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Build your own cable radar:
10/01/98 Electronic Design - Ideas for Design / A
time domain reflectometer (TDR) is a handy but
rather expensive instrument, and isn’t commonly
found on every bench. I used to rent them, but after
having paid large bills for several years, I decided
to make my own. I saved a bundle and was able to. .
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Digital Radar Speedometer:
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Economy radar detector
: This circuit uses a 1458 dual
op-amp to form a radar detector. C1 is the detector
of the radar signal. The first op-amp forms a
current-to-voltage converter and the second op-amp
buffers the output to drive the piezo transducer. R5
sets the switching threshold of the second op-amp;
normally it is adjusted so that the circuit barely
triggers on background noise, then it`s backed off a
bit. The response of the circuit may be tuned by
adjusting the length of the leads on C1. For typical
road-radar systems, the input capacitor`s leads
should be about 0.5 to 0.6 inches long.
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"Radio-Electronics" Magazine, Jul,86 issue (C)
Copyright Gernsback Publications, Inc.,1986
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