On Thu, Feb 13, 2003 at 06:14:03AM -0800, Robert Ritchey enlightened us thusly
> Hi Matthias,
> OK, I got the data sheet. Its still not clear to me if the zener goes
> between the gate and the 5V input or the gate and ground? Even
> with the data sheet I don't quite understand how a Triac works. I
> have looked through my books here and have not found a write-up
> on this. I don't understand how this is triggering using the zener.
> Thanks,
> >> Triacs and have no literature on their operation. The data sheet is not
> >> a lot of help.
> >> Thanks,
>
I had backed out of this one, but now feel like getting back in. A triac is
an A.C. device, with two scrs back to back. Why is it suggested as a
crowbar? Probably in case you had an A.C wall wart. Personally, I think
it's not the way to go at all. The idea with a triac is that you control
A.C. I would use an SCR if you have to have a crowbar. I would never try
to fire one with simply a zener. Gates get sensitive in the heat ...
You are going to fart around and lose a week with the triac unless you
find an application and copy it.
Have you considered a low drop regulator? I recently used a LP 2981
which is guaranteed max 0.1V drop at full load. Put a schottky in
series, use a 6V supply and you're smiling. You may just need a little
more bottle with whoever is telling you to use a 5V regulated external
supply, which leaves your circuit exposed. Tell him it cannot be done
safely. He must hold his face up if/when the solids hit the ventilation
as his part of the design goes down the tubes. Write a memo warning them
- that is a great scare tactic, and your backside is covered.
--
With best Regards,
Declan Moriarty.
--
Author: Declan. Moriarty
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