Peltier Cooling of Meade DSI

[Heian (Mark)]

Hi everyone,
after watching with interest the various projects regarding cooling of webcams I got inspired to make an efort on cooling my meade dsi. I did not cut into the case as I did not want to go beyond a point of no return, this is a primitive + cheap add on. The dsi rear case is a simple heat sink, which "should" be connected by a finger to the ccd chip. My plan was to cool the rear case and then cool the ccd.
I got a peltier module from Jaycar, a heat sink and a fan from an old PC power supply.
The voids between the fins on the dsi case were filled with alfoil to maximise conduction, heat transfer grease was applied to this area and the peltier, the heat sink + fan were then tied together onto the case. the photo's show the arrangement.
And it worked , too well as the chip condensed up during testing...

I also have a range of gadgets from Steve Mogg, an adapter for slr lenses, and an 1.25" filter holder. The idea of sealing the chip from ambient air was done by the use of an o-ring placed between the filter holder and the meade front face, the slr adapter then screws down on the filter holder/o-ring giving a reasonable seal.
Testing showed condensation dripping off the case within 20 mins and the chip staying clear. After 50+ mins the chip was still clear. So, all i need now is for some clear skies...

Total cost: Peltier $12, heat grease $4, heat sink $9, fan free.

The shots show the effects; dsi on for 40mins, and then after cooling for 20mins. The capture settings were indentical, 4 min exposure, no dark subtraction.

[bojan]

This looks very promising :-)

[[1ponders] (Paul)]

Nicely done Heian.

If you haven't done so already check out www.webcaddy.com.au and look for the "Outback Cooler" link at the side bar for some ideas

[Heian (Mark)]

Paul,
I have been looking at them for some time..(fence sitting can be so painful at times ). I also got inspiration for my mod on the web, where some people had done the same thing...

with someluck I'll be able to see what a difference it makes to images..

[[1ponders] (Paul)]

At least it's a picket fence and not barbed wire

I know what you mean. Wish I new how to make camera lenses

[LX200]

Great Heian
Will give it a go on the DSI-PRO
in this wet'n wild weather

[Omaroo (Chris Malikoff)]

Dang it! I'm going to do my LPI now too.

LOL!!

Nice work BTW Heian

[Heian (Mark)]

The biggest problem I could see is having to take darks each time the camera is in use, especially on the DSI PRO versions. It's my understanding that their software will tell you if there is a temp difference between the chip and the temp of the dark frame.
Over the course of a night, dark frames may have to be done fairly regularly..

Just another complication...

cheers

[ballaratdragons (Ken)]

hmmmm, I just re-found this old thread!

Would one of those Peltier coolers out of one of those 'carry' car fridges work in this application. Dork Smith is selling the fridges for $20 at the moment!
And what would be the Voltage and Amps needed to run this successfully?

I can keep the condensation out (to a point) with my IR/UV filter attached to the front of the nosepiece.

EDIT: It's OK, I just found out by reading the ad properly: 12v, 3 amp, 20 degrees below ambient

http://www.dse.com.au/cgi-bin/dse.st...uct/View/M4500

[Karls48 (Karl)]

I’m going to fit Peltier to my DSI Pro also. I tried the camera last night and find out that on coolish night it got a lot of hot pixels. That means that it will get much worse in the summer. But I’m waiting for K140B - NEW TEMPERATURE CONTROLLER KIT from Oatley Electronics. With temperature controller the CCD chip should be kept at reasonably constant temperature therefore reducing number of hot pixels and number of dark frames required. It should also reduce power consumption somehow ( if not set for maximum cooling). I will also make little box from polystyrene to fit over camera heatsink with square hole in the middle for hot heatsink and fan. Heatsink on the camera has been designed to radiate heat away and it is inefficient to cool such a large piece of aluminium that is exposed to ambient temperature

[Heian (Mark)]

Ken,
In my first trial I did take the peltier from a car fridge. The problem I found was that it was physically the same size as the DSI case. This meant that there would need to be more "fiddling around" to get good contact between the cooler and the metal case. By using the Jaycar peltier, it was smaller, lighter and hence easier to fit.
I just connect it up to a 12v power source and let it run without temp control. As I mentioned in the original post, a series of darks may need to be taken each time you go out with it, but after 20mins of "cool down" a single frame at each exposure setting is fine.
If you can, get a Mogg adapter and connect slr lenses to the DSI. It works really well.

