Hacking A Heating Pad

December 16, 2013 by James Hobson 18 Comments

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[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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A New Way To Heat People

December 16, 2013 by James Hobson 146 Comments

[Leigh Christie] is a researcher at MIT, and he’s developed an interesting solution to heating people, not buildings.

His TEDx talk, “Heating Buildings is Stupid,” demonstrates the MIT SENSEable City Laboratory’s efforts to tackle energy issues. Their research focuses on finding an alternative to the staggering waste of energy used to heat large spaces. Although TED talk articles are a rarity at Hackaday, we think this idea is both simple and useful. Also, [Leigh] is the same guy who brought us the Mondo Spider a few years ago for the Burning Man exhibition. He’s a hacker.

Anyway, what is it? The system he’s devised is so simple that it’s brilliant: a person-tracking infrared heat spotlight. Using a Microsoft Kinect, the lamp follows you around and keeps the individual warm rather than the entire space. [Leigh] has grand plans for implementing what he calls “Local Heating” in large buildings to save on energy consumption, but smaller-scale implementations could prove equally beneficial for a big garage or a workshop. How much does your workspace cost to heat during the winter? Hackerspaces seem like the perfect test environment for a cobbled-together “Local Heating” system. If anyone builds one, we want to hear about it.

Check out the full TEDx talk after the break.

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Raspberry Pi Wall Calendar

December 15, 2013 by James Hobson 49 Comments

Do you let Google know every aspect of your personal and social life? Do you have a spare LCD monitor kicking around? Why not make your own Raspberry Pi Wall Calendar?

[Alex] recently bought his first home (congratulations!), which happened to have a TV wall mount in the kitchen. Personally, we don’t think TVs belong in the kitchen, and neither did [Alex]. Not wanting to tear the mount out of the wall (and thus require home renovations too soon), he devised a clever solution: why not make a digital calendar?

[Alex] connected a Raspberry Pi model B to the LCD monitor, which provides convenient access to his Google Calendar. His Instructable is both meticulous and approachable, so novice hackers should have no trouble replicating this build. The only improvement we can think to suggest is substituting a touchscreen LCD, which would allow him to interact with the schedule.

Whether you “let” Google know about your life— or it just knows—this is certainly a handy hack for the 21st century home!

Digital Electric Meter Monitor Goes Old School

December 14, 2013 by Adam Fabio 22 Comments

[Sal] sent us his digital electric meter monitor, which immediately made us nostalgic for some of Forrest Mims’ books. Sal’s schematic and circuit description are similar to Forrest’s style, and we mean that as a compliment. Even in today’s world of CAD and EDS packages, sketching out a circuit by hand is sometimes both easier and faster. The schematic isn’t the only classic aspect of [Sal’s] design. He’s collecting data using a parallel port on an unused PC: in this case, a Toshiba Libretto running Windows 95. Before cheap flash-based microcontrollers and dev boards were available, the PC parallel port was the go-to hardware hacking interface for many of us. Plenty of the software running those old hacks was written in basic, and [Sal’s] meter is no exception. His software runs on Microsoft QBasic, which shipped with Windows 95.

The circuit takes advantage of the digital meter’s output: a 10 ms pulse for every 1 Wh of energy used. An IR photo detector from RadioShack detects the meter pulses, which are amplified by an LM324 Op Amp. An NPN transistor then shifts the output to send it to two 74LS73 JK flip flops. The first flip flop uses a transistor to drive an LED for visual output. The second JK flip flop sends the data to the PC. The flip flop has the effect of dividing the number of meter pulses by two, creating a much longer toggled signal that a PC can better detect.

Although using an AVR or PIC would consume less power, [Sal’s] setup has already more than paid for its power usage. By monitoring and adapting his electrical usage, [Sal] is saving $20 a month on his electric bill. We’ve included [Sal’s] circuit diagram and source code after the break (apologies to our readers on RSS).

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Real Life Sonic Screwdriver For Home Automation

December 12, 2013 by James Hobson 11 Comments

Any Doctor Who fans out there? [Pat] just sent us his project on home automation… using a Sonic Screwdriver!

Ever since he pre-ordered his Raspberry Pi at the beginning of February 2012, he knew he wanted to try his hand at home automation. The easy way was to use X10 outlets, but at $20+ an outlet, it’s not that affordable. Instead, he managed to find a rather cheap system on Amazon — RF controlled outlets. They only cost about $35 for a 5-pack!

It’s a very basic system: five outlets with five buttons on the remote. All he had to do was wire up the Raspberry Pi to simulate the button presses by setting the GPIO pins high, and presto, a simple but effective home automation setup.

This is where it starts to get fun. Unfortunately, unlike a real Time Lord, [Pat] didn’t build his sonic from scratch. Instead, he found a universal remote control — styled after [Smith]’s sonic. Add another RF receiver to the Pi, a web-based interface to extend the range, and bam, you’ve got one geeky, but awesome, home automation setup.

Stick around after the break to see it in action!

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Mains Frequency Display

December 12, 2013 by James Hobson 45 Comments

[James] lives in the UK where the frequency of electricity is suppose to be 50Hz, but it tends to fluctuate based on supply and demand. He decided he wanted a display to track this.

Now, the National Grid Website shows a real-time graph of the last 60 minutes. But that’s way too easy. Time to bust out the soldering iron!

Armed with pencil and paper [James] scribbled down some ideas on how to count the frequency — he settled on counting 200 cycles, which means that at 50.000Hz, it would take exactly 4 seconds. The next problem was getting a timing source that was accurate enough for the job. An ATtiny84 wouldn’t do the trick (too inaccurate), nor would an external crystal (too expensive) — But a real-time clock? That’s the ticket! He’s using a DS3231 RTC chip, which at +/- 2ppm 32.768kHz is more than precise enough.

Some math, programming, and soldering later and the display is complete! He’s even added an up/down arrow to show the most recent trend of the electricity.

Nice one [James]! Last year [Ch00f] did a similar project, where he tore down a 194 discrete transistor clock kit to see how it worked — as an aside, he needed to know how accurate the 60Hz coming out of his wall was!

$50 Backyard Rollercoaster

December 8, 2013 by James Hobson 36 Comments

This is great. What happens when you bet a group of friends they can’t build a roller coaster in their backyard for under $50? They build one.

They built it almost entirely out of old forklift pallets, some wood from Home Depot, assorted nails and screws, some caster wheels and a folding seat from an old arena. It was built in just over 9 hours by three people. Once assembled they tested it with a 15lb cinder block — safety first right? The cinder block survived the ride, and by that logic, a 160lb+ person should be fine as well!

Well… they were right! To finish it up and get into the holiday spirit they also decked it out in Christmas lights and let the neighborhood kids use it all night. The total came to $49.27 from Home Depot for the wood and wheels.

Stick around after the break to see a .GIF of it in action!

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