Hacking a Heating Pad


[Bob] and his wife use a bed heating pad. In the winter, they typically turn it on about an hour before bedtime so the bed is nice and warm. The problem is, if they accidentally leave it on, they’ll wake up a few hours later: overheated. What they needed was an advanced timer system.

A normal outlet timer wouldn’t fit his needs: most of the year the pad should shut off after a slight delay, but in the winter they prefer to leave the heating pad on at a much lower temperature. [Bob] decided to create a custom timer with a microcontroller to provide adjustable duration and heating levels.

The circuit is simple. It consists of a microcontroller, a 2-digit LED display, two buttons, and two wires that connect to the heating pad’s original controller. The final build allows you to set the time the pad turns on, turns off, and/or down a few levels. It’s a fantastic hack, and you can see how the interface works in the video following the break.

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How to build a vacuum form table that gets it right every time

[James] builds all sorts of robots and superhero costume replicas at home, so he is always searching for a better way to get consistent results when using his vacuum table. A lot of people use their oven or exposed heating coils from electric frying pans to warm the plastic sheets, but [James] wasn’t really interested in going down that route. He cites that he would rather not heat plastic in the oven where he cooks his food, nor is he really keen on the idea of exposed heating elements.

Instead, he opted for a slightly pricier, though completely reasonable setup that produces consistent results every time. Most of the forming table was built using MDF sheeting, as you can see in the video below. His heating apparatus was the most expensive part of the rig, since it’s an off the shelf quartz-based room heater. He lays the heater on its back side, and directs the heat up through an MDF frame using aluminum foil as a reflector. The plastic sheeting mounted at the top heats evenly, and in no time, he has a perfectly vacuum formed prop that is ready to be painted.

Sure, it might cost a bit more than some other vacuum formers we’ve looked at before, but spending a bit more up front to get consistent results is well worth it if you ask us.

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Hot resistors used for color-changing clock face

[Sprite_TM] built a full clock display using thermochromic paint. This picks up where he left off with his paint-based 7-segment display prototype. He never really saw that design through to a finished project, but he recently came across the leftover paint and decided to do something with it. Instead of making thin traces on a PCB he’s heating up resistors mounted on protoboard. Each resistor has been coated with the black/light grey paint after getting a rough sanding on the tops of the packages. Run around 500mW through a segment and they heat up enough to change the paint to light grey. Once shut off, the segments gradually fade over the next 60 seconds.

Add-on panel brings automated vents flaps to a PC

[SXRguyinMA] built a replacement top bezel for his computer case. He wanted to add vents that would automatically open or close based on the cooling needs of the computer. With some careful measurements he modeled the parts in Sketchup and sent out for them to be cut from styrene with a water jet cutter. The parts came back looking great and the assembly of the shutters went swimmingly. The bezel also includes a lighted screen for temperature information, as well as the front USB ports, headphone and mic jacks, etc. Hidden underneath is an Arduino board and servo motor. The Arduino polls the temperature and drives the servo to adjust the fins accordingly. There’s even a supercap in the circuit that will close the vents when the PC powers down or when power is unexpectedly lost. See it in action after the break.

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Pipe heating with an ATMega8

[Viktor] wanted a system to keep his pipes from freezing.  The common method of using heat tape works pretty well, but can be wasteful. Many people just turn it on for the entire winter. [Viktor] wanted to automate the heat tape’s power so that it only activated during times that the pipes could actually freeze. To do this, he rigged an ATMega8 to a temp probe and is using it to control an ATX power supply. Pretty slick [Viktor].

[via HackedGadgets]

Better temperature readings using an aspirated thermometer

Unlike regular thermometers that can get incorrect readings because of the sun’s heat, shading, and airflow, aspirated thermometers isolate the temperature sensor from precipitation and the sun, while providing constant air circulation. Take ten 1-wire T2SS boards and combine them with DS18B20s and you’ve got yourself the start of an aspirated thermometer. A foot of PVC pipe, fans, and the above mentioned parts and you’ll have accurate temperature readings in no time.

[Dave] made his to control a natural gas boiler, pumps, and 11 gas-fired unit heaters for a combined output of 5.3 million BTUs per hour – keeping his greenhouse nice and toasty.

Update: Thanks Firetech for pointing out our silly typo.

IR air conditioner timer

installed (Custom)

[Tom] has an office job in China. His office is cooled by a small single room air conditioner. In an effort to make his office a little more comfortable, he built this IR timer unit. It cools his office down before he gets there so he doesn’t have to wait for it in the morning. He started by decoding the IR signal from the remote for the unit. He then built this ATiny13 based remote. He notes that the internal clock of this thing isn’t that accurate. power cycling it every day seems to help. It is also pretty cool that he built the unit to not only send the cooling code, but he can switch it to the heating code for the winter.

[thanks Mario]