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I'd like to build the circuit detailed here, which calls for a 12V DC 260Ω resistance relay:

Looking at some relays, what consequence would using a 400Ω relay have? Would I be able to use one without a problem?

Unrelated: I believe it's a non-latching SPST NO relay that I need here, right? From what I understand, a SPDT can function as a SPST by ignoring one of the pins; is this correct?

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2 Answers 2

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The 400 ohm relay will stay closed longer. You should reduce the capacitor by about 260/400, so about 220uF in order to make the time similar.

Yes, you can just ignore the normally closed contact.

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A higher ohm relay would have the consequence of slowing down the charge of the capacitor. So just pick a smaller capacitor to go with it. The author notes something like that from this quote: " You can also use a 5V relay and supply, but you may need to experiment with the capacitor value. (100uF ….470uF). " Your other question is completely correct. Just ignore the throw you don't want to use.

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