital Inputs (IN1 & IN2):
\end_layout

\begin_layout Standard
The inputs IN1, IN2 can act as both analog and digital inputs.
 In the digital mode, any voltage less than 1 volt is treated as logic 0(LOW)
 and anything higher than 2.5 volts is treated as logic 1(HIGH).
 If the voltage input is changing periodically between HIGH and LOW, these
 terminals can measure the frequency and duty-cycle of the connected signal.
 Time interval between voltage transitions on these pins can be measured
 with microsecond resolution.
\end_layout

\begin_layout Paragraph*
Digital Output (OD1) :
\end_layout

\begin_layout Standard
The voltage at OD1 can be set to 0 or 5 volts, using software.
\end_layout

\begin_layout Paragraph*
Square Waves SQR1 & SQR2 : 
\end_layout

\begin_layout Standard
Output swings from 0 to 5 volts and frequency can be varied 0.7Hz to 100kHz.
 All intermediate values of frequency are not possible.
 SQR1 and SQR2 can be set to different frequencies.
 It is also possible to set them to same frequency, with a specific phase
 shift between the two.
 These outputs also can be programmed to generate Pulse Width Modulated
 waveforms.
 SQR1 is wired to channel 6 for read-back and SQR2 is wired to channel 7.
\end_layout

\begin_layout Standard
Setting frequency to 
\begin_inset Formula $0$
\end_inset

Hz will make the output HIGH and setting it to 
\begin_inset Formula $-1$
\end_inset

 will make it LOW, in both cases the wave generation is disabled.
 When the wave generation is disabled, SQR1 and SQR2 can act as digital
 outputs on channel 8 and 9 respectively.
\end_layout

\begin_layout Standard
SQR1 output has a
\series bold
\shape slanted
 
\begin_inset Formula $100\Omega$
\end_inset

 series resistor
\series default
\shape default
 so that it can drive LEDs directly.
 
\end_layout

\begin_layout Paragraph*
Infrared Transmission
\end_layout

\begin_layout Standard
An Infrared Diode connected to SQR1 can transmit data using IR transmission
 protocol.
 The 4 byte transmission can be used for emulating common TV remotes.
 It also supports a single byte transmission that can be received by a program
 running on a micro-controller
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://expeyes.in/micro-controllers-for-hobby-projects-and-education
\end_layout

\end_inset

.
\end_layout

\begin_layout Paragraph*
SINE wave: 
\end_layout

\begin_layout Standard
Fixed frequency sine wave generator, frequency is around 150 Hz.
 Bipolar signal output with an amplitude of around 4 volts.
\end_layout

\begin_layout Paragraph*
Constant Current Source (CCS) : 
\end_layout

\begin_layout Standard
The constant current source can be switched ON and OFF under software control.
 The nominal value is 1mA but may vary from unit to unit, due to component
 tolerances.
 To measure the exact value, connect an ammeter from CCS to GND.
 Another method is to connect a known resistance (~3.3k) and measure the
 voltage drop across it.
 The load resistor should be less than 4k for this current source.
\end_layout

\begin_layout Paragraph*
Microphone (MIC) :
\end_layout

\begin_layout Standard
There is a built-in condenser microphone (on the side, near CCS).
 Its output, amplified 51 times, is available on MIC output.
 Connect it to A1 or A2 for viewing.
\end_layout

\begin_layout Paragraph*
Inverting Amplifier (IN->OUT) : 
\end_layout

\begin_layout Standard
The inverting amplifier is implemented using TL084 op-amp.
 Rf=51000 and Ri = 1000, giving a maximum gain of 
\begin_inset Formula $\frac{51000}{1000}=51$
\end_inset

.
 The gain can be reduced by feeding the input via a resistor.
 For example, using a 50k series resistor will make it a unity gain inverter.
\end_layout

\begin_layout Paragraph*
Ground : 
\end_layout

\begin_layout Standard
The four terminals marked as GND are the reference ground.
 All the generated/measured voltages are with respect to these terminals.
\end_layout

\begin_layout Subsection
Accessory Set
\end_layout

\begin_layout Standard
Some accessories are provided with expEYES Junior, a photograph is given
 on back cover of the manual.
\end_layout

\begin_layout Itemize
Crocodile Clips with leads (4) : If the connection to any terminal is changed
 many times during an experiment, it is easier to make the connection using
 the crocodile clip provided.
\end_layout

\begin_layout Itemize
3000 Turns Coil (2) : 44SWG copper wire, Inductance 
\begin_inset Formula $\approx$
\end_inset

 125 mH, Resistance 
\begin_inset Formula $\approx$
\end_inset

 550 
\begin_inset Formula $\Omega$
\end_inset

 .
 These coils can be used for studying inductance, electromagnetic induction
 etc.
 
\end_layout

\begin_layout Itemize
Piezo Electric Discs (2) : Resonant frequency is around 3500 Hz.
 Can be energized by SQR1 or SQR2.
 Discs are enclosed in a plastic shell that forms a cavity, that enhances
 the amplitude of sound produced.
\end_layout

\begin_layout Itemize
DC Motor : Should be powered by a DC voltage less than 3 volts.
\end_layout

\begin_layout Itemize
Permanent Magnets : (a) 10mm dia & length (b) 5 mm dia & 10 mm length (c)
 Button size magnets(2)
\end_layout

\begin_layout Itemize
5mm LEDS : RED, BLUE, GREEN, WHITE
\end_layout

\begin_layout Itemize
Capacitors : 47uF, 1uF, 0.1uF & 0.01 uF
\end_layout

\begin_layout Itemize
Resistors : 560
\begin_inset Formula $\Omega$
\end_inset

, 1
\begin_inset Formula $k\Omega$
\end_inset

, 2.2
\begin_inset Formula $k\Omega$
\end_inset

 , 10
\begin_inset Formula $k\Omega$
\end_inset

 , 51
\begin_inset Formula $k\Omega$
\end_inset

 and 200 
\begin_inset Formula $k\Omega$
\end_inset


\end_layout

\begin_layout Itemize
LDR & Thermistor
\end_layout

\begin_layout Itemize
Two silicon diodes (1N4148) and a Transistor( 2N2222)
\end_layout

\begin_layout Itemize
5 pieces of wires (8cm) and a Screwdriver 
\end_layout

\begin_layout Section
Software Installation
\end_layout

\begin_layout Standard
ExpEYES can run on any computer having a Python Interpreter and a Python
 module to access the Serial port.
 The USB interface is handled by the device driver program that presents
 the USB port as an RS232 port to the application programs.
 The communication the expEYES is done using a library written in Python
 language (also available in C language).
 Programs with GUI have been written for many experiments.
 There are many ways to get the software running:
\end_layout

\begin_layout Subsubsection*
The expEYES Live CD 
\end_layout

\begin_layout Standard
The easiest way to get started is to boot your PC with the expEYES Live-CD.
 From the PC BIOS, make the CD drive as the first boot device, insert the
 live CD and reboot the PC.
 A desktop will appear and you can start expEYES Junior from the menu 
\series bold
Applications->Science
\series default
->EYES-Junior.
 You can also start it from a Terminal using the command:
\end_layout

\begin_layout LyX-Code
$ python /usr/share/expeyes-junior/croplus.py
\end_layout

\begin_layout Subsubsection*
Installing on Debian or Ubuntu GNU/Linux distributions
\end_layout

\begin_layout Standard
Download 
\series bold
expeyes-3.0.0.deb
\series default
 , or higher version, from the software section of 
\series bold
http://expeyes.in
\series default
 and install it.
 It depends on python-serial, python-tk, python-scipy and grace (a 2D plotting
 program).
\end_layout

\begin_layout Subsubsection*
For other GNU/Linux distributions
\end_layout

\begin_layout Standard
Download 
\series bold
expeyes-3.x.x.zip
\series default
 from 
\series bold
http://expeyes.in
\series default
 and follow the instructions in the README file.
 It is important to give read/write permissions for all users on the USB
 port where expEYES is connected.
 This can be done by running the 
\shape italic
postint
\shape default
 shell script, included in the zip file.
\end_layout

\begin_layout Subsubsection*
On MSWindows
\end_layout

\begin_layout Standard
Even though expEYES is Free Software and is developed using Free and Open
 software, it runs on non-free platforms also.
 To install it on MS windows, you need (1) MCP2200 drivers (2) Python-2.x
 version, python-serial, python-tk, python-numpy and python-scipy (3) expeyes-3.x.
x.zip
\end_layout

\begin_layout Standard
Unzip the file 
\series bold
expeyes-3.x.x.zip
\series default
, and double click on 
\series bold
croplus.py
\series default
 inside the newly created directory named expeyes-3.x.x
\backslash
eyes-junior.
 If you have expEYES liveCD, browse inside the directory names WINEYES.
 All the files mentioned above are inside that directory.
 Double click on them in the order mentioned above to install them.
 See the software section on the expeyes website for more details.
\end_layout

\begin_layout Section
The main GUI program
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/benchmark.png
	lyxscale 50
	width 11cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
The croplus screen showing a sine-wave connected to A1.
 
\begin_inset CommandInset label
LatexCommand label
name "fig:The-croplus-screen."

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Start Applications->Science->EYES-Junior from the menu.
 A four channel oscilloscope screen with several extra features will open
 as shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-croplus-screen."

\end_inset

.
 The 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 
\shape default
button pops up a menu of programs for several experiments.
 The main window will become inactive when an experiment is selected and
 running.
\end_layout

\begin_layout Subsubsection*
The Plot Window
\end_layout

\begin_layout Standard
The plot window works like a low frequency four channel oscilloscope.
 The maximum sampling rate is 250 kHz only, sufficient for exploring audio
 frequency range.
 A brief description of this GUI program is given below.
\end_layout

\begin_layout Itemize
On the left side, the Inputs (A1,A2,IN1,IN2,SEN and read backs of SQR1 &
 SQR2) are shown.
 
\shape italic
Clicking on any of them will display the voltage/logic level present.
 
\shape default
To plot any of them, drag it to the desired channel (CH1 to CH4).
 The names of inputs selected for display are shown on the right side of
 the plot window, using a unique color for each channel.
\end_layout

\begin_layout Itemize
For online help, place cursor on any item, press and hold the left mouse
 button.
\end_layout

\begin_layout Itemize
Dragging ATR to any of the inputs will make it the CRO trigger source.
\end_layout

\begin_layout Itemize
This program allows different types of triggering.
 For example, dragging WRE to IN1 will enable rising edge triggering on
 it.
 It also supports setting levels or generating pulses on Digital outputs
 just before capturing the waveform.
 Dragging SHI to OD1 will keep OD1 HIGH during the capture process.
 For more details refer to the programmers manual.
\end_layout

\begin_layout Itemize
Dragging any of the channels, CH1 to CH4, to FIT will enable calculating
 amplitude and frequency by fitting the data using the equation 
\begin_inset Formula $V=V_{0}\sin\left(2\pi ft+\theta\right)+C$
\end_inset

 , 
\begin_inset Formula $V_{0}$
\end_inset

 and 
\begin_inset Formula $f$
\end_inset

 will be displayed.
 Dragging the channel to NML will disable the FIT option.
\end_layout

\begin_layout Itemize
Right clicking on IN1, IN2, SEN, SQR1 or SQR2 will measure the frequency
 and duty cycle of the voltage waveform present at the terminal.
\end_layout

\begin_layout Itemize
If two adjacent channels are assigned, Right-clicking on the first will
 calculate frequency and phase difference between the two inputs.
\end_layout

\begin_layout Itemize
Dragging a channel to FTR will show the Fourier Spectrum of the waveform
 in a separate window.
\end_layout

\begin_layout Itemize
To remove a displayed input, drag it to DEL.
\end_layout

\begin_layout Itemize
Horizontal scale (ms/division) adjustment.
 Set this to the minimum value and increase to view more number of cycles
 on the screen.
 Drag the rider or click on the left/right sides of it.
\end_layout

\begin_layout Itemize
Vertical scale (volts/division).
 Maximum values is 5 volts per division.
\end_layout

\begin_layout Itemize
Vertical offset sliders are provided for each channel to shift the trace
 up or down.
\end_layout

\begin_layout Itemize
The Check button LOOP selects Single/Continuous mode of scanning.
\end_layout

\begin_layout Itemize
The traces can be transferred to an Grace plot window, using XMG.
\end_layout

\begin_layout Itemize
SAVE button to save the data to the specified file in
\shape italic
 
\shape default
two column text format.
\end_layout

\begin_layout Standard
In addition to the CRO features, you can also control SQR1, SQR2, PVS etc.
 from the GUI.
 You can execute Python functions to access the hardware from a command
 window.
\end_layout

\begin_layout Itemize
For the Square waves , the frequency and phase difference in percentage
 are entered in two text fields.
 SQR1 & SQR2 can be set to different frequencies or to a single frequency
 with desired phase difference.
 Re-activate the check buttons after changing frequency or phase difference.
 