cheers
Mark

[Karls48 (Karl)]

This afternoon I fitted Peltier on my DSI Pro. First I machined heatsink fins flat, it doesn’t need much machining about 2mm. Then I cut and squared piece of aluminium plate slightly larger then Peltier. Filled the gaps between heatsink fins with compressed aluminium foil. I should have use heatsink compound but I could not find it. I used Superglue to attach aluminium plate to DSI heatsink. Don’t laugh; Superglue is often used in commercial production to attach small heatsinks. Connected Peltier briefly to the battery to find out which side is hot and which cold one. Then I Superglue Peltier to the aluminium plate and Superglue old computer CPU heatsink and fan on hot side of Peltier. I covered rest of the camera heatsink with antistatic foam sheet. And that’s it. I connected this contraption to 10A variable Power Supply and it worked. At 13.8V it draws 3.2A, so battery will not last long. Now I’m waiting for Temperature Control Kit to arrive.
Wanted to try it tonight but it is cloudy. So I’m running it on the bench. Yes there is a big improvement in noise and hot pixels. But it is not getting as cold as I expected. Before cooling the temperature (measured inside nosepiece) was over 6 degrees above ambient. Now after running it for an hour it is 4 degrees bellow ambient.
I think that computer fan is too small and I should have used heatsink compound. Also I will have to unscrew the fan and reverse it as it is now blowing hot air on the camera.

[ballaratdragons (Ken)]

Originally Posted by Heian

Ken,
In my first trial I did take the peltier from a car fridge. The problem I found was that it was physically the same size as the DSI case. This meant that there would need to be more "fiddling around" to get good contact between the cooler and the metal case. By using the Jaycar peltier, it was smaller, lighter and hence easier to fit.
I just connect it up to a 12v power source and let it run without temp control. cheers
Mark

Thanks Mark, glad I didn't have the money to buy one today, it would've been too big

Originally Posted by Heian

If you can, get a Mogg adapter and connect slr lenses to the DSI. It works really well.
cheers
Mark

No thanks. That's more expense I can do without

[Heian (Mark)]

Good luck with the mods Ken.

Maybe you can do a better job than mine and not use wire and cable ties to hold it all together...

cheers
Mark

[Karls48 (Karl)]

I have redone my Peltier cooling for DSI Pro. First attempt by filing spaces between cooling fins was not very successful. It did not cool enough. This time I machined cooling fins right off used plenty of silicone heat transfer compound and installed stronger fan. I was able to cut groves in two heatsink fins and to clip fan and the small heatsink on Peltier in same way as it was originally attached to CPU.
I also received and build Temperature Control kit and it is working fine. I set the temperature on 10 Deg and with ambient at 20 Deg it reaches this temperature in about 15 minutes and it got no problem keeping it there.
If anyone will build this kit please note that there is an error on PCB overlay and in the instructions. To set it for cooling the link must be soldered to C-A not B-A as stated in the instruction

[xelasnave]

For what it is worth... I have had them running at only 5.8 volts...
slower but they work..
Ken it seems as the effort to sort out a cooling solution is worth the trouble as the facts are cooling works... end of story really.
alex

[ballaratdragons (Ken)]

Originally Posted by xelasnave

Ken it seems as the effort to sort out a cooling solution is worth the trouble as the facts are cooling works... end of story really.
alex

It appears I won't need any peltier cooling for a while still. Our night temps are still hovering between 2 degrees and -2 degrees!!!!

I have a nice cold camera

[Karls48 (Karl)]

Well, I cannot get camera that cold even with Peltier.

[xelasnave]

I had to scrap my unit I had made from the remains of the Dck Smith cooler as the weight was too much to handle without an elaborate counter weight system... I am going to bolt it straight on the camera body within a sortta alfoil bag... Up North the noise really shows up from this time of the year..
I have been playing around with the units a fair bit as one is my only hope of a little fridge up home... its large enough to hold some cooked meat for a couple of days.. I was surprised the low voltage that they will work at..
I leave the 300d in the cooler all day and that helps for a while I think.

Having one in the car is neat... I mean once if you had a fridge in your car that was a big deal ..now $20 ..what a wonderful planet this is.

alex

[xelasnave]

Heian I really like what you have done ... the comparison shots show a dramatic improvement.
Great work thanks for sharing
alex