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In lugnet.robotics.handyboard, Chuck McManis <cmcmanis@mcmanis.com> writes:
> At 02:43 PM 1/26/00 +0000, E158 (M.FAZAL) wrote:
> > hi chuck
> > i tried using the photocells i got with the gleason research sensor motor
> > kit. i used red green and blue filter, but the values are almost same (with
> > a variation of 1 or 2). the variation is much more sensitive to the distance
> > between the sensor and the surface. what am i doing wrong?
> >
> > you also mentioned optical sensor. is that the same as the photocell?
I posted to this yesterday, but my reply seems to have not appeared.
What you need to have, is four sensors, not three. The fourth has no filter,
and measures 'ambient' light. You then need to compare the return from this,
to the other three sensors. You will have to amplify the signals from the
three 'filtered' sensors, since they will be proportionately 'less'. So when
the light level changes because of distance, this compensation factor changes
with this, and you are looking at the relative returns for each colour.
Best Wishes
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Message is in Reply To:
 | | Re: colour sensor
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| (...) I have typically used phototransistors rather than CDS photocells but both will work depending on the application. Sensors are like computer programs, when they do one thing they are fairly easy, if they do multiple things they are more (...) (25 years ago, 26-Jan-00, to lugnet.robotics.handyboard)
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