This project is the documentation on how I built a Peltier element based cloud chamber. The motivation came from having most of the required parts laying around, and since it works quite well, here are instructions on how it is made.
This project requires to work with 220V, which can be deadly. Do not attempt to build it if you are not familiar in dealing with mains voltage!
- The Peltier elements I used did not consume the wattage according to the specs, so I assume them to be of inferior quality, and therefore will not provide links to where I got them. They do the job, but if they would work according to specs, they should provide even greater cooling.
- This project was not planned, but rather built as a proof of concept to see if the concept works at all, so there are many things that can be improved or changed, e.g. less glueing.
- I did not make use of a high voltage field, it did not seem necessary but might be added at some point in the future. Everything is prepared for it (switch, location for power adapter), so it shouldn't be hard to add it.
- Pictures in this document were taken at different build stages and might not be fully accurate, since I added e.g. the light part later on.
I had some parts laying around, but for the sake of completeness, I created a list with all parts and their price in Aug 2026 on Amazon. The total value of the parts is about 250 Euro. Here a list with links.
| Part | Amazon Link | Image | Notes |
|---|---|---|---|
| Power adapter 220V->24V | Amazon |  |
|
| 1x CPU Cooler with Fan | Amazon |   |
|
| 1x Peltier 12709 |  |
||
| 1x Peltier 12715 |  |
||
| 3x Low Power Voltage Converter | Amazon |  |
|
| 2x High Power Voltage Converter | Amazon |  |
|
| 2x simple voltage meters | Amazon |  |
|
| Copper Plate 5x5x0.3cm | Amazon |  |
The image is not of the actual part, but a thinner plate |
| Acrylic Case 8x8x8cm | Amazon |  |
|
| Foam rubber 2mm | Amazon |  |
|
| Heating Element | Amazon |  |
|
| Felt | Amazon |  |
|
| Magnets | Amazon | |
|
| 12x WAGO Connector 2x | Amazon |  |
|
| 2x WAGO Connector 5x | Amazon |  |
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| 5x Low Power Switches | Amazon |  |
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| LED Spotlights | Amazon | ||
| Thermal pads | Amazon | ||
| 220V power switch | Amazon | ||
| 220V power socket | Amazon | ||
| 6x Insulated flat connectors | |||
| AWG 10 cable | |||
| AWG 16 cable | |||
| AWG 16 cable lugs | |||
| Insulated flat connectors | |||
| 4 Screws 4x8mm | |||
| x Screws 3x8mm | |||
| x Screws 3x12mm | |||
| x Screws 2x4mm | |||
| x Screws 2.5x5mm | |||
| 8x screw inserts M3x5x5 | |||
| Silicone | |||
| Black spray paint | |||
| Super glue |
All printed parts are openscad code, you can open them with openscad and then directly change variables at the beginning to adjust the screw diameter or part dimensions. Please note that I haven't tested changing them, so this might result in non printable models.
| Part | Image | Link | Notes |
|---|---|---|---|
| Case Bottom |  |
stl | best printed standing up with support |
| Case Cover |  |
stl | best printed standing up with support |
| Case Cooler Frame |  |
stl | |
| Top Part |  |
stl | |
| Top Insulation Cover |  |
stl | |
| Top Insulation Stencil Copper |  |
stl | optional part, only used as stencil for the insulation |
| Top Insulation Stencil Peltier |  |
stl | optional part, only used as stencil for the insulation |
| Light Connector Box |  |
stl | |
| LED Carrier |  |
stl |
- Voltage Meter - for adjusting the voltages
- Soldering Iron, for soldering cables to the low power adapters, plugs and switches.
A simple diagram showing how everything gets connected. There is not much going on but voltage getting adjusted for different parts.
Once all parts are printed, the assembly is pretty much straight forward.
Note: all connections with the 220V->24V voltage adapter have to be done with cable lugs. Don't screw in cables directly!
1.1 Prepare case
- insert the screw inserts into the screw holes of the bottom part of the case with a hot soldering iron.
