Momentary to Pulse Relay

Hi,

My first post here and I know nothing about electronics and wondered if I could get a little advice?

I wired up a relay following this diagram and it works fine.

https://www.the12volt.com/relays/relaydiagram20.html

However, is it possible to make the capacitor discharge more quickly so that the relay becomes operable in a shorter space of time?

Is it simply a matter of using a lower value resistor than the 10k one in the diagram and if so how low of a value can that be? I would like a recovery time of about 1 second rather the the 10 seconds it is taking now.

Any help would be very much appreciated.

Thanks

Dave

Use a smaller capacitor for a shorter output duration using the constant to momentary diagram you linked to in your post, however it sounds like you're using a larger capacitor than the one shown.

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Thanks for the advice.

I am using a 1k uf capacitor and a 1k ohm resistor as per the diagram and the output time is about 1/2 second and that is just fine.

Holding the input switch down for any length of time, gives a constant 12v supply and produces the same 1/2 second pulse which is just what I need.

However, the input switch may be pressed for different lengths of time and may need pressing again after a couple of seconds but I am finding that it takes about 10 secs for the capacitor to bleed it's charge down to ground through the resistor and it's that time that I am trying to shorten.

My thoughts were that if I used a smaller resister, say 5k ohms, would the capacitor discharge more quickly without causing a direct short circuit?

Dave

Think less resistance rather than smaller. 5K is more resistance than 1K. You can try a 500 ohm resistor with the 1K micro farad capacitor, but I would suggest using a smaller capacitor instead. Both will give you a shorter output than the 1/2 second output you have now.

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the12volt • Support the12volt.com

Ok.

I made a mistake in my previous post I am using a 10k ohm resistor and not 1k as posted.

The output time of 1/2 second is just fine and I don't want to change that.

After the 12 volt input is removed it takes about 10 secs for the capacitor to bleed it's charge down. If I re-apply the input within that 10 seconds the relay does not operate.

It's the 10 seconds "recovery" time I want to shorten so that I can re-apply the input within, say 2 seconds.

Thanks

Dave

No problem. In that case, try a 5K resistor and please post your results.

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the12volt • Support the12volt.com

Thanks for the help.

I ordered a few resistors of different values so hopefully I'll be able to try it over the weekend if they show up in time.

I will, certainly, let you know the results.

Dave

I fitted a 5K ohm resistor.

The pulse time of 1/2 second stayed the same.

The capacitor discharged in about 7 seconds rather than the 12-15 seconds previously.

thanks for the help.

Dave

Hi...i am a new user here. I think 5K is more resistance than 1K. You can try a 500 ohm resistor with the 1K micro farad capacitor, but I would suggest using a smaller capacitor instead. Both will give you a shorter output than the 1/2 second output you have now.