Electronics bootcamp II: feedback systems
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--Steven Wasserman (talk) 21:14, 27 October 2018 (CDT)
Time and frequency response of a feedback system
In the second part of the boot camp, you will build the circuit below and characterize its time and frequency response.
Overdamped | Critically damped |
---|---|
Slightly underdamped | Underdamped |
- Find the transfer function of the RC network inside the feedback loop (not including the amplifier). Use an appropriate approximation to dramatically simplify the algebra.
- Find the transfer function of the entire system, including the amplifier, as a function of the amplifier's open-loop gain, A.
- Build and test the circuit in the diagram.
- Connect the output of a signal generator to channel 1 of an oscilloscope and also to the input of your circuit.
- Connect the output of your circuit to channel 2 of the oscilloscope.
- Set the function generator to produce a 100 Hz, square wave output with an amplitude of 100 mV.
- Adjust Rgain (between pins 1 and 8 of the AD622 instrumentation amplifier) so that the system response is slightly overdamped and record the response.
- Adjust Rgain so that the circuit is critically damped and record the response.
- To achieve critical damping, start with an over damped response and vary Rgain by turning the potentiometer until there is a slight overshoot in the response. Then turn the potentiometer back until the overshoot just disappears.
- Adjust Rgain so that the circuit is slightly underdamped (two or three overshoots) and record the response.
- Adjust Rgain so that the circuit is underdamped with at least a dozen or so overshoots and record the response.