In this lab, we explored another mathematical operation that can be performed by op amps; differentiation. Essentially, you can set up the op amp as an inverting amplifier, but replace input resistor with a capacitor. Essentially, if you feed a time-varying signal into the differentiator, it will output the derivative of the signal function with respect to time.
We used a 1.0 uF capacitor, and were instructed to choose a resistor that would give us a gain of -1. Since gain = -RC, we initially chose R to be 1.0 MOhm, but for some reason the op amp would saturate, so we kept swapping it for lower and lower resistors until we achieved a circuit that did not saturate. We also had to turn down the input voltage, but eventually we found that a 1 kOhm resistor and a 100 mV supply did the trick. The circuit, as well as the WaveForms oscilloscope, are pictured below:
Actual Resistor and Capacitor values
Photo of the actual circuit
Sinusoidal wave being fed into the circuit. f = 1 kHz, V = 100 mV
Yellow = Input Voltage, Blue = Output Voltage
f = 1 kHz
f = 2 kHz
f = 500 Hz
In Class Examples
1. Sketch the input and output waveforms for 1kHz sine wave, triangle wave, and square wave inputs.
2. Given vC(t) = [5 u(t) +6 r(t)] V, find iC(t) for the circuit shown.
3. Find the step response v(t) and i(t) to vs = 5u(t)V in the circuit below:
4. Example: Find v0(t) for t>0 in the circuit below.
I am literally just taking this blog from someone else, I wasn't here for this class so I feel that my experiences of the day would not be beneficial to the contribution of this blog so someone elses' will have o do.
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