Peltier cooling of 1100D sensor chip

[Gina]

Here are a some ideas for the cooling arrangement.

1. My original idea - replacing the LCD Display with the cooler. Lighter and neater but no display.
   
2. Taking the copper strip out through the side of the camera using the cold finger I've already made.
   
3. More efficient side-entry system using a coldfinger bent to a "dog leg".
   

[Gina]

Been having a good think about positioning the cooler. I would like to keep the display I think. One of the problems with the side mounted hot side cooling is the USB connection. The supplied cable has a straight plug which sticks out quite a long way. This means either putting the cooler some way from the camera or far enough back or forward to clear the plug. I think the forward direction will interfere with a filter wheel. So to the back looks the only option. This will put the weight even further from the mount and add to the balancing problem.

[Gina]

Hot side cooler towards back.

[Gina]

While I've been running noise tests on the modified sensor assembly, I've been doing a lot of thinking about cold finger placement and studying my other camera. I believe I've found a better way of doing it - quite similar to the 100D and 450D mods. There is a space between the main board connectors on the right hand side and the frame where it would be possible to have the cold finger provided it was drilled with holes to clear the main board supports and the fixings for the sensor.

[Gina]

While I've been running noise tests on the modified sensor assembly, I've been doing a lot of thinking about cold finger placement and studying my other camera. I believe I've found a better way of doing it - quite similar to the 100D and 450D mods. There is a space between the main board connectors on the right hand side and the frame where it would be possible to have the cold finger provided it was drilled with holes to clear the main board supports and the fixings for the sensor.

[Gina]

More exact drawing. Cold finger needs slight bend to clear the connectors and standard USB cable replaced with right angle one.

[ponytale]

hI Gina , just thinking about your cold finger problem, hope this is not stupid in any way as electrical circuits are not my area , why not use copper cable with insulation to make cold finger perhaps with copper disks (eg small copper coin ground flat and soldered on to each end or even several small cables that you can thread around the circuit boards , if the small circuits that power the chip can deliver the energy to heat it why can't the same sort of cuircuits diisipate it if there are conected to a cooling device?

sorry if it sounds too simplistic but thats the 1st way i always think about a problem

then move on from that. best o luck with it anyway.

Tony

[Gina]

Well, I've never thought of using cable to conduct heat! Might work but would need heavy cable I'm sure. No, I'll stick with the tried and tested method of copper sheet. Interesting thought though

Actually, I think I have pretty much sussed out how to do it now and I'm just about to start cutting a new cold finger to shape.

[Gina]

OK... Guess who bent the cold finger the wrong way! Wonder if it'll bend back without breaking

[yesyes]

do you have something to make it hot while bending? That might prevent it from breaking...

[Islander]

Heat it to cherry red and then quench it - that'll make it soft enough to bend without breaking. Once it's in the right shape, heat to cherry red again and let it cool slowly

[Gina]

It was alright - Bent it back flat then bent it the other way at a slightly different place. The cold plate is just a little bit further from the camera body, that's all.

Clod finger now finished ready to fit into camera

[Gina]

Here's the finished cold finger with holes and notches to miss screws and brackets. (It's even got some thermal paste on it where I tried the Peltier TEC which I took off the cool box I was playing with earlier.) The right hand part goes between the sensor chip and the board it's mounted on. I have left the plastic film on part of one side to provide electrical insulation from the pins of the processing chip which protrude through the board.

[2stroke]

Gina mine had problems with cable H, use a bit of force as its extremely hard to get seated, it took me 30 mins to get right. On first fire up the cam didn't work because of this. Use a magnifying glass and look at your working 1100D as a reference, there 2 small out indentation that kinda go over a indentation in the clip or close to it. Anyhow is it safe to run the whole cam with back removed? cheers Jay

PS. Maybe trying carbon fiber or fiberglass would be a much safe and better electric insulator then plastic film on your cold finger. You could even use epoxy resin and build up coats

[Gina]

Gina mine had problems with cable H, use a bit of force as its extremely hard to get seated, it took me 30 mins to get right. On first fire up the cam didn't work because of this. Use a magnifying glass and look at your working 1100D as a reference, there 2 small out indentation that kinda go over a indentation in the clip or close to it.

