>> 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)?
>>

        Our ELM337 was designed with this in mind (12C508 based). It uses a
single CdS cell to detect the presence of visible light but provides a 10
minute delay before changing states. This prevents someone's headlights in
the driveway  affecting your blinds or sprinkler system or whatever. If
you're using a PIC, it's easy to make delays this long.


        Jim Nagy
        Elm Electronics
  ICs for Experimenters
http://www.elmelectronics.com/

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