\end_layout

\begin_layout Itemize
SQR1 can be set using a slider also.
\end_layout

\begin_layout Itemize
To Set PVS, type the voltage (0 to 5) and press Enter key.
 The PVS output has a readback and the read back value is displayed in the
 message field.
\end_layout

\begin_layout Itemize
Checkbuttons are provided to control OD1 and CCS.
\end_layout

\begin_layout Itemize
Capacitance connected between IN1 and GND can be measured.
\end_layout

\begin_layout Itemize
Python functions to communicate to the hardware can be entered in a Command
 Window.
\end_layout

\begin_layout Section
Basic measurements using expEYES
\end_layout

\begin_layout Standard
Before proceeding with the experiments, let us do some simple exercises
 to become familiar with expEYES Junior.
 Boot your computer from the LiveCD, connect the device a USB port and start
 the EYES-Junior program from the menu 'Applications->Science'.
\end_layout

\begin_layout Subsection
Generate & measure voltages
\end_layout

\begin_layout Itemize
Connect PVS to IN1 and Assign IN1 to CH1
\end_layout

\begin_layout Itemize
Set PVS to some voltage and observe the trace
\end_layout

\begin_layout Itemize
Click on IN1 to display the voltage.
\end_layout

\begin_layout Subsection
Observe voltage waveforms
\end_layout

\begin_layout Itemize
Connect SINE to A1 and Assign A1 to CH1
\end_layout

\begin_layout Itemize
Adjust the horizontal scale (ms/Div) to view 4 or 5 cycles of the square
 wave
\end_layout

\begin_layout Itemize
Set frequency to to 100 and Check SQR1.
\end_layout

\begin_layout Itemize
Assign SQR1 to CH2
\end_layout

\begin_layout Itemize
Change frequency.
 Uncheck and Check SQR1.
\end_layout

\begin_layout Itemize
Explore the FIT and FTR options.
\end_layout

\begin_layout Subsection
Measure frequency & Duty cycle
\end_layout

\begin_layout Itemize
Set SQR1 to 1000
\end_layout

\begin_layout Itemize
Right Click on SQR1 to display frequency and duty cycle.
\end_layout

\begin_layout Itemize
To set 488 Hz 30% PWM, enter 
\shape italic
set_sqr1_pwm(30)
\begin_inset Foot
status collapsed

\begin_layout Plain Layout

\shape italic
For information about all the commands, refer to the Programmer's manual
\end_layout

\end_inset

 
\shape default
inside the Command window.
\end_layout

\begin_layout Itemize
Measure again by Right Clicking on SQR1
\end_layout

\begin_layout Subsection
Accuracy and resolution
\end_layout

\begin_layout Standard
Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-croplus-screen."

\end_inset

 shows a 3V, 3000.5 Hz sine wave from an Agilent 33220A Function generator,
 connected to A1.
 The voltage at IN1 is measured as 3.000 by a Keithley 2100 multimeter, off
 by 2mV.
 The frequency of audio frequency sine wave is measured with less than 0.1%
 error.
 The voltage measurement has 12 bit resolution but the absolute accuracy
 may change slightly with ambient temperature.
\end_layout

\begin_layout Section
Experiments
\end_layout

\begin_layout Standard
The expEYES hardware can generate/measure different kinds of voltage signals.
 For measuring any other parameter it should be converted into a voltage,
 using appropriate sensor elements.
 For example a temperature sensor will give a voltage indicating the temperature.
 
\end_layout

\begin_layout Standard
A GUI program is provided for every experiment given in this manual.
 However, it is possible to do the same by writing few lines of code in
 Python language.
 All the communication to expEYES is done using a Python library called
 
\shape italic
eyesj.py
\shape default
.
 Data analysis and graphical display is also done in Python.
 If you are interested in developing new experiments based on expEYES, it
 would be a good idea to learn Python programming language.
 Almost every experiment can be extended in several ways and some hints
 are given in this direction.
 
\end_layout

\begin_layout Standard
The following chapters describe experiments from different topics like electrici
ty, magnetism, electronics, sound, heat etc.
 Since the expEYES kit is meant for self learning, we have included some
 very trivial experiments in the beginning.
\end_layout

\begin_layout Chapter
Electricity
\end_layout

\begin_layout Standard
We start with the simple task of measuring the voltage of a dry-cell.
 Current and resistance are introduced next, followed by resistances changing
 with temperature and light.
 The concept of Alternating Current is introduced by plotting the voltage
 as a function of time.
 The behavior of circuits elements like capacitors and inductors in AC and
 DC circuits are explored, by measuring parameters like amplitude, frequency
 and phase.
 The transient response of a resistor and capacitor in series is used for
 measuring the capacitance.
 Inductance also is measured in the same manner.
 The Fourier analysis of waveforms are done to study the harmonics.
 Integration and differentiation of a square wave using RC circuits also
 is explored.
 
\end_layout

\begin_layout Standard
For each experiment, make connections as per the diagram given.
\end_layout

\begin_layout Section
Measuring Voltage
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn to measure voltage using expEYES and get some idea about the concept
 of Electrical Ground.
 A dry-cell and two wires are required.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/measure-dc.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
Click on A1 to display the voltage
\end_layout

\begin_layout Itemize
Repeat by reversing the cell connections.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
Voltages measured value is +1.5 volts and it becomes -1.5 after reversing
 the connections.
\end_layout

\begin_layout Standard
We are measuring the potential difference between two points.
 One of them can be treated as at zero volts, or Ground potential.
 The voltage measuring points of expEYES measure the voltage with respect
 to the terminals marked GND.
 We have connected the negative terminal of the cell to Ground.
 The positive terminal is at +1.5 volts with respect to the negative terminal.
 
\shape italic
Will it show correct voltage if GND is not connected ?
\end_layout

\begin_layout Standard
If the input voltage is within 0 to 5V range, use IN1, which is directly
 connected to the ADC input.
 Resolution of bipolar inputs A1 and A2 are half of that of IN1.
 The offset and gain errors of the level shifting amplifiers also affect
 the accuracy of A1 & A2.
 
\end_layout

\begin_layout Section
Voltage, current & resistance
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn about Current, Resistance and Ohm's law, using a couple of resistors.
 The voltage across a conductor is directly proportional to current flowing
 through it.
 The constant of proportionality is called Resistance.
 This is known as Ohm's Law, expressed mathematically as
\begin_inset Formula 
\[
V\varpropto I\,\,\,;\,\,\,\, V=IR\,\,\,\, or\,\,\, R=\frac{V}{I}
\]

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/resistors.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Set PVS to some voltage, read the actual value set from the message field.
\end_layout

\begin_layout Itemize
Click on IN1 to measure its voltage.
\end_layout

\begin_layout Itemize
Repeat for different values of PVS.
 
\end_layout

\begin_layout Itemize
Repeat for other resistance values.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The total voltage and the voltage across R1 are measured.
 The voltage across R2 is 
\begin_inset Formula $V_{PVS}-V_{R1}$
\end_inset

.
 The current through R1, 
\begin_inset Formula $I=V_{R1}/R1$
\end_inset

.
 The same amount of current flows through R2 and the voltage across R2 can
 be calculated using 
\begin_inset Formula $V_{R1}=IR1$
\end_inset

.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="5">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
\begin_inset Formula $V_{PVS}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
\begin_inset Formula $V_{IN1}=V_{R1}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
\begin_inset Formula $I=\frac{V_{IN1}}{1000}$
\end_inset

A
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
\begin_inset Formula $V_{R2}=V_{PVS}-V_{IN1}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\size footnotesize
\begin_inset Formula $V_{R2}=I\times2.2k$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.313
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.313
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.687
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.688
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.626
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.626
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.374
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.377
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.94
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.94
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2.06
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2.07
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
Expand this experiment by connecting three resistors in series and connecting
 the junctions to IN1 and IN2.
 Another exercise is to connect a 
\begin_inset Formula $5.1k$
\end_inset

 resistor from SEN to GND and measure the voltage at SEN.
 Remember that SEN is internally connected to 5 volts through a 
\begin_inset Formula $5.1k$
\end_inset

 resistor.
\end_layout

\begin_layout Section
Calibrating Current Source
\begin_inset CommandInset label
LatexCommand label
name "sec:Calibrating-Current-Source"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
The actual output of constant current source may be different from the specified
 1 mA, due to the tolerance of the resistors used.
 It can be measured by connecting an ammeter from CCS to GND, or by connecting
 a known resistance to CCS and measuring the voltage across it.
 The resistor should be in 2k to 4k range.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/ccs-calib.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Enable CCS 
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The measured values of the resistance is 3.876k and the voltage is 3.725 volts.
 The actual value of the constant current source is 3.725/3.876 = .961 mA.
 
\end_layout

\begin_layout Standard
For better accuracy, the measured value should be used in experiments using
 CCS.
\end_layout

\begin_layout Section
Resistances in series
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Finding the effective resistance of a series combination of resistors, 
\begin_inset Formula $R=R1+R2+\cdots$
\end_inset

, using a constant current source.
 A 
\begin_inset Formula $560\Omega$
\end_inset

 and a
\begin_inset Formula $1k\Omega$
\end_inset

 resistors are used.
 
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/res-series.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Connect R1, R2 alone and then both
\end_layout

\begin_layout Itemize
Measure IN1 for each case
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R(
\begin_inset Formula $\Omega)$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
V(volts)
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
560
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.558
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1000
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.998
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1000+560
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.556
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
Since the current is same, the total voltage drop gives the effective resistance.
 It can be seen that it is the sum of the individual values, within the
 measurement error.
 For more accurate results, use the value of current measured as explained
 in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Calibrating-Current-Source"

\end_inset

, instead of 1mA.
\end_layout

\begin_layout Section
Resistances in parallel
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Find the effective resistance of parallel combination of resistors, given
 by 
\begin_inset Formula $\frac{1}{R}=\frac{1}{R1}+\frac{1}{R2}+\cdots$
\end_inset


\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/res-parallel.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
Connect 1
\begin_inset Formula $k\Omega$
\end_inset

 resistor from CCS to Ground.
\end_layout

\begin_layout Itemize
Repeat the same with two resistors connected in parallel.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $R_{connected}(\Omega)$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $V_{measured}(V)$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1000
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.008
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1000
\begin_inset Formula $\parallel$
\end_inset

1000
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.503
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
Since we know the current, we can calculate the resistance from the measured
 voltage.
 As per the measured voltage the resistance of the parallel combination
 is 
\begin_inset Formula $\frac{0.503V}{0.001A}=503\Omega$
\end_inset

.
\end_layout

\begin_layout Section
Measure resistance by comparison
\begin_inset CommandInset label
LatexCommand label
name "sec:Measure-resistance-by"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn to apply Ohm's law to find the value of an unknown resistance by comparing
 it with a known one.
 Voltage across a resistor is given by 
\begin_inset Formula $V=IR$
\end_inset

 .
 If same amount of current is flowing through two different resistors, the
 ratio of voltages will be the same as the ratio of resistances, 
\begin_inset Formula $I=\frac{V1}{R1}=\frac{V2}{R2}$
\end_inset

.
\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/res-compare.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Connect the unknown resistor R from PVS to IN1.
\end_layout

\begin_layout Itemize
Connect 1
\begin_inset Formula $k\Omega$
\end_inset

 (R1) from IN1 to Ground.
\end_layout

\begin_layout Itemize
Set PVS to 4 volts.
\end_layout

\begin_layout Itemize
Measure voltage at IN1
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
Voltage at IN1 = 1.254, implies voltage across the unknown resistor is 
\begin_inset Formula $4-1.254=2.746$
\end_inset


\end_layout

\begin_layout Standard
Current 
\begin_inset Formula $I=\frac{1.254}{1000}=1.254mA$
\end_inset

 .
 Unknown resistor value = 
\begin_inset Formula $\frac{2.746}{1.254mA}=2.19k\Omega$
\end_inset


\end_layout

\begin_layout Standard
What is the limitation of this method ? How do we choose the reference resistor
 ? suppose the unknown value is in Mega Ohms, what will be the voltage drop
 across a 
\begin_inset Formula $1k\Omega$
\end_inset

 reference resistor ? Our voltage measurement is having a resolution of
 
\begin_inset Formula $\frac{1}{4095}$
\end_inset

.
\end_layout

\begin_layout Standard
We will use this method later to measure the resistance of solutions, using
 AC.
\end_layout

