Peltier cooling a DSI II

[pmrid]

I bought this DSI II recently, with the idea in mind of using it for planetary work but it seemed to me to a lot noisier than it's press would suggest. SO I decided to do this mod:

http://astromodifications.blogspot.com.au/2010/01/im-testing-this-now-by-adding-some-text.html

It's a bit of a leap to take the angle grinder to the back of the camera but it worked out pretty much as it should. I took the peltier and heatsink out of the chinese (supposedly 60 watt but only in someone's dreams) peltier assembly I had bought for my 350D but decided not to use. The best I could get was about 10C using it that way. SO I ditched the cooler side heatsink and fan and attached the peltier to the back of the DSI directly. Also put a small temperature probe inside the DSI.

Time to fire it up. Ambient was 28.3C. I didn't run the camara for this test. I really wanted to see how the peltier would work in this configuration. Bottom line is it's didn't work a whole lot better.

I ran it for 20 minutes and managed to hit equilibrium at about 11C below ambient.

I should be reasonably happy with that I suppose since that means I have reduced thermal noise by about 85% (using the 5C rule). The next test will be with some darks.

But that's it so far. Here's the graph from this first run.

Peter

[ZeroID]

Is your TEC a 12706 ? I've managed to push my AS! 120 down to -10C from ambient 24C with one of those (50 watts). It does have a substantial thermo radiator assembly on the back and the camera is buried in insulation. I ran it at 12 volts and about 4 amps with a fan on the output radiator. Check the DSLR Peltier thread for pix and any details.

[pmrid]

G'day again. Yes. I've been on the DSLR thread too. It's the same assembly and the same peltier as yours and the performance is about the same. Tests yesterday and today came up with the same result - a drop of about 11.5 below ambient after 10-15 minutes - it was running at 3 amps/12 volts.

I did a test this morning wrapping the outer camera case in insulation but the result was indistinguishable from the uninsulated ones.

I did install a dehumidified plug (a Farpoint one designed for old ST7s) to keep humidity inside the camera case down. But there is going to be a problem with that little UV/IR cut filter that Meade have put across the nosepiece area. That did fog up on the outside - so I'm going to have to solve that issue on humid nights I guess. Might be a job for a heater strap.

Anyway, it's all academic isn't it? There hasn't been a clear night since I don't know when and there doesn't seem to be any prospect of any coming soon either. That's what bringing on this tinkering urge. It has to stop!!!

peter

[gb44]

Another possibility is - using the cooler box for the canon 350d I added a hole for the my Meade DSI IIIC so I can cool one or other camera.

One cooler device without opening the camera.

Same problem - dew on the IR filter.

My 350d got too cold one night and it ceased to function temporarily.

GlennB