Hi all. I just completed the building of a Peltier cooler for my ZWO 178-MC. Since posting a few photos of the completed project on Facebook, I have been asked by several people to please do a write-up and documentation for my project. I benefited greatly from two YouTube videos in constructing this cooler, one by Martin Pyoff and the other by Ewan the Astronomy Addict. You will find links to both videos below. In addition, I made some modifications to the design of my own. Also, in these two videos, some things were just not shown in enough detail or description. As a result, I am adding this detailed tutorial to the conversation, hoping to help anyone who wants to take this project on for themselves. I am initially posting this tutorial here on my frankleonard.com website. For those who have arrived here, this will have the advantage of me being able to directly give you links to Martin and Ewan’s videos, as well as links to the actual components I purchased for this project. It is my hope, that this tutorial will be of tremendous help to you. Rather than trying to catch the name of a component on the fly in a YouTube video, you will find close up photos below which you can carefully study. So, here goes. I am appreciating this opportunity to give back as others have been so gracious and willing to do for me.
Martin’s video: https://www.youtube.com/watch?v=rba94dKfsjs
Ewan the Astronomy Addict’s Video: https://www.youtube.com/watch?v=XSLIaLzFBW4
List of parts used in this project, with an Amazon link for each:
TES1-12704 12V 4A Peltier Cooling Module – $9.99 – https://www.amazon.com/dp/B07D348WW5?psc=1&ref=ppx_yo2_dt_b_product_details
Large Aluminum Peltier Heatsink – $9.99 – https://www.amazon.com/dp/B07THL51ZD?ref=ppx_yo2_dt_b_product_details&th=1
Aluminum Sheet, 12″ x 6″, 1/8 Inch(3mm) Thickness – $17.99 https://www.amazon.com/dp/B09LLX9P63/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B09LLX9P63&pd_rd_w=bufw9&pf_rd_p=0c758152-61cd-452f-97a6-17f070f654b8&pd_rd_wg=snsnr&pf_rd_r=NFWNWGHDKMAK2H185TCV&pd_rd_r=6cf6fdae-66cb-4713-a9e1-cd8ad5a93c3a&s=industrial&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzOEc4MVIxMlpJRVlaJmVuY3J5cHRlZElkPUEwMTY4ODQ0M0w5NzVXTkxVUkxWTyZlbmNyeXB0ZWRBZElkPUEwNTk5NjI2MjBHQUtKRTI3UzlVUCZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
AMD Original/Foxconn PVA070E12L 4-Pin Fan – $15.99 – https://www.amazon.com/dp/B00T6SONJG?psc=1&ref=ppx_yo2_dt_b_product_details
12V Temperature Controller – $12.88 – https://www.amazon.com/dp/B092H3WSZX?psc=1&ref=ppx_yo2_dt_b_product_details
Thermal Pad Material, 200x200x0.5mm – $9.98 – https://www.amazon.com/dp/B086VZQYGH?psc=1&ref=ppx_yo2_dt_b_product_details
4 Strand 22-guage wire – $15.58 – https://www.amazon.com/dp/B07TLB9VYX?psc=1&ref=ppx_yo2_dt_b_product_details
.38 Ohm Resistor – Purchased at my local electronics store – very inexpensive – Note: As you will see in the item immediately below this one, I needed to change Martin and Ewan’s design from a 2 amp power source to a 3 amp power source. Their 2 amp design called for a .58 ohm resistor, but for my 3 amp design, the resistor needed to be changed out to a .38 ohm resistor.
12 volt, 3 amp AC to DC transformer – $14.99 – https://www.amazon.com/dp/B07HNV6SBJ?psc=1&ref=ppx_yo2_dt_b_product_details Note: The power source that Martin and Ewan used was 12 volts, 2 amps, but as you shall see in my tutorial below, that did not work for me. I needed to move up to a 12 volt, 3 amp power supply, which also meant changing the value of the resistor that reduces amperage for the .2 amp fan, as well as the inline fuse. I will be sharing all this in more detail below.
Assorted Hardware Store Items: 4 – M4 machine screws, 8mm in length; 4 – 3″ x 6-32 machine screws with nuts; assorted small rubber and metal washers, electrical box, 3 small on-off switches.
AS YOU CAN SEE, MY TOTAL FOR PARTS WAS RIGHT AROUND $120.
SO, HERE WE GO, WITH PHOTOS AND DESCRIPTIONS OF MY PROJECT AND PROCESS:
My final schematic:
Photos and Comments/Suggestions:
I built a handmade wooden cover for my control box. Then I discovered that the old style electrical box I had purchased wasn’t deep enough to hold all that needed to go into it. However, the old style box didn’t come in a deeper variety, and a standard deeper electrical box didn’t accommodate my hand made cover, So, I ended up buying a second “old style” box, cut the bottom off of it, and cemented the two together, to create a deeper box.
