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ZWO ASI385MC Peltier Cooler


Stargazer33

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Whilst browsing through astronomy videos on YouTube,  I came across a couple of videos on fitting a peltier cooler to standard ZWO cameras. I had been thinking of doing this to my ASI385MC since I made a coolbox for my DSLR back in 2016. Martin Pyott's (Astronomy 4 Beginners) build just had a heatsink and fan; Ewan, Astronomy Addict added a cheap Chinese temperature sensor and controller.

I have added a cpu cooling unit instead of just a fan:

I purchased a hotshoe adaptor from ebay to use to attach the cool plate to the camera and to act as a bit of a cold finger, getting as close to the sensor as I could without actually opening the camera. I chose an aluminium one as the thermal properties would be the same as the camera body. I had to cut down the thread to fit into the tripod mount hole on the camera and also round off the  corners of the hot shoe plate to fit into the recess I cut into the cold plate in order to get a flush surface for the peltier to sit against. I used an old forstner bit to remove just enough material from the cold plate to allow the hot shoe adaptor to sit flush.

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I bought the Arctic Freezer 34 esports tower cpu cooler to help speed up heat dissipation from the hot plate side of the peltier. The cold and hot plates are 100 x 100 x 3 mm aluminium plates. The Arctic Freezer 34 esports come with various fixings for different CPUs, including double ended threaded stand-offs. Drilling and tapping four holes in the corners of the cold plate allowed me to screw these in.

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I cut some thin foam I had lying around to 100 mm square and cut a hole in the centre the size of the peltier. I poked the wires through the foam and then using some MX-4 thermal paste on the cold side of the peltier, I placed the foam/peltier onto the cold plate. More MX-4 paste was spread onto the hot side of the peltier and then the hot plate, with larger holes cut into the corners so the stand-offs could pass through, was placed on top.

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Yet more MX-4 paste was spread onto the plate of the cpu cooler and this was then attached to the stand-offs using the supplied thumb nuts (?).

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The camera screwed onto the cooler:

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The next part was a bit of a pain! I couldn't find a project box of the dimensions that I wanted and the one I eventually bought had large areas cut out to enable securing , which left me with even less room for the wiring. This coupled with the atrocious Chinese to English translation for the temperature controller had me muttering under my breath some rather unpleasant things!

Eventually I managed to get everything wired up, but not before I had to order another Bionix fan after allowing the magic factory smoke to escape from the original one when I got the wiring mixed up! I knocked up a small bracket to mount the control box to the cooler and with the temperature probe placed next to the camera I put the insulated cup around the camera body.

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I forgot to take a picture at the time, but during the first trial, I had a reading of 4°C from the temperature sensor and it was still falling when I turned the unit off. As I was testing it inside, a lot of condensation was forming on the cold plate and on the nosepiece and ir/uv filter of the camera. The sensor however looked clear.

I may have to buy one of the ZWO camera dew heater units or possibly knock something up myself to keep the filter clear of condensation. 

With hindsight I think I should have gone for a cpu cooler of this design: 

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This would mean less side force on the nosepiece.

Edited by Stargazer33
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  • 3 months later...

As I've not been able to get out at all this holiday I decided to reduce the weight of the cooler. I also wasn't happy with how far the CPU cooler extended out from the back of the camera. 

I saw this cooler shortly after I finished the original and decided then to modify the unit. ARCTIC_Freezer_11_LP.jpg.387b661860d5aee1d4df069f7de457bc.jpg

The unit now looks like this:

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For comparison, the original CPU cooler weighed 627g; the new one weighs only 239g. So it's nearly two thirds lighter. 

Edited by Stargazer33
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