Experiments
About
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ExpEYES is an instrument that can act as a Collection of Test Equipment, like DC power supply, Function generator, Oscilloscope, Frequency counter, Capacitance meter etc. It also supports I2C sensor elements for measuring physical parameters like temperature, pressure, magnetic field etc. This device can be used along with Desktops, Laptops, single board computers like Raspberry or Android phones. Details of the project are on the ExpEYES Website.
Participants are advised to go through the material below before attending the program. Click on the links for the details of each activity.
Click here to install Android App Seelab 3
All the participant groups should have ExpEYES-17 (or the latest upgrade SEELab-3) functioning with their phones before starting the session.
Ground Terminals : All voltage levels are with respect to the terminals marked as GND.
A1 and A2 : These are Oscilloscope/Voltmeter inputs. The input range is -16V to +16V. Maximum sampling rate is 1MHz.
PV1 and PV2 : Programmable Voltage Sources (DC supplies). PV1 can be set anywhere from -5V to +5V and PV2 from -3.3V to +3.3V.
WG : Waveform Generator. Frequency of the sine wave can be set between 5 Hz and 5000 Hz. The amplitude can be set to 3V, 1V or 80mV from the software.
$ \overline{WG} $ is just inverted WG output. On SEELab3, amplitude of it can be reduced by connecting an external resistor.
SQ1 : A 0 to 5V square wave. Frequency up to 5000 Hz. SQ2 is similar but it is not available when WG is active.
OD1 : Digital output that can be set to 0 or 5 volts.
IN1 : Capacitance meter
IN2 : Frequency counter with duty cycle measurement, TTL input levels.
SEN : Measures resistance values between 100 $ \Omega $ to 100 $ k\Omega $. Mainly used with sensors like photo-transistors.
A3 : Similar to A1 and A2 but maximum range is -3.3V to +3.3V only. The input to A3 can be amplified by connecting a gain resistor Rg.
MIC : A condenser microphone can be connected between MIC and ground to digitize sound.
CCS : 1.1 mA Constant Current Source (0 to 1mA programmable for SEElab3)
Dual DC Supply : A +6V and -6V outputs are provided for performing experiments using op-Amps. The current capability is around 10mA only.
I2C Interface: External I2C sensors can be connected to the pins 5V, GND, SCL and SDA. The software can auto-detect and use several sensors for measuring distance, pressure, temperature, acceleration etc.
The functionality of the terminals will be verified by the participats, using the Oscilloscope GUI, by performing the following activities.
From now onwards, we will use the Experiments part of the GUI program. The documented experiments are arranged under different sections like Getting Started, School level, Electrical, Electronics, Mechanics etc. Participants are expected to perform a selected set of activities from this collection. Schematics and connection diagrams are provided. An online help also is available for each experiment (from the pulldown menu on the top right corner). Experiments listed below are along with the Section names.
Getting Started->Measuring a DC voltage : Measure the voltage between the terminals of single drycell. Also their parallel and series combinations.
Getting Started->Generating and Measuring Voltage : How to set and measure DC voltages, using the terminals PV1 and A1.
Getting Started->Measuring Capacitance : Measure the capacitance of different types of capacitors, including a home-made parallel plate capacitor.
Getting Started->Measuring Resistance : Measure the capacitance of different types of capacitors, including a home-made parallel plate capacitor.
Getting Started->DC Resistance of Human Body : A small DC voltage is applied across human body to measure it’s resistance.
School-Level->Electromagnetic Induction. A magnet is dropped into a coil and the resulting induced voltage waveform is captured.
School-Level->Simple AC Generator. An AC generator is made by placing a coil near a rotating magnet.
School-Level->Direct and Alternating Currents. Explains the difference by plotting the voltage as a function of time.
School-Level->Resistor in AC Circuits. Explores the current and voltage of AC across a resistor. Amplitude and phase relationships are observed.
School-Level->Capacitor in AC Circuits. Explores the relation between current and voltage of AC applied to a capacitor. The phase shift between voltage and current is demonstrated. The capacitive reactance is obtained from the voltage and current ampltudes. $ X_C = \frac{V_C}{I_C} $. Value of the capacitance used can be evaluated usig the equation $ C = \frac{1}{2 \pi f X_C} $.
Electrical->RC circuit steady state response. Circuit is same as in the previous experiment. The phase shift of voltage across the capacitor in an RC circuit is measured and compared with $ d\phi = \tan^{-1}(\frac{Z_C}{R}) $
School-Level->Inductor in AC Circuits Explores the relation between current and voltage of AC applied to an Inductor.
School-Level->AC to Series LCR circuit, Resonance. Explores the series LCR circuit under AC. Voltage across various circuit elements during resonance is measured. The measured resonant frequency is compared with the theoretical value $ f_o = \frac{1}{2 \pi \sqrt{LC}} $. Voltage across LC vanishes at this frequency. The individual voltages across L and C are equal and outof phase at resonance.
School-Level->Distance measurement using Echo module. Measurements on oscillating Mass and Spring system.
School-Level->AC Resistance of Human Body. Role of capacitance in the resistance of human body is explored.
Most of the experiments in this section are part of the B.Sc syllabus. Conventional method requires DC power supply, oscilloscope, function generator and frequency counter to perform them. Experiments like studying the Transient Response of LCR circuits is difficult with conventional equipment, but ExpEYES can be used to perform them.
Day 2
Electrical->RLC circuit transient response. Apply a voltage step to a series RLC circuit and capture the resulting voltage across the capacitor. Study the underdamped, overdamped and critically damped cases.
Frequency Response of Filter Circuits. Active filters are made using Op-Amps and Bode Plots are generated.
Electronics->Oscillator using IC555 An Astable Multivibrator circuit is wired using IC555. The output is displayed on the oscilloscope. The frequency and duty cycle are measured by feeding the output to the terminal IN2.
Acoustics->Velocity of Sound The velocity of sound can be obtained by measuring the wavelength directly, which is done by finding out the distance between two adjacent points having minimum and maximum pressure.
So far we have used the Android version, mainly due to it’s ease of setting up. GUI Program is available for GNU/Linux, Mac and MSWindows systems also.
Visit the Software Installation Section for more information.
Even though GUI programs are available for many experiments, programming ExpEYES gives a deeper understanding.
On GNU/Linux systems like Debian and Ubuntu, installing the Debian package providing the GUI is enough.
On MSWindows, open a command terminal and install the ExpEYES modules using the command
py -3 -m pip install eyes17lib
For more details, refer to the ExpEYES Programming manual for more details.
Some of the experiments done using the Android App will be performed by writing Python code.
The Android App SEELab3 supports Visual Programming, to develop new experiments. Visual programs to perform some experiments will be demonstrated. A WhatsApp group is desirable to share the code quickly
ExpEYES supports a range of I2C sensors. We will explore them using Visual programming. Sensors to measure the following physical parameters will be demonstarted.
