Op-Amp Based PWM Circuit


Posted on Feb 6, 2014

This circuit uses the LM358 operational amplifiers (or any single supply op amp) to generate a pulse-width modulated signal. In most cases, I would just use a microcontroller to generate PWM signals. Unfortunately, the circuit was designed for a local marine repair company which requested the circuit to be easily repairable and built without the n


Op-Amp Based PWM Circuit
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eed of an external programmer, etc. Since this is rail to rail design, a reference voltage (changed using potentiometer RV1`) has to be placed on the non inverting pins of the U2A` op-amp. The R8 resistor and C4 capacitor acts as a low pass filter which will filter some a the high frequency spikes and smooth the transition peak. I believe this portion of the circuit is optional but I just added it to make the triangle signal looks nice on my oscilloscope. Unfortunately, I have forgotten to take a picture of the completed PCB board and the working prototype. However, I did took a picture of the 3 Amp solenoid actuator which was tested on.




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