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Author Topic: Triac changeover switch (SPDT) schematic?  (Read 1587 times)
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Hi,

I'm looking for a triac SPDT schematic.
There are allot triac schematics for on/off but i can't find some for SPDT.

I want to change the 240V/10A relays to SSR.
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Left Coast, CA (USA)
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Wouldn't that just be a matter of using two SSRs with there inputs wired in opposite logic state input and the appropriate AC wiring to the SSRs output terminals?

Lefty
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I was hoping for a all purpose solution.
But the more i look around the more i think normal relays are the best.
You can switch everything with them - AC, DC, lamps, motors, valves...

I can't see that for SSR (triac/ fet).
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Anything and everything is possible.  You just have to get the engineering right.
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Manchester (England England)
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I was hoping for a all purpose solution.
That is an all purpose solution.What is wrong with it?
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That is an all purpose solution.What is wrong with it?
Can't see one.
All schematics and calculations i found are for MOS-FET DC or Triac AC and all
calculations require the knowing of the load. If i have a mechanical relay with
250V/16A i can switch everything and I'm flexible - no matter if its inductive load or not,
or AC or DC. And i think its more failsafe.
If a mechanical relay fails then at 99% its off and my motor is not running.
If a MOS-FET or Triac fails then the chance is big that they have a short.
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calculations require the knowing of the load. If i have a mechanical relay with
250V/16A i can switch everything and I'm flexible - no matter if its inductive load or not,
Not true, you need to know the current an if it is AC or DC in order for you to know if your relay contacts are rated correctly. Same goes for inductive loads, you need to know what spark quenching components to use.
If you choose to ignore this for relay contacts you can have the same success as with a triac.

You mentioned a triac, those are AC only devices, that is if you want to be able to easly control them to turn off.
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I never saw special relays in commercial products.
From header to washing machine to pump controllers - they all have the
cheap 1$ Omron relays.
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I never saw special relays in commercial products.
Yes you did.

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 they all have the cheap 1$ Omron relays.
And why do you think they are cheap. Because they had thr right specification for the contacts and they made gazillions of them.
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Sorry, maybe it's a little bit hard for me in English to express how i mean it.

If the 1$ relays are not cheap (in the meaning of quality) then it does not
change the thing that i can use them for almost anything without to think
to much about it.

What is a cheap relay where i need to be scared that it runs with a lamp
but get killed if i use it on a valve - one for 2 cents?
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