project key

Posted on Feb 4, 2014

This battery-powered monitor has been designed to provide an audible indication of keying for those whose rigs lack a CW sidetone. Its sensor wire is wrapped around the transceiver`s coax no direct connection is required. Of course Morse isn`t the only use for this nifty circuit it should also be useful any time you need a simple alarm tha

project key
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t detects the presence of RF. RF collected at the sensor wire is rectified by a germanium diode. This produces a DC voltage that triggers a transistor switch. This then turns on a 555 audio oscillator that drives a speaker.

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