I am going to start off with the disclaimer that I have a Software Engineering background and very little electrical engineering background.
I am using a 3q triac on a breadboard circuit. My gate current/voltage is supplied by a a 9VDC battery. The circuit I am using is more or less represented here:
When I use a 3q triac, my load is getting about 5/6th of the voltage. The rest is dissipating across the triac. The waveform is chopped off/flatted above a certain voltage and becomes sinosidal again below it.
When I use a 4q triac, I don't face this issue.
The 3q triac I have been using in the circuit is T405-800B-TR whereas the 4q triac I tried is BT138-800,127.
Is this normal for 3q triacs to eat up some of the Voltage or is there something wrong with this particular triac that I am using?
Best Answer
You should flip the battery around and drive the gate with -V with a 3-quadrant triac.
That will use quadrants II and III.
The T405-800B-TR is not guaranteed to trigger in quadrant IV at all, so it's not at all surprising that it doesn't work properly.