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ASI174MM With Cooling Modification

astrophotography DIY equipment imaging
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#1 AbsoluteZero

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Posted 24 August 2015 - 01:25 PM

Greetings everyone!

 

I hope that this is the proper place for this post.  Please let me know if it is not, and I will work to remedy it.

For a few months, I've been working with my ASI174MM and various software platforms to attempt to use the camera for long exposure astrophotography, even though it was specifically designed for planetary work.

Long story short, I settled on a software program that I felt was capable of doing the things I needed it to do, but the camera was quite noisy when the shutter was left open.  What doesn't help is the fact that in North Texas, the temperatures are still in the low 90's and upper 80s well after sundown.  I decided that a cooled camera would be better - but I don't have the funding right now to allow such a large purchase.  Instead, I'll have to make do with what I have.

I researched online, and found a thread on another forum (I will link to it in a comment if requested - and linking is permissible) which outlined how to use a peltier cooling device to cool ZWO cameras.  The modifications looked simple enough so I spent a few days this past weekend buying the parts and building my own hacker-cooled camera.

I'm posting from my work computer and don't have all the photos, but as soon as I get home I will post more photos of the actual camera.  What I do have is a photo that I created from taking dark frames with the ZWO ASI174MM camera.  The right column of images are 180s sub exposures with 10s dwell between each image.  The left column are also 180s with a 10s dwell - however the TEC was allowed to run for 5 minutes before that series was exposed, and continued running for the entire acquisition.

 
CooledASI174MM

As you may be able to see from this - there was a substantial drop in sensor temperature, and a huge reduction in the thermal noise produced by the chip.  Amp glow is still an issue - but I played around with the Gain settings and nearly eliminated it with a gain setting of 50 as opposed to setting of 150 from the tests.

Again, as soon as I can tonight, I'll upload more photos of my modifications from this weekend.


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#2 chasing photons

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Posted 24 August 2015 - 01:35 PM

Nice!  It looks like your cooling mod is quite successful.  The IMX174 (and IMX249) are good mid-sized mid-resolution CMOS sensors.  I will look forward to seeing more results from your camera.


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#3 AbsoluteZero

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Posted 24 August 2015 - 01:39 PM

Thanks, Todd!
I'm really looking forward to setting up and testing this out, but it looks like the next few nights at a minimum will prevent this setup from getting a first light.  In the meantime, I'm working on testing out settings for the camera and finding ways to minimized the presence of the amp glow.

With the ASI174MM, I've not been able to find a way to open the camera and get to the internals - which can probably benefit from being directly chilled.  One day I'll get in there and properly void my warranty :)



#4 orlyandico

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Posted 24 August 2015 - 01:44 PM

isn't there an issue with dew?

 

the problem with cooling isn't the cooling itself, but moisture control.



#5 AbsoluteZero

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Posted 24 August 2015 - 01:47 PM

isn't there an issue with dew?

 

the problem with cooling isn't the cooling itself, but moisture control.

 

I'm almost certain that there will be an issue with dew - since there was considerable condensation on the camera body in my home office.  I have plans to test desiccant packets and see if they are able to absorb enough of the humidity in an hour as to avoid any condensation on the sensor window and filter placed in front of the camera.



#6 Guest_djhanson_*

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Posted 24 August 2015 - 02:15 PM

Thanks for the post.  

 

I am also working on a Peltier mod to cool my ASI174MM.  In my case, I use the camera for strictly planetary imaging.  However, in the summertime in AZ, the camera is often running at 48-50 C!  And with Saturn, high gains involved, I find the raws are very noisy maybe beyond my taste.  And I don't like running the camera above it's 45 C rating really.  Anyways, here's some pics of my first mod try.  Things I've learned about a cooling mod:

 

1. Fin: big fin is a must.  Else, no cooling takes place of course.  Originally I tried a smaller fin with and it didn't work well.  Finding a fin is not simple for me.  I had to search several Fry's Electronics stores for cooling fins.  The problem is now, chips are smaller and don't need so much cooling, so these are becoming harder to find.  But they're cheap, maybe $10-$20 for a good fin (often includes fan).

 

2. Fan: I think the fan does help of course.  I'm using a 50mm fan as its standard mount positioning matches perfect to the 39mm hole spacing of the ZWO top plate.  A bigger fan might help more, just that I got to figure out how to mount it.  That's why I like the smaller 50mm fan.

 

3. TEC: I'm using a 3amp and 15volt TEC (it's really a TES).  Takes 12volt no issues that I see.  Got this at Fry's Electronics too.  They have a 6amp one, slightly larger surface area but didn't know about powering it.

