Cooling The ASI range

robert

I have read in a few sites that cooling is a option that vastly improves the ASI range of cameras also I read that ZWO is working on a cooled camera and I wonder if anyone has cooled the 120mc without voiding the warranty and to what level cooling can be obtained by whatever method also a direct query to Sam.

Can the new cooling system your working on be retro fitted to the cameras we have now?

Sam@ZWO

the easiest way is add the TEC to the back of the camera.

but its not very effective

we are going to make a completly new one intead of an upgrade part if we have such plan

marcos

Good day,

I have measured the depth of the of the center hole at the back of my ASI120MC It this is 12mm.

I have not opened completely the body of the camera, but it looks like that the back side of the camera sensor is touching inside structure of this hole so to disperse the generated heat to the housing of the camera.

If this is the case, than we could made and aluminium/copper bolt that come flat to the outside surface of the camera.

And then once a Peltier cooling element is connected to it, it will act a cold finger improving the cooling performance that is obtained by simply adding a Peltier to the back of the ASI.

Regards

Marco

Sam@ZWO

yes, the sensor is touching inside.

ags

This is my effort, no idea how good it will be. Weather is bad so may be a while till I can test it. If it is better than non cooled it will be amazing.

marcos

Nice Try, did you put something into the center hole of the ASI to transmit the cooling effect in a more directly way to the camera sensor that as Sam state is touching the housing?

This is how I will do it, I have attached the ASI to an Old Olympus OM 70/210mm zoom lens, and made a support to use it as a guide/wide field scope.

I am now just waiting for the TEC to arrive.

P6076254.JPG

P6076255.JPG

By the way, the cooler attached to the EOS in your pic, is it a liquid cooler? looks like a nice mod!

Regards

Marco

ags

One of my better Mars from April 2014 using the ZWO 120mm. I replaced the internal cmos pad and filled the centre bolt hole with the same thermal putty which I bought for the water cooled Canon. Initial testing: After 30 mins at 12v DC the heat sink was warm and the camera body was too cold to hold for long. I have a small voltage controlled heater in front of the cmos in the canon and may have to do the same for the ZWO to prevent fogging when humid.

ags

Yes the Canon is water cooled, actually it's not water but a mixture or methanol and radiator fluid. It is pumped from a 40 ltr tank in a fridge then under ground to the observatory through insulated pipes.

marcos

Very nice Mars pic ags! top!

and nice set up you have...

chripell

Tied yesterday, it achieves just a 6-7° gain (45W TEC and 13000 RPM fan) but better than nothing now that finally summer is here.

marcos

Hi Chripell,

nice,

Do you mean 6-7° under ambient temperature?

did you get much improvement in the noise?

I'm waiting for this one to arrive:

http://www.ebay.com/itm/1PCS-TEC1-12706-Heatsink-Thermoelectric-Cooler-Peltier-Plate-Module-12V-60W-72W-/400553393364?ssPageName=ADME

ags

Filling the rear void with silica like I do with the Canon should keep any moisture away. This is reusable marked silica which I dry in the oven when it changes colour to pink. I have a litre of this so only need to dry it 1 or 2 times a year.

chripell

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marcos

HI Chripell,

I do not mind the waiting time, this a long term project, I'm now assembling the power splitter/ controller to feed the dew shield and all the other accessory from a single power source.

It will be a while before I'm due to the cooler... :-).

you should use an aluminium or brass bolt, they conduct better than steel, of maybe as Ags did fill the hole with thermal compound?

Clear skies

Marco

lantaca

Sam wrote:
we are going to make a completly new one intead of an upgrade part if we have such plan

Hello, this is a great idea, i'll wait, thank you!

riklaunim

60W-72W Peltier is way to much. If a camera uses like 3W of electric energy, then it can't produce more than 3W of heat. Even 4W Peltier could cool it as he wants to even to negative temperatures (C).

I've played with USB powered Peltier (so up to 2,5W) and he easily made the whole case cold and the noise dropped as the sensor temperature also got lower. If the sensor would have a cold finger at the back the effect would be even stronger.

chripell

riklaunim wrote:
60W-72W Peltier is way to much..

You are right, I power the cell with a 12V to 5V step-down converter which results in a 6-7W power usage. Unfortunately I haven't had any luck by trying different type of photographic bolts as a cold finger.

Now I get the same temperature drop like robbeh reported on the German forum, from 33 to 19 degree C. I'm just a bit worried about dew.

murison

This is incorrect. It would be correct if the heat transfer from the CMOS chip to the Peltier cold plate were perfect, but it is far from that -- the losses between the cold plate and the chip are considerable. I don't know the transfer efficiency (which depends on a lot of things), but you need considerably more than just a few watts if you're cooling by Peltier transfer (via a good thermal compound) to the back plate of the ASI housing.

murison

I have gone the Peltier cooling route as well. This is the thermoelectric cooler (TEC) I ordered:

http://www.marlow.com/products/thermoelectric-modules/single-stage/rc12-8-01ls.html

I fried my cooling fan so I'm waiting for a replacement to arrive before I do tests for real. But I did drill holes in the heat sink that match the M4 holes on the back of my ASI120mm (thank you, ZWO!) and then, with a couple of M4 hex bolts, sandwiched the TEC between the (for the moment fanless) heat sink and the back plate of the ASI (using a good thermal paste). I didn't fill the 1/4-20 hole with anything. The TEC is rated 71W maximum, so its cold plate cools down very fast, which means it heats up the heat sink also very fast. Without the fan, I could only leave the power on for about 15 seconds before the heat sink got more than finger hot (I am not going to risk damaging that very nice TEC!). But during that brief cool-down the temperature reading from the ASI120mm as reported by FireCapture dropped by 12C. I take that as a good sign that I should be able to get ~15C or so below ambient, perhaps even a bit more, when the mod is completed.

But here's the thing: before the test, I had set the camera to auto-run 10-second dark-frame exposures with the gain cranked all the way to 100. Lots of warm pixels, lots of noise, which was the intent. The noise improvement after just ~5-8C of cooling was astonishing: the mean noise level dropped by a factor of ~20(!), as measured by the histogram in FireCapture. All those warm pixels just disappeared -- all of them -- leaving a most-lovely, smooth black image. A hopeful sign! (Also, many thanks to ZWO for using what is clearly a good CMOS chip for this camera. Beats the pants off of my other two older CMOS cameras.)

I'll post pictures, a better description, and test results after the new fan arrives and I get everything put back together again later this week.

BTW, the heat sink/fan I am trying out is Arctic's Alpine 20-plus (rated 130W): http://www.arctic.ac/us_en/alpine-20-plus-co.html. It's pleasingly quiet yet moves a fair amount of air through the heat sink fins. I figure this should more than handle the theoretical 71W max. (significantly less under normal operating conditions) of the TEC. At least I hope so! In my brief test above, the TEC drew 4.5A from a 13.8V power supply. The TEC's maximum possible current draw is 7.4A, so I was operating significantly below the rated 71W maximum, as expected. According to the published performance curves for this TEC, the voltage drop was probably about ~11V and the heat load was probably around 50W (4.5A*11V = 50W, check) -- again, as more or less expected under real-world conditions. Provisionally, I am very pleased.

Question for ZWO: is the temperature sensor in the ASI120mm mounted directly to the CMOS chip? That is, is the reported temperature the actual temperature of the chip?

Sam@ZWO

the temperature is read from the sensor

the sensor itself provide such function

so that's the real temp of the sensor