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Old 01-11-2008, 05:26 PM
TrevorW
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Peltier cooled cold plate

I'm toying with the idea of making a cold plate using a Peltier and heatsink fan from a PC etc etc that can be attached to the base of the camera to cool it during those warmer summer nights, but itstead of reinventing the wheel or be another person who have tried but found the idea useless please let me know.

Thanks
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Old 01-11-2008, 05:33 PM
Ian Robinson
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Bit cumbersome.

Thermoelectic cooling is much much more efficient and easier to impliment, especialy multistage thermoelectric cooling.

See http://www.rmtltd.ru/tec_modules.htm...FQykagodCHDo3Q
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Old 01-11-2008, 05:52 PM
TrevorW
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From looking at the site Ian I got the impression these are Peltier devices anyhow.

The Peltier device I have measures 40 X 40 X 5mm, the bulky part is the heat sink fan etc required to remove excess heat created by the Peltier.

Correct me if I'm wrong but a lot of CCD camera's incorporate Peltier cooling devices.

Cheers

Last edited by TrevorW; 01-11-2008 at 06:03 PM.
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Old 01-11-2008, 06:20 PM
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Bert's (avandonk) fridge cooler could be just the project you're looking for.
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Old 01-11-2008, 06:25 PM
Ian Robinson
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Quote:
Originally Posted by TrevorW View Post
From looking at the site Ian I got the impression these are Peltier devices anyhow.

The Peltier device I have measures 40 X 40 X 5mm, the bulky part is the heat sink fan etc required to remove excess heat created by the Peltier.

Correct me if I'm wrong but a lot of CCD camera's incorporate Peltier cooling devices.

Cheers
This will explain the principle.http://www.digit-life.com/articles/peltiercoolers/ and gives some useful info.


The attachment is a simplified sketch of how TEC of a camera CCD chip would be achieved (without pulling the CMOS CCD chip off the circuit board which is probably a very bad idea), guess it depends on how free space there is behind the circuit board the CMOS CCD chip is soldered to, the copper heat cooling sheet need not be more than mm thick (probably a lot less) to get efficient cooling.

I do not think cooling the outer body of the camera by peltier TE cooling will be very effective as the body of the camera will probably be ineffective as a medium to cool the CMOS CCD chip - a lot air spaces and gaps and air is a very effective thermal insulator.

Close contact to the CMOS CCD chip is required I think to cool effectively.

Another option may be to pump superchilled , dried and filtered air into the camera somehow directing it at the CMOS chip (which might be achieved by directing filtered and dried air over a multistage TEC and passing the very cold air over the CMOS CCD chip via some insulated plumbing that will enter the camera body at an appropriate location ). This would I think be easier to impliment and would involve only drilling two holes in the camera body.



Would I do this to my 40D? ... No not at this time or any time in foreseeable future.
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Last edited by Ian Robinson; 02-11-2008 at 07:03 PM.
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Old 02-11-2008, 05:45 PM
TrevorW
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I made up a temperature controller device from a kit that should allow the Peltier to acheive sub zero C temperatures but was wondering should I use thinner or thicker aluminum for the cold plate toss up between 2mm and 5mm, also I was going to use nylon bolts to hold the Peltier between the cold plate and heat sink should they be OK, any feedback welcome. I don't envisage glueing a plate to the back of the CCS circuit board until sometiem after the warranty expires.

Cheers

Cheers

Last edited by TrevorW; 02-11-2008 at 06:03 PM.
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Old 02-11-2008, 07:10 PM
Ian Robinson
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Quote:
Originally Posted by TrevorW View Post
I made up a temperature controller device from a kit that should allow the Peltier to acheive sub zero C temperatures but was wondering should I use thinner or thicker aluminum for the cold plate toss up between 2mm and 5mm, also I was going to use nylon bolts to hold the Peltier between the cold plate and heat sink should they be OK, any feedback welcome. I don't envisage glueing a plate to the back of the CCS circuit board until sometiem after the warranty expires.

Cheers

Cheers
Another concern may be how well the soldering will handle thermal shock (in summer of going from maybe mid 20s - mid 30s C to - 60 to -70C) in a few minutes or maybe a lot less (depending on how efficient and effective the heat pump is), and how the circuit board will cope with thermal shock in general.
I suspect provisions for this are made in cooled cameras at the design stage and in construction and assembly. The average DSLR is not designed to cope with extreme thermal shock.

The thermal conductivity at room temp of aluminium is 250 W/m K, cupper is much better at 401 W/m K and silver is 429 W/m K. I'd use chunk of copper as my heat drain.
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Old 02-11-2008, 07:22 PM
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TEC's and Peltiers are much the same... if not identical...