1.2 Connect voltage adapter with 220V switch and socket
- Screw the 220V socket into the case
- Insert the 220V switch into the case
- Screw the power adapter into the bottom of the case with 4x8 mm screws from below
- Connect N (blue) and L (black) from the 220V socket to the 220V switch using insulated flat connectors and AWG 16 cables
- Connect N (blue) and L (black) from the 220V switch to the N and L connection on the 220V voltage adapter using insulated flat connectors and AWG 16 cables
- Connect E from the 220V socket to the E connection on the 220V voltage adapter using insulated flat connectors and a green-yellow AWG 16 cable
1.3 Add cables for later connection to 24V->3-12V adapters
- Connect 2 (red) AWG 16 cables for the Peltier elements to one of the +24V connectors of the 220V voltage adapter and let them hang loose for now
- Connect 2 (black) AWG 16 cables for the Peltier elements to one of the GND connectors of the 220V voltage adapter and let them hang loose for now
1.4 Install low power adapters
- Glue 2 WAGO-5x connectors onto the square field, one for +12V and one for GND connections
- Connect the remaining +24V connection of the 220V voltage adapter to one 5xWAGO connector with a (red) AWG16 cable
- Connect the remaining GND connection of the 220V voltage adapter to the other 5xWAGO connector with a (black) AWG16 cable
- Solder (red and black) AWG10 cables to the low power adapter input and output connections.
- Screw in the 3 low power voltage adapter with 2.5x5mm screws
- Attach the +V input side of the low power adapters with the 5xWAGO connector that is connected to the 24V+ connection of the 220V voltage adapter
- Attach the GND input side of the low power adapters with the 5xWAGO connector that is connected to the GND connection of the 220V voltage adapter
- Glue 6 2xWAGO connectors onto the side of the case
- Connect the three V+ and three GND output cables of the low voltage adapters with the 6 2xWAGO connectors (one connection per WAGO)
Connect a voltage meter to the 2x WAGO adapters and adjust the output voltage of the three low voltage adapters using a screw driver.
WARNING: You have to connect the system to mains and switch it on for this step, make sure you never touch the 220V conducting parts!
| Instruction | Image |
|---|---|
| Set 12V for the fan |  |
| Set 3.5V for the heating element |  |
| Set 3V, 5V or 12V for the LED lighting (For the LED lights linked in the parts list above, please use 3V. The picture was taken before that was installed) |
 |
NOTE: All wires should have their ends soldered before putting them into the WAGO connectors. It's not mandatory, but prevents problems of bad connections
- Glue in 7 WAGO-2x connectors
- Solder 2x AWG16 cables to the 2 Peltier power switches
- Solder 2x AWG10 cables to the Light and Heating switches
- Plug switches in their holes in the cover
- Feed the AWG16 wires from one connection of the Peltier switches through the holes to the high power voltage adapter
- Connect the AWG16 cables from the other Peltier switch connection to the Lower and Upper Peltier WAGO connector (make sure to not mix them up)
- Connect the AWG10 wires of one connection of the Light and Heating switches to the corresponding WAGO connectors
- Leave the 2 AWG10 wires from the other connection of the Light and Heating switches hanging loose (they'll be connected to the case base later)
- Insert mini voltage meters in the holes in the cover and also feed the wires through the holes to the high power voltage adapter
| Instruction | Image |
|---|---|
| - Rotate cover and make sure power and voltage meter cables are available |  |
| - Screw in high power voltage converters using 3x12mm screws - Screw in the AWG16 cables and the cables from the voltage meters into the out connectors of the voltage converters (take care of correct polarity) |
 |
The cooling tower consists of the copper plate on top of 2 stacked Peltier elements on the CPU cooler with thermo paste or pad in between (Both worked, I used pads in the final build, since they are less messy). This schematic of the cooling tower shows the different layers:
Note: Usually the side with the printing is the cooling side of the Peltier elements. But double check if that is true for the ones you use.
