Electronics > Beginners

how do I make a time delay that turns on a relay upon power on and turns it off.

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TerminalJack505:
If that's the case then it looks like you should be able to remove R1, C1, and M2 from Zero999's circuit and connect R2 and M1 to ground instead of M2's drain.

Zero999:

--- Quote from: ELS122 on February 15, 2020, 06:03:19 pm ---well I meant 1 delay, one delay that when powers on IS on, but after 10s turns of. so is on. then turns off.
why I want this?
because I don't want the relay being on for all the time when the amp is on.
although it shouldn't be a problem if the voltage is right I just don't like the idea of something uselessly drawing current all the time.

--- End quote ---
OK, then it appears, the other people who have responded are right and I am the one who was mistaken. The circuit posted by TerminalJack505 will work.
https://www.eevblog.com/forum/beginners/how-do-i-make-a-time-delay-that-turns-on-a-relay-upon-power-on-and-turns-it-off/msg2919276/#msg2919276


--- Quote from: TerminalJack505 on February 15, 2020, 06:12:47 pm ---If that's the case then it looks like you should be able to remove R1, C1, and M2 from Zero999's circuit and connect R2 and M1 to ground instead of M2's drain.

--- End quote ---
Yes, like this.

ELS122:
I'll use a 2n7000.
then I'll put a 10k resistor across the drain and positive rail then I'll put a switch in series with the relay coil as a separate "standby" or mute switch.
I think the resistor would be better than none since when I switch the switch off it will just disconnect any load from the MOSFET. and I think that would probably cause some noise or something.
and also a 470pF across the switch so I don't get any possible oscillations, this is probably useless but I want to be safe of ANY noise.

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