I've used peltiers to cool processors of computers (back in the days when I did crazy things with computer, along with phase change evaporative cooling setups and water cooling) And Peltiers and TEC's work in much the same way..
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Old 02-11-2008, 07:26 PM
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I tried this, went nuts with it

Use a copper finger, aluminium is a waste of time, lousy thermal conductivity.

you will have to permanently butcher your camera, the peltier-cooled finger has to directly contact the CCD sensor.

What killed it for me, was condensation, very hard to eliminate.

Its all doable, apparently Houghys commercial mod works very well, but your in for a world of pain doing it youself, a real challenge.
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Old 02-11-2008, 07:29 PM
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Ian, you are right here.

In cooled cameras, only sensor is cooled. Soldering on cooled parts and circuits is avoided (crimping is preferred method)
But most importantly, all connections are made such they allow for expanding/contraction. I saw a lot of solder connections teared apart by thermal stress in the course of my work, after only couple of cycles (from +80 to -35 and back).
That is why I think Avandonk's method (fridge) is what I would do myself (however so far I do not see the need for this, since Melbourne's LP prevents me from going any longer than 1minute, so noise is not the problem for me, at the moment)... Simply and slowly lower the environment temperature camera is in.. Mimicking the natural cooling when you take camera outside from relatively warmer room.
DSLR's are NOT design to survive extreme thermal shocks.
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Old 02-11-2008, 08:36 PM
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Another home made fridge...
http://ghonis2.ho8.com/rebelmod450d16c.html

Cheers
Doug
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Old 02-11-2008, 09:10 PM
TrevorW
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Thanks Dougie seen that one but didn't like the cumbsersome nature of the container.

I'm not talking about drastic temperature differences here a drop of 10 degrees or so on ambient air temp significantly reduces noise created by the CCD.

Condensation occurs when the is a signicant drop especailly sub zero in temperature relevative to ambient air temperature as it will be external to the camera and temperature controlled condensation shouldn't be an issue.

I had thought about copper but sometimes hard to get in small sizes and more expensive and the only scrap metal yard I know that may have had it closed down recently after 60 years in business.

But it's all fun trying
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Old 03-11-2008, 09:08 AM
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Hi Trev,
I have been experimenting with cooling my camera with a peltier cooler and cpu heatsink for sometime. It`s definitely worth giving it a go I reckon....Either by enclosing and chilling the whole camera (like a cold winters night) or directly to the cmos..
Still contemplating how to modify the camera internally as yet to make it more efficient? but a copper plate on the back of the cmos bridged to the cold finger would be the way to go..
At he moment I just attach via the tripod socket and I get maybe 7-8 degree C drop inside the camera. But do get some condensation on the base and sometimes ice..Cold finger is a 4mm thick piece of Alluminium. Also a lightwieght foam surrounds will be in the making to insulate it more and get the temp down even more.
Attached a pic of what I have been using so far..
I would be interested in info about that kit but Trev! as I am after a way to monitor and control the peltier..
I am aiming at getting the camera a few degrees above 0 on warm nights..
cheers Gary
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Old 03-11-2008, 10:00 AM
TrevorW
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If you go to this link belwo you can get the termprature controller, I've also toyed with the idea of having a LCD incorporated to show the temp of the Peltier.

http://secure.oatleyelectronics.com//index.php?cPath=80&osCsid=2c1ed9960 98ba9ab78e39ca7aa4560e2

PM me your design mine looks simlar but attached to the base of the camera

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Old 03-11-2008, 03:40 PM
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Here is a side by side comparison of a 400px crop from the center of the frames..
Ambient temp was 30 degrees C.
First frame: Camera was left on for 45min to allow it to reach operating temp then a 5min exposure at iso 1600 was taken.
Second frame: Peltier turned on after first exposure and left for 45min then a 5min exposure was taken..Ambient temp stayed pretty constant and within a degree or two..
I reckon a good 8-10 degree difference there..
cheers Gary
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Old 03-11-2008, 07:29 PM
TrevorW
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A marked difference considering it was also a 30 degree night and are talking only and 8-10 degree difference in temp overall. This difference would help produce better subs and darks.

Cheers
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Old 07-11-2008, 05:24 PM
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I've got the Peltier down to -10 will post some pocs when done
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Old 07-11-2008, 05:35 PM
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Cool Trevor, that was quick. Looking forward to pics.

BTW I had trouble finding copper, until I twiged on to flattening 3/4 copper plumbing pipe, worked well.
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Old 08-11-2008, 09:39 AM
TrevorW
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Ok here's the result I'm yet to field test it but want to use a 12v 5 amp regulated power supply and not my battery pack as the Peltier draws 4 amps. I would like to also attached a LCD temperature display so I can monitor the cold plates temp I've got the parts just need to work on it. I've covered the base of the cold plate with neoprene. I've incorporated a power switch with LED. A work in progress so to speak nothing original.

Cheers
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Old 08-11-2008, 10:30 AM
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OK, thats one hell of a heatsink .

Should get you some usefull degrees below ambient.
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