I discovered that instead of tying knots in my cables as they entered and exited the control box, electrical ties are a great way to secure the cables, to keep them from being able to be pulled out of the box, which avoids putting any pressure on soldered joints and connections.
This photo shows the back side of the thermostat module. Please see the schematic above for specifics about what wires go where.
Here is another view. As you can see from the schematic above and this photo, there was no way that all the wires that needed to run into the first (+) slot of the thermostat would fit, so I ran a single short wire out of slot 1 to connect on its other end with the several (+) wires coming from the power supply main switch, the fan switch, and the peltier switch. I did the same thing with the second (-) slot, running a short wire out to meet the negative wires from power supply, fan, and peltier.
The camera attaches to the extra aluminum plate that Ewan added to this project. I made my plate smaller than Ewan’s, hoping to cut down on weight as much as I could. My plate measures 3″ x 4-1/4 inches. There is a piece of the thermal pad material in between the camera and the aluminum plate.
This is the back side of the aluminum plate. It is attached to the camera using 4 – M4 machine screws, each 8mm in length. Please note the metal and rubber washers that were added to accommodate expansion and contraction of the materials during heating and cooling. When I first constructed this cooler I glued the Peltier module to the aluminum plate with permanent thermal glue (as shown in the above photo. That was a mistake. As it turns out the thermal glue I used only had a thermal conductivity rating of 1.2 W/m-k. As a result the maximum temperature drop I could achieve, below ambient temperature, was 20 degrees. I was not satisfied with that result, so I disassembled the cooler, removed the Peltier module, breaking it in the process, and replaced it with the second Peltier module I had purchased for backup. This time I used the same thermal pad material (with a thermal conductivity of 6.0) that I had used in between the camera and the aluminum plate and in between the Peltier module and the heatsink. What a difference this made! Now the temperature drop is 35 degrees F below ambient temperature!
This is the bottom of the heatsink. Several things to note: The heatsink was the perfect width for the fan, but it was too long, so I cut it into a square to fit the fan perfectly, and again, to cut down on weight. Also, note the indentations I drilled into the bottom of the heatsink. That is so the screws that attach the aluminum plate to the camera do not keep the heatsink from making contact with the Peltier module. And finally, as you’ll better see in subsequent photos, the corners of the heatsink needed to be notched, to make room for the machine screws that attach the fan to the heatsink to the aluminum plate. Note that there is also another piece of thermal pad that will end up in between the heatsink and the Peltier module.
Here you see the bolts being placed into position to hold everything together.
This is the same fan that Ewan used in his project.
Note that rubber washers, to are being used everywhere, even in between the heatsink and the fan.
Originally, I did not have the notches cut out of the heatsink. Instead I ran them in between the fins of the heatsink. However, I realized that this was going to trap hot air and not allow it to escape as easily.
The two screws in the foreground of this photo have nothing to do with attaching the heatsink to the aluminum plate. They are what attach the small plastic box to the aluminum plate, inside of which the wires coming from the fan and the Peltier will connect with the corresponding wires coming from the control box.
So, this is a bit of a story, but here is the explanation for why I needed to switch from a 12 volt 2 amp power supply to 12 volt 3 amps. When I first completed the construction of this cooler, something was very wrong. Every time I would fire up the system (main switch, fan switch, Peltier switch) the temperature controller would come on, show temperature readings, and then within a second it would shut down and the screen would go blank. A second later it would come back on, only to shut down again, repeatedly, over and over. I thought I had wired it wrong. I began a long process of troubleshooting, eliminating one variable at a time. I did much more research on the wiring of the thermostat, only to discover that I had done it correctly. I was pretty frustrated and thought I might actually have to shelve the whole project. Finally, after double and triple checking everything I have done, I thought I would switch out the power supply to 3 amps instead of two. I believe the thought to even give this a try came from the knowledge in the back of my mind that somehow my TES1-12704 Peltier module, instead of being listed at 3.3 amps, as was Martin’s and Ewan’s, was actually listed at 4 amps. I thought that perhaps the 2 amp power supply was not enough for this particular TES1-12704, and as it turns out, I was correct. As soon as I installed a 3 amp power supply, everything worked beautifully. HOWEVER, because I increased the amperage of the power supply, it was also necessary to change the resistor from Ewan and Martin’s 5.8 ohms to a new value of 3.8. Here is where I learned about Ohm’s law and inverse proportions. You would think that a higher amperage power supply would result in a larger resistor needed to protect the .2 amp fan, but not so. Instead of 5.8 ohms, the new resistor needed to be just under 4 ohms, so I went with 3.8. My electronics store, however, did not have a 3.8, so I purchased a 3.3 and and a .51 – When wired together, end to end (in serial) they gave me 3.81, perfect!
The final product.
I am so grateful to Martin Pyott and Ewan the Astronomy Addict for inspiring me to take on this project. Hopefully, between their videos and this tutorial of my own, should you decide to build this cooler, your path will be smooth and enjoyable. Should you have any further questions, I would be more than happy to try and help. Just write me at firstname.lastname@example.org