why use always-on optotriac to drive TRIAC?

Thread Starter


Joined Dec 13, 2021
Can anyone tell me in the attached circuit why use always-on optotriac to drive TRIAC?

What is the purpose of using phototriac in the circuit?

This circuit is used to control the speed of ac motor and between pin 1 and 2 of CN2 is placed the RV1 (potentiometer).

Usually use phototriac for isolation but in this circuit, we don't need isolation. There is not a DC source or microcontroller for turning on the optotriac.

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Joined Jul 18, 2013
The "Null" , earth GND references used for power common are rather meaningless, the way they are used/labeled. :(
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