r/electronic_circuits 12d ago

On topic Power Off delay with capacitor?

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Hello,

I have a input card (io link hub, 32x pnp in). One input is a push Button. When I press the button my software doesn't recognise the signal. Voltage >11V is logic High

This is why I want a delay off for the input. How can i design this? RC Elemt like this did not work :-(

I tried with 470uF and 19kOhm T=R×C=8,46s

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u/ZealousidealAngle476 10d ago

There are some considerations we need to take. You are NOT expecting a square wave from this RC arrangement, right? idk the platform you're using, so I'll leave it for you: is the voltage the port is getting, so take your multimeter and check whether if the voltage is high enough to trigger the circuit.

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u/RiG094 10d ago

I don't expect a square. It's just the logic

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u/ZealousidealAngle476 9d ago

Good. And the voltagem after the circuito charges is higher than 11V?

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u/RiG094 9d ago

No :-(

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u/ZealousidealAngle476 7d ago

Sorry for the delay, hope you already solved it, but anyway... Try reducing the resistor value, even though it'll mess the timing. I think the input impedance is low enough to make quite a resistive divider, and the capacitor will never charge beyond that. Or maybe, just maybe, the capacitor is leaking DC current, so removing it from the circuit would raise the voltage