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Subject: Re: VERY short range Proximity Sensor
Date: Sat, 11 Jan 2003 15:13:26 +0800
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"Gerry Schneider" wrote in message
> Neil wrote:
> > Anyone have a schematic for a proximity detector that would be triggered
> > a hand being placed less than a inch from the antenna?.
> > All the ones that I find trigger from several feet away.
> > Thanks in advance,
> > Kim
> Turn down the gain or use a smaller pickup antenna.
I assume (but may be wrong) that this set up uses 50/60Hz stray fields and
the receiver reads the strength of this signal and switches on a threshold.
Would using an oscillator with its own antenna and a receive antenna
adjacent be an improvement? Set up so that he nearby hand couples the tx
signal to the rx antenna. Just a thought.
Local public amenities have a system installed in the hand basins - when
your hand is within 2" of the side of the basin the water solenoid opens. It
works quite well - except that the water outlet is offset from the sensor
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