Introduction: Cloud Chamber Particle Detector

In this instructable, you will learn to build your own cloud chamber! This design utilizes peltier thermocoolers, a power supply, and CPU cooler instead of dry ice, to give consistent and remarkable results! The cost of building this reusable turn key cloud chamber is between $150-$200. To start, you'll need to gather materials.

Materials List and links:

8" x 16" x 1/2" piece of plywood

4'6" of corner moulding trim

Black spray paint

4 - 1" adjustable feet screws

430 W power supply

V8 GTS CPU cooler

12709 peltier

12710 peltier

7g arctic silver thermal paste

100mm petri dish

3" x 3" x 1/8" project panel

3/4" diameter black flex tubing

13" LED string lights

2 - #6-32 x 2" machine screws

2 - #4-1/2" self driving screws

3.5" square of chamois

1/4" diameter heat shrink

2 -1.5" x 5/8" L brackets

2- #10-3/4" screws

Electrical tape

3D printed materials:

4 parts of this cloud chamber are pieces we printed using a 3D printer. If you have your own printer, feel free to copy the STL files found above and print on your own. Otherwise, email and we can ship you all the necessary 3D printed parts.



Drill bits sized 3/8" and 5/32"

Hammer or mallet


Wood glue


2-part plastic epoxy

Concrete cement


2.5mm allen key

Wire cutters/wire strippers

Masking tape

Solder/soldering equipment

Needle-nosed pliers(optional)

Step 1: Assembling the Base

To begin, use brown stain to completely coat your board and trim. Pick one large face of the board to be the top. This side should be the one with the best finish. Measure and mark a 1" border along each edge of the board. On the corners of the border, use a 3/8" drill bit to drill a hole directly down, from top to bottom.

Flip over your board and hammer in adjustable wedges. Screw in feet.

Lay your base flat on the table and arrange the 4 pieces of trim around the base. Use wood glue to attach the trim and hold in place using large clips.

Step 2: Mounting the CPU Cooler

To mount the CPU cooler, pick a short edge of the board to be the top. Use a ruler to find the middle of the board and trim. Measure 1” down from the trim to make a mark. Place a second mark 5.125” straight down from the first mark.

Drill through the board at the two points from the top using a 9/64" drill bit. Flip the board over. Screw in the long screws until they pop through the other side about 1/2".

Unscrew the 2 screws on the bottom of the CPU cooler using a 2.5mm allen wrench and place CPU cooler so that the wires on the CPU cooler are facing your top side. The screws coming through the board should enter the CPU cooler in the threads from which you removed the screws. Tighten the screws all the way.

Step 3: Converting Power Supply

To begin, we need to be able to work with the wires. Find the 24 pin adapter. Using scissors, cut only the mesh wire organizer from the 24 pin adapter an inch from the power supply. Cut all the way around. Using scissors, cut the adapters, rubber and the zip tie from the wires and slide off the mesh. Throw away the adapters, mesh, rubber and zip tie.

Next, grab the following wires:

  • 5 Black
  • 2 Yellow
  • 1 Red
  • 1 Green

They can be any wire as long as they match the color description. Label the wires with masking tape and a marker near the power supply. Your black wire labels will be 1 - 5 (yellow will be 1 and 2). The red and green wires will both be labeled 1.

Step 4: Converting Power Supply

Cut and remove the adapters off all other wires and remove the mesh wire organizers. Label one solid yellow wire number 3. This can be any solid yellow wire that is not from the 24 pin adapter.

Cut all unlabeled wires to 2" long. They are unnecessary for the completion of the cloud chamber. This does not have to be exact. Bunch together wires of the same color and tape the ends together. Different colored wires should not touch. Tape together all bunches into one group.

Step 5: Converting Power Supply

Turn your attention to the labeled wires. Using your wire cutters, cut the wires to the following lengths:


1 - 6.25"

2 - 4"

3 - 8"

4 - 8"

5 - 12.5"


1 - 6.25"

2 - 9"

3 - 12.5"


1 - 9"


1 - 4"

Strip the end of each wire .5".

Step 6: Soldering the Wires Together!

In order to make the connection between the power supply and the CPU cooler, we need to solder a couple of wires together. If you haven't soldered before, follow along below.

Solder the ends of black wire 2 and green wire 1 together. Wrap this connection with electrical tape.

Make sure none of the exposed wires are touching. Plug in the power supply with the provided cable. If the fan spins, you have done this correctly. You may continue to the next step.

If the fan does not spin, double check the connection between your soldered wires and make sure exposed wires of different colors are not touching. Try again.

Step 7: Connect CPU Cooler to Power Supply

Take black wire 1. Create a V shape with the exposed wires (one side of the V should have about 2/3 of the exposed wires). Take the larger group and cut the wires at the point where they meet the rubber casing.

Twist the remaining group into a tight spiral. You may use needle-nosed pliers if needed.

Repeat those steps with yellow wire 1.

Pick up the adapter connected to the CPU cooler. Looking above the adapter, you should see different colored wires. Position the adapter so the black wire is on the left.

Plug black wire 1 into the adapter slot all the way to the left, which is also the adapter slot that attaches to the black wire on the CPU cooler.

Yellow wire 1 will be plugged in to the right of the black wire where the yellow wire connects to the adapter.

Make sure none of the exposed wires are touching. Plug in the power supply again. The fans on the power supply and CPU cooler should turn on.

Step 8: Printing Supplies and Assembling the Chamber Base

Our version of the cloud chamber has four printed parts for a sleek design. To print, download the STL files from the materials and tools section and tailor them to your printer's needs. You may also contact and we will print and mail you the necessary pieces.

Once printed, attach the peltier holder to the top of the CPU cooler by sliding the side with an already attached arm over the metal on the CPU cooler. The open side of the holder should face away from the wires on the CPU cooler. Use 2-part plastic epoxy to glue on the peltier arm to the peltier holder so it is clipped onto the metal piece on the side of the CPU cooler.

Take a 3" square of project panel, 1/8" thick, and use an exacto knife or hot wire cutter to cut the project panel into 3 pieces. Pieces 1 and 2 will be identical, and need to measure at 1 7/8" by 1/2" and be 1/8" thick. The third piece will still be 1/8" thick, but will have slightly different dimensions. It needs to measure at 1 1/2" by 3/8".

Step 9: Attaching the Peltiers

Take your peltiers and cut 5.5" off of the black wires and 4.5" off the red wires from the ends of the wires. Be sure to notice you are measuring not from the peltiers, but from the end of the wire. Strip each wire .5".

Slide an inch of heat shrink down the following wires, being sure to slide the heat shrink all the way down the wire so it does not melt during the soldering process:

  • Yellow wire 2
  • Black wire 3
  • Red wire 1
  • Black wire 4

First, connect the 12710 peltier. Solder the red wire to yellow wire 2 and the black wire to black wire 3. Slide the heat shrink over the connection and shrink with a heat gun.

With the black wire on the right and the red wire on the left, apply a thin, even layer of thermal paste onto the peltier. Use a credit card like material to spread. Take the sticker off the top of the CPU cooler, this is where you will place the peltiers. Firmly press the peltier, thermal paste down, onto the CPU cooler. Plug in your power supply (no wires touching) and test that the top of the peltier is cold. If not, flip it over and try again.

Now, connect your 12709 peltier. Solder the red wire to red wire 1 and the black wire to black wire 4. Cover the connections with heat shrink.

Apply the same amount of thermal paste to the top of the 12710 as the bottom and press the 12709 down firmly on top of it with the red wire on the right and the black wire on the left. Plug in the power supply and make sure the top is cold.

The project panel can now be placed around the peltiers. The longer sides go on the left and right of the peltiers. The shorter side is to be placed in between the peltiers and peltier holder, opposite the peltiers' wires.

Step 10: Make the Petri Dish Chamber

Attaching the PVA:

To create a chamber in which alcohol is super saturated, you need a material that releases alcohol at a slow rate. We use PVA, which can be found in most auto parts store or section.

To get the correct size for your chamber, use the base of the petri dish to trace a circle, using a pencil. Cut the circle out. Cut the PVA circle directly in half.

Now cut smaller half circles out of the half circles you already have, creating two rainbow shaped arcs, about a 1/4" thick. Use epoxy and a paint brush to paint the smooth side of the PVA arcs and place along the edge of the inside of the bottom of the petri dish. Be very careful when using the epoxy cement to assure no extra glue gets on the petri dish, it will obstruct viewing.

For the base of your cloud chamber, you will need to spray paint the top of the petri dish with black spray paint, after taping the sides so they remain clear. This will allow the trails to be seen clearly.

Step 11: Completing the Chamber

Take the LED strip lights and cut them to 13" or at a point that is relatively that size where it is instructed for you to cut.

Solder black wire 5 to the negative connection of the LED and yellow wire 3 to the positive connection of LED strip. To make this easier, use the solder to make small hershey kiss sized solder droplets on the LED strip at the connection point. Then press the respective wires into the kiss and cover with solder.

Once attached wrap a small amount of electrical tape around the connection. Poke the string of lights through the hole of the LED holder and use epoxy to attach the LEDs to the rim of the holder. Use tape to hold in place while it dries.

Turn on your cloud chamber to make sure the LEDs turn on. Align the LED holder so the screw holes on the peltier holder are directly below the screw holes on the LED holder. Use two .5” screws to attach the LED holder to the peltier holder.

Put a more generous, but still even layer of thermal paste on top the the 12710 peltier and press the black part of the petri dish to the top of the peltier. It is very important that the petri dish is pushed firmly and makes very good contact with the peltiers.

Place the petri dish with PVA on top of the black petri dish. Use the LED cover to shield your eyes from the LEDs.

Step 12: Mounting the Power Supply

To mount the power supply, place next to the CPU cooler with the fan facing away and the wires pointing off a long side of the board. Center on the base at about 2” from the CPU cooler.

Take out the 2 screws on the power supply on fan side that are closest to the table. Place the black foam under the L brackets. Align the L brackets so that one hole is up against the power supply and the other holes go into the base. The .75” screws go into both screw holes on the base and then into the power supply.

Wrap black flex tubing around the wires going from the power supply to CPU cooler. Congratulations, you have finished your cloud chamber particle detector!