We were asked to design a motor speed control circuit using the following components:
15V source -> potentiometer -> LPF -> OpAmp -> ADC -> DAC -> OpAmp -> Motor Driver -> 3V DC Motor (because of its low cost)
I am going to wire this on a breadboard.
1. First things first, I have a 15 and -15 Source (VCC, VEE)
1.1 (Update) I have two 20k resistors before the pot so I would have finer control over the motor (-3V to +3V)
2. A low pass filter with a cut off frequency of 100Hz (My prof suggests that we use this value just to clear unwanted signals)
3. An OpAmp with unity gain because I need something to drive the transistors from the high-impedance output of the pot.
4. A push-pull amp configuration that consists of the NPN and PNP transistors so that I can make my motor spin either way (i.e., a motor driver).
So my questions are:
Are my resistor/capacitor values practical?
How do I implement the ADC -> DAC part?
Do I need to place a resistor before the pot so that it won't burn out due to high voltage?
The motor driver circuit can also be an H-Bridge circuit or IC but I think that would be more expensive.
I also need some suggestions on how to improve the circuit.