Fail of the Week: Project Frosty Mug is Merely Chilly

beverage cooler failLike many of us, [C] enjoys an ice-cold, refreshing soda while coding. Driven by a strong desire to keep a soda ice-cold indefinitely without using ice, [C] started Project Frosty Mug.

[C]‘s stated goal is to keep a 20oz plastic bottle of soda at ~35F indefinitely while it sits in a room temperature environment. He started with a thermoelectric unit to cool an aluminium disc, like a cold coaster. Builds one and two made him realize that dealing with the generated heat was a big issue: it got so hot that it deformed the PLA frame. [C] also realized that bottom-only cooling wasn’t going to get the job done.

This project is now in its third build, which is pictured above. As you can see, it’s more koozie than coaster. That 3-D printed holster is lined with aluminium sheeting. Another flat piece covers the opening and attaches to the cooling element. A beefy CPU heat sink does its best, and a couple of U-brackets hold it all together.

[C]‘s tested it with a glass bottle of Diet Sun Drop chilled to 38F. After 30 minutes in an ambient temperature of ~70F, the soda measured 45F. [C] lamented having not used a control bottle for comparison and reports that the power supply became quite warm. [C] isn’t going to give up that easily. Do you have any ideas for the fourth build?

Editor’s Note: This is one of the last Fail of the Week tips we have stored up. If you want to see the series continue on a weekly basis, we need help finding more documented fails! Please look back through your projects and document the ones that didn’t go quite right. We also encourage you to send in links to other fails you’ve found. Just drop the links in our tips line. Thanks!

2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.


Goldilocks Climate Box Keeps Lager Fermentation Environment Just Right

Climate box for lager brewingSeptember was warmish in many places around the world including [Ole]‘s native Denmark. But that did not stop him from brewing lager flavored with plums from his own garden, and neither did his indifference to lagers in general.

Lager fermentation requires a consistent, low temperature. While many homebrewers might modify an electric refrigerator, [Ole] wasn’t interested in the cost of running a second one just for brewing beer. Instead, he built a climate box to work with the cool temperature in his garage. Starting with scrap wood from other projects, he lined the walls with polystyrene and put a layer of wood on the floor to help support the fermentation bucket.

Maintaining a consistent temperature in the box called for both heating and cooling. He pulled the Peltier from a 12V cooler meant to run off a car’s cigarette lighter, and used a spare ceramic heater that was lying around in case his primary reptile warmer went on the fritz.

An Arduino and a custom shield drive separate PID controllers for the Peltier and the heater. The shield has a temperature probe, and he extended the USB outside the climate box so the PIDs can be adjusted without disturbing the inside temperature. The schematic, board file, and code are all available in a zip you can get from his post.

The Peltier couldn’t quite compensate for the overly warm weather and the heat caused by the fermentation, but it was stable enough to produce a nice, plum-flavored lager he has dubbed Lektor Blom­mes malt­bol­che, which is a triple Danish pun he explains in the write-up.

DIY Coolsculptor Freezes Fat with Cryolipolysis


You’re probably wondering why [Eddy], pictured above, decided to clamp two CPU cooling blocks to his torso. We were a bit concerned ourselves. As it turns out, [Eddy] has managed to construct his own Cryolipolysis device, capable of delivering targeted sub-zero temperatures to different parts of the body using a technique more popularly known as “Coolsculpting.”

Cryolipolysis is a non-surgical method of controlled cooling that exposes fat cells to cold temperatures while also creating a vacuum to limit blood flow to the treated area. [Eddy's] challenge was to discover exactly how cold to make the treatment surfaces—a secret close-guarded by the original inventors. After digging through the original patent and deciding on a range between -3C and 0C, [Eddy] began cobbling together this medical masterpiece and designing a system capable of controlling it.

His finished build consists of a simple three-button interface and accompanying LCD screen, both wired to an Arduino, allowing the user to adjust temperatures and keep tabs on a session’s time. Unfortunately, results can take several months to appear, so [Eddy] has no idea whether his creation works (despite having suffered a brush with frostbite and some skin discolorations, yikes!) You can pick through a gigantic collection of photos and detailed information over at [Eddy's] project blog, then stick around for a video from an Australian news program that explains the Coolsculpting process. Need some additional encouragement to experiment on yourself? You can always strap some electrodes to your head and run current through them. You know, for science.

