triggering my Triac...

Community Projects
1

Hi,

I have a small project and Im looking for some clarification…please

I fairly NEW to this so bear with me…

I have a triac with a gate voltage of 1.5v and a max gate current of 100ma

it will run an AC voltage motor…

I have power on L1 (110v) that runs straight to one leg(L1) of the motor and the other leg(L0) runs to

the A2 of the triac.

the A1 of the triac is connected to L0 (neutral)

I believe I have that set up ok, here is the issue Im not sure about.

Also connected to L1 is a power resistor and diode that reduces 110vac down to 7vdc

its from here that I get my gate(G) voltage for the triac.

Im wanting to create a voltage divider to further reduce the 7vdc to 1.5vdc @ 100ma

using 2 resistors spanning from the +7vdc terminal to L0(neutral)

the best configuration I can up with R1= 56ohm and R2= 13ohm both at 1/2watt

this gives me a V-out of 1.32vdc and an Ig of 101ma to trigger the gate on the triac.

( a 55ohm and a 15ohm would have been perfect, but havent been able to find them)

anyway, is there gonna be an issue with the gate current at 101ma?? Is that too much for the triac and

burn up the gate circuit??

I believe the gate voltage is acceptable…

The triac specs say 0.2v to 1.5v max should activate the gate, its the current that has me worried>>>

the specs say 100ma max on the gate current

also I need to have this gate circuit remain active anytime I want to run the motor…is this OK…

Thanks so much in advance

2

Hello webwiz355,

Sounds like you are using live mains with this project. Can I respectfully suggest that you fully read up on safety before you go any further. IMHO you need to fully understand the dangers of the situation, and how to manage them before you worry about blowing up TRIACs.

While not complete, https://hackaday.com/2016/05/11/looking … ng-part-1/ is a good start to understanding the situation.

Regards,

Mark

3

Something like https://www.sparkfun.com/products/14236 may be a better choice if you are new to this.

4

I would suggest using an optotriac to drive the triac (though a packaged unit with a relay is safer and better). How are you planning on controlling the triac? If the answer involves anything that is not wireless or double-insulated, the opto is mandatory for safety.

/mike

5

I tend to agree with darrellg’s suggestion as a safe approach to the problem. Opto-TRIACs have their place, but only if the all-encompassing issue of electrical safety is fully understood first, and the OP appears to be new to this whole arena.

-mark