EC330: Analog Circuits Lab, Jan.-May 2007
Coordinators
Schedule
Teaching assistants
Q slot: Arun M., Sagar Kumar, Kapil Kesarwani.
S slot: Raja Prabhu J., Mrinmay Talegaonkar, Sriganesh C.
Evaluation
Attendance
Attendance will be strictly enforced and those falling short will receive a W
If you arrive more than 10 minutes late to the lab, you will not be admitted
Prerequisites
Instructions
Buy a breadboard, wire stripper, and nose pliers
Get the required components from the
IE Lab
Wire up the circuit (neatly!) before the lab session. No debugging assistance will be given for overly messy wiring
Test your circuit during the lab session
Maintain a lab notebook in which you briefly record the results and troubleshooting information
Be familiar with component pinouts. You don't wan't to be connecting opamps in positive feedback or driving the outputs of gates with signals.
Draw schematics of the experiments with expected bias voltages, bias currents, and signal levels marked on them. This is a very good debugging aid.
Debugging
Whenever a circuit isn't behaving as expected, it pays to go through these steps systematically. This also applies when you simulate circuits and the results aren't as expected.
Verify that the power supplies and signal sources are on, and are correctly connected to the board.
Measure the power supplies and bias points, at the component pins. You may have “wired up” the circuit with loose wires or altogether incorrectly. This is where the schematic with expected bias and signal levels will be a great help
Bias points: Check these with a multimeter. Note that the multimeter's input resistance of 10MΩ, while much larger than the impedance of most circuits you will be dealing with, can disturb the bias of high impedance circuits.
supply levels
opamp inputs should be virtual shorts
opamp outputs should be well within swing limits for the given supplies
transistors' base-emitter drop should be about 0.65 V
transistors must be in their active regions(CB reverse biased)
Signal levels: You need to check these with an oscilloscope. An oscilloscope's input impedance (approx 1MΩ in parallel with 100pF) can disturb high frequency circuits. So use 10x mode where necessary. Generally many circuits we use are excited with periodic inputs and it is convenient to check the signals progressively through the circuit, starting from the input.
Measuring “AC” voltages with the multimeter: The digital voltmeter typically measures the average value of the rectified input and gives you readings in rms Volts assuming that the input is a sine wave. The readings will be horribly off if the input is not a sine wave. Also, the frequency response of the multimeter is only upto about 500Hz. So do not use the multimeter to measure ac signals unless you are absolutely sure of what you are doing.
Experiments
Information for experiments will be put up on this page in advance so that you can come prepared to the lab. Familiarise yourselves with the characteristics of the components by reading the data sheets of the components given below
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1/2/2007: Make up class
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10/4/2007, 12/4/2007: Make up classes
17/4/2007: Make up class
18/4/2007: Lab exam-430pm, ESB 127, 128, 129
Component data sheets
Go through these data sheets before wiring up the circuit. Pay particular attention to pinouts, power supply polarity, and maximum voltage ratings.