Surprisingly simple magnetic card spoofer

[Craig's] magnetic card spoofer is both simple and brilliant. There are two parts to spoofing these cards and he took care of both of them. The first part is getting the actual card data. He designed the spoofer board with a header that connects to a card reader for doing this. The second part is the spoofing itself, which is done with an electromagnet. As with past spoofers, he wrapped a shim with enamel-coated magnet wire. An old knife blade was picked for its thickness and ferromagnetism.  This magnet is driven by an ATtiny2313 which stores the data, and is protected by a transistor driving the coil. There were a few design flaws in his board, but [Craig] was able to get the same track data out of the spoof as the original card despite the LED being used as a protection diode and an ‘aftermarket’ resistor on the transistor base.

Rodent-based power generation

Your hamster lives to good life, with food delivery and a maid service that cleans up after him. [DanF] helped to brighten up this hamster’s life even more by improving its exercise equipment and giving it a small night-light as well. This project adds a low RPM alternator to the hamster wheel.

The first part of the process was to reduce energy lost to friction by fitting the wheel with a bearing. From there a ring of permanent magnets was added which will pass by a stationary coil and induce a current. It works, but unfortunately there’s not enough power generated to charge a battery. That means the light is only on when the hamster is running. But maybe you can figure out a way to use a super-capacitor like we saw in that exercise bike hack.

One nice finishing touch to the setup is a bicycle computer to track how much time was sent on the wheel, and the distance traveled.

[Thanks Dizzy]

You’ll shoot your eye out, another coilgun

All we needed to read was 4x 3900uF capacitor bank to know we had yet another decently sized homemade coilgun on our hands. And for the math buffs, that equates out to 1.25kJ of potential energy (efficiency kills it down to 37j of kinetic, but large numbers are more fun) which is more than enough to break skin; of course we recommend you just shoot old electronics rather than friends. On the more technical side, sure its only a single stage for now and we’ve seen some slightly more impressive triple stage guns, but it may just be more beautiful than our previously featured coil pistol. You guys be the judge. Catch a complete video after the jump of the internals and build process, skip ahead to 2:40 for the destruction.


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Robotic eye surgery controlled with magnets

If you’re in need of eye surgery you might just find yourself strapped into this contraption. It’s a magnetic field generator used to manipulate a tiny, untethered probe. It’s called OctoMag and the idea is that a robot less than half a millimeter in size is injected into your vascular system and, through the use of those coils, it busts up blood clots in the small passages inside of the eye.

Once you’ve seen the clip after the break we’re sure you’ll agree that this is amazing technology. Nonetheless it makes us cringe to think of the procedure done on a living organism but we’re sure that fear will subside given time. For now this seems more like a treatment from A Clockwork Orange.

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Adjustable Tesla coil build

This coil has no trouble shooting sparks across four meters of empty air. [Finn Hammer] has been putting in some long hours on this labor of love, and we put in some time reading through his progress thread. He started down this path about a year ago and every step of the way he produces beautiful work. We enjoy seeing his prototyping techniques, moving from concept to hand drawing to CAD diagram before starting the physical build. Check out the demo video after the break and as you read through his thread look for the green arrows that lead to other videos and resources.

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Power drill solder spooler

[Scott] over at has posted an instructable detailing how to use an Arduino and a power drill to spool solder. The Arduino senses the speed that the drill is going via an opto interrupter and a laser and adjusts with a servo hooked to the trigger. While we don’t think many people will be dying to spool some solder, this system might be useful for all kinds of things, like winding yarn or making coils.

Final Projects: WiFi coil gun turret

[Chris Farnell] and [Michael Helms] are the brains behind this scary looking piece of machinery. It is a Coil gun, mounted on a turret, that is controlled over WiFi. If that wasn’t scary enough, they have rigged it to their iphone/ipad for remote shooting. Though it looks bulky, you can see that it is surprisingly responsive in action.


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