Smooth and remove pulsed signal

Im trying to used a hacked optical mouse to drive a relay. The tracking LED in the mouse is lit when the device is on and the LED is off when the unit is in sleep mode (the USB port has power in both modes).

The tracking LED is pulsed around 4Khz. I want to smooth the 4Khz signal so that I can drive a relay (ie LED lit - even +/- 4Khz the relay triggers, LED off the relay is off).

I was fooling around with some RC filters but couldn't get the desired result.

Some help would be appreciated.

by JackPollack
September 02, 2017

You're on the right track with filters. Try adding a transistor to provide enough current to drive the relay.

by mikerogerswsm
September 04, 2017

1 Answer

Answer by JackPollack

Thanks. The transistor wan't the problem (always intended to use one). problem was the 4K signal was causing the relay to buzz. ended up using RC filter with a diode and it worked.

+1 vote
by JackPollack
September 04, 2017

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