Hi tony,
I thought about that, but I quess, what I really want is better resolution,

IE 10k 8bit pot gives (10k/256) approx = 39ohms.
if I had a 1k digital pot it would be (1k/256) 3.9ohms.  This would allow
me to calculate distance more accurately.


>Less resistance is easy, just put in a parallel resistor.
>R_total=R_1*R_2/(R_1+R_2)
>Of course the output is no longer linear through the full range of the POT.

>
>tony
>
>-----Original Message-----
>From: Kevin A. Benedict [mailto:kben@DCA.NET]
>Sent: Thursday, December 20, 2001 10:47 PM
>To: PICLIST@MITVMA.MIT.EDU
>Subject: [PIC]: PIC IR Proximity Detector ?
>
>
>Hi,
>I am trying to build a PIC IR Proximity Detector, the bascic TX circuit
>is figure 2 on this page >>>
>http://www.rentron.com/Infrared_Remote_Control.htm
>If I add a small resistor (10-330 ohms) between the IR led and gnd,
>it changes the distance the RX circuit detects a reflection from
>(10cm -120cm)
>So, I thought if I add a digital pot instead of manually changing
>the resistor,
>I could make a rudimentary IR Proximity Detector.
>Problem Digikey only sells a 10k digital pot, I was hoping to find a smaller

>
>one,like <= 1k, anybody know where I could get one ?
>Is their an easier way to do this with a PIC ?
>I already looked at the Sharp GP2D02, but I wanted someting cheaper.
>
>Thanks in advance,
>                   Kevin
>
>P.S. I am a programmer not an EE, so my electronics background is limited.

>
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