enter image description hereAs per the schematic two same value triacs and driver circuits are connected parallel, Triacs are BTA24 and Opto-couplers are moc3021 and the load is inductive, when i trigger the MOC U1 the Triac Q1 works as desired, similarly when i triggered MOC U3 triac Q3 works as desired, but when i trigger both the MOCs the circuit makes buzzy sounds and any one triac just got damaged and ended up MT1 and MT2 pins short.

this is just an idea and i am working on it for my personal interest in electronics, so i have no deep experience with mains supplies and power electronics, this circuit i am trying to developing is kind of dimming any inductive load without Humming sound , so for three different speeds i use trig1, trig2 and for the third speed i use both trig1 and trig 2 at same time.

please let me know that am i doing something wrong here or any other ideas to make this work and any help would really appreciated.

so my questions are

1) Why one of that two triac got damaged every time when i trigger both MOC at same time? 2) why circuit makes buzzy sound noise? the buzzy sound noise comes from which part (possibly)?

  • That buzzy sound might be the burning of silicon. – Edgar Brown Nov 21 at 5:42
  • possible , but any idea why that sound occurs whenever the triac work in parallel? (whenever i trigger both MOC at same time) – JkumaR Nov 21 at 6:33

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