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Old 31-10-2007, 11:31 AM
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rogerg (Roger)
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Question CCD cooling limits - is damage possible?

When I first bought my ST7 I read in it's manual how I should not "over stress" the peltier cooler. That is, I should try to have it sitting at about 50% power.

I typically sit it around 60% power. In winter that gets me to -20, in summer that gets me to 0.

Does anyone know if there really is any problem with putting it at something like 85% power for extended periods? In summer it'd make a huge difference, allowing me to get down to -10 or so.

Roger.
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Old 31-10-2007, 02:41 PM
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turbo_pascale (Rob)
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In my limited experience with my ST7, the reasoning is to leave head-room for variances in the ambient temp. In the end, you want to achieve the setpoint temp and keep it there regardless of the ambient temp (which can have a decent swing at night!). Hence, 50% leaves plenty of room to move.

I can't categorically answer the question of if you can do damage (I seriously doubt it unless it was running at 100% all the time).

Turbo
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Old 31-10-2007, 03:21 PM
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I'm with Turbo, and with the warmer weather I too am finding -20 more difficult. Not impossible, but try taking darks for a library during the day.
I agree though, that the lee-way that you have at 50% is the likely reason, not so much the stress.
Write to SBIG, or post this on the SBIG forum, someone will know for sure.
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Old 31-10-2007, 05:09 PM
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[1ponders] (Paul)
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Just reading the SBIG and CCDSoft booklet for the ST-7XME and their suggestion is between 75% and 85%. There is no danger at running it at 100% but if your ambient temperature goes up then it will be harder to match your darks.

Will you do damage to the chip. No. CCD chips in professional observatories used to be cooled in a Dewar with liquid nitrogen. I'm sure they have advanced past that now, but it was effective and didn't hurt the CCD.
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Old 31-10-2007, 06:04 PM
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rogerg (Roger)
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Thanks all, I must have mis-remembered what I read.

85% sounds good.

Roger.
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