Need help for motor driving with triacs

Thread Starter


Joined Jan 17, 2011
Hello people;
I really need help friends

I am tring to drive a single phase (230V AC) motor 4A with BT137(8A), but triac gets hot like 35 celcius degree (even I am using cooler) and after some switching it is getting failed. So that later on I have changed the triac with BTA41(40A) and bigger cooler, but it is still hot around 30 degree, and in one week BTA41 also gets failing. I am tring to drve the triac with Moc3041, and I am tring to switching the triac when 5Vdc available on Moc3041.
I have tried to use snubber but it is not solving the problem
you can reach the view of my circuit on
here I am triying drive the motor with 5V dc control to moc3041 so triac fries and the motor starts, and one more think I am also drving a 25uf 400 V capacitor (paralell with the motor) with that motor for compansating

if someone has an advice I will be really thankfull to him/her


Joined Nov 28, 2008
It is a bad idea to place in series a LED with the MOC3041 at 5V drive voltage and I'm going to tell you why.

The MOC3041 IR emitter requires a typical of 30mA for reliable operation and at that current the typical voltage drop is between 1.25V and 1.5V. With the added LED voltage drop of 2~3V(depends on color), you don't have much headroom for the series resistor.

30mA for a common LED might also be a bit too high.

If you want indication, connects them in parallel, LED and IR emitter each having its own current limiting resistor.