Hackaday Links: January 31st, 2010

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]


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]

14 thoughts on “Hackaday Links: January 31st, 2010

  1. Just a small suggestion here, I think it would make more sense to put subheadings above the relevant image.

    Oh yeah, if anyone is interested to learn more about opamps, download the Texas Instrument’s Handbook of Operational Amplifiers. It has a number of fundamental opamp circuits, complete with equations, etc.

  2. The circuit in the opamp tutorial really sucks; no AC coupling to the speaker, and it requires a symmetrical power supply, while two extra resistors could be used to add a Vcc/2 bias to the microphone signal.

    The pee-back project seems like fun; it’s simple, effective, and has a high potential for amusing footage.

  3. The problem with the pee-back sensor is that it uses only a humidity sensor, meaning if the humidity outside went up (say, it rained or something) then your door would be peeing on itself all day….

  4. Hannes’ website is unreadable to me – it’s all upercase and the character span is too large. I don’t really like this artsy approach.

    The idea though is great. You could use this to shoot all kinds of fluids and acids onto the subject.

    I think the best way to keep your doorway clean is to not make it look like a public toilet… remove the grafiti, clean it up etc.

    And yeah, he got a broad german accent.

  5. About the peeing sensor… Let’s see, drunk people, who are easily amused, constantly peeing on your wall to experience the sensor.

    Beautiful hack by someone who doesn’t comprehend human nature.

  6. OK so the pissing door is great. But what a bunch of artsy-fartsy shite. I mean, its like someone said in another post, don’t try and justify something by making up a load of contrived bollocks…simply put, “I thought it would be funny to have the door piss back on the dirty prick”.

    Otherwise, funny.

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