[Read more...]

Peltier Joule Thief Power Supply

Peltier Joule Thief Power Supply

[Steven] manages to power an LED for 15 minutes using hot and cold water as a battery. He does this using the thermoelectric effect also known as the Seebeck effect, Peltier effect or Thomson effect. This isn’t particularly new; in fact there are commercial products that you can use to charge a cell phone using a small campfire or internal burner that works on the same principle.

What is interesting about [Steven’s] device is that he uses a salvaged Peltier device not meant for generating electricity, coupled with a home built joule thief circuit. In the video he describes how the joule thief functions and powers the LED using the small voltage generated by the Peltier device. The energy for the thermoelectric effect is conducted from a hot water bath through aluminum plates, through the positive and negative sides of the Peltier device, through more aluminum plates and finally into a cold water bath. As the heat energy transfers through the Peltier device a small electric current is generated and flows in two small wires coming out the side of the device.  The energy generated by the Peltier device is stored in the joule thief and periodically dumped at a voltage high enough to forward bias the LED “on” for a brief moment. Technically the LED is flashing but at a frequency too high for our eyes to see. As the hot water bath cools, the LED goes from very bright, to dim, to off in about 15 minutes.

Not a very practical power supply but still quite the parlor trick. He wraps up the tutorial specifying that a TEG thermoelectric generator would be a much better choice for generating power and can handle much higher temperatures. You can watch the video after the break.

[Read more...]

Energy harvesting to build a Carbon Monoxide Detector with no battery


There are a few devices that work tirelessly to protect our lives. We’re talking about smoke detectors and carbon monoxide detectors. Increasingly these either need to be hardwired into the home, or have a sealed battery which is good for ten years (in the case of smoke detectors). [Gelmi] recently had to change the battery in his Carbon Monoxide detector — which happens very rarely — and he it got him to thinking. If the batteries need to be changed so rarely, how hard would it be to harvest energy to power the device?

Our first thought was that he’d use inductance like those spy birds which perch on power lines. But instead he went for the heat lost from using the hot water spigot. Above you can see his test rig which attached a Peltier device to the faucet in his bathroom. Whenever you turn on the hot water the faucet also heats up. The differential between faucet temperature and ambient room temperature generates a small amount of power. This is a suitable source, but only if he could also cut the amount of power needed by the detector. This adventure takes him down the rabbit hole, learning about how the sensors work and designing for reliability at the lowest consumption level possible.

The faucet application might seem peculiar. But if you use a natural gas water heater you want a carbon monoxide detector near it. Attach the Peltier to the outflow and every time any hot water tap in the house is opened your system will get a bit of a recharge.

[Read more...]

Generating electricity from alcohol


Here’s a thermoelectric generator which [x2Jiggy] built. The concept uses heat from a flame, biased against cooler temperatures produced by that huge heat sink making up the top portion of the build to produce electricity via the Peltier effect.

The build is passively cooled, using a sync assembly that takes advantage of heat pipes to help increase the heat dissipation. A nearly flat heat sink makes up the mounting surface for the hot side, which faces down toward a flame driving the generator. [x2Jiggy] started the project by using a can, wick, and olive oil as the heat source. He managed to get about 2V out of the system with this method. What you see here is the second version. It swaps out the olive oil lamp for an alcohol stove. The cans with holes punched in them act as a wind screen while also providing a stable base. This rendition produces about 3V, but it doesn’t sound like there are any precise measurements of what it can do under load.

Temperature controlled wine cellar substitute


Serious wine enthusiasts keep their bottles in a room built for the task. If you don’t have that kind of space you can still fabricate a similar storage environment. This foam box keeps stored wine at a controlled temperature. It also keeps light off of the precious goods. [Michael] built it himself to use in his apartment and published a description of the build process.

He picked up some foil-coated foam board from the home store. Six sections come together into a box about the size of a mini-fridge; 24″ by 24″. A square hole was cut in the center of the top section. This receives the smaller of two heat sinks mounted to a Peltier cooler. The temperature inside is monitored by a thermistor which [Michael] tore out of an old iPod battery. To give him some visual feedback on the internal temperature he added that yellow and black striped meat thermometer.

Since this is for long-term storage, we’d bet the system is rather efficient. As long as the door isn’t frequently opened the temperature change should be quite slow thanks to the insulation and the cool liquid in wine bottles.


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