\begin_layout Section
Voltage of a lemon cell 
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Make a voltage source by inserting Zinc and Copper plates into a lemon.
 Explore the current driving capability and internal resistance.
\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Subsection*
\begin_inset Graphics
	filename schematics/lemon-cell.png
	height 1.3cm

\end_inset


\end_layout

\begin_layout Itemize
Click on A1 to measure voltage
\end_layout

\begin_layout Itemize
Measure the voltage with and without the 1k resistor
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
Voltage across the Copper and Zinc terminals is nearly .9 volts.
 Connecting the resistor reduces it to 0.33 volts.
 When connected, current will start flowing through the resistor.
 But why is the voltage going down ?
\end_layout

\begin_layout Standard
What is the internal resistance of the cell ?
\end_layout

\begin_layout Standard
Current is the flow of charges and it has to complete the path.
 That means, current has to flow through the cell also.
 Depending on the internal resistance of the cell, part of the voltage gets
 dropped inside the cell itself.
 Does the same happen with a new dry-cell ?
\end_layout

\begin_layout Section
DC, AC and power line pickup
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Introduce the concept of time dependent voltages, using a V(t) graph.
 Compare the graph of DC and AC.
 Learn about the AC mains supply.
 Explore the phenomenon of propagation of AC through free space.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/ad-dc.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/pickup.png
	lyxscale 50
	width 6cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Plotting Voltage Vs Time.
 (a) graph of DC and AC (b) AC mains pickup 
\begin_inset CommandInset label
LatexCommand label
name "fig:Graph-of-DC"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/ac-dc.png
	height 0.7cm

\end_inset

 
\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Set PVS to 1 volt
\end_layout

\begin_layout Itemize
Assign CH1 to FIT, to measure AC parameters.
\end_layout

\begin_layout Itemize
Remove SINE and connect a long wire to A2
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/line-pickup.png
	height 1cm

\end_inset


\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Graph-of-DC"

\end_inset

(a) shows that the graph of DC is horizontal line and for AC it changes
 direction and magnitude with time.
 The voltage is changing with time.
 It goes to both negative and positive around 150 cycles per second.
 This voltage waveform is generated by using electronic circuits.
\end_layout

\begin_layout Standard
Enabling FIT option calculates the amplitude and frequency by fitting the
 data with the equation 
\begin_inset Formula $V=V_{0}\sin(2\pi ft+\theta)$
\end_inset

 , where 
\begin_inset Formula $V_{0}$
\end_inset

 is the amplitude and 
\begin_inset Formula $f$
\end_inset

 
\begin_inset space ~
\end_inset

is the frequency.
 What is the significance of 
\begin_inset Formula $\theta$
\end_inset

 in this equation ?
\end_layout

\begin_layout Standard
The power line pickup is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Graph-of-DC"

\end_inset

(b).
 The frequency is obtained by fitting the data.
 Without making any connection, how are we getting the AC voltage from the
 mains supply ?
\end_layout

\begin_layout Section
DC & AC components of a voltage
\begin_inset CommandInset label
LatexCommand label
name "sec:DC-&-AC"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Separating AC and DC components of a voltage waveform using a capacitor.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/acdc-sep-screen.png
	lyxscale 40
	width 6cm

\end_inset

 
\begin_inset Graphics
	filename pics/body-resistance.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) A 0 to 5V square wave, with DC component blocked (b) Resuming electrical
 resistance of human body
\begin_inset CommandInset label
LatexCommand label
name "fig:Square-wave"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/acdc-separating.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Set SQR1 to 500 Hz
\end_layout

\begin_layout Itemize
Assign SQR1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Adjust the horizontal scale to see several cycles.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The observed waveforms with and without the series capacitor are shown in
 figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Square-wave"

\end_inset

.
 The voltage is swinging between 0 and 5 volts.
 After passing through the capacitor the voltage swings from -2.5 volts to
 +2.5 volts.
\end_layout

\begin_layout Standard
What will you get if you subtract a 2.5 from the y-coordinate of every point
 of the first graph? That is what the capacitor did.
 It did not allow the DC part to pass through.
 This original square wave can be considered as a 2.5V AC superimposed on
 a 2.5V DC.
\end_layout

\begin_layout Standard
You may need to connect a resistor from A2 to GND to see a waveform swinging
 between -2.5 to +2.5 volts.
 Remove the resistor and observe the result.
 
\end_layout

\begin_layout Section
Resistance of human body
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Get some idea about the resistance of the skin and how it varies.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/res-body.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Join PVS and A2, through your body and measure voltage at CH2
\end_layout

\begin_layout Itemize
Calculate your body's resistance, as given in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Measure-resistance-by"

\end_inset


\end_layout

\begin_layout Itemize
Repeat using SINE instead of PVS.
 Enable FIT to measure voltage.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The observed waveform is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Square-wave"

\end_inset

(b).
 Voltage at A2 is 3V, the variation is due to the 50Hz AC pickup.
 
\end_layout

\begin_layout Section
Temperature dependent resistors 
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Show the dependence of resistance on temperature, using a thermistor,
\begin_inset Formula $1k\Omega@25^{0}C$
\end_inset

, with negative temperature coefficient.
 Introduce temperature sensor.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/thermistor.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Click on IN1 to measure the voltage
\end_layout

\begin_layout Itemize
Repeat at different temperatures
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Setup
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
V=IR
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $R=\frac{V}{I}$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
In cold water
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1200
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Room Temperature
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.935
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
935
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Section
Light dependent resistors
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn about LDR.
 Measure intensity of light and its variation with distance from the source.
 Use the comparison method to find out the resistance.
\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/ldr.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Set PVS to 4V and note down the value set
\end_layout

\begin_layout Itemize
Click on IN1 to measure it, Assign IN1 to CH1.
\end_layout

\begin_layout Itemize
Calculate the LDR's resistance, as explained in
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Measure-resistance-by"

\end_inset


\end_layout

\begin_layout Itemize
Repeat by changing intensity of light falling on LDR
\end_layout

\begin_layout Itemize
Connect an LED from SQR1 to GND.
 Set SQR1 to 10 Hz
\end_layout

\begin_layout Itemize
Show the LED above LDR and watch waveform at IN1
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The resistance vary from 1k
\begin_inset Formula $\Omega$
\end_inset

 to around 100 k
\begin_inset Formula $\Omega$
\end_inset

 depending on the intensity of light falling on it.
 The voltage is proportional to the resistance.
 The resistance decreases with intensity of light.
 If you use a point source of light, the resistance should increase as the
 square of the distance.
\end_layout

\begin_layout Standard
Illuminate the LDR using a fluorescent tube and watch the waveform at CH1.
 The frequency of the ripple is related to the mains frequency.
\end_layout

\begin_layout Section
Conductivity of water, using DC & AC
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Measure the resistance of ionic solutions, using both DC and AC voltages.
 We have used normal tap water.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
R1 should be comparable to R, start with 10k.
\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2, enable FIT on both
\end_layout

\begin_layout Itemize
Calculate the resistance as explained in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Measure-resistance-by"

\end_inset


\end_layout

\begin_layout Itemize
Repeat using a DC voltage, PVS instead of SINE
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename schematics/res-water.png
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/water-conduct.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Conductivity of water.
 (b)Total voltage applied and the voltage across the 10k resistor.
\begin_inset CommandInset label
LatexCommand label
name "fig:Conductivity-of-water."

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="6">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $V_{total}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $V_{10k\Omega}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $V_{liq}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $I=\frac{V_{10k\Omega}}{1000}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $R_{liq}=\frac{V_{liq}}{I}$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SINE
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3.25
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2.6
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.65
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.26 mA
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2.5 k
\begin_inset Formula $\Omega$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PVS
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
4
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2.3
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.7
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.23 mA
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
 7.4 k
\begin_inset Formula $\Omega$
\end_inset


\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
Observed values are shown in the table.
 The DC and AC resistances seems to be very different.
 With DC, the resistance of the liquid changes with time, due to electrolysis
 and bubble formation.
 The resistance does not depend much on the distance between the electrodes,
 the area of the electrode is having some effect.
 The resistance depends on the ion concentration and presence of impurities
 in the water used.
\end_layout

\begin_layout Standard
Try changing the distance between electrodes.
 Try adding some common salt and repeat the measurements.
 Why is the behavior different for AC and DC ? What are the charge carriers
 responsible for the flow of electricity through solutions ? Is there any
 chemical reaction taking place ?
\end_layout

\begin_layout Section
Measuring Capacitance
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
expEYES Junior has an internal programmable current source, that can be
 enabled on IN1.
 Connect a capacitance C and switch on current (5.5 
\begin_inset Formula $\mu A$
\end_inset

) for a fixed time interval.
 The accumulated charge 
\begin_inset Formula $Q=It=CV$
\end_inset

 .
 By measuring 
\begin_inset Formula $V$
\end_inset

 , the value of C is calculated.
 For better results the stray capacitance need to be subtracted.
 Measure C without connecting anything to IN1, and subtract that value from
 the C measured with capacitor.
 This method can be used for values upto 10000 pF.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
Beyond that you need to use the Python function that can specify the charging
 current, duration of charging etc.
\end_layout

\end_inset

 Touching the capacitor during the measurement will corrupt the result.
 
\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/measure-cap.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Measure C without anything connected, to get the stray capacitance.
\end_layout

\begin_layout Itemize
connect the capacitor from IN1 to ground.
 
\end_layout

\begin_layout Itemize
Click on the Button
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Measure C on IN1}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Repeat with different capacitors
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The empty socket measures 34 pF.
 Several capacitors were measured.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="6" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
 Value
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Measured value (pF) - 34pF
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
10
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
11
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
20
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
19
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
680
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
664
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
180
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
176
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3000
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2900
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Section
Measuring Dielectric Constant
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Measure the dielectric constant of materials like glass, paper, polyester
 etc., by making a capacitor.
 Capacitance 
\begin_inset Formula $C=\epsilon_{0}k\frac{A}{d}$
\end_inset

, where 
\begin_inset Formula $\epsilon_{0}$
\end_inset

 is the permittivity of free space, 
\begin_inset Formula $k$
\end_inset

 the dielectric constant , 
\begin_inset Formula $A$
\end_inset

 the overlapping area of plates and 
\begin_inset Formula $d$
\end_inset

 the separation between them.
 We have used a 13 cm x 10.6 cm piece of window glass having 4 mm thickness
 to make a capacitor by pasting metal foil on both sides.
\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Itemize
connect the capacitor from IN1 to ground.
 
\end_layout

\begin_layout Itemize
Click on the Button 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Measure C on IN1}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Repeat without connecting anything to IN1
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The measured capacitance is 225 pF.
 The stray capacitance is measured after removing the wire from IN1 and
 it is 30pF, means C = 195pF.
 
\begin_inset Formula $k=\frac{Cd}{\epsilon_{0}A}=\frac{195e-12\times0.004}{8.854e-12\times.13\times.106}=6.37$
\end_inset

.
 Touching the capacitor during the measurement gives wrong results.
 
\end_layout

\begin_layout Standard
Using two parallel plates, the dielectric constant of liquids also can be
 measured.
\end_layout

\begin_layout Section
AC Phase shift in RC circuits
\begin_inset CommandInset label
LatexCommand label
name "sec:Capacitor-in-AC"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Explore the effect of a series capacitor in AC circuits, under steady state
 conditions.
 Impedance of a Capacitor 
\begin_inset Formula $X_{c}=\frac{1}{2\pi fC}$
\end_inset

 , where 
\begin_inset Formula $f$
\end_inset

 is the frequency in Hertz and 
\begin_inset Formula $C$
\end_inset

 is the capacitance in Farads.
 
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/rc-acphase.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Adjust the horizontal scale to view more than 4 cycles.
\end_layout

\begin_layout Itemize
Right click on CH1 to calculate the phase shift.
\end_layout

\begin_layout Standard
For a detailed study select 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Study of AC Circuits}
\end_layout

\end_inset


\shape default
 from 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The voltage waveform before and after the capacitor are shown in figure
 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:AC-Phase-in-RC"

\end_inset

(a),and the calculations are shown in the table.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="2" columns="5">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
C(uF)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
R(
\begin_inset Formula $\Omega$
\end_inset

)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Freq (Hz)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\bigtriangleup\Phi$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\arctan\left(\frac{X_{c}}{X_{R}}\right)$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1000
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
147.3
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
47.7
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
47.2
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
where 
\begin_inset Formula $X_{c}=\frac{1}{2\pi fC}$
\end_inset

 is the impedance of the capacitor, Frequency is 147.3 Hz.
 