 

4. TEC spacing: I might not have enough spacing between the TEC and the ZWO top plate.  After running some time, the heat seems to transfer back to the ZWO top plate.  On youtube, there is a guy who found out he had to place a second fin, so ZWO=>fin=>TEC=>fin=>fan.  Right now I have ZWO=>Al spacer=>TEC=>fin=>fan.  I have a small aluminum spacer between the ZWO and TEC using conductive grease.  I don't really want to slop the grease on top of the ZWO top plate though (I'm trying to keep this project clean and not muck up the nice camera body if possible).

 

Anyways, I'm still messing around with my home-brew Peltier :D  I've attached some pics.  Would be interested to get your feedback on your project.  I still think I need another fin between the ZWO and the TEC.  I might order something up off of Amazon and also place some insulation around it to keep radiant heat from going back into the ZWO body.  And on another note, ZWO is supposed to come out with a cooled camera later.

 

cheers, dj


Edited by djhanson, 24 August 2015 - 02:15 PM.


#7 AbsoluteZero

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Posted 24 August 2015 - 02:25 PM

djhanson,

 

My TEC is the 12 volt by 6 amp version - and I run it dirctly off of my 12v telescope battery.  It's plenty big, as I designed it to be that way.
My TEC is mated directly to the top of the ZWO with nothing in between it, including any paste/grease/plates.

Since this was a budget mod, I went as cheap as I could.  The heat sink and fan were originally designed for use with an Intel Celeron processor, so they don't carry away a huge amount of heat - but they carry enough away that I could cool my imaging sensor by about 40 degrees F.  No doubt that I could do better if I had your heat sink and fan!

Good looking mod so far! I'll upload more photos in a few hours once I'm back home.

In the meantime - here is a YouTube video shot from my mobile phone that shows the mod in action.



#8 AbsoluteZero

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Posted 24 August 2015 - 08:39 PM

Here are some additional photos showing how simple the modifications were

 

This shows the heat sink with the TEC element attached.  I used Antec brand Formula 7 Nano Diamond Thermal Compound leftover from my server build earlier this year.  It has the ability to transfer a high throughput of heat, and it didn't cost any extra since it was laying around.

The TEC is a TEC1-12706 that I picked up at Frys electronics.  It runs on 12 volts DC and pulls 6 amps.

TEC And Heatsink
 
And this is the whole setup strapped together.
I cut a beer coozie up and made a neoprene jacket for the camera.  I assume that it would work well enough to keep the warm air heat from saturating the camera housing, therefore increasing the efficiency of the TEC/Heat sink and fan combination.  A pair of 3.25 inch inner diameter o-rings that I picked up at an auto parts store are holding things together for now.  I had to use some zip ties to take up the slack.  Smaller, 3 inch rings are on order, should be in any day.  I'll see how those work.
Cooled ASI Assembled


#9 A. Viegas

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Posted 24 August 2015 - 09:06 PM

Is the TEC actually in contact with the Ccd/CMOS or is it just touching the backpanel of the 174?

 

Al



#10 AbsoluteZero

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Posted 24 August 2015 - 09:47 PM

Is the TEC actually in contact with the Ccd/CMOS or is it just touching the backpanel of the 174?

 

Al

 

Al,

 

The TEC is in contact with the top of the ZWO ASI174MM back panel.  I've not yet found a way to open the camera so I can directly cool the PCB / ICs inside.

 

-Mitchell



#11 mclewis1

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Posted 25 August 2015 - 09:51 AM

And I bet Sam (wenjha) is just cringing as he reads this thread.

 

I do however love to see brave folks try different approaches to reducing noise. I think it teaches us all a lot about how our cameras operate and the impact of outside influences like temperature ... and the lengths the camera designers have gone to trying to reduce noise.


Edited by mclewis1, 25 August 2015 - 09:53 AM.


#12 Guest_djhanson_*

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Posted 25 August 2015 - 11:26 AM

AbsoluteZero:  that's looking like a nice mod!

 

Wow (ZWO's new cooled cam's expected $300-350 more): http://www.cloudynig...cooled-cameras/

 

-dj



#13 AbsoluteZero

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Posted 29 August 2015 - 04:12 PM

Today I was able to properly void the warranty of my ASI174MM and remove the imaging sensor board.

 

 

ASI174MM Open
 
 
On the back of the board, there is a bank of resistors.  The bank corresponds to a short side of the image sensor.  I suspected that these resistors were creating a warm side on the chip.
Back Of Image Sensor PCB


#14 AbsoluteZero

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Posted 29 August 2015 - 04:15 PM

I fashioned a heat spreader out of a soda can.

