Cutting out a triac

Thread Starter

Iodem_Asakura

Joined Sep 14, 2004
140
Does somebody know how to turn off the conduction of a triac without open the line and don't wait until the line current reach 0?

I think it can not be done, but i don't lose anything asking. Maybe you supprise me!

Thanks for your answers.
 

hgmjr

Joined Jan 28, 2005
9,029
There is one way that it can be done. Simply place a normally-open switch in parallel with the TRIAC. You can then close the switch which will starve the triac of current thus turming it off.

Of course this assumes that the trigger condition is not present.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,029
I take it you are looking for something that allows you to use an electronic control signal to reset the traic to the non-conducting state.

What about using a power mosfet device in parallel with the triac. Then you could drive the gate to turn on the mosfet and starve the traic of current.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,029
You are correct.

The mosfet will only turn off the triac in one direction.

As I recall, if the voltage that is being switched by the triac is AC then the triac automatically turns off as the AC voltage across it passes through the zero crossing.

Isn't this true?

hgmjr(200)
 

hgmjr

Joined Jan 28, 2005
9,029
Originally posted by Iodem_Asakura@May 29 2005, 06:30 AM
That's right. And that is the problem, in some cases i would like to shut down the triac before the ac current passes through zero.
[post=8031]Quoted post[/post]​
I see. Interesting challenge. I'm going to need to think about that one. I'll get back to you in the next day or so.
 

hgmjr

Joined Jan 28, 2005
9,029
Originally posted by Iodem_Asakura@May 30 2005, 08:28 PM
I think it's really hard to do that (to not say impossible).
[post=8076]Quoted post[/post]​
Hi Iodem_Asakura,

After giving your triac cutoff problem a good deal of thought, I think your assessment of the difficulty of a solution is correct.

If you do find a solution, I hope you will post it here so that others can benefit from your success.

hgmjr
 

mozikluv

Joined Jan 22, 2004
1,437
Originally posted by hgmjr@Jun 1 2005, 08:46 PM
Hi Iodem_Asakura,

After giving your triac cutoff problem a good deal of thought, I think your assessment of the difficulty of a solution is correct.

If you do find a solution, I hope you will post it here so that others can benefit from your success.

hgmjr
[post=8137]Quoted post[/post]​
hi

it's like trying to figure out how to stop an F1 racer running at 300kph without skidding and turning turnturtle or burning tire rubber :p :D :lol:

but those are the kind of thoughts that sometimes starts the ball rolling ;)

moz
 
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