\begin_inset Formula $X_{R}$
\end_inset

 is the resistance.
\end_layout

\begin_layout Standard
Current through a capacitor leads the voltage across it by 
\begin_inset Formula $90^{0}$
\end_inset

.
 Why ?
\end_layout

\begin_layout Standard
Why does the phase of the voltage advance? Assume we have connected the
 AC to plate A and at an instant 
\begin_inset Formula $t=t_{0}$
\end_inset

 the input voltage is at zero volts.
 We can see that the slope of the curve is maximum there, i.e.
 the rate of change of voltage is maximum.
 The capacitor gets charged very fast at this point.
 The plate B also gathers the same charge as plate A , that is how a capacitor
 works.
 The current to plate B is flowing from ground through the resistor and
 we are measuring the IR drop across the resistor, it will be already positive
 when plate A is at zero.
 This results in the phase advance.
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/rc-phaseshift.png
	lyxscale 40
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/rl-phaseshift.png
	lyxscale 40
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Phase shift of AC in an (a) RC circuit (b) RL circuit 
\begin_inset CommandInset label
LatexCommand label
name "fig:AC-Phase-in-RC"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
AC phase shift in RL circuits
\begin_inset CommandInset label
LatexCommand label
name "sec:Inductor-in-AC"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Measure the AC voltage phase shift in an RL circuit.
 Impedance of an Inductor 
\begin_inset Formula $X_{L}=2\pi fL$
\end_inset

 , where 
\begin_inset Formula $f$
\end_inset

 is the frequency in Hertz and L is the inductance in Henry.
 In an LC circuit, the phase lag across the inductor is given by the equation
 
\begin_inset Formula $\triangle\Phi=\arctan\left(\frac{X_{L}}{X_{R}}\right)$
\end_inset

, where R is the resistance in Ohms.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/rl-acphase.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Adjust the horizontal scale to view more than 4 cycles.
\end_layout

\begin_layout Itemize
Right Click on A1 to view voltage, frequency and phase difference.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The measured phase shifts are shown below.
 Waveforms for the 125 mH inductor is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:AC-Phase-in-RC"

\end_inset

(b).
 The resistance of the inductor also should be included while calculating
 the phase shift.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://www.play-hookey.com/ac_theory/ac_inductors.html
\end_layout

\end_inset

.
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="2" columns="4">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
L(mH)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $R=R_{coil}+R_{ext}$
\end_inset

(
\begin_inset Formula $\Omega$
\end_inset

)
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\bigtriangleup\Phi=\arctan\left(\frac{X_{L}}{X_{R}}\right)$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\bigtriangleup\Phi_{measured}$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
125
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
565 + 560
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3.71
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
-3.8
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
Insert an iron or ferrite core to the coil and observe the effect of ferromagnet
ic materials.
 Self Inductance of a solenoid is given by 
\begin_inset Formula $L=\frac{\mu N^{2}A}{l}$
\end_inset

 , where N is the number of turns, A is the cross sectional area, 
\begin_inset Formula $\mu$
\end_inset

 is the permeability of the surrounding media and 
\begin_inset Formula $l$
\end_inset

 is the length.
\end_layout

\begin_layout Section
Transient Response of RC circuits
\begin_inset CommandInset label
LatexCommand label
name "sec:Capacitor-charging-&"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Plot the voltage across a capacitor, when it is charged by applying a voltage
 step through a resistor.
 Calculate the value of the capacitance from the graph.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/RCcircuit.png
	height 0.8cm

\end_inset

 
\end_layout

\begin_layout Itemize
From 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset


\shape default
 , select 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{RC Circuit}
\end_layout

\end_inset


\shape default
 
\end_layout

\begin_layout Itemize
Click on 
\shape italic
0->5V STEP
\shape default
 and 
\shape italic
5->0V step
\shape default
 Buttons to plot the graphs
\end_layout

\begin_layout Itemize
Adjust the horizontal scale, if required, and repeat.
\end_layout

\begin_layout Itemize
Calculate RC time constant.
\end_layout

\begin_layout Itemize
Use CCS instead of OD1 to charge capacitor with constant current.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/RC-curves.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/cap-linear.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a)Transient response of RC circuit.
 (b) Charging of capacitor with constant current.
 
\begin_inset CommandInset label
LatexCommand label
name "fig:Transient-RC"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Applying a 0 to 5V step makes the voltage across the capacitor to rise exponenti
ally as shown in the figure
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Transient-RC"

\end_inset

(a).
 By fitting the discharge curve with 
\begin_inset Formula $V(t)=V_{0}e^{-\frac{t}{RC}}$
\end_inset

 ,we can extract the RC time constant and find the values of capacitance
 from it.
 
\end_layout

\begin_layout Standard
The voltage across a capacitor is exponential only when it is charged trough
 a linear element, a resistor for example.
 When charged from a constant current source, the voltage shows linear increase,
 as shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Transient-RC"

\end_inset

(b), because 
\begin_inset Formula $Q=It=CV$
\end_inset

 , and voltage increases linearly with time as 
\begin_inset Formula $V=\left(\frac{I}{C}\right)t$
\end_inset

 .
\end_layout

\begin_layout Section
Transient Response of RL circuits
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Explore the nature of current and voltage when a voltage step is applied
 to resistor and inductor in series.
 By measuring the voltage across the inductor as a function of time, we
 can calculate its inductance.
\end_layout

\begin_layout Standard
In an RL circuit 
\begin_inset Formula $V=IR+L\frac{dI}{dt}$
\end_inset

 and solving this will give 
\begin_inset Formula $I=I_{0}e^{-\frac{R}{L}t}$
\end_inset

.
 The coefficient of the exponential term R/L can be extracted from the graph
 of voltage across the inductor.
 The resistance of the inductor coil should be included in the calculations,
 
\begin_inset Formula $R=R_{ext}+R_{L}$
\end_inset

.
 
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/esc102/node14.html
\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/RLcircuit.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Inductor is the 3000 Turn coil
\end_layout

\begin_layout Itemize
From 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset


\shape default
 select 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{RL Circuit}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Click on 
\shape italic
0->5V STEP
\shape default
 and 
\shape italic
5->0V step
\shape default
 Buttons to plot the graphs
\end_layout

\begin_layout Itemize
Adjust the horizontal scale, if required, and repeat.
\end_layout

\begin_layout Itemize
Calculate the value of inductance
\end_layout

\begin_layout Itemize
Insert an iron core into the inductor and repeat
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/RL-curves.png
	lyxscale 40
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Transient response of RL circuit
\begin_inset CommandInset label
LatexCommand label
name "fig:Transient-RL"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
The transient response of the inductor is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Transient-RC"

\end_inset

.
 The exponential curve is fitted to extract the L/R value.
 The resistance of the coil is measured by comparing it with the known external
 resistance under DC conditions.
 IN1 is connected to OD1 for a more accurate measurement of the coil resistance.
\end_layout

\begin_layout Standard
The applied voltages are above zero, but the graph went to negative voltages.
 Why ?
\end_layout

\begin_layout Standard
What was the current before doing the 5->0 step ? What is back EMF ?
\end_layout

\begin_layout Standard
Repeat with two coils in series, by (a) placing them far away (b) placing
 one over the other and (c) after changing the orientation.
 The effect of mutual inductance can be seen.
\end_layout

\begin_layout Section
Transient response of LCR circuits
\begin_inset CommandInset label
LatexCommand label
name "sec:Step-Response-ofRLC"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Explore the oscillatory nature of L and C in series.
 Resonant frequency of series LC circuit is given by 
\begin_inset Formula $\omega_{0}=\frac{1}{2\pi\sqrt{LC}}$
\end_inset

.
 The damping factor is 
\begin_inset Formula $\frac{R}{2}\sqrt{\frac{C}{L}}$
\end_inset

, and it is equal to 1 for critical damping.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://en.wikiversity.org/wiki/RLC_circuit
\end_layout

\end_inset

 Depending upon the value of C/L and R, the response could be under-damped,
 critically-damped or over-damped.
 
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/RLC-curves.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/RLC-curve-damped.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Transient response of LCR circuit,(a)Under-damped (b)Over-damped.
\begin_inset CommandInset label
LatexCommand label
name "fig:LCR Transient-response"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/LCRcircuit.png
	height 0.8cm

\end_inset

 
\begin_inset Graphics
	filename schematics/LCRRcircuit.png
	height 0.7cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset


\shape default
 select
\shape italic
 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{RLC Discharge}
\end_layout

\end_inset


\shape default
 
\end_layout

\begin_layout Itemize
Click on 5->0V STEP.
 Adjust x-axis and repeat if required.
\end_layout

\begin_layout Itemize
FIT the graph to find the resonant frequency & Damping.
\end_layout

\begin_layout Itemize
Repeat the experiment with different values of L, C and R
\end_layout

\begin_layout Itemize
Repeat with a resistor in series.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
We have used the 3000 turn coil and a 0.1uF capacitor, added a 2.2k series
 resistor in the second case.
 The voltage across the capacitor after a 5 to 0V step is shown in figure
 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:LCR Transient-response"

\end_inset

 .The measured resonant frequency tallies with 
\begin_inset Formula $f=\frac{1}{2\pi}\sqrt{\frac{1}{LC}}$
\end_inset

 , within the component tolerance values.
\end_layout

\begin_layout Section
RC Integration & Differentiation 
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
RC circuits can integrate or differentiate a voltage waveform with respect
 to time.
 A square wave is integrated to get a triangular wave and differentiated
 to get spikes at the transitions.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/rc-integ.png
	height 0.8cm

\end_inset

 
\end_layout

\begin_layout Itemize
Set SQR2 to 1000Hz
\end_layout

\begin_layout Itemize
Assign SQR2 to CH1 and A1 to CH2
\end_layout

\begin_layout Itemize
Adjust the horizontal scale to view more than 4 cycles.
\end_layout

\begin_layout Itemize
Set SQR2 to 1kHz (T = 1mS) and other values and view the waveforms.
\end_layout

\begin_layout Itemize
Repeat the same for RC differentiator, at 100Hz.
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/rc-diff.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/rc-integ1khz.png
	lyxscale 50
	width 5cm

\end_inset


\begin_inset Graphics
	filename pics/rc-diff100Hz.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a)1kHz Squarewave after RC Integrator (b) 100Hz after RC Differentiator
\begin_inset CommandInset label
LatexCommand label
name "fig:RC-int-diff"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Integration observed at 1kHz and differentiation at 100Hz are shown in figure
 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:RC-int-diff"

\end_inset

, using an RC value of 1 milliseconds.
 When the time period becomes comparable with the RC value, the output waveform
 is triangular.
 The differentiation can only be shown at lower frequency since capturing
 the narrow spike requires a fast oscilloscope.
\end_layout

\begin_layout Section
Fourier Analysis
\begin_inset CommandInset label
LatexCommand label
name "sec:Fourier-Transform-**"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn about Fourier Transform of a signal.
 Time and Frequency domain representations.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/ftran.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Set SQR1 to 150Hz
\end_layout

\begin_layout Itemize
Assign A1 to CH1 and SQR1 to CH2
\end_layout

\begin_layout Itemize
Assign CH1 & CH2 to FT to view the Fourier transform
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/fft-sine147Hz.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/fft-sqr150Hz.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Frequency spectrum of (a)Sine wave.
 (b) Squarewave
\begin_inset CommandInset label
LatexCommand label
name "fig:Frequency-spectrum-of"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
In the Fourier transform plot, frequency is on the x-axis and the y-axis
 shows the relative strength of each frequency components of the signal.
 This is called the frequency domain representation
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://en.wikipedia.org/wiki/Fourier_transform
\end_layout

\end_inset

.
 For the sine wave there is only one dominant peak, the smaller ones are
 a measure of distortion of the sine wave.
 