Yes, I noticed those little pips on closer inspection.

Anyhow is it safe to run the whole cam with back removed?

Yes, seems quite safe but I find it useful to have the display and control buttons. I ran my camera without the back on for a week or more when we had some clear nights and I did a nice bit of imaging.

PS. Maybe trying carbon fiber or fiberglass would be a much safe and better electric insulator then plastic film on your cold finger. You could even use epoxy resin and build up coats

Carbon fibre is a conductor. I might try to push some very thin plastic sheet in but the gap is minuscule.

[Gina]

I now have cold finger v2 finished and fitted to sensor unit and both fitted into my working camera, which still works I decided to use the second sensor unit to fit my version 2 cold finger into rather than disturb the first so I had the filter mod to do too. This time I decided to put the IR/UV (front/bigger) filter back.

[Gina]

Cold finger in camera, camera all back together and working fine.

Here are various photos of the cold finger and how it fits in the camera. To cater for going through the side of the case a small piece was taken out of the side of the back cover and a section taken off the cover for the connectors. The cold finger itself had holes and notches cut to clear screws and brackets etc.

Cold finger fitted into sensor unit between sensor and processor board.

This photo shows the back cover side and connector cover cut out to miss the cold finger.

The components on the image processing board covered with insulating thermal paste to prevent any condensation causing short circuits.

Finally, the cold finger protruding through the camera side with the 40mm square pad for attaching the Peltier TEC.

[Gina]

Have simply added a 50mm square finned heatsink (without fan) on the cold finger directly without Peltier TEC to see how passive (unpowered) cooling works with this setup. Been running darks tests for 2 hours now and EXIF temperature is showing 30C - about 6C above ambient. This is lower than without the cold finger so the passive cooling is working. The test schedule runs for three hours and I'll post the final temperature later.

Later I'll try the Peltier TEC but I want to put a temperature sensor directly on the cold finger close to the sensor rather than relying on the processor temperature (though I think the two will be fairly close). I meant to do this before replacing the camera back.

[Gina]

Test run finished. Last half hour sub read 29C with ambient of 23C so with this setup we seem to be running at just 6-7C above ambient

[Gina]

Testing rig.

I've put Peltier TEC onto cold finger and a 60mm sq heatsink on top. Found a fan was essential or hot side got too hot and no cooling was being applied. So added fan. Now running 12v 50W Peltier on 8v and it's drawing 2A. EXIF T now stabilised at 15C with 22C ambient. Must set up some 1-wire temp sensors to read ambient, heatsink and cold finger temps and log these on PC.

Checked for misting up of filter or sensor and none - perfectly clean and clear image. Looking in through lens mount (having removed lens) and setting live view to lock mirror up, there was no sign of any condensation inside. The external part of the cold finger itself was running with condensation and I shall be applying thermal insulation both to stop this and reduce atmospheric warming.

Tomorrow I plan to mount the Peltier etc. properly and run further tests.

BTW - I now have APT set to record the EXIF T in the image file name. The more I use APT the more I like it

[AstroShomy]

We want an update!

[Gina]

This is an old thread of an old mod that has been superseeded - I am on version 3.

[AstroShomy]

Could you please give me the links to the "version 2" and "version 3" please? Thanks Gina

[Gina]

OK - here's some links :-

Version 3 :- http://stargazerslounge.com/topic/171415-1100d-set-point-cooling-with-peltier-tec-and-air-cooling-v3/

http://stargazerslounge.com/topic/157627-air-cooled-tec-with-cold-finger-dslr-cooling/

http://stargazerslounge.com/topic/163752-dslr-cooling-to-near-ambient-with-fan-cooler/

http://stargazerslounge.com/topic/163185-dslr-cooling-cold-finger-with-air-cooled-tec-working-version/

[AstroShomy]

Thank you so much!