 

Heat Spreader 1
 
By coating one side of the heat spreader with clear coat nail polish I could put a resistant barrier between any metal contacts and the aluminum can material and prevent short circuits.
The foam spacer is used to press the aluminum up to the resistors so that I can ensure that I have a secure fit against them.
Heat Spreader 2
 
The heat spreader would be placed along the back like so - with the sensor board being screwed in on top of it.
Heat Spreader 3


#15 AbsoluteZero

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Posted 29 August 2015 - 04:17 PM

I took an image with the heat spreader removed but cooling on.  I took a second image with the spreader in place, and cooling on.  As you can see the heat spreader and foam solution was a bad idea.  I wasn't able to draw the heat away, and may have trapped more heat than I could remove.
Heat Spreader Test


#16 Stargazer3236

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Posted 30 August 2015 - 02:34 PM

Is the fan positioned to draw away the heat or blow cool air onto the fins?



#17 Stargazer3236

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Posted 30 August 2015 - 02:39 PM

What was the total cost of all the materials to make the cooler? I want to make one myself and not pay the extravagant price for the cooler. What kind of TEC plate should I buy? And what size heat sink should I get as well? Is bigger better or just use a 50mm heat sink with the 50mm fan? 



#18 Stargazer3236

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Posted 30 August 2015 - 02:48 PM

Can I splice the fan power wires with the peltier power wires to cut down on the amount of connection I need to make?



#19 AbsoluteZero

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Posted 30 August 2015 - 03:30 PM

Is the fan positioned to draw away the heat or blow cool air onto the fins?

The fan is in a position to draw air down, and through the fins.  This was how the factory installed it when they packaged it.

 

What was the total cost of all the materials to make the cooler? I want to make one myself and not pay the extravagant price for the cooler. What kind of TEC plate should I buy? And what size heat sink should I get as well? Is bigger better or just use a 50mm heat sink with the 50mm fan? 

Total cost is about $50 USD at this point.  
As for what TEC Plate you should buy?  Buy whatever you can afford. I shelled out $20 for mine.  

The heat sink and fan I have works well for a 72 watt Peltier element.  I'm sure whatever you buy will be just fine.

 

Can I splice the fan power wires with the peltier power wires to cut down on the amount of connection I need to make?

You're going to need the make the same amount of 'connections' regardless of splicing - since splicing is in fact a connection.  That being said, I soldered my peltier power wires to my fan wires and then crimped those to the positive and negative leads coming from my 12v plug.  I kinda wish I didn't do that...  I have plans to put the fan and the Peltier on seperate circuits.


Edited by AbsoluteZero, 30 August 2015 - 03:31 PM.


#20 Stargazer3236

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Posted 30 August 2015 - 04:00 PM

Thanks for the info. I am a computer builder and build my own rigs. I am pretty knowledgeable about fans and heat sinks for CPU's. Can I just attach a fan and heat sink with thermal grease to the back of the ZWO camera and still get significant cooling? Or is the Peltier going to cool down the back side of the camera and draw the heat off to be expelled by the fan?



#21 AbsoluteZero

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Posted 30 August 2015 - 04:55 PM

Thanks for the info. I am a computer builder and build my own rigs. I am pretty knowledgeable about fans and heat sinks for CPU's. Can I just attach a fan and heat sink with thermal grease to the back of the ZWO camera and still get significant cooling? Or is the Peltier going to cool down the back side of the camera and draw the heat off to be expelled by the fan?

 

No.  The idea behind this is to create a high Delta-T.  Ambient air blowing across a room-temperature heat sink won't create as high of a temperature differential as the ambient air being blown across a heat sink that's been warmed to 120F.

Removing heat from the 120F side of the Peltier cooler is what allows you to remove an equal amount of heat from the cold side of the Peltier cooler.  If you were to water cool the Peltier instead of using a fan, you would be able to remove even more heat from the cold side, and super-chill the camera.  I'd suppose that my example of going to 40 degrees F below a non-cooled sensor temperature would likely be closer to 50 or 60 degrees F if I had a water cooling rig at my disposal.

 



#22 Stargazer3236

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Posted 30 August 2015 - 05:16 PM

Another idea is, what about a closed loop liquid cooling system, that pumps water around, cooling the ZWO camera by removing heat from the back of the camera housing without a TEC attached?

 

http://www.newegg.co...=9SIA0ZX2C33876



#23 Stargazer3236

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Posted 30 August 2015 - 05:20 PM

I suppose I could add the TEC to super chill the camera down. Do I need to add any electronics to the TEC like resistors or can I just wire it up to the 12v battery by way of a 12vdc lighter plug?



#24 AbsoluteZero

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Posted 30 August 2015 - 06:07 PM

I suppose I could add the TEC to super chill the camera down. Do I need to add any electronics to the TEC like resistors or can I just wire it up to the 12v battery by way of a 12vdc lighter plug?

I'm not running any resistors between my 12v power supply and the 12v TEC, because the TEC runs off of 12v.



#25 Stargazer3236

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Posted 30 August 2015 - 06:37 PM

Stupid question: Which side of the TEC is cold and which is hot?


Edited by Stargazer3236, 30 August 2015 - 06:37 PM.



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