Controlling octocoupler with pwm

Nigel Goodwin

Super Moderator

Most Helpful Member

• Nov 11, 2022

• #2

I wouldn't have thought you could run a compressor like that?, speed control of motors is quite complicated, and entirely dependent on the type of motor.

 

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M

mikeggg

New Member

• Nov 11, 2022

• #3

In using and isolation relay from 115v source but I'm trying to trigger the relay with pwm fan so the compressor cuts off when the refrigerator makes temp and fan slows ... the refrigerator won't trigger the defrost until it senses a temp drop

 

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MaxHeadRoom78

Well-Known Member

Most Helpful Member

• Nov 11, 2022

• #4

Conflicting details, Controlling the compressor? or just the Fan??
Opto-coupler & PWM for what?

 

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crutschow

Well-Known Member

Most Helpful Member

• Nov 11, 2022

• #5

You could try adding a diode in series to the capacitor so the capacitor will charge to the peak value of the PWM signal, regardless of the PWM duty-cycle.
Using that should trigger the relay anytime there's a PMW signal.
Is that what you want?

 

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M

mikeggg

New Member

• Nov 12, 2022

• #6

Sorry to be clear I'm trying to use the signal from the pwm evap fan to trigger a isolation relay to power the compressor of the refrigerator

 

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M

mikeggg

New Member

• Nov 12, 2022

• #7

I have tried using a capacitor before and it helped as I was on the right track however I didn't try a diode .. I'm gonna see if that helps

 

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ChrisP58

Well-Known Member

Most Helpful Member

• Nov 12, 2022

• #8

Posting a schematic of what you're doing would make it much easier for us to help you.

 

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