Making a sunshine detector is easy.  Put a light sensitive device (LDR,
phototransister/diode, etc) in the area you want to sense the sun in.

It sounds, however, as though your real desire is to measure either 1) the
angle of the sun, or 2) whether the blinds are keeping the direct sunlight
out.

Take two translucent film canisters, put a short wall between them, and
aim them at the sun (so the wall is perpendicular to the path of the
sun).  Depending on the height of the wall past the canisters, a given
angle of the sun will shine more light on one canister than the other.  If
you have LDRs (Light Dependant Resister, such as the venerable CDS cell
(Cadmium Sulfide?)) then you can measure the resistance and tell which one
is getting more light, which would give you angle of the sun within the
range of your detector.  You can use a resister divider from the LDRs
going to a comparaor if all you want is "The sun is within the angle of
interest, close the blinds" output.

-Adam

"P.C. Uiterlinden" wrote:
>
> What 's the best way to make a sunshine detector?
>
> The purpose of this detector is to control (via a PIC of course)
> electrically actuated sun screens in front of a window of my house.
>
> First question is: would I need two photo sensors (one "looking"  to the
> sun, one looking in the other direction, so a differential measurement
> can be made)? Or would one sensor suffice (by measuring the absolute
> level of brightness)?
>
> Second question: would a sensor in the visible light range be the best
> choice, or UV (or perhaps even IR)?
>
> I'm considering to do a first test with a TSL230 (Texas Instruments).
> This device outputs a frequency proportional to the irradiance (visible
> light), so interfacing to a PIC is straight forward.
>
> Does anyone has experience in this field? Any suggestion is welcome.
>
> Paul.
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body