[MakeLV] Photoresitors

[Will]

I looked up online... the example I wrote is the one recommended from the
arduino site. Any use of a capacitor will only act as an integrator which
might be nice if want a nice analog ghetto way of building an averaging
system for measuring light (which will fluctuate a lot). In any case, in
terms of the class I think I'll pull a cap and make another circuit for
experimentation and demonstration purposes.

-Will C

On Fri, Dec 7, 2012 at 2:41 PM, Bill Heffner <wrh304 at lehigh.edu> wrote:

>  Jared, Sure, but Parallax gives you the data sheet so you can match them
> to the same product on Digikey.  And Parallax has already done the
> development work for the microcontroller use - can just grab figures etc
> with resistance values - saves a lot of time.  But many ways to skin the
> cat.
>
> Bill
> On 12/7/2012 1:23 PM, Will wrote:
>
> Bill,
>
>  The problem with the photo resistors from parallax is that they are
> expensive. Given the fact that this class we are teaching is a champagne
> class on a beer budget, we need to be careful.
>
>  Jared,
>
>  As far as how photo resistors work, the idea is that we will need to
> order some more resistors. The way the photo resistor will work in a
> circuit is vary similar to a pot with the exception that 1 side will not
> change resistance. What essentially happens is that the photo resistor will
> work like a rheostat (think Pot with only 2 leads) that is in series with
> another resistor which values are known. Measurement is taken between the
> two.
>
>  Given the series resistor relationship, we may never see the full
> granularity of measurements between 0-1023 on the arduino unless something
> is done creatively with voltage references.
>
>
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>
> --
> Bill Heffner, Ph.D.
> Associate Director
> Int. Material Institute for New Functionality in Glass
> Lehigh University610-758-6677wrh304 at lehigh.edu
>
>
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