\end_layout

\begin_layout Standard
A square wave function can be represented as 
\begin_inset Formula $f(\theta)=sin(\theta)+\frac{sin(3\theta)}{3}+\frac{sin(5\theta)}{5}+\cdots$
\end_inset

.
 In the Fourier transform of a square wave of frequency 
\begin_inset Formula $f$
\end_inset

 , there will be a 
\begin_inset Formula $3f$
\end_inset

 component (having an amplitude of one third of 
\begin_inset Formula $f$
\end_inset

 ), 
\begin_inset Formula $5f$
\end_inset

 component (amplitude one fifth) etc.
 as shown in the figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Frequency-spectrum-of"

\end_inset

(b).
 Note the peak at 0 Hz, due to the DC component.
\end_layout

\begin_layout Chapter
Electricity & Magnetism
\end_layout

\begin_layout Standard
Electromagnetic induction is demonstrated by dropping a magnet in to a coil.
 Working of transformer is demonstrated using two coils.
 A simple AC generator, capable of generating multi-phase output, is made
 using a rotating magnet.
\end_layout

\begin_layout Section
Electromagnetic induction
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Explore the voltage induced across a coil by a changing magnetic field,
 by dropping a small cylindrical magnet into a coil.
 Use a tube to guide the magnet through the coil.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/induction.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

open 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EM Induction}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Click on Start Scanning.
 A horizontal trace should appear
\end_layout

\begin_layout Itemize
Drop the magnet through the coil, until a trace is caught.
\end_layout

\begin_layout Itemize
Repeat the process by changing the parameters like magnet strength, speed
 etc.
\end_layout

\begin_layout Subsection*
Observation 
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/induction-screen.png
	lyxscale 40
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/transformer-screen.png
	lyxscale 40
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a)Voltage induced on a coil by a moving magnet.(b)Mutual Induction between
 two coils, the applied and induced voltages are shown 
\begin_inset CommandInset label
LatexCommand label
name "fig:Voltage-induced-on"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
The result is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Voltage-induced-on"

\end_inset

(a).
 The amplitude increases with the speed of the magnet.
 From the graph, we can find the time taken by the magnet to travel through
 the coil.
\end_layout

\begin_layout Standard
The second peak is bigger than the first peak.
 Why ? Where will be the magnet at the zero crossing of the induced voltage?
 Drop the magnet from different heights and plot the voltage vs square root
 of the height.
\end_layout

\begin_layout Section
Mutual induction, transformer
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Demonstrate mutual induction using two coils.
 One coil is powered by the SINE output.
 The axes of the coils are aligned and a ferrite core is inserted.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\align left
\begin_inset Graphics
	filename schematics/tran.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The applied waveform and the induced waveform are shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Voltage-induced-on"

\end_inset

(2).
 A changing magnetic filed is causing the induced voltage.
 In the previous two experiments, the changing magnetic field was created
 by the movement of permanent magnets.
 In the present case the changing magnetic field is created by a time varying
 current.
\end_layout

\begin_layout Standard
The output should have been in phase with the input as per the theory.
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://sound.westhost.com/xfmr.htm
\end_layout

\end_inset

However, this is not happening if the coupling is not enough.
 With more ferrite material, the phase shift is as expected from the theory.
 Try doing this experiment using a squarewave of 100 Hz, 1000 Hz etc.
 Connect a 1k
\begin_inset Formula $\Omega$
\end_inset

 resistor across secondary coil to reduce ringing.
\end_layout

\begin_layout Section
A simple AC generator
\begin_inset CommandInset label
LatexCommand label
name "sec:A-simple-AC"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Measure the frequency and amplitude of the voltage induced across a solenoid
 coil by a rotating magnet.
 Gain some understanding about the AC generators by looking at the output
 and the drawbacks of the setup.
 Use the 10 mm x 10 mm magnet and the 3000T coils that comes with the kit.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename schematics/ac-generator.png
	width 4cm

\end_inset

 
\begin_inset Graphics
	filename pics/ac-gen-screen.png
	lyxscale 40
	width 4cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Wiring schematic and voltage output of the AC generator, with coils placed
 on opposite sides of the rotating magnet.
\begin_inset CommandInset label
LatexCommand label
name "fig:AC generator output"

\end_inset

.
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
Mount the magnet horizontally and power the DC motor from a 1.5 volts cell
\end_layout

\begin_layout Itemize
Hold the coil perpendicular to the axis of rotation of the motor, close
 to the magnet.
 Be careful not to touch it.
\end_layout

\begin_layout Itemize
Assign A1 to CH1 & A2 to CH2
\end_layout

\begin_layout Itemize
Assign CH1 and CH2 to FIT
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The voltage output is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:AC generator output"

\end_inset

.
 The phase difference between the two voltages depends on the angle between
 the axes of the two coils.
\end_layout

\begin_layout Standard
Bring a shorted coil near the magnet to observe the change in frequency.
 The shorted coil is drawing energy from the generator and the speed get
 reduced.
 The magnetic field in this generator is very weak.
 The resistance of the coil is very high and trying to draw any current
 from it will drop most of the voltage across the coil itself.
 
\end_layout

\begin_layout Chapter
Electronics
\end_layout

\begin_layout Standard
The non-linear elements like diodes and transistors are studied by drawing
 their characteristic curves and making simple circuits to demonstrate their
 functioning.
 Photo-transistor is used for transparency measurements, optical signal
 transmission and for timing mechanical movements.
 Amplitude and Frequency modulation are explored.
 A bread board is required to carry out some of the experiments described
 in this section.
\end_layout

\begin_layout Section
Half wave rectifier, PN junction
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn the working of a PN junction diode.
 Making DC from a sinusoidal AC.
 Filtering to reduce the AC component.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/half-wave-screen.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/half-wave-filter-screen.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) Half wave rectifier input and output.(b) With capacitor filter.
\begin_inset CommandInset label
LatexCommand label
name "fig:Diode-rectifier"

\end_inset

 
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/half-wave.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Add different values of filter capacitors from A2 to ground 
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The negative half is removed by the diode as shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Diode-rectifier"

\end_inset

(a).
 Also notice that the voltage in the positive half is reduced by around
 0.7 volts, the voltage drop across a silicon diode.
 A load resistor is required for the proper operation of the circuit, it
 could be more than 1k
\begin_inset Formula $\Omega$
\end_inset

 but do NOT use very low values since our AC source can drive only up to
 5 mA current.
\end_layout

\begin_layout Standard
The effect of a capacitor is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Diode-rectifier"

\end_inset

(b).
 We can see that the capacitor charges up and then during the missing cycle
 it maintains the voltage.
 The remaining AC component is called the ripple in the DC.
\end_layout

\begin_layout Standard
Can we use very large capacitance to reduce the ripple ?
\end_layout

\begin_layout Standard
During what part of the cycle does current flow through the diode ?
\end_layout

\begin_layout Standard
Amount of peak current is decided by what ?
\end_layout

\begin_layout Section
180
\begin_inset Formula $^{\circ}$
\end_inset

out of phase sine waves
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
To demonstrate the working of a full-wave rectifier using two diodes, we
 need two AC waveforms, differing by 180 degree in phase.
 We do this by inverting the output of SINE using an inverting amplifier.
 The gain is made near unity by feeding the amplifier input through a 51k
\begin_inset Formula $\Omega$
\end_inset

 series resistor.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/ac-invert.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/full-wave.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a)Inverting Amplifier making 180
\begin_inset Formula $^{\circ}$
\end_inset

out of phase sine wave.(b)Fullwave rectifier, two inputs and the output.
\begin_inset CommandInset label
LatexCommand label
name "fig:Inverting-Amplifier-making"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/ac-invert.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Right-click on CH1 to measure phase difference
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The result is shown in the figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Inverting-Amplifier-making"

\end_inset

.
 The amplitudes are not exactly equal.
 The gain is given by 
\begin_inset Formula $G=\frac{51000}{51000+1000}$
\end_inset

.
 
\end_layout

\begin_layout Section
Fullwave rectifier
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Make a full wave rectifier, using two diodes.
 Two AC waveforms, differing by 180 degree in phase as required, are made
 as described in the previous section.
 The rectified output is connected to the third channel.
 
\end_layout

\begin_layout Subsection*
Procedure 
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/full-wave.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
Assign A1 to CH1, A2 to CH2 and IN1 to CH3
\end_layout

\begin_layout Itemize
Add Capacitor from IN1 to ground , for filtering.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The result is shown in the figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Inverting-Amplifier-making"

\end_inset

.
 Adding capacitors to reduce the ripple is left as an exercise to the user.
 This experiment is only to demonstrate the working of a full wave rectifier,
 it cannot provide more than few milli amperes of current.
 
\end_layout

\begin_layout Standard
Why full-wave rectifier is superior to half-wave rectifier ?
\end_layout

\begin_layout Section
Diode I-V characteristic
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Draw the I-V Characteristic of diode and compare the result with the theory.
 The IV characteristic of an ideal PN junction diode is given by equation
 
\begin_inset Formula $I=I_{0}\left(e^{\frac{qV}{kT}}-1\right)$
\end_inset

, where 
\begin_inset Formula $I_{0}$
\end_inset

 is the reverse saturation current, 
\begin_inset Formula $q$
\end_inset

 the charge of electron, 
\begin_inset Formula $k$
\end_inset

 the Boltzmann constant, 
\begin_inset Formula $T$
\end_inset

 the temperature in Kelvin.
 For a practical, non-ideal, diode, the equation is 
\begin_inset Formula $I=I_{0}\left(e^{\frac{qV}{nkT}}-1\right)$
\end_inset

, where 
\begin_inset Formula $n$
\end_inset

 is the ideality factor, that is 
\begin_inset Formula $1$
\end_inset

 for an ideal diode.
 For practical diodes it varies from 1 to 2.
 We have used a IN4148 silicon diode.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\align left
\begin_inset Graphics
	filename schematics/diode-iv.png
	width 3cm

\end_inset

 
\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 select 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Diode IV}
\end_layout

\end_inset

 .
\end_layout

\begin_layout Itemize
Click on START to draw the characteristic curve.
\end_layout

\begin_layout Itemize
Click on FIT to calculate the Diode Ideality factor.
\end_layout

\begin_layout Itemize
Plot the IV of LEDs
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/diode-iv-screen.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/led-iv-screen.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
I-V characteristic of (a) Silicon diode (b) several LEDs
\begin_inset CommandInset label
LatexCommand label
name "fig:I-V-characteristic-of"

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
The curves obtained are shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:I-V-characteristic-of"

\end_inset

(a).
 The value of n for 1N4148 is around 2.
 We have calculated the value of 
\begin_inset Formula $n$
\end_inset

 by fitting the experimental data with the equation
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
If the FIT is not successful, transfer data to 
\shape italic
xmGrace
\shape default
 and use the option Data->Transformations->Nonlinear curve fitting with
 equation y=a0*exp(a1*x).
 
\end_layout

\end_inset

.
 Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:I-V-characteristic-of"

\end_inset

(b) shows the IV curves of few LEDs, of different wavelengths.
 
\end_layout

\begin_layout Standard
The voltage at which LED starts emitting light depends on its wavelength
 and Planck's constant.
 Energy of a photon is given by 
\begin_inset Formula $E=h\nu=hc/\lambda$
\end_inset

 .
 This energy is equal to the energy of an electron that overcomes the junction
 barrier and is given by 
\begin_inset Formula $E=eV_{0}$
\end_inset

.
 So Planck's constant 
\begin_inset Formula $h=eV_{0}\lambda/c$
\end_inset

 , where 
\begin_inset Formula $\lambda$
\end_inset

 is the wavelength of light from the LED, 
\begin_inset Formula $e$
\end_inset

 the charge of electron and 
\begin_inset Formula $c$
\end_inset

 the velocity of light.
 
\end_layout

\begin_layout Standard
Repeat the experiment by heating the diode to different temperatures.
\end_layout

\begin_layout Section
Transistor CE characteristic
\begin_inset CommandInset label
LatexCommand label
name "sec:Transistor-CE-Characteristic"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Plot the CE characteristic curve of a transistor.
 Collector is connected to PVS through a 1K resistor.
 The base voltage is obtained by filtering a variable duty cycle pulse from
 SQR1.
 Base current is decided by this voltage and the 200
\begin_inset Formula $k\Omega$
\end_inset

 series resistor.
 For better results use an external DC supply (1.5V cell will do) for base
 voltage.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename schematics/transistor-ce.png
	width 4cm

\end_inset

 
\begin_inset Graphics
	filename pics/transistor-ce.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Transistor common emitter characteristics
\begin_inset CommandInset label
LatexCommand label
name "fig:Transistor-common-emitter"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 open 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Transistor CE}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Enter the Bias supply voltage to the base and START.
 Repeat for different Vb.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The characteristic curves for different base currents are shown in figure
 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Transistor-common-emitter"

\end_inset

.
 The collector current is obtained from the voltage difference across the
 1k resistor.
 
