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Subject: Re: Need help designing a circuit
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Sat, 2 Nov 2002 20:43:33 -0500
NNTP-Posting-Date: Sat, 02 Nov 2002 20:43:49 EST
Organization: Bell Sympatico
Actually, this sounds like a fairly good idea to use a resistance circuit.
I'm using a series of PIR sensors from exterior lights that seem to be cheap
as dirt nowadays. These will either be driving relays, or opto-isolators, to
make certain no nasty line level voltages get in the circuit. Would you
happen to have a schematic that illustrates your idea?.
"Wafer" wrote in message
> The first thing that comes to mind is perhaps a Decimal to BCD encoder.
> Each detector would then give a different number for the output of the
> chip. Another way might be an analog multiplexer. Actually, now that I
> have had another moment to consider it, this might be best done with a
> simple array of sensors connected with a series of resistors, all the
> same value. Each sensor has one lead connected to a different resistor,
> and all the other leads of the sensors are then connected to a common
> point. This means you get a different voltage depending on which sensor
> is on. Now you have a pot on the shaft of the turntable so that it's
> position determines the resistance of the pot. Using a simple op-amp
> circuit or voltage comparator, you have the motor move until the voltage
> from the array equals that from the pot. In this manner, you can also
> determine which direction to turn, based on the polarity of the two
> signals being compared. It's actually quite similar to the way polar
> rotors for C-Band satellite dishes work.
> Neil wrote:
> > Ok...I'm not very bright...I haven't embraced microcontrollers, and like
> > do things with good old fashioned components and IC's. Keeping this in
> > I need a circuit that senses the position of an object, then turns on a
> > motor to power a turntable to turn toward the object. I have several
> > detectors that will be placed in the center of the turntable. So I need
> > circuit that will sense which PIR has detected the object, and then
> > off once the turntable is has turned towards the direction of the
> > PIR.. It doesn't need to have any sort of accuracy, as long as the
> > stops close to the subject(within about +/- 20 or 30 degrees). The
> > switching can be either electro mechanical, or use LED Emitter/
> > Any ideas?.
> > Thanks in advance.
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