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Help with one shot circuit

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compprod

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I'm trying to design a circuit where when a toggle switch is turned on, it will trigger a relay for about a second, then disengage it.

The relay should not engage again until the toggle swith is turned off, then back on again.

I tried to modify a 555 one shot circuit, but it keeps re-triggering because of the lenght of time the switch is on, which could be hours.

Any help would be greatly appreciated. Thank you!
 

Maybe you could trying taking the control shot not from the relay directly but after a differentiatot (RC Cicruit) followed by a voltage clipper (Diode + R) to take only the off-on transistion.

i.e. Relay -> Differentiator->Negative level

94_1161638386.jpg
 

Hi Compprod,

You can choose from two circuits. If you are building it for yourself
you can use the second circuit, it has the advantage that you don't
need a PCB. If you are building it for somebody else, you gonna have to
go for the circuit with the timer because it will bring you more money.
And don't forget to put at least two leds in the circuit, the more leds
in the circuit, the more money you can get ! 8)

on1aag.

41_1161647029.GIF
 

    C

    compprod

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Use high pass circuit to apply edge trigger to 555, you must add the protection diode otherwise you get negative voltage when the switch released
 

Sorry elmolla, didn’t see yours post
 

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