\end_layout

\begin_layout Standard
The base current is set by setting the voltage at one end of the 200 k
\begin_inset Formula $\Omega$
\end_inset

 resistor, the other end is connected to the transistor base.
 The value of base current is calculated by, 
\begin_inset Formula $I_{b}=\frac{V_{bias}-0.6}{200\times10^{3}}\times10^{6}\mu A$
\end_inset


\end_layout

\begin_layout Section
Transmission of Light, Photo-transistor 
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Measure the transmission of light through semi-transparent material using
 a photo-transistor.
 The material is kept between an LED and the photo-transistor.
 The collector current depends on the amount of light falling on the transistor.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/light-tranmission.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Set SQR1 to 0 Hz, to turn on the LED
\end_layout

\begin_layout Itemize
Assign SEN to CH1
\end_layout

\begin_layout Itemize
Measure voltage at SEN, by clicking on it.
\end_layout

\begin_layout Itemize
Repeat by changing the material between LED and photo-transistor.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The voltage at the collector of the photo-transistor reduces with the intensity
 of light falling on the transistor.
 The voltage measured after placing a piece of paper between LED and photo-trans
istor is shown in figure
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Phototransistor output"

\end_inset

(a).
\end_layout

\begin_layout Section
Opto-electric signal transmission 
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Demonstrate the transmission of signals using light.
 An LED is powered by a 1kHz signal and the light is made to fall on a photo-tra
nsistor.
 The SEN input is internally connected to 5 volts through a 5.1k resistor.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/opto-electric.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Keep the LED facing the photo-transistor and set SQR1 to 1000Hz
\end_layout

\begin_layout Itemize
Assign SQR1 to CH1 and SEN to CH2
\end_layout

\begin_layout Itemize
Repeat the experiment by changing the frequency.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/light-transmission.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/opto-electric-transmission.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) Voltage at the photo-transistor with light passing through a piece of
 paper.
 (b) Pulse transmission, voltage driving the LED and the voltage across
 the photo-transistor.
 
\begin_inset CommandInset label
LatexCommand label
name "fig:Phototransistor output"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
The output of the photo-transistor at 1kHz is shown in figure
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Phototransistor output"

\end_inset

.
 The square trace is the voltage across the LED.
 When the LED is ON, photo-transistor conducts and the voltage across the
 collector drops to .2 volts.
 When the LED is OFF the photo-transistor goes into cut off mode and the
 collector shows almost the supply voltage.
 The rise and fall times of the photo-transistor seem to be different.
\end_layout

\begin_layout Standard
Repeat this experiment with a Fiber Optic cable to guide the light from
 LED to the photo-transistor.
\end_layout

\begin_layout Section
IC555 Oscillator
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Make an astable multivibrator using IC555 and measure its frequency and
 duty cycle.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
Set OD1 to HIGH, to power IC555
\end_layout

\begin_layout Itemize
Assign IN1 to CH1 and enable FIT on CH1
\end_layout

\begin_layout Itemize
Right-click on IN1 to measure frequency and duty cycle.
\end_layout

\begin_layout Itemize
Repeat by changing the value of R1
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename schematics/osc555.png
	width 5cm

\end_inset


\begin_inset Graphics
	filename pics/ic555-screen.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
IC555 astable multi-vibrator.
 (a) schematic (b) Output waveform
\begin_inset CommandInset label
LatexCommand label
name "fig:IC555-astable-multi-vibrator."

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
IC555 Monostable multivibrator
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Make a monostable multi-vibrator using IC555 and measure the time delay,
 at different RC values.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
Set SQR2 to 0 Hz (to set it to 5V DC)
\end_layout

\begin_layout Itemize
Enter 
\shape italic
set_pulsewidth(1)
\shape default
 in the command window
\end_layout

\begin_layout Itemize
Assign LTP (Low True Pulse) to OD1, trigger input for 555
\end_layout

\begin_layout Itemize
Assign IN1 to CH1 , watch it by varying R1
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename schematics/mono555.png
	lyxscale 80
	width 5cm

\end_inset


\begin_inset Graphics
	filename pics/mono555-screen.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
IC555 monostable multi-vibrator.
 (a) schematic (b) Output waveform
\begin_inset CommandInset label
LatexCommand label
name "fig:IC555-astable-multi-vibrator.-1"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Logic gates
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Study of logic gates using two square waves with a phase difference, using
 TTL logic ICs 7408 and 7432.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/and-gate.png
	height 1cm

\end_inset

 
\begin_inset Graphics
	filename schematics/or-gate.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
Assign SQR1 to CH1, SQR2 CH2 and IN1 to CH3
\end_layout

\begin_layout Itemize
Set 100Hz, 25% and enable BOTH.
 (SQR1 & SQR2)
\end_layout

\begin_layout Itemize
Check OD1, to power the TTL AND gate 7408
\end_layout

\begin_layout Itemize
Repeat using the OR gate, 7432
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/and-gate.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/or-gate.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Operation of logic gates with square wave inputs.(a)AND gate (b) OR gate
\begin_inset CommandInset label
LatexCommand label
name "fig:Operation-of-logic"

\end_inset

 
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Clock Divider
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Study of a clock divider, using a D flip-flop (TTL family, 7474).
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/clock-divider.png
	height 1.5cm

\end_inset


\end_layout

\begin_layout Itemize
Set SQR1 to 500 Hz.
 Assign SQR1 to CH1 and IN1 to CH2
\end_layout

\begin_layout Itemize
Check OD1, to power the flipflop
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The output toggles at every rising edge of the input, resulting in a division
 of frequency by two.
 The output is a symmetric squarewave, irrespective of the duty cycle of
 the input pulse.
 The HIGH output of the TTL IC is around 4 volts only.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/clock-divider.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/clock-divider2.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
A clock divider circuit, using a D-flipflop.
 Outputs for two different types of input are shown
\begin_inset CommandInset label
LatexCommand label
name "fig:A-clock-divider-1"

\end_inset

 
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Non-inverting Amplifier
\begin_inset CommandInset label
LatexCommand label
name "sec:Non-inverting-Amplifier"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Make a non-inverting amplifier, using op-amp OP27, and measure the gain.
 The gain and input should be chosen such that the output is in the 0 to
 5 volts range, otherwise the device will malfunction.
 The op-amp is powered by an external 
\begin_inset Formula $\pm9V$
\end_inset

 supply.
 A series resistor is added to prevent any damage to expEYES from over voltage.
 This circuit will be useful while measuring temperature using PT100 and
 expEYES.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/amp-test.png
	height 1.5cm

\end_inset


\end_layout

\begin_layout Itemize
To find out the offset, Ground the amplifier input and measure the output.
 
\end_layout

\begin_layout Itemize
Set PVS to to .1 volts and Click on IN1 for the output voltage
\end_layout

\begin_layout Itemize
Repeat it for several input voltages
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="2" columns="6">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $Ri$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $Rf$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $1+\frac{Rf}{Ri}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $Vin$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $Vout$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\frac{Vout}{Vin}$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1k
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
10k
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
11
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1.105
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
11.05
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Section
Amplitude & Frequency Modulation
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Study amplitude and frequency modulation of a signal.
 Analyse the AM output mathematically to see the sidebands.
 This experiment requires some source of modulated waveform, we have used
 the PHOENIX Analog Box.
\end_layout

\begin_layout Standard
Phoenix Analog Box has a sine wave generator (around 100 Hz) whose amplitude
 can be controlled using a DC control voltage.
 It also has a 4kHz sine wave generator with AM and FM control inputs.
 Use PVS to change the depth of modulation by changing the amplitude of
 the 100Hz sine wave.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/am.png
	height 1cm

\end_inset


\end_layout

\begin_layout Itemize
Connect Analog Box and expEYES grounds.
\end_layout

\begin_layout Itemize
Assign A1 to CH1 and A2 to CH2
\end_layout

\begin_layout Itemize
Capture 900 samples with 20 microsecond interval
\end_layout

\begin_layout Itemize
De-select A2 and capture with 1800 samples 
\end_layout

\begin_layout Itemize
Click on Power Spectrum to do a Fourier transform
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/am-screen.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/am-ftran.png
	lyxscale 50
	width 4.6cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Modulated wave and its Fourier Spectrum.
\begin_inset CommandInset label
LatexCommand label
name "fig:Amplitude-modulation"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
A carrier signal having a frequency of around 4kHz is modulated by a sinewave
 of around 100Hz.
 A small portion of the output (400 points with 20 usec gap) along with
 the modulating signal is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Amplitude-modulation"

\end_inset

(b).
 Power spectrum is calculated using Fourier transform.
 To get better results a larger sample (1800 samples with 50 usec gap) is
 taken for this purpose.
 The two sidebands are clearly obtained on both sides of the carrier peak,
 separated by the modulating frequency.
\end_layout

\begin_layout Standard
The AM output looks similar to the sound beats we obtained in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Interference-of-sound"

\end_inset

, but taking a power spectrum of beats gives two peaks corresponding to
 the individual frequencies.
 How do they differ despite of the similar looks ?
\end_layout

\begin_layout Standard
Doing frequency modulation, just changing the connection from AM to FM,
 is left as an exercise to the user.
\end_layout

\begin_layout Chapter
Sound
\end_layout

\begin_layout Standard
Pressure variations, about an equilibrium pressure, transmitted through
 a medium is called sound.
 They are longitudinal waves.
 Moving a sheet of paper back and forth in air can generate these kind of
 pressure waves, like the paper cone of a loudspeaker.
 When the frequency is within 20 to 20000Hz range, we can hear the sound.
 In this chapter, we will generate sound from electrical signals, detect
 them using the built-in microphone (a pressure sensor) and study the properties
 like amplitude and frequency.
 Velocity of sound is measured by observing the phase shift of digitized
 sound with distance.
\end_layout

\begin_layout Section
Frequency of sound
\begin_inset CommandInset label
LatexCommand label
name "sec:Sound Frequency"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Digitize sound and measure its frequency.
 Use the Piezo buzzer or any other source of sound like a tuning fork.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/sound.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
Set SQR1 around 3500Hz, keep buzzer in front of the microphone
\end_layout

\begin_layout Itemize
Enable FIT to measure the frequency
\end_layout

\begin_layout Itemize
Repeat with other sources of sound
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The amplified output of the microphone is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Digitized-sound"

\end_inset

(a).
 The amplitude is maximum near 3500 Hz, due to resonance.
 Driving with 1200Hz gives more amplitude than 2000Hz, due to the third
 harmonic of the square wave matching the resonant frequency.
\end_layout

\begin_layout Standard
Sound waves create pressure variations in the medium through which it travel.
 The microphone generates a voltage proportional to the pressure.
 Since this signal is very small, we amplify it 51 times before digitizing
 it.
 The voltage variations are in tune with the pressure variations.
 You can consider the microphone as a pressure sensor, but working only
 for time varying pressures.
 
