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Transistor relay with NO and NC? Answered

Does anyone know how to make a solid state relay with a NO contact and a NC?
Does anyone have a schematic?
Thanks.

17 Replies

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Padlock (author)2009-07-24

Easy enough. Use two transistors (or SSRs). Attach the base of one transistor directly to the input (with a resistor, if needed), and another, to a NOT gate, and then to the input. (Again, with the appropriate protection.) I'll make a schematic...

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Padlock (author)Padlock2009-07-24

Pardon my spelling mistake, paint doesn't have a spell check.

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thermoelectric (author)Padlock2009-07-24

Ah, thanks. I don't mind the spelling mistake, lol

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Padlock (author)thermoelectric2009-07-25

Take note that common MUST be ground, or at least lesser than the input voltage.

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Padlock (author)Padlock2009-07-25

Correction: Lesser than the input, NO, and NC voltages, (if present). That means that it won't work with AC, and when put in a electrical path the common must be attached to ground. Put bassically, the current must follow the path of the arrow in the transistor. This also means that the input voltage will be using the common as ground. I'm working on another, more complicated version w/ mosfets that would allow AC, and such.

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Padlock (author)Padlock2009-07-25

Scratch the MOSFETs, it's easier to do it like this:

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lemonie (author)2009-03-22

What is a NO and what is an NC?

L

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whatsisface (author)lemonie2009-03-22

Normally Open and Normally Closed. Interesting question, I'd say it could be done with gates.

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user

Oh, I'll have to look into gates....

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Goodhart (author)thermoelectric2009-07-24

not the Bill kind, either ;-)

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NachoMahma (author)lemonie2009-03-22

. Normally Open and Normally Closed

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11010010110 (author)2009-03-22

for small audio signals etc - use c4016 or c4066 for larger signals that flow in one direction only - just use transistors or fets i think there is way to use fets / triacs for 2 way switch (one that can pass current in both directions when closed) each switch you make has its natural attitude NO or NC. if you want to swap it add a not gate (npn transistor) on the control wire

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Goodhart (author)110100101102009-07-24

A flip flop would work, wouldn't it?

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Derin (author)2009-07-24
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thermoelectric (author)Derin2009-07-24

Ooh, That looks interesting, I will have to try that once I can get my hands on new TRIAC's Thanks

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