Tuesday, April 16, 2013

BT136 Triac AC mains - TTL interface circuit

Its a common need to control 240V AC mains supply with TTL circuits. Given below is a simple circuit based on BT136600D triac. Using triacs we are able to avoid bulky,noisy and less efficient relay mechanism.

Above circuit turns the lamp ON and OFF according to the TTL input. Resistor R2  is chosen so as to limit the gate current to triac within the safe operating area. You can connect R1 to the required TTL circuit for switching.

  • Do not interchange phase and neutral line.  
  • Also do not connect the phase line directly to triac.
Violation of the above will cause severe burn out of components.

You are free to point out the mistakes and ask doubts.

Technoburst will not be responsible for any damages both physically or financially occurred due to the use of this circuit.


Albin George said...

did the neutral line need to connect the ground of the circuit?

Anil C S said...

Yes you need to connect neutral to the ground of the circuit. Be careful while using the above circuit. Even a tiny mistake in the wiring can cause component burnout.

Anonymous said...

yes just like i burnt mine

Sudarshan k.c. said...

In this circuit in 547 transistor in base pin which voltage is passing and if the negative voltage is input does the transistor works and I don't know which is the output pin collector or emitter, which voltage is outputted negative or positave from where...

Anonymous said...

Hi I'm new to circuits using AC and I wanted to use TRIAC to switch the AC through a bulb. I connected 60W bulb from phase of AC to MT1 and Neutral of AC to MT2. I used an SMPS 5V to the gate through a 330ohm resistor and connected the ground of 5V(SMPS) to MT2(the neutral of AC). I switched on the AC and bulb glowed for a second and immediately my neutral wire caught fire. Could anybody help get this correcctly and tell me what went wrong?

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