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Topic: Triac changeover switch (SPDT) schematic? (Read 1 time) previous topic - next topic

MrGlasspoole


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.

Grumpy_Mike

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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.

MrGlasspoole

I never saw special relays in commercial products.
From header to washing machine to pump controllers - they all have the
cheap 1$ Omron relays.

Grumpy_Mike

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I never saw special relays in commercial products.

Yes you did.

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Insert Quote
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.

MrGlasspoole

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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