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DIY Mini-TEC for Non-Cooled Cameras

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#1 MarMax

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Posted 08 June 2022 - 07:01 PM

EDITED to say I'm not sure where this post should go. I figured if I put it in the EAA forum it would get moved to either the Beginning DSI or Experienced DSI froums, so I turned left and put it here. If the Mod thinks this should be elsewhere please move as you see fit.

 

I started this as a reply to the thread about the Saturn (IMX 533) non-cooled camera but now that I'm almost finished with the cooler a separate thread is best.

 

I know through the research that many say "don't do it" because of condensation on the sensor but for $27 I figure what the heck. This really is a Mini-TEC, much smaller that some I found in the research. Part of the reason for going small, besides the simplicity, was to minimize condensation and current draw, at the expense of overall temperature drop.

 

Once the camera attachment is completed it will just thread on the back using the 1/4" -20 hole. For the testing in the garage today I placed the Mini-TEC on top of the ASI290MM and ran SharpCap to track the sensor temperature drop for 14 minutes, the point where the temp stabilized.

 

The TEC pulls 1.9A at 12V and the net (delta) drop was 7.6° C (13.7° F). Here is the temp curve.

 

TEC_Cooler_Curve_06082022s.jpg

 

I'll do the final wiring quite a bit shorter with the standard female barrel connector so I can plug into the same power cable for my cooled cameras. I also have a Player One Neptune-CII and just ordered a Uranus-C so I'll use the 1.5" washer as a spacer with them so the TEC is flush with the mounting point.


Edited by MarMax, 08 June 2022 - 10:02 PM.

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#2 SchoolMaster

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Posted 08 June 2022 - 07:18 PM

Good cost/cooling value and can be used on other camera.

 

When you get it going I hope you post com on/off comparison pics.



#3 gregj888

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Posted 09 June 2022 - 10:43 AM

It's not very efficient and you need to stay above dew point, but it can help. 

 

The Astro cameras should be OK but some of the industrial cameras (my Flea for instance) lower the noise but also eat signal. 



#4 MarMax

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Posted 10 June 2022 - 12:44 AM

Running the Mini-TEC on the Neptune-CII camera tonight I was able to get an 8° C (15° F) drop from 30.5 to 22.1. It takes a while with the 40mm x 40mm x 8mm aluminum plate between the TEC and the camera. Instead of 13 minutes to equilibrium it's more like 30 minutes. The mounting method works well. There was some condensation on the perimeter of the aluminum plate.

 

The marine layer rolled in so besides taking some flats and a bunch of darks I did not get to test things under the stars.



#5 SchoolMaster

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Posted 10 June 2022 - 08:51 AM

I lived in Huntington Beach for 8 years and that marine layer is fierce.

 

Did you use PC thermal paste between the plate and the camera?  8C is still a meaningful drop in noise at those higher temps.



#6 MarMax

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Posted 10 June 2022 - 10:38 AM

I lived in Huntington Beach for 8 years and that marine layer is fierce.

 

Did you use PC thermal paste between the plate and the camera?  8C is still a meaningful drop in noise at those higher temps.

I'm only using thermal tape between the heat sink and TEC plate and TEC plate to 40x40x8 aluminum mounting block. I need to easily install/remove the TEC so the camera connection is contact only with the 1/4"-20 fastener. 

 

Here is the mounting plate with fastener. Depending on the camera I use either 2" (ZWO) or 1.5" (Player One) aluminum washers to keep the fastener from bottoming out in the camera.

 

TEC_Al_Plate.jpg

 

Here is a couple pics of the setup.

 

C11 Hyp NCII TECa 06092022m
 
You can see the stack of three 1.5" washers between the plate and camera.
C11 Hyp NCII TECtop 06092022m

 

I had high hopes of some time on M57 with the ALP-T filter. Maybe tonight, or tomorrow or . . . .


