Build Your Own Magnetic Levitator

August 31, 2010 by Mike Szczys 34 Comments

Here’s a great magnetic levitator build. [Scott Harden] dug up the link after seeing that awesome rotating globe this morning. This version hangs objects below an electromagnet but it has a sensor system to provide a constant distance between magnet and object even if the payloads are a different weight. This is done with a couple of infrared sensors. One acts as a reference detector, always viewing an IR LED in order to get a baseline measurement. That measurement is compared to a second detector mounted slightly lower. The circuit adjusts the electromagnetic field, making sure the object is always breaking the lower beam but never interrupting the reference beam. No microcontroller needed, this is handled with a couple of OpAmps. See it in action after the break.

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Terminate RFID Tags

December 22, 2009 by Mike Szczys 49 Comments

This gun hunts only RFID tags.[mnt], who brought us laser gesture control, built this RFID Zapper but included so much more. Any good weapon has to sound mean, a feat he’s accomplished by incorporating an MP3 player into the rifle. The coil that zaps the RFID tag is powered by a photo-flash unit, but for visual feedback he’s got a second unit that flashes light to signal the demise of your German passport (see the video after the break).

It’s hard to believe we haven’t covered RFID Zappers yet. The concept came out of the Chaos Communication Congress a few years back. This method works by sending a very strong electromagnetic field through the RFID tag that causes it to burn out. There’s a wiki post on RFID Zappers but Firefox threw a certificate warning when we loaded it up; read at your own risk.

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Table For Electronic Dreams

May 29, 2009 by Caleb Kraft 7 Comments

table

The table for electronic dreams is an interactive table that is sensitive to electric activity. Though it looks similar to the table built by EMSL, this one lights up based on electromagnetic fields. You can get the schematics and such from the instructable, but there is also a video located at the bottom of the project’s home page. It would be really cool if the effect could be localized more.

TEMPEST: A Signal Problem

January 25, 2009 by Eliot 12 Comments

TEMPEST is the covername used by the NSA and other agencies to talk about emissions from computing machinery that can divulge what the equipment is processing. We’ve covered a few projects in the past that specifically intercept EM radiation. TEMPEST for Eliza can transmit via AM using a CRT monitor, and just last Fall a group showed how to monitor USB keyboards remotely. Through the Freedom of Information Act, an interesting article from 1972 has been released. TEMPEST: A Signal Problem (PDF link dead, try Internet Archive version) covers the early history of how this phenomenon was discovered. Uncovered by Bell Labs in WWII, it affected a piece of encryption gear they were supplying to the military. The plaintext could be read over that air and also by monitoring spikes on the powerlines. Their new, heavily shielded and line filtered version of the device was rejected by the military who simply told commanders to monitor a 100 feet around their post to prevent eavesdropping. It’s an interesting read and also covers acoustic monitoring. This is just the US history of TEMPEST though, but from the anecdotes it sounds like their enemies were not just keeping pