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Electronics => Hardware and Tools => Topic started by: OleRuffo on August 27, 2008, 05:37:46 05:37



Title: Some help with a simple triac
Post by: OleRuffo on August 27, 2008, 05:37:46 05:37
Hi all:
I was working with the good old opto triac plus triac to move some gear with a micro controller and all goes perfect, you know, the very simple array with a snubber less TRIAC. i attach the basic output of every channel to make the things more clear.
So the problem/question is: if i drive an incandescent lamp all goes perfect, if i fire a solenoid, all goes perfect, if i run an AC motor, all goes perfect, BUT if i try to light one of those new led lamps or a saving energy lamp (kinda flourecent lamp) then the lamp goes dimmed when it should be off and full light when on, even the fluorecent one starts to flashing (some models) in the off cycle......
Have you any ideas about this behavior or how to avoid it?

Any input is most appreciated
Thanks in advance for your help and time
Cheers


Title: Re: Some help with a simple triac
Post by: zuisti on August 27, 2008, 08:06:12 08:06
...
So the problem/question is: if i drive an incandescent lamp all goes perfect, if i fire a solenoid, all goes perfect, if i run an AC motor, all goes perfect, BUT if i try to light one of those new led lamps or a saving energy lamp (kinda flourecent lamp) then the lamp goes dimmed when it should be off and full light when on, even the fluorecent one starts to flashing (some models) in the off cycle......
Have you any ideas about this behavior or how to avoid it?

Hi;
I think this is caused by the R3-C1, the LED or the saving energy lamp is still working in a 'dimmed mode' (with a low current via R3-C1) also without the triac, try it.
Do not use R3-C1 but increase the value of the R2 (from 180 Ohm to 470 Ohm, for example).

zuisti 

EDIT:
Sorry for my mistake: R3-C1 (of course)  


Title: Re: Some help with a simple triac
Post by: Silent_Thunder on August 27, 2008, 08:46:28 08:46
Hi
here is a link to application note that might help u with ur problem.
http://www.fairchildsemi.com/an/AN/AN-3008.pdf

Regards


Title: Re: Some help with a simple triac
Post by: Ichan on August 27, 2008, 10:55:37 10:55
The lamps that you mentioned usually had some electronics inside, they won't work with phase controller.

-ichan


Title: Re: Some help with a simple triac
Post by: OleRuffo on August 27, 2008, 05:16:07 17:16
Hi all:
Very informative and enlighting input of all you, dear fellows
all you are right, the parasite current derived from the R3- C1 is enough to fire those lamps ( at least the LED ones at 1.8 W), as Zuisti mentioned.
And as cleverly ichan pointed, the electronics inside the lamps makes this work a bit more tricky so the intention never was to dimm them, just turn them on or off,
The silent_thunder app note is solid gold as well!, i will back to the proto board (just like the old school days) to make some adjustments and share my results right here.
Cheers

Conclusion:
Well due to the low current this devices needs to fire, the one passing cross the snubber circuit is enough to dim the lights, so a tiny triac like the MAC97 and just a 2K ohms resistor leading the opto coupler is enough to make them work,
Anyway they ere not a good choice for a rapid chase sequence due the big light inertia those led lamps has, contrary to what i think before, the good old halogen dicroic lamps are still the best bet, still just a MAC97 is enough to drive a 75W lamp and now the original snubber circuit work perfect.
Cheers


Title: Re: Some help with a simple triac
Post by: jordi2t on November 07, 2008, 07:36:56 19:36
Forgives no groins i no if the translator translates it well.
Hello, want to give me of low in the forum but do not eat do it. ¿Can you help me doing it?