Hi guys

  Ok, now back in town again I can get back to this project.

  Neil had asked if I was trying to use the collector voltage as an  analog signal that indicates the degree of alignment.  Its more  of....is it there or not there, like within its field of view.   Using something like the light-2-freq chip wont work as well because I  have designed it to be looking for either no IR reflection (black),  most IR reflection (white paper) or in between the two (open to ambient  light).

  Mike H asked the end goal...its a combination of things to detect  relative position and alignment detection.  I have connected the  LED thru a NPN transistor so I can pulse it on and off from the PIC, so  adjust the current limiting resistor should be able to give me  "brighter?" IR pulse?  How exactly does that work.  If I  pulse the IR with more current, does it increase the sensitivy of the  reciever circuit?  I've thought of a simple transistor amp but  also need to keep the costs down so trying it right now.  I can  also deal with slower response time with a higher pull up if that will  increase the range detection from lower to higher.  Oh, and the  LED is NOT driven directly from the PIC, but via the transistor for  swithing the ground pin on them, via the PIC. 

  Jinx did ask if the 150ohm was low for a pull up on the collector  feeding the PIC.  Maybe it is,  but how do you calculate the  best value for the rx?  Obviosly I would like to have a lot higher  value resistor because this will be battery operated and I want to keep  the power consumption as low as possible.

  Again, thanks to everyone for the ideas and suggestions

  -JJ




			
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