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Old 17-02-2020, 08:48 PM
Sunfish (Ray)
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Peltier Cooling ASI Camera

Finally tested a peltier cooler for an ASI Camera. After a few runs I managed to get the temperature down from 30-35 degrees down to 12 degrees with a 100W TEC1 12712

I simplified the construction using a heat sink and fan connected straight to an aluminium disk screwed onto the ASI 120MM. I have not shown the stubby cooler which was my insulation sleeve. Perfect fit for the ASI.

Did not fog up the inside window at this temperature, but the outside when I took off the stubby cooler.

Maybe I will work up to trying on a ASI 1600

Ran the little DiaMec 12v battery down in about 20 minutes though. Perhaps i need to try a lower wattage or find a better power supply..

I took some sample images with the camera covered at 60sec 14 degrees, 30 sec 23 degrees and 30 sec 35 degrees. Not sure how much better this will be in practice.
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Old 17-02-2020, 08:51 PM
glend (Glen)
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You should look at the histogram for your darks to determine what effect your getting. Good luck, i suspect, without dessicant in the sensor chamber, that you will shorten the life of the camera considerably.
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Old 18-02-2020, 10:22 AM
Sunfish (Ray)
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I checked the statistics in Fits Liberator . The standard deviation I think shows the level of thermal noise in the dark frames and at 35 degrees it is 16, at 23 degrees it is 9 and at 14 degrees it is 5.9. The peak is 200, 185, 37 respectively , all humped on the left at 14 degrees. Seems a big improvement.

I have seen projects with large crystal desiccant used in filling the unused ST4 port. I wonder how different it is when using the camera cooled at this level than using it outdoors at 5 degrees which is probably what the minimum outer casing is.

Like a nice cold beer. Perhaps it will work bolted to the base of my sealed DSLR if I keep it in the fridge in a bag with some desiccant first.
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Old 20-02-2020, 08:59 AM
Sunfish (Ray)
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Thanks Glen. A good reminder about condensation.

I tried another test, limiting the cooling to 17 degrees and not using any thermal grease on the 1/4 camera bolt. The outer case stays about the same temperature as the sensor and there is no fog on the outside of the sensor window at that temperature on a humid 25 degree night.

Dropping from 35 degree sensor to 17 degree sensor changes dark frame standard deviation on Fits Liberator from 16.9 to 4.9 so a big improvement according to Primaluce cooling discussion. Am not sure how to judge from the histogram otherwise.

I wonder if I can control the 12 amp TEC module with a 14 amp rated dew heater controller using a 12 amp fuse. Any suggestions?
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Old 22-02-2020, 08:36 PM
Sunfish (Ray)
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Connected the peltier and fan to a 12v 10-14amp rated Kendrick dew heater controller. Works a little slower but does get down to 17 degrees from 30 after a while.

Each channel only provides a maximum of 6v. Does preserve the battery life.

The two critical elements in cooling appear to be thermal grease between the peltier, the heat sink and the cool plate/ pin and also insulation of the area of immediate connection at the peltier and cool plates. Isolation of connection of the two plates also is required with nylon spacers or nylon bolts.
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Old 22-02-2020, 09:22 PM
glend (Glen)
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I used a 12V 6amp PWM controller to throttle my Peltier, in the cold finger coolers I built, you can buy them on eBay for about $5. I suggest a temperature sensor with remote cabled probe that can be inserted into the sensor area. A small plastic project box can house both the PWM and temp display head.
You will need a heat sink/fan to exhaust heat from the hot side of the Peltier device.Little Laptop scroll fans (ebay) can do the job. Obviously the bigger the heat sink and fan combo the better in terms of Delta T.
If you do not exhaust the heat from the Peltier hot side you will cook it pretty quickly.
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Old 22-02-2020, 09:57 PM
Sunfish (Ray)
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Thanks Glen for the advice about the power supply . I need to find something to run it.

I have been using a large 100x 60x60mm aluminium heat sink and 100 mm power supply fan from an old Pentium 2 . Works well with the 10mm thick aluminium cool side disk and thermal grease . A little bulky but effective and free.
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