Instruction |
Image |
|---|---|
| - Overview of used parts for the top |  |
| - Use the stencils to mark cutout from the foam rubber |  |
| - Create two cutouts for the peltier elements and one for the copper plate |  |
| - Put silicone into the indentation in the top main part |  |
| - Glue in the copper plate. Make sure there are no gaps, the silicone acts as insulation and to prevent liquid from leaking out from the cloud chamber -Let it fully cure before continuing - Once cured, put it the other way around and let some isopropanol sit on top of the cover to make sure nothing leaks |
 |
| - Place the rubber foam insulation for the copper plate around it. It has to fit smoothly and must not bend or have too large gaps |
 |
| - Add the thermal pad or paste onto the copper plate |  |
| - Put one rubber foam insulation for the Peltier elements on the copper plate - Feed the wires from the 12709 Peltier element through the holes on the side of the top main part - Place the Peltier element with the printing onto the thermal pad/paste. |
 |
| - Add the thermal pad or paste onto the Peltier element |  |
| - Feed the wires from the 12715 Peltier element through the other two holes on the side of the top main part - Place the Peltier element with the printing towards the thermal paste/pad |
 |
| - Put the second rubber foam insulation for the Peltier elements around the Peltier element |  |
| - Close the stack with the Top Insulation Cover |  |
| - Add the thermal pad or paste onto the Peltier element |  |
| - Screw the brackets of the CPU cooler onto the Top Main Part - Attach the CPU cooler to the brackets with the two thumb screws on the cooler Screw them tight, so there is good thermal conductivity, but always check the top, so the printed part does not start cracking from the pressure |
   |
| - Turn the whole cooling tower over and spray the top with black spray paint |  |
| Instruction | Image |
|---|---|
| - Stick the heating element on top of the acrylic case - Fixate a piece of felt in the acrylic cover using the magnets |
 |
| Instruction | Image |
|---|---|
| - Print the Light Connector Box and the LED Carrier - slide the carrier into the box and screw in one or two 2mm screws to fixate the carrier |
 |
| - Screw the LED spot lights onto the carrier and feed their cables through the small opening of the box |  |
| - Attach the box to the cooling tower - Fixate it with screws if necessary The height of the LED spot lights can be adjusted by moving the LED carrier and fixating it with the screws from behind |
 |
| Instruction | Image |
|---|---|
| - Glue the cooling tower frame on the case cover |  |
| - Stick the cooling tower with the attached fan into the frame - Feed the cables from the Peltier elements, the heating element and the lights through the hole beside the tower frame in the case cover |
  |
- Connect the V+ wires of the Peltier elements to the corresponding WAGO connectors
- Connect the GND wires of the Peltier elements to the corresponding WAGO connectors
- Connect the V+ wires from the LEDs and heating element with the corresponding WAGO connectors
(Please note that in the picture, the GND cable wrongly is connected. The cable is supposed to be red, not black) - Leave the GND wires from the LEDs and heating element hanging loose
- Connect the loose cables from the top on the cover with the corresponding connectors in the base
- Light V+ (red wire from the power switch)
- Light GND (black wire from the cooling tower)
- Heating V+ (red wire from the power switch)
- Heating GND (black wire from the cooling tower)
- Fan V+ (wire from the cooling tower)
- Fan GND (wire from the cooling tower)
Before using the cloud chamber the first time, you need to adjust the voltage for the peltier elements.
- Make sure all power switches for the cooling tower are switched off
- Connect the 220V socket with a cable and plug it into mains
- Switch the 220V power switch
- The fan will start turning and the voltage displays will show the voltage they deliver to the peltier elements
- Adjust the voltage output of the voltage adapters on the case cover for the peltier elements using a screw driver and rotating the voltage adjustment clockwise. These values worked well for me:
- Upper Peltier: 5V
- Lower Peltier: 10.5V
- Make sure that you open up the current fully for the adapters
- Screw the current adjustment clockwise as far as it goes
- Drop 5ml of 70% isopropanol on the felt in the acrylic case
- Place a radioactive source on top of the cooling tower
- Put the acrylic case on top of the cooling tower, closing the chamber
- Switch on peltier elements
- Switch on lights
- Switch on heating element
- Wait for approx 5min
- Enjoy :)