\end_layout

\begin_layout Section
Frequency response of Piezo
\begin_inset CommandInset label
LatexCommand label
name "sec:Resonance-frequency-of"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Plot the frequency response curve of the Piezo disk by scanning through
 the frequency and measuring the amplitude of the microphone output.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/sound-frequency.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/piezo-freq-resp.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) Digitized sound wave (b)Frequency response curve of the Piezo disc
\begin_inset CommandInset label
LatexCommand label
name "fig:Digitized-sound"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/sound.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 select 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Frequency Response}
\end_layout

\end_inset

 
\end_layout

\begin_layout Itemize
Press START button
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The Frequency Vs Amplitude plot is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Digitized-sound"

\end_inset

(b).
 The amplitude is maximum around 3700 Hz.
\end_layout

\begin_layout Section
Velocity of sound
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Calculate the velocity of sound by measuring the pressure variation with
 distance.
 Sound travels as a series of compressions and rarefactions.
 Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Sound-waves"

\end_inset

(a) shows the High and Low pressure regions along the direction of travel,
 along with output of a pressure sensor at corresponding positions.
\end_layout

\begin_layout Standard
We can display the pressure variation at any point with respect to the variation
 at the starting point.
 The phase of the microphone output changes as you change its distance from
 the Piezo.
 Moving by one wavelength changes the phase by 360 degrees.
 If the phase changes by 
\begin_inset Formula $X$
\end_inset

 degrees for 
\begin_inset Formula $\triangle D$
\end_inset

 cm change in distance, the wavelength is given by 
\begin_inset Formula $\lambda=\frac{360\times\triangle D}{X}$
\end_inset

 .
 The velocity of sound can be calculated by multiplying the frequency with
 this.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/sound_waves.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/velocity-sound.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a)Propagation of sound waves, variation of microphone output with pressure.
 (b) Output of microphone
\begin_inset CommandInset label
LatexCommand label
name "fig:Sound-waves"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/sound.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 start 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Velocity of Sound}
\end_layout

\end_inset

 
\end_layout

\begin_layout Itemize
Set frequency to resonant maximum by measuring the frequency response 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Resonance-frequency-of"

\end_inset


\end_layout

\begin_layout Itemize
Keep the Piezo facing the microphone, on the same axis
\end_layout

\begin_layout Itemize
Measure Phase difference at different distances.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
At 3500 Hz, for a 2 cm change in distance the phase changed from 176 to
 102.
 Using the equation, 
\begin_inset Formula $v=f\times\frac{360\times\triangle D}{X}=3500\times\frac{360\times2}{(176-102)}=34054$
\end_inset

 cm/sec.
 It is important to keep the mic and the Piezo disc on the same axis, for
 accurate results.
\end_layout

\begin_layout Section
Interference of sound 
\begin_inset CommandInset label
LatexCommand label
name "sec:Interference-of-sound"

\end_inset


\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Study the interference of sound from two individual sources.
 Two Piezo buzzers are powered by two different sources, and the sound is
 directed towards the microphone.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/inter-sound.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/beats-ftran.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) Sum of sound having two nearby frequencies (b) Fourier transform showing
 the frequency components.
\begin_inset CommandInset label
LatexCommand label
name "fig:SoundBeats"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/sound-inter.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 start 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Interference of Sound}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Set SQR1 to 3500 Hz and SQR2 to 3600 Hz
\end_layout

\begin_layout Itemize
Adjust positions of Piezo buzzers, from the mic, to get clear beat pattern.
\end_layout

\begin_layout Itemize
Repeat with other values of frequencies.
\end_layout

\begin_layout Itemize
Capture with NC=1800 and take Fourier Transform
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
From figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:SoundBeats"

\end_inset

(a) it can be seen how the low frequency envelope is created.
 Distance between two minimum pressure points., of the envelope, corresponds
 to the beat wavelength.
 The Fourier transform of the output is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:SoundBeats"

\end_inset

.
\end_layout

\begin_layout Section
Forced Oscillations of Piezo-electric crystal
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Study the behavior of a Piezo-electric disc at low excitation frequencies,
 using a square wave.
 
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/sound.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 open 
\shape italic

\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Interference of Sound}
\end_layout

\end_inset


\end_layout

\begin_layout Itemize
Tick only SQR1, set it to 100 
\end_layout

\begin_layout Itemize
Press START to capture mic output
\end_layout

\begin_layout Itemize
Try different frequencies
\end_layout

\begin_layout Itemize
Capture with larger NS (<=1800) for doing Fourier transform.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The resonant frequency of the Piezo crystal is around 3600 Hz.
 Driven by a square wave, the piezo gets a kick on every rising and falling
 edge, and it undergoes several cycles of oscillations at its natural resonant
 frequency.
 The Fourier transform shows a peak at the resonant frequency and side band
 200 Hz separated from the peak.
 It may be interesting to repeat this study using a variable frequency sine
 wave instead of the square wave.
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/piezo-drive100Hz.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/piezo-drive100hz-fft.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Sound output from Piezo, driven by 100Hz square wave and the Fourier transform
 of the output.
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Capturing a burst of sound
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Digitize sound from a transient source.
 A bell or two metal plates can be used as source of sound.
 The capturing of sound is synchronized with the burst of sound by waiting
 for microphone output to go above a threshold.
 A better way is to make IN1 go HIGH with the sound and the capture routine
 waiting for that.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/sound-burst.png
	height 1.2cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 select 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Capture Burst of Sound}
\end_layout

\end_inset

 
\end_layout

\begin_layout Itemize
Check Wait on HIGH, if the diode and resistor are wired.
\end_layout

\begin_layout Itemize
Click on 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Start Scanning}
\end_layout

\end_inset

 and make the sound.
 
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
A burst of sound captured is shown below.
\end_layout

\begin_layout Standard
\align center
\begin_inset Graphics
	filename pics/sound-burst.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Chapter
Mechanics, Optics & Heat
\end_layout

\begin_layout Standard
Resonance phenomena is studied using a driven pendulum.
 Value of acceleration due to gravity is measured using a pendulum.
 Cooling of a liquid is studied using a PT100 sensor.
\end_layout

\begin_layout Section
Resonance of a driven pendulum
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Demonstrate the resonance of a driven pendulum.
 .
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
Make a pendulum using two button magnets and a piece of paper.
 Suspend it and place the 3000T coil near that.
 Connect the coil between SQR1 and ground
\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 select 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Driven Pendulum}
\end_layout

\end_inset

 
\end_layout

\begin_layout Itemize
Scan the frequency upwards starting from 1Hz, very slowly.
 
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
When SQR1 reaches the resonant frequency of the pendulum, the amplitude
 goes up due to resonance.
 A 4 cm (from the center of the magnet to the axis of oscillation) long
 pendulum resonated at around 2.5 Hz, almost tallying with its calculated
 natural frequency.
 The resonant frequency of the pendulum is given by 
\begin_inset Formula $f=\frac{1}{2\pi}\sqrt{\frac{g}{\ell}}$
\end_inset

, where 
\begin_inset Formula $\ell$
\end_inset

 is the distance from the center of the magnet to the point of suspension
 and 
\begin_inset Formula $g$
\end_inset

 is the acceleration due to gravity.
 
\end_layout

\begin_layout Standard
Repeat the experiment by changing the length of the pendulum.
 
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
SQR1 cannot go below 0.7 Hz
\end_layout

\end_inset


\end_layout

\begin_layout Section
Value of 'g', Rod pendulum
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Measure the period of oscillations of a rod pendulum using a light barrier
 and calculate the value of acceleration due to gravity.
 Period of oscillation of a uniform rod about one end is given by 
\begin_inset Formula $T=2\pi\sqrt{\frac{2\ell}{3g}}$
\end_inset

, where 
\begin_inset Formula $\ell$
\end_inset

 is the length and 
\begin_inset Formula $g$
\end_inset

 is the acceleration due to gravity.
 The pendulum (T-shaped, a knife edge attached to a 6mm dia rod) is made
 to swing between an LED and photo-transistor, connected to expEYES.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/light-barrier.png
	height 1.5cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 Start 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Rod Pendulum}
\end_layout

\end_inset

 
\end_layout

\begin_layout Itemize
Oscillate the pendulum and click on START
\end_layout

\begin_layout Itemize
Repeat with different pendulum lengths.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The time period is measured 50 times, using a 14.6cm rod pendulum, and the
 average value is 0.627 seconds.
 The calculated value of 'g' is 977.4 
\begin_inset Formula $cm/sec^{2}$
\end_inset

, slightly different from the actual value due to the following reasons.
 The length is measured from the knife edge to the bottom and used in the
 formula.
 But there is a small mass projecting above the knife edge that is not included
 in the calculation.
 Another reason is that the pendulum may not be exactly vertical in the
 resting position.
\end_layout

\begin_layout Section
Oscillations of a pendulum
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
To study the nature of oscillations of a pendulum.
 An angle encoder is required for measuring the angular displacement as
 a function of time.
 But using a DC motor as a sensor, we can measure the angular velocity as
 a function of time.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
Attach some sort of rigid pendulum to the axis of the motor.
\end_layout

\begin_layout Itemize
Connect the motor between IN and GND
\end_layout

\begin_layout Itemize
Connect OUT to A1
\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 start 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Pendulum Waveform}
\end_layout

\end_inset

.
\end_layout

\begin_layout Itemize
Oscillate the pendulum and START digitizing
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The observed waveform is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Cooling-curve-of"

\end_inset

(a).
 Fitting it with equation 
\begin_inset Formula $A=A_{0}sin\left(\omega t+\theta\right)*\exp\left(-dt\right)+C$
\end_inset

, using Grace gave an angular frequency of 10 Hz.
\end_layout

\begin_layout Standard
The pendulum should be made with a heavy bob and a light weight rod connecting
 it to the axis of the motor.
 The DC motor acts like a generator in this case.
\end_layout

\begin_layout Section
Temperature measurement, PT100
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Record the temperature of a liquid by using a Platinum Resistance Thermometer.
 Resistance of a PT100 element is related to the temperature by the equation
 
\begin_inset Formula $R_{T}=R_{0}\left[1+AT+BT^{2}\right]$
\end_inset

, where 
\begin_inset Formula $A=3.9083e-3$
\end_inset

 and 
\begin_inset Formula $B=-5.775e-7$
\end_inset

.
 
\end_layout

\begin_layout Standard
This require a low offset non-inverting amplifier, so that we can use 0
 to 5V input IN1.
 Since that is not available on expEYES Junior, we use the inverting amplifier,
 after reducing its gain by an input series resistance, and connecting the
 output to A1.
 The accuracy is not very good in this case but temperature variations can
 be studied.
 
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
To measure the resistance of the PT100 element, we connect it from the CCS
 to ground and measure the voltage across it.
 The actual current of CCS should be measured as explained in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Calibrating-Current-Source"

\end_inset

.
 
\end_layout

\begin_layout Standard
\align left
\begin_inset Graphics
	filename schematics/pt100.png
	height 0.8cm

\end_inset


\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 start 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{PT100 Sensor}
\end_layout

\end_inset

.
 
\end_layout

\begin_layout Itemize
Enter the measured current value.
 
\end_layout

\begin_layout Itemize
Select the required parameters and press START 
\begin_inset Foot
status open

\begin_layout Plain Layout
 The resistance of PT100 is
\begin_inset Formula $100\Omega$
\end_inset

 at 
\begin_inset Formula $0^{0}C$
\end_inset

 .
 It changes nearly 
\begin_inset Formula $0.4\Omega/C$
\end_inset

 , changing the voltage by 0.4 milli volts.
 The 12 bit ADC output changes by 1 LSB for 1.22 mV change in input voltage,
 hence any temperature change less than 3 degrees will not be detected.
 Use an external non-inverting amplifier to increase the resolution.
 The gain of the amplifier should be such that the maximum temperature measured
 should give an output less than 5 volts.
 Change the gain field entry accordingly.
\end_layout

\end_inset


\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/pendulum-screen.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/cooling-curve.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) Oscillations of a pendulum.
 (b)Cooling curve of water
\begin_inset CommandInset label
LatexCommand label
name "fig:Cooling-curve-of"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Cooling curve of water is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Cooling-curve-of"

\end_inset

.
 The temperature is changing in big steps, this can be improved by using
 an amplifier between CCS and IN1, as explained in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Non-inverting-Amplifier"

\end_inset

.
\end_layout

\begin_layout Standard
Instead of measuring the current and calculating the actual amplifier gain,
 one can follow a calibration procedure to obtain good results.
 This procedure assumes a linear variation of resistance with temperature.
 To do calibration, place the sensor in ice and click on 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Freezing Point}
\end_layout

\end_inset

.
 Immerse the sensor in boiling water and click on 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Boiling Point}
\end_layout

\end_inset

.
 After that click on 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Calibrate}
\end_layout

\end_inset

.
 Once the calibration is done the temperature is calculated using the calibratio
n constants.
\end_layout

\begin_layout Section
Stroboscope
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
An object executing periodic motion will appear stationary when it is illuminate
d with a light pulse of the same frequency, since the object is illuminated
 every time only when it reaches the same point.
 If the frequencies are slightly different, it will appear to move with
 the difference in frequency.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Itemize
From 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{EXPERIMENTS}
\end_layout

\end_inset

 select 
\begin_inset ERT
status open

\begin_layout Plain Layout


\backslash
menuitem{Stroboscope}
\end_layout

\end_inset

 
\end_layout

\begin_layout Itemize
Connect the White LED from SQR1 to GND
\end_layout

\begin_layout Itemize
Power the motor by a battery and illuminate it with the LED
\end_layout

\begin_layout Itemize
Adjust SQR1 to make the motor appear stationary.
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
As you adjust SQR2, the movement of the disc on the axis of the motor appears
 to slow down and then at some point reverses the direction of motion.
 Note down the frequency at the direction reversal.
\end_layout

\begin_layout Standard
When viewed in a pulsed light source of frequency 11 Hz, a motor rotating
 clockwise at 10 rotations per second will look like rotating anti-clockwise
 once a second.
 During stopping and starting, the ceiling fans sometimes looks like rotating
 backwards, in the light of fluorescent tubes.
\end_layout

