Re: ATM 245 Cookbook Cooling

["Tony Cecce, Corning, NY" <CECCE_AJ@corning.com>]

There are a couple of points which haven't been made yet.  First
consider that Peltiers yield a delta temperature from one side 
(ambient) to the other.  Secondly, dark currents vary with 
temperature thus dark frames should be taken at the same chip 
temperature as the image.  Thirdly, ambient air temperatures change 
throughout the night.

All this means you have three options; actively control chip 
temperature, control ambient temperature, or take a new dark frame
whenever ambient temperature changes.

Option one is what the pro cameras do, they typically monitor
the temp with a thermistor and vary the power going to the
cooler.  Option three will obviously reduce productivity.

Berry has offered an elegant temperature stability system by
cooling with ice water which will always provide a constant
ambient temperature of ~0oC, and thus a constant chip temperature
when running the Peltier at a constant power.  Another added
advantage is the constant cold ambient throughout the seasons 
(except when it gets real cold).

Tony