Triac problem at startup

[quincisoft]

Hi, I use a small mac97a6 triac to control a small 10w LED lamp with a moc3021 photo coupler driven with an esp32 output. The problem happens when I power the triac circuit with 230 V for a moment the lamp turns on, but this does not always happen. I tried changing the Gate R (330 ohm) but nothing..... Do you have any suggestions?

 

[rjenkinsgb]

A trigger circuit of that type should be connected between A2 and gate, rather than A1.

(If it were a circuit that supplied a voltage such as a transformer based one, that would be between A1 and gate).

 

[Nigel Goodwin]

I presume it does this when the ESP32 is unpowered?, because if the ESP32 is powered it has some 'unusual' quirks with it's I/O pins, and you might be using one which triggers briefly on power up?.

 

[quincisoft]

I presume it does this when the ESP32 is unpowered?, because if the ESP32 is powered it has some 'unusual' quirks with it's I/O pins, and you might be using one which triggers briefly on power up?.

yes,

Having noticed that the problem also occurred with the gate control circuit, I found this solution which seems work.