I need to control the AC FAN with raspberry pi and i am using optoisolator MOC3021 ..but ckt is not working properly by varying the pwm pulse..is there any other methods for doing this??? Can zero crossing detector is usefull for PWM variation?

 

datasheets?

 

Why you are using raspberry pi ?
why not micro controller?

 

Attach your schematic first.

 

Hello,

PWM will not work with an AC fan.
You will need phase angle control for it.
This page of the EDUCYPEDIA will have more info about this:
http://educypedia.karadimov.info/electronics/powerelectronicsdiac.htm

Bertus

 

I just find out my mistake ...i am giving the pwm pulse variation to MOC3021 but that is not the right way..
we need to measure firing angle by the formula then give the proper time period to fire the gate terminal of TRIAC
you so much for reply..