\begin_layout Standard
How is the RPM of a car engine adjusted ?
\end_layout

\begin_layout Section
Speed of rotation of a motor
\end_layout

\begin_layout Subsection*
Objective
\end_layout

\begin_layout Standard
Learn about making sensors to detect mechanical movements.
 Use a photo-transistor to find the rotational speed of a motor.
\end_layout

\begin_layout Subsection*
Procedure
\end_layout

\begin_layout Standard
A single leaf is attached to the motor and it is placed between the photo-transi
stor and the LED, intercepting the light once during every rotation.
\end_layout

\begin_layout Standard
\begin_inset Graphics
	filename schematics/motor-rpm.png
	height 1.5cm

\end_inset


\end_layout

\begin_layout Itemize
Set SQR2 to 100Hz, to rotate the motor
\end_layout

\begin_layout Itemize
Assign SEN to CH1
\end_layout

\begin_layout Itemize
Right Click on SEN to measure the frequency (FIT option may not work for
 these pulses)
\end_layout

\begin_layout Subsection*
Observation
\end_layout

\begin_layout Standard
The photo-transistor output shown spikes when the light is obstructed.
 The observed values can be cross checked by using a magnet and coil as
 explained in section 
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:A-simple-AC"

\end_inset

.
\end_layout

\begin_layout Chapter
Coding expEYES in Python
\end_layout

\begin_layout Standard
The GUI programs described in the previous sections are meant for a fixed
 set of experiments.
 To develop new experiments, one should know how to access the features
 of expEYES Junior from software.
 Important function calls used for communicating with the device is given
 below.
 For more details, refer to the 
\emph on
Programmer's manual
\emph default
.
\end_layout

\begin_layout Section
Installing the Python Libraries
\end_layout

\begin_layout Standard
The expEYES Junior package consists of three files (eyesj.py, eyeplot.py and
 eyemath.py) inside a subdirectory named expeyes.
 This subdirectory should be inside your PYTHON LIBRARY PATH ( or inside
 your working directory).
 On Debian based GNU/Linux systems, this will be done by installing the
 expeyes-3.x.x.deb file.
 On other systems unzip the file expeyes-3.x.x.zip and follow the instructions
 in the README file.
\end_layout

\begin_layout Section
Start Communicating
\end_layout

\begin_layout Paragraph*
Channel Numbers
\end_layout

\begin_layout Standard

\emph on
A channel number is assigned to identify every Analog/Digital signal, as
 given in table 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Channel-numbers-of"

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="14" columns="2">
<features tabularvalignment="middle">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Channel #
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Name
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Analog Comparator output
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
A1
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
A2
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
IN1
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
4
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
IN2
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
5
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SEN
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
6
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SQR1 readback
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
7
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SQR2 readback
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
8
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SQR1 output
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
9
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
SQR1 output
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
10
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
OD1 output
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
11
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
CCS output control
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
12
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
PVS Readback
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Channel numbers of Input/Output terminals
\begin_inset CommandInset label
LatexCommand label
name "tab:Channel-numbers-of"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Start the Python Interpreter (from the directory where you have the expeyes
 subdirectory), by the command;
\end_layout

\begin_layout LyX-Code
$python
\end_layout

\begin_layout LyX-Code
Python 2.7.3 (default, Apr 20 2012, 22:44:07)  
\end_layout

\begin_layout LyX-Code
>>>
\end_layout

\begin_layout Standard
The triple angle bracket implies that you using Python in the interactive
 mode.
 Type the following two lines to load the library and establish connection
 to the device.
\end_layout

\begin_layout LyX-Code
>>>import expeyes.eyesj
\end_layout

\begin_layout LyX-Code
>>>p=expeyes.eyesj.open()
\end_layout

\begin_layout Standard
If you get an error message, check the connections, and other programs already
 using expEYES.
 Only one program can use expEYES at a time.
 We will start by measuring the stray capacitance of the socket IN1:
\end_layout

\begin_layout LyX-Code
>>>p.measure_cap()   # measure C on IN1
\end_layout

\begin_layout Standard
A value of 30 to 35 pF will be printed.
 Connect a capacitor (smaller than 0.01 uF) from IN1 to GND and repeat the
 command.
 Subtract the stray capacitance from the values obtained.
 
\end_layout

\begin_layout Standard
Digital Input/Output features are available.
 To test them, connect OD1 to IN1 using a piece of wire and try the following:
\end_layout

\begin_layout LyX-Code
>>>print p.get_state(3)    # status of IN1
\end_layout

\begin_layout LyX-Code
>>>p.set_state(10,1)       # make OD1 logic high
\end_layout

\begin_layout LyX-Code
>>>print p.get_state(3)    # new status of IN1
\end_layout

\begin_layout Standard
For the second call, get_state(3) should print 1.
 
\end_layout

\begin_layout Standard
Now let us start generating/measuring voltage signals.
 Connect PVS to IN1 and try:
\end_layout

\begin_layout LyX-Code
>>>print p.set_voltage(2.5) # returns the value set 
\end_layout

\begin_layout LyX-Code
>>>print p.get_voltage(3)   # channel 3 is IN1
\end_layout

\begin_layout Standard
It should print 2.5 volts, within 2-3 millivolts.
\end_layout

\begin_layout Standard
Now connect SINE to A1 and try:
\end_layout

\begin_layout LyX-Code
>>>print p.get_voltage(1)
\end_layout

\begin_layout Standard
You will get different results every time you issue the command
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
use up arrows to edit previous commands
\end_layout

\end_inset

.
 It makes better sense to measure this voltage for some duration and plot
 it.
 We will import the matplotlib library for plotting, capture the sine wave
 and plot it.
\end_layout

\begin_layout LyX-Code
>>>from pylab import *
\end_layout

\begin_layout LyX-Code
>>>ion()   # set pylab interactive mode
\end_layout

\begin_layout LyX-Code
>>>t,v = p.capture(1,300,100) 
\end_layout

\begin_layout LyX-Code
>>>plot(t,v)
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/pylab-sine.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/pylab-sine-sqr.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Inputs captured and plotted using pylab(a) Sine wave (b)Sine and square
 
\begin_inset CommandInset label
LatexCommand label
name "fig:Sine"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
We have sampled the voltage on A1 300 times with a delay of 100 micro seconds
 between two consecutive readings, i.e.
 the voltage is captured for total 30 milliseconds.
 Each data word is 1 byte in size and the maximum number of samples possible
 is 1800, limited by the RAM on expEYES.
 
\end_layout

\begin_layout Standard
The graph will popup in a new window, as shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Sine"

\end_inset

(a).
 For measuring with higher resolution (12 bits), you may use capture_hr(),
 but the total number of samples will be limited to 900 in that case.
 
\end_layout

\begin_layout LyX-Code
>>>t,v = p.capture_hr(1,300,100) 
\end_layout

\begin_layout LyX-Code
>>>plot(t,v)
\end_layout

\begin_layout Standard
Now let us add a square wave to the plot by:
\end_layout

\begin_layout LyX-Code
>>>print p.set_sqr1(100)         # set 100Hz on SQR1
\end_layout

\begin_layout LyX-Code
>>>t,v = p.capture(6,300,100)    # channel 6 is SQR1 readback
\end_layout

\begin_layout LyX-Code
>>>plot(t,v)
\end_layout

\begin_layout Standard
The output is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Sine"

\end_inset

(b).
\end_layout

\begin_layout Standard
Some experiments will require capturing more than one waveform with timing
 correlation, use capture2, capture3 or capture4 for this.
 For example to view the phase shift of a sine wave, connect SINE to A1,
 a 1uF capacitor from A1 to A2 and a 1k resistor from A2 to GND.
 Capture the voltage before and after the capacitor by;
\end_layout

\begin_layout LyX-Code
>>>t1,v1,t2,v2 = p.capture2(1, 2,300,100)       
\end_layout

\begin_layout LyX-Code
>>>plot(t1,v1, t2,v2)
\end_layout

\begin_layout Standard
The out put is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:(a)Phase-shift-of"

\end_inset

(a).
 The last line plots a Lissajous figure as shown in figure
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:(a)Phase-shift-of"

\end_inset

(b).
 There are more than one ellipse since we captured more than one cycle.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/pylab-sine-phase.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/lissaj.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a)Phase shift of sine wave across a capacitor.
 (b) Lissajous plot of the voltages
\begin_inset CommandInset label
LatexCommand label
name "fig:(a)Phase-shift-of"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Most of the time the captured voltage is generated by some other actions
 like setting a voltage.
 This is done by implementing capture modifiers.
 This can be easily explained by capturing the voltage across a capacitor,
 just after applying a voltage step to it through a resistor.
 Connect 1k resistor from OD1 to A1, a 1uF capacitor from A1 to GND, and
 run;
\end_layout

\begin_layout LyX-Code
>>>p.set_state(1)        # OD1 5 volts
\end_layout

\begin_layout LyX-Code
>>>p.enable_set_low(10)  # Effect only during capture 
\end_layout

\begin_layout LyX-Code
>>>t,v=p.capture_hr(1,300,20)  # OD1->0 before capture 
\end_layout

\begin_layout LyX-Code
>>>p.disable_actions()   # No more actions on OD1
\end_layout

\begin_layout LyX-Code
>>>plot(t,v)
\end_layout

\begin_layout Standard
The result is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:(a)-PWM-waveform"

\end_inset

(a).
\end_layout

\begin_layout Standard
The outputs SQR1 and SQR2 can generate square waves ranging from .7Hz to
 200kHz, function returns the actual frequency set.
 They can also be programmed to generate Pulse Width Modulated (PWM) waveforms,
 at some fixed frequencies.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename pics/pylab-cap-discharge.png
	lyxscale 50
	width 5cm

\end_inset

 
\begin_inset Graphics
	filename pics/pylab-pwm.png
	lyxscale 50
	width 5cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
(a) Capacitor discharge (b) PWM waveform
\begin_inset CommandInset label
LatexCommand label
name "fig:(a)-PWM-waveform"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout LyX-Code
>>>print p.set_sqr1_pwm(30)    # 30% duty cycle, 488 Hz
\end_layout

\begin_layout LyX-Code
>>>t,v=p.capture_hr(6, 300,50)   # get the wave form
\end_layout

\begin_layout LyX-Code
>>>plot(t,v)
\end_layout

\begin_layout Standard
The result is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:(a)-PWM-waveform"

\end_inset

(b).
 
\end_layout

\begin_layout Standard
expEYES can measure time interval between voltage transitions at the digital
 inputs.
 Connect SQR1 to IN1 and try:
\end_layout

\begin_layout LyX-Code
>>>print p.r2ftime(3,3)      
\end_layout

\begin_layout LyX-Code
>>>print p.set_sqr1(1000)    # 1kHz square wave
\end_layout

\begin_layout LyX-Code
>>>print p.r2ftime(3,3)      # rising to falling
\end_layout

\begin_layout LyX-Code
>>>print p.multi_r2rtime(3)  # two rising edge 
\end_layout

\begin_layout LyX-Code
>>>print p.measure_frequency(3)
\end_layout

\begin_layout Standard
Try to set square waves of different frequencies and measure them.
\end_layout

\begin_layout Standard
From a captured waveform, we can measure the amplitude and frequency by
 curve fitting.
 The results are accurate with a sine wave input but frequency measurement
 works with other shapes also.
 Connect SINE to A1 and try:
\end_layout

\begin_layout LyX-Code
>>>import expeyes.eyemath as em
\end_layout

\begin_layout LyX-Code
>>>t,v= p.capture_hr(1, 400,50)
\end_layout

\begin_layout LyX-Code
>>>vfit, par = em.fit_sine(t,v)
\end_layout

\begin_layout LyX-Code
>>>print par[0], par[1]*1000   # Amplitude & Frequency
\end_layout

\begin_layout Standard
The peak voltage and the frequency will be printed.
\end_layout

\begin_layout Standard
For more information read the Programmer's manual.
 You can get a brief description of all the functions by giving the command
\end_layout

\begin_layout LyX-Code
>>>help(expeyes.eyesj)
\end_layout

\begin_layout Standard
Once you learn Python language, it will be easier to read through the source
 code 
\shape italic
eyesj.py
\shape default
 to understand the working of the program.
 In fact all the real-time measurements are done by the C program 
\shape italic
eyesj.c
\shape default
 running on the micro-controller.
 The Python library sends commands to get the required data, and uses the
 power of Python for data analysis and display.
\end_layout

\begin_layout Standard
The latest PDF versions of this manual can be downloaded from http://expeyes.in
\end_layout

\begin_layout LyX-Code
If you find mistakes, send a mail to ajith@iuac.res
\end_layout

\begin_layout LyX-Code

\end_layout

\end_body
\end_document