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#7 MarMax

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Posted 11 June 2022 - 11:01 AM

Here is some more temperature data for the Mini-TEC with the Neptune-CII camera. One thing that happens because of the fairly massive (in comparison to the TEC plate) aluminum mounting plate w/washers, is a rise in sensor temperature initially as the Mini-TEC works to cool all that aluminum.

 

At time zero the sensor was 25.5 C and it went up to 27.1 C before starting to cool down. It took about 7 minutes to get back to 25.5 C and then continued to drop over the next 40 minutes to 17.5 C. It looks like the delta of 8 C is where this is going to operate.

 

I ran the Mini-TEC for 2.5 hours while I was doing EAA and noticed condensation on the outside of the aluminum plate/washers and on the outside of the NCII but did not notice any impact on the images. I did not remove the camera after to check the sensor but based on the FWHM and Brightness filters there was no condensation on the sensor.


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#8 SchoolMaster

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Posted 11 June 2022 - 11:32 AM

I'm wondering if a larger disc that covers the entire camera base might be a modest improvement.

 

You are giving me ideas for a project that my students next year might like to work on.  Lots of STEAM.



#9 MarMax

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Posted 11 June 2022 - 12:12 PM

I'm wondering if a larger disc that covers the entire camera base might be a modest improvement.

 

You are giving me ideas for a project that my students next year might like to work on.  Lots of STEAM.

It's a really cool (lol.gif ) and fun little project.

 

I'm using 1.5" washers on the Player One because of the recessed hexagon in the back of the camera. I will use 2" washers on the ZWO.



#10 SchoolMaster

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Posted 11 June 2022 - 12:29 PM

Did you look at copper plates?  12 to 18 gauge



#11 RogerM

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Posted 11 June 2022 - 02:36 PM

Food for thought, since air is a poor thermal conductor you would want to maximize not just surface area of the heatsink (think at least double the surface area/thickness of what you currently have)   and the cooling fins seems too closely spaced for the current thickness and may be restricting airflow.

 

Also, your operating ambient may be working against the 'cold' side since it is exposed, I recommend that you also insulate the cold plate from the external environment.  Little things can add up to several degrees (or more) of cooling capacity.   Here's a Heatsink Calculator that you can help you find an optimum size heatsink for your setup.

 

Best of luck with your project!



#12 MarMax

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Posted 11 June 2022 - 02:38 PM

Did you look at copper plates?  12 to 18 gauge

Yes, I looked for copper first but could not find any reasonably priced stamping blanks. There are lots of choices on Amazon and about the thickest I could find was 14 ga. aluminum in the sizes I needed.



#13 MarMax

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Posted 11 June 2022 - 02:59 PM

Food for thought, since air is a poor thermal conductor you would want to maximize not just surface area of the heatsink (think at least double the surface area/thickness of what you currently have)   and the cooling fins seems too closely spaced for the current thickness and may be restricting airflow.

 

Also, your operating ambient may be working against the 'cold' side since it is exposed, I recommend that you also insulate the cold plate from the external environment.  Little things can add up to several degrees (or more) of cooling capacity.   Here's a Heatsink Calculator that you can help you find an optimum size heatsink for your setup.

 

Best of luck with your project!

Good points Roger. I not familiar with the terms for the heatsink calculator but I do know that my TEC plate is operating at 24W maximum. The size of the heatsink is 4cm x 4cm x 2cm with between gentle and moderate air flow. I was not planning to regulate the plate so the operating wattage was a mystery until I plugged it in.

 

I've thought about insulating the edges of the aluminum plate. My be good for another degree.

 

EDITED to add that a reasonable highest ambient temperature is probably 25 C for my night-time summer weather. With the typical temps being 20 C or a bit less.


Edited by MarMax, 11 June 2022 - 03:03 PM.


#14 MarMax

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Posted 03 August 2022 - 06:37 PM

I've built another cooler and this one is the Mini-TEC2. Here is the post with a couple pictures and the cooling data.

 

I was able to get a 13.8° C drop in sensor temperature in the 35° C ambient garage.




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