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Make a led shut down immediately after power off

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geotFM

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Hello.i have a full wave rectifier followed by a capacitor and a led in series with a resistor.When i power off the circuit the led slowly turns off due to the capacitors charge.How to make it turn off immediately at the moment i remove the ac power? i dont mind using extra circuit.
 

Hi,

omit the capacitor

Klaus
 

Add a second rectifier (full or half wave) and a much smaller capacitor (or no capacitor) for driving the LED.
 

Do you want the capacitor to discharge too or just the LED? As an engineer who has to touch high voltage circuits I like LED's that are on until there is truly no power.

Either move your LED onto its own source without any C or make an AC detection circuit that disables the LED.

A capacitively coupled solution may be good in either case.
 

Or:
and put a series blocking diode between the rectifier and the bulk capacitor. Wire your LED right after the bridge rectifier, but BEFORE the bulk capacitor.
 

and put a series blocking diode between the rectifier and the bulk capacitor. Wire your LED right after the bridge rectifier, but BEFORE the bulk capacitor.
I think that should read... "but BEFORE the series blocking diode."

Brian.
 

You are absolutely correct Brian, but you still were able to get the gist of it.
 

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