Clear Sky Detector

[Tom Droege <tdroege2@earthlink.net>]

Last night was almost solid clouds.  I set up the Mark IV so that it would 
take darks when the sky was cloudy and object frames when the Clear Sky 
Detector said it was OK.  The result was that the detector found 3 patches 
of clear sky out of about 150 images.  Since only one of these was really 
clear, I think I have it set about right.

Next comes the Day/Night detector.  I found a Panasonic device that might 
do the trick.  The PNA4603H.  I ordered 10 at $3.51 each.  We shall see.

I will then just turn on at dusk and let the Mark IV decide what to do.

For those that have asked, the TEC I am using is a Melcor 
CP1.0-127-05L.  If I were designing from scratch rather than taking a 
device out of a cabinet, I would use one with longer junctions.  For this 
purpose I would pick one with the largest number of junctions.  The signal 
is of order a millivolt so a low offset amplifier is needed.

Edison is supposed to have said "Invention is having an idea and a lot of 
junk".  I do have a wonderful collection of junk.

Tom Droege