modified 10 years ago

HELP photoresistor controlled PWM

00:58:26

Hey guys, I've been trying to create a circuit that would make pwm just using a photoresistor to control it. That means no potentiomenter. This is the best result I've come up to... But obviously won't work as intented. 

I wanna know what you guys come up with, thanks

THE ORANGE RESISTOR IS THE PHOTORESISTOR. (Ignore the values, I'm only interested on the schematic) 

published 10 years ago

bakupcpu

10 years ago

You might want to use an opamp pwm version. It consist of 2 opamp one as a triangle wave generator and the second as a wave shopper's. I've use this type of circuit several time.

faceblast

10 years ago

it depends on how important frequency is. a simple multivibrator works fine if you don't care about frequency shift. if you need the frequency to be maintained you need to isolate the sawtooth generator from your level input into your comparator circuit. comparators work best for this purpose

Aristizabal95

10 years ago

You guys just blew my mind, I've never thought about this. Now I'm just an amateur (If I can even call that myself haha) and I don't know how to do this. Looking through Google I found some schematics but they all require 3 op amps. I don't know If you can show me the schematic with only 2, since I only have 2 right now haha.

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