Day: January 31, 2010

120v Switching

January 31, 2010 by 52 Comments

[Kenneth] built a 5v controlled power outlet inside of a junction box. We’ve seen plenty of projects that can switch 120v outlets using 5v logic for refrigerator controllers, lighting controllers, or grow systems, but they almost always use solid state relays to facilitate the switching. This iteration uses mechanical relays along with the necessary protection circuitry. The project is housed in an extra deep single-gang box and allows for individual switching of the two outlets. You can see this connected to an Arduino switching two lamps after the break.

Continue reading “120v Switching” →

Hacking A Digital Bathroom Scale

January 31, 2010 by 18 Comments

[Micah] was inspired by projects he had seen of people using the Wii balance board as an input. He realized the balance board was overkill, and pricey for many applications. Since it is basically just 4 weight sensors, he thought, why not just use a scale? Often, only one sensor is needed and they’re really cheap from big box stores. He picked up a digital scale and cracked it open. As he moved forward, he wanted to keep this pretty simple. There are other ways of getting the information from a scale, but they have been generally more complicated than what he had in mind. He ended up bypassing the internal unknown microcontroller and just connecting the analog sensors to his parallax setup. You can read all about the process an download some source code on his site.

[via Flickr]

Recycled Cat Feeder

January 31, 2010 by 25 Comments

I find that I do a lot of fun projects but I’m very bad about documenting them when I’m done. Holidays are for hacking (in my mind) so I usually plan ahead and do something cool during my time off. This project, which I loving call the Autodine-2009, was a spontaneous event over Thanksgiving that I’m just getting around to writing about.

Our cat’s want to be fed at 6am and are very insistent about it. Like most folks, I’d rather be sleeping at that time of day so I built an automatic cat feeder. Now we sleep while the cats eat. We don’t want to rely on a hack to feed our cats when we’re away so I didn’t go the route of an Internet-enabled multiple-dose feeder. Instead, I used parts on hand to create a single-serving dispenser on a timer. A servo rotates a false bottom to gravity-feed the cat food. The servo doesn’t have control circuitry so it is controlled through an h-bridge (I did have to buy 2 transistors for that) by an AVR ATmega8 microcontroller. There are two salvaged tactile switches to set the time and timer, and a serial LCD display that I’ve had sitting around for years. Power comes from an old cell phone charger a friend had just given me that spawned the feeder idea when I asked myself “hmmm, what can I use this for”?

I’ll demonstrate this recycled device for you in a video after the break. This wasn’t as hardcore as my AVR Tetris build but I’m much happier now that I can sleep in a bit.

Continue reading “Recycled Cat Feeder” →

Add A Bluetooth Terminal To Your Kindle

January 31, 2010 by 6 Comments

This is an Amazon Kindle DX with a Sparkfun Bluetooth Mate stuck in it. [Darron] hacked the two together in order to have a wireless serial terminal on the device. There are three big pads in the middle of the Kindle PCB labelled GND, RX and TX, making it easy to figure out those connections. Getting voltage was a bit more difficult. He managed to find 4V coming off of one side of the Kindle’s wakeup switch which works well because the Bluetooth Mate has a voltage regulator on board. To protect the Bluetooth module he modified it to pull-up the TX from the on-board regulated 3.3V rather than the 4V coming in from the Kindle.

He’s also been doing some software work on the device now that he has easy access to it. Along the lines of the Ubuntu-on-Kindle hack from September, he’s compiled QT for the Kindle and written a couple of programs such as Sudoku to show that it works.

Hackaday Links: January 31st, 2010

January 31, 2010 by 14 Comments

Marble Junker

Here’s a quick and dirty kinetic sculpture. It’s a track for a steel marble to roll around in with a magnet on a rotating wheel to pick it up and start it over again. Not every hack has to be a beautiful masterpiece, they just need to be fun. Of course, if this were an incredibly complicated piece it probably wouldn’t have ended up in a links post.

Eight-eyed Computer

[AlexP] has been involved in the NUI Group and in writing drivers for the PS3 Eye. This time around he’s got eight of them running on one computer at 60fps. Security cameras come to mind but this could be useful in a lot of projects. We’d be interested in seeing what you come up with. [Thanks Kyle]

Urine-gone

If you have a problem with folks peeing on your stoop then this is the answer. [Hannes Nehls] put together a urinating-drunkard deterrent by placing a humidity sensor in the (achem…) trouble-spot and a small tube above. When they pee on the sensor, it pees right back on them. Video available if you click through to the link.

Amplifier Tutorial

If you’re a little shaky when it comes to understanding and working with amplifiers this tutorial is for you. It’ll walk you through the basic concepts, then apply that knowledge in a simple op-amplifier circuit.

Severed Heads

It’s always nice to end a links post with something creepy. These faces are made from a cast of the artist’s face. They sing a trio of nonsense and it’s the life-like movements combined with the obviously mechanical backend that tingles our spine. But they’re really just a novelty and not the real thing. [Thanks Browneyedalbino][via Powered by Nerd]