Peltier Cloud Chamber Produces Some Lovely Trails

[Advanced Tinkering] over on YouTube has some pretty unique content, on subjects of chemistry and physics that are a little more, interesting let’s say — anyone fancy distilling cesium? The subject of this build is the visualization of ionizing radiation tracks, with one of our old favorite physics demonstrators, the venerable cloud chamber. The build video (embedded below,) shows the basic construction and performance of a Peltier effect cooler setup. The system is used to create a layer of supersaturated (and cold) alcohol vapor in which the radiation source or other experiment can be immersed.

Peltier modules are a great solution for moving heat from one surface to another, but they are not terribly efficient at it, especially if you don’t keep the hot side temperature in check. Effectively they are a short-distance heat pump, so you need to dump the hot-side heat elsewhere. The method [Advanced Tinkering] chose here was to use a pair of off-the-shelf water cooling blocks, mounted into a 3D printed plate. The hot side dumps into a pair of fan-cooled radiators. Four double-layer Peltier modules are wired in parallel to a 60A power supply, which seems like a lot, but Peltier modules are hungry little things. A reasonable amount of power is needed to drive the cooling fans and water pump. The vapor source is a simple pad of liquid alcohol at the top of the stack, just above a metal screen which is held at a high voltage. The vertical electric field allows visualization of the charge of emitted particles, which will curve up or down depending on their polarity.

As can be seen from the second video linked below, some really nice cloud trails are produced, so it looks like they got the setup just right!

Do you need all this complexity to visualize simple radiation paths? No, you don’t, but just temper your expectations. Peltier-based builds are not uncommon, here’s another one, but some builders say they’re not very robust, so this build uses phase-change technology instead for some serious runtimes.

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Maker Faire NY: Cocoa Press Chocolate Printer

If you haven’t figured it out by now, the hype over desktop filament printers is pretty much over. But that doesn’t mean there aren’t new avenues worth exploring that use the basic FDM printer technology. If anything, the low cost and high availability of 3D printer parts and kits makes it easier to branch off into new territory. For example, experimenting with other materials which lend themselves to being “printed” layer by layer like a thermoplastic. Materials such as cement, clay, or even chocolate.

[Evan Weinstein] brought his Cocoa Press printer to the 2018 World Maker Faire in New York, and we have to say it’s a pretty impressive piece of engineering. Hackers have been known to throw a syringe-based paste extruder onto a regular 3D printer and try their luck with squirting out an edible object from time to time, but the Cocoa Press is truly a purpose built culinary machine.

Outwardly it features the plywood case and vaguely Makerbot-looking layout that we’ve seen plenty of times before in DIY 3D printers. It even uses the same RAMPS controller running Marlin that powers your average homebrew printer. But beyond these surface similarities, the Cocoa Press has a number of purpose-built components that make it uniquely qualified to handle the challenges of building with molten chocolate.

For one, beyond the nozzle and the walls of the syringe, nothing physically comes into contact with the chocolate to be printed; keeping the mess and chance of contamination to a minimum. The leadscrew actuated plunger used in common paste extruders is removed in favor of a purely air powered system: a compressor pumps up a small reservoir tank with filtered and dried air, and the Marlin commands which would normally rotate the extruder stepper motor are intercepted and used to trigger an air valve. These bursts of pressurized air fill the empty area above the chocolate and force it out of the 0.8 mm nozzle.

In a normal 3D printer, the “melt zone” is tiny, which allows for the heater itself to be relatively small. But that won’t work here; the entire chocolate load has to be liquefied. It’s a bit like having to keep a whole roll of PLA melted during the entire print. Accordingly, the heater on the Cocoa Press is huge, and [Evan] even has a couple spare heaters loaded up with chocolate syringes next to the printer so he can keep them warm until they’re ready to get loaded up.

Of course, getting your working material hot in a 3D printer is only half the battle, you also need to rapidly cool it back down if you want it to hold its shape as new layers are placed on top of it. A normal 3D printer can generally get away with a little fan hanging next to the nozzle, but [Evan] found the chocolate needed a bit of a chill to really solidify.

So he came up with a cooling system that makes use of water-cooled Peltier units. The cold side of the Peltier array is inside a box through which air is forced, which makes its way through an insulated hose up to the extruder, where a centrifugal fan and 3D printed manifold direct it towards the just-printed chocolate. He reports this system works well under normal circumstances, but unusually high ambient temperatures can overwhelm the cooler.

While “the man” prevented show goers from actually eating any of the machine’s creations (to give out food in New York, you must first register with the city), they certainly looked fantastic, and we’re interested in seeing where the project goes from here.

Trinket Chills Your Drinks

Who wants warm drinks? Well, coffee drinkers, we guess. Other than them, who wants warm drinks? Tea drinkers, sure. How about room temperature drinks? No one, that’s who. It’s silly to buy a refrigerator to cool down a single drink, so what option are you left with? Ice cubes? They’ll dilute your drink. Ice packs and a cooler? Sure, they’ll keep your drinks cold, but they’re hardly cool are they? No, if you want a cold drink the cool way, you build a thermoelectric cooler. And if you want to build one, you’re in luck, because [John Park] has a tutorial to do just that up on AdaFruit.

The parts list includes an AdaFruit Trinket M0, a more powerful version of AdaFruit’s Trinket line. The Trinket is used to control the main part in this build, a Peltier thermoelectric cooler, as well as the temperature display and switches. The other part controlled by the microcontroller is a peristaltic pump, which is used to do the dispensing of the liquid. The code to control everything is written in Python as the Trinket M0 comes with AdaFruit’s CircuitPython by default. Also included in the tutorial are the files for the stand, should you want to 3D print it or cut it with a CNC or laser cutter.

After the break, you can watch as [John] goes over the project and builds it, or go to the AdaFruit website and follow the instructions to build your own. As [John] says, there might be better ways to chill your drinks, but this is “definitely one of the more science-y and interesting ones.” For more projects using the Peltier Effect, try this one that uses the effect in sous-vide cooking, or this one, a Peltier cooled micro-fridge!

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peltier mini fridge

Building Your Own Mini Fridge?

Ever play with a Peltier plate? They’re these really cool components that kind of look like a ceramic sandwich, and when you put power into them, one side gets hot, and one side gets freezing cold! [Joseph Rautenbach] decided he wanted to try making his own mini fridge out of one — which is typically how most modern mini fridges work these days.

The peltier plate he’s using draws 12v at about 3.5 amps — so about 50W — and if you don’t heat sink it properly you could burn it out in a matter of seconds. Peltier plates only care about the temperature differential between the two sides — if you don’t take the heat away from the hot side, it will soon overheat and destroy itself.

[Joe’s] using a styrofoam cooler for the fridge with a pair of computer heat sinks and fans for the peltier plate, and a temperature PID controller he bought off eBay. The external heat sink sucks away the excess heat generated by the peltier plate, and the internal one helps spread cooled air around the inside of the styrofoam cooler. The PID controller allows him to set a preferred temperature to maintain in the box, which will then control the outputs to keep it that way.

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2.5kW Of Beverage-Cooling Awesomeness

We’ve covered many thermoelectric beverage coolers in the past, but none come close to the insane power of the AbsolutZero. [Ilan Moyer] set out to design a beverage cooler that chills a drink from room temperature to 5 degrees Celsius as quickly as possible, and it looks like he succeeded. The AbsolutZero consumes around 2.5kW of power and runs 8 water-cooled thermoelectric modules to quickly chill a drink.

[Ilan] put his machinist skills to work and fabricated many custom parts for this build. He machined water blocks for each thermoelectric cooler out of solid copper which draw heat away from each thermoelectric cooler. He also fabricated his own bus bars to handle the 200A+ of current the system draws. To transfer heat from the beverage to the thermoelectric modules, he turned and milled a heat spreader that perfectly fits a can of any beverage.

[Ilan]’s design uses a closed-loop water cooling system and 4 radiators to dissipate all of the heat the system produces, which is quite a lot: thermoelectric modules are typically only 10-15% efficient. The whole design is buttoned up in a custom polycarbonate enclosure with a carrying handle so you can conveniently lug the massive setup wherever quickly chilled beverages are needed. Be sure to check out [Ilan]’s build photos to see his excellent machining work.

Thanks for the tip, [Stefan].

Pain Machine Brings Pleasure, Too

Pain is a good thing. It tell us to pull our hand away from the stove and to stay off a turned ankle. But we all have different experiences of pain, and chronic pain degrades our quality of life. A person’s reports of pain will vary from one day to the next based on many factors, so the 1-10 scale isn’t universally effective in determining a person’s pain level. [Scott]’s entry into The Hackaday Prize is based on the classic cold pressor testing device, which measures changes in heart rate and blood pressure in a patient while their hand is immersed in ice water for one minute.

[Scott] has tentatively dubbed his device The Pain Machine, but it does more than the typical cold pressor apparatus; it also delivers simulated pain relief in the form of warm water when the valves are reversed. In addition, the subject under testing can push a button when they’ve had enough. While his original plan used external sources of hot and cold water, [Scott] pulled a couple of Peltier coolers from some wine chillers for a more contained design.

The Pain Machine uses an Arduino ATMega 2560 to control gravity flow solenoids, collect temperature data, and send the data cloudward. A couple of 110V pumps circulate the water. [Scott] will open up the code once he has finished commenting it and fleshed it out with use cases. For now, you can check out his two-minute entry video after the break.

SpaceWrencherThis project is an official entry to The Hackaday Prize that sadly didn’t make the quarterfinal selection. It’s still a great project, and worthy of a Hackaday post on its own.


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Peltier Mini-Fridge Preserves Chip Quik, Marriage

[Charles] uses Chip Quik to solder his SMD parts, and that stuff can keep for more than six months if it’s kept cool. His wife banned all non-food items from their refrigerator, so he had to think fast and came up with this Peltier effect Chip Quik cooler.

He first looked into that man cave essential, the mini-fridge, but they’re too expensive and use too much power. [Charles] got a nice wooden box from a hobby store and some reflective insulation from Lowe’s. He first tried using a couple of heat sinks but they weren’t going to cool things down enough. Once he got a Peltier cooling kit, he was in business. The temperature in his workshop averages 80°F, and he says the box gets down to 58°F. This is cold enough to keep his paste fresh.

[Charles] plans to use a PC power supply in the future rather than his bench supply. He estimates that his Peltier cooler uses 25-50% of the power that a mini-fridge would, and now his wife won’t overheat. Many great things can be accomplished with the Peltier effect from air conditioning to sous-vide cooking to LED rings. What have you used it for?