I have built a simple PWM using a 555 IC to drive a motor for an optical chopper and I want to be able to use the output of the chopper signal as a speed correction feedback for the PWM. I think I should be able to do this using pin 5 on the 555 chip but I have no real idea how to do it. The current idea is to take the signal from the chopper through a F/V converter, into some sort of comparator and then use that output to increase/decrease the duty cycle of the PWM to adjust the speed of the motor up or down. I think I'm on the right track, I just have no real idea how to go about doing it because I'm an astronomer who dabbles in electronics but doesn't have any real training in circuit design. Please help if you can.
Electronic – How to use pin5 to control duty cycle of a 555 based PWM
555pwmvf-fv-converter
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Best Answer
The solution suggested by tcrosley is an old favorite, uses very inexpensive parts, and it does include the 555.
If you'd like to try another type of chip, the LTC6992 is literally designed for this kind of application. It's in a fairly small 6-pin SMT package so you'd need a breakout or an evaluation board to work with it unless you're making a PCB.
It accepts a 0-1V control signal and you can program the frequency and frequency range with (at most) three resistors on the SET and DIV pins, from less than 4 Hz to 1 MHz.