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Subject: 
Voltage or resistance
Newsgroups: 
lugnet.robotics
Date: 
Sun, 27 Dec 1998 21:36:46 GMT
Original-From: 
mwalimub@aol.comSPAMLESS
Viewed: 
1103 times
  
After experimenting with various photo sensors, it appears that resistance is
what is measured.  Solar cells produce no change in readings, but CdS photo
resisters do.

I managed to hook up a BASIC STAMP (a small microcomputer by Parallax) to one
of the input ports using an LED (using pulse width modulation to vary
brightness) and a photoresister.  The idea is to use the light input to signal
changes in the STAMP - perhaps touch sensors - the STAMP has 7 inputs left
over.

The problem is that the readings on the RCX fluxuate too much.  I figure that
with some creative programming, I might can get 3, maybe 4 identifiable
readings.  I'll look for an octocoupler that uses resistance.  Maybe that will
give me a more stable reading.

chris



Message has 1 Reply:
  Re: Voltage or resistance
 
I'm joining this thread a little late, so sorry if any of this has already been stated... For "passive" sensors, the RCX measures a voltage level, but since there's a pullup you may not get what you expect. If memory serves, the RCX ADC uses a 5.0V (...) (26 years ago, 27-Dec-98, to lugnet.robotics)

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