Re: ATM cookbook 245 and computer power supply

[Brian Nestel <blast@aloha.net>]

 Eldereis de Paula wrote:
> I am building the Richard Berry Cookbook  CCD camera.
> I was wondering if someone had used a computer power supply instead of
> building one?
> Computer's power supply are of "switched" type and I am afraid this can damage
> the CCD chip!
Hi:
One problem is that most pc switching supplies put out only +/- 12v, 
and the -12v side is usually low current, also you really need a couple of 
volts higher for the regulators in the camera to work right.
Another problem is that you need to control the current going
to the peltier to have a gradual cooldown so you don't thermal shock the CCD
chip, the 5v pc supplies like to start under a medium load otherwise they get
erratic. 
The third problem is noise, if you don't have proper filtering and
shielding you will get noise in the preamp.
You are better off building the power supply as described in the book or
getting commercial linear supplies.


-- 
Aloha   159 30 W, 21 55 N
Brian   Middle of the Pacific,
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