Looking for a way to remotely measre 12v and 24v with a single measuring wire

Yeah. But my relay gizmo is way cooler. ;)

Cheers

Phil Hobbs

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He can make two over/under '431 comparators confirming say 7.5% supply tole rances signaling the result over the single wire using the 12V wire-AND out put to drive a LED or something. Then he has the 12V signal and the 24V sou rce both available for observation by meter if needed, although not necessa ry unless something breaks.

Yeah I put that away in the back of my brain, in case someday I have to sample two time varying signals over one wire.

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But it's only a pass/fail indicator and you can get that by seeing if the g ate works.

Seems to me the oscillator is a pretty good idea. I'm not sure how the fir st poster was trying to use it, but using a ~50/50 duty cycle running betwe en the two power supplies slowly enough you can just connect a meter to the single wire and read the two voltages in just three or four seconds. No c onversions or translations or diode adjustments needed.

I don't think a 555 timer could be used though. None of them I've seen are rated for 24 volts. A simple 2 transistor astable oscilator would work fi ne.

Yup. And better, too, because then he can actually measure the voltages.

Ed