How to Build a Portable Cloud Chamber




Introduction: What Is It?

A cloud chamber simply lets you see traces of ionizing radioation such as alpha and beta particles. What happens in the chamber is that at the bottom the peltiers cool down to at least -18f or below, to supersaturate 99% isopropanyl alcohol. When charged particles pass thru the supersaturated mist of alcohol at the bottom of the chamber, the air gets ionized and the alcohol almost instantly condense and forms small visible tracks. That's pretty much it, you can find further information at Google!!

This is a piece a Fiestaware saucer in my chamber.

Step 1: Gather Materials

Here´s a list of what I bought for my final version of the chamber. This is the part where you have to decide how much money you want to spend. Cheap TECs from China may fail to function after a short while of usage. I bought a whole bunch of different TECs from both China and HK and so far I havent encountered any problems. But if you are buing cheap ones, you might aswell buy a couple of them to have as a backup. The watercooling system costs alot, in sweden about 100 $. I choosed this one because I wanted to have a stable cooling solution at higher temperatures (I tried to run the chamber with both 2, 3 and 4 TECs with as high wattage of heat as 500 with no results at all) You definetly dont need watercooling when you stack 2 peltiers but I found it easier and way more fun to do it :-) There are very succesful builds out there using 4 aircooled TECs so go with whatever you feel is right.

Electrical components:

1 pcs TEC 12709 (Bottom) Found at eBay
1 pcs TEC 12706 (top) Found at eBay
Switched powersupply 12V, 200W, 17A (To run the 12709 TEC, fans and the Corsair H60) Found at eBay
Switched powersupply 5V, 100w, 3.5A (To run the 12706 TEC)
Corsair H60 v2 complete watercooling system
1 Scythe GT 5400 rpm (Fitted onto the radiator, LOUD AS F**K)
2 x 120mm outlet fans
1 pcs of 12V splitter 1 to 6
1 pcs Maglite
Wires, shrink hose, screws, connections etc. ("Stuff you have at home")


9 mm Plywood
Acrylic sheet 3mm
Filt fabric (the kind you have to cover loudspeakers with),
Insulation (make sure its dense),
Silicone (to make your setup airtight)

Chamber & other:

Glass vase or acrylic dome
2 mm black Delrin (acetal) plastic to make the floor of the chamber (1 mm gets you better results tho)
1 sponge
1 ltr of Isopropanol
A radioactive source of some kind
Balloon or other static source
Thermal grease

Step 2: Build the Housing

Its easy to build your own chamber, this is a short guide on how I built mine.

Assemble the housing, mine is made out of 9 mm Plywood. The housing measures 300 x 200 mm and 400 mm high. I glued togheter the parts as shown in the picture leaving one side open to be able to "serve the machinery" :-)

Step 3:

Make holes for the inlet- and outletsfans and mount the radiator, the fans and the fan protections. The fans and the waterpump are contected to the 1 to 6 12v splitter. I mounted the radiator in the bottom of the housing and the outlet fans at one of the sides (one above the other). Make sure theres an open flow for both intake and outlet, otherwise the setup might get overheated and your chamber wont get cold enough for trails to be visible. The bottom TEC you must run at 12V (approx) and the top one at 5V, this is a must as the bottom TEC must be able to handle the heat from both the top TEC and from itself. This is the values I have for my chamber, you might get good results with other voltages.

Step 4: Mount the TECs

At this picture you can see how the cooling block are fitted on top of the chamber, Then the two TECs mounted on top of the block. This is where you need to be gentle.

a. First apply the thermal grease at the coldplate, it's a good idea to use a razor to get it as even as possible.

b. Gently press the 12709 TEC at place, make sure you put it as shown in the pic, black wire facing you and red one at the back. This is essential as the side facing upwards in this setup is the side that gets cold, the other side will get very hot. If you do this wrong you might end up burning you device and even destroy the waterpump.

c. Apply thermal grease on top of the 12709 and firmly spread it to a even layer.

d. Gently press the 12706 TEC on top of the 12709.

Step 5: Testing

The copper block with TECs, mounted at the housing.

As shown in picture I must mount a frame to be able to support the top plate and the floor of the chamber made of 2mm Delrin. Before you put you chamber floor on top of the TECs is a good time to test if you can get your setup icecold. Make sure all cables are connected correctly before you turn it on.Otherwise you might end up with a damaged TEC or two as they get HOT very fast. If everything works you shall get a very cold area almost instant! You might wanna use a thermometer to check the temperature of the peltier!

If not:

- Check your cables once again.
- Make sure the TECs are connected correctly.
- Make sure your waterpump and radiator fan are running
- Are the TECs damaged?
- Check the thermal paste, it's probably more important than you think to get that part right!

Step 6: Insulation

Now you need to insulate you setup making it airtight aswell. The insulation is added to make the peltiers work more efficient as it costs alot of energy to pump the heat from one side to another. The insulation is also the key to not get water into places you dont want them. Ice will build up quickly and producing ice costs alot of energy and can destroy you chamber aswell. I use common insulation and you can use whatever you have lying around but make sure it is somewhat dense and doesnt let air thru. I also use alot of silicon to glue the parts togheter and make an absolute airtight setup.

More frames are added to support the top plate.

Now it is time to add thermal paste to the top TEC, dont be shy, you need to fill all the small gaps in the plastic sheet you have as a floor in the chamber. I use Delrin 2mm and Im pretty satisfied with it, it is prefered to use even thinner Delrin but I got good results with 2mm so I stick with that. Make sure you dont get any small pockets of air between the TEC and the plastic , that might drastically decrease the heat transfer from the plastic sheet to the TEC.

Step 7: Further Assembling

The top of the chamber is made of grey, frosted acrylic (covered in felt) with a hole cut out in the middle where the cooled chamber floor will be visible. Make sure there are a small pressure onto the plastic sheet (chamber floor) to make it airtight and to increase the heattransfer.

Step 8: Almost Done

At last it is time to put it all together and fire it up! I covered the whole chamber in felt because it looks awesome! Make sure you can be able to open one of the sides of the chamber, things can break and if it does you might want to fix it!

Step 9: Fire It Up

- This is the exciting part, add isopropyl to a sponge, I accually soak it, and put it into your chamber along with your radioactive sample. - Place a balloon on top of the chamber, make sure you rub it in your hair or something similar first to build up a static field. This is a must to be able to se the trails from the particles. - Turn on your machine, you should be able to see something within 5 minutes.

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    6 years ago

    You also find this guide on my project page along with more photos and links where to find sources of radiation, visit >>>>