My take on a peltier cooler box

[RAC]

Nothing really new here but i thought i would share my very simple cooler box idea.

Basically it's a soldered up copper box with polystyrene around the outside and a polystyrene lid. The peltier is bolted to the copper with a water cooler on the hot side and a low profile pc video card fan and heatsink on the cold side and of couse thermal paste is used between surfaces.

The camera has an MPCC on it to suit my scope so this suits as the box is held between the T-piece and the MPCC.

The total weight with camera is 1150grams so not too bad.

Water is pumped through the cooler then through a small raidiator in a chilly bin with ice then to a bottle used as a reservoir then back to the pump then peltier cooler ........

A thermocouple is bluetacked in the cameras trypod mount thread hole and it takes about 1 hour to get to -5deg C. There is a dew heater sitting in the focuser just under the MPCC to keep it dry. The dew heater is just made out of two old fuel tank resistor cards(nichrome wire) wire in parallel running on 12 volts.

The peltier and fan in the cooler box are run at 14.8 volts from a modified 10 amp battery charger.

Very cheap and very effective. I would call this my version two.

The ducktap is just there to help the polystyrene last a little longer. A glue gun was used to hold the polystyrene on.

[MG1]

Great job there, nicely put together...I need to think about something like this soon.

Can I ask a silly question?

Do you turn the fan off while imaging and if so doesn't the chip warm back up again...if not does in not cause vibrations in the image?

Sorry if that seems really daft question, just something that's played on my mind having seen a few of these recently.

[Gina]

WOW! I like it - lovely job Do you find it makes a big difference to your images?

Could you give us more info on the Peltier device and pump etc. please? This could well be something I might try later on

[RAC]

Great job there, nicely put together...I need to think about something like this soon.

Can I ask a silly question?

Do you turn the fan off while imaging and if so doesn't the chip warm back up again...if not does in not cause vibrations in the image?

Sorry if that seems really daft question, just something that's played on my mind having seen a few of these recently.

I leave it on fill time, it makes no change to anything, the vibration from the small fan is very very little.

If i don't have the camera on it will get to about -10deg C but with it on and taking shots it sits at -5 all night.

[RAC]

WOW! I like it - lovely job Do you find it makes a big difference to your images?

Could you give us more info on the Peltier device and pump etc. please? This could well be something I might try later on

Hi thanks. I havn't done any tests but yes it does make a large difference. With the camera at say 20degC i get about 50 odd hot pixels and with it at -5 i get about 1 or 2 and the noise is a hell of alot better.

The pump is far too big, its a water pump you would find in a camper that looks like this but i've got a pwm speed controller circuit running it very slowly. One bag of ice will last about 4-5 hours easly. The next thing i want to do is insulate the hoes feeding the cooler so the water is even colder at the peltier.

[martin_h]

I should imagine a small aquarium pump would do the job.

[RAC]

I should imagine a small aquarium pump would do the job.

I did think of that but most have a head height of only about 1m. You would need to try one, this pump i have was a spare so thats the only reason i'm using it.

One big advantage of using the water cooling is you lose the weight of another big heat sink and fan and you get to choose the temp alot more easy.

[Coco]

Any chance of seeing some single image samples..

[Earl]

Humm liquid cooled CCD piece of cake to do just like a CPU do any commercial CCD's do this?

[dark star]

Is it possible to do the same sort of thing with a DMK41 CCD camera?

I use this for spectroscopy and will not be able to afford a cooled CCD for a long time.

Given my lack of knowledge of electricity I will try some even simpler projects first!

I am just curious if it would be possible.

David

[RAC]

Any chance of seeing some single image samples..

Both of these are 100% crops of the exact same part(top left corner). The brightness slider in Canon DPP was set to 1.33 for both shots and everything with else was 100% the same. The small white dots seem to be some sort of jpg artifact.

5min at 20DegC

5min at -5degC

[Earl]

Do you get any condensation issues?

[RAC]

Do you get any condensation issues?

No none what so ever as i never open the box when its cold. There is only x amount of moisture in the air to start with and as soon as the cold side of the peltier gets below the dewpoint for the air inside the box any moisture will form on it and then freez, this leaves no moisture to form on and maybe in the camera. There seems to be nothing ever frozen on the front of the senor even after 10 or more hours at -5deg. If i don't have my dew heater on then the front of the MPCC fogs over very fast as its open to the outside air.

[RAC]

I did some more testing today and also made a cold finger for the sensor. My thinking was that if the camera frame temp is -5deg(at the trypod mount) and the air temp around the camer is around -8 to -10deg then if i was to add a heatsink to the sensor so it could access this colder air it would keep the sensor colder and if nothing else keep a more stable sensor temp.

I've never had a temp probe right on the sensor befor so i cant say i know what the sensor temp was really doing.

This is the cold finger i made today.

IMG_0093 | Flickr - Photo Sharing!

I've put my thermocouple right up against the sensor and copper coldfinger. I would love to be able to have had this before this mod as even with the cold finger that has alot more heatsinking than the standard sensor the temp will raise from -5 to -4 on the first 5min shot then after 9 5min subs it will get no warmer than -1.8degC and just set there from there on. It takes about 10min of no shooting to get the sensor back to -5deg.

Next will be to insulate the water lines to the cooler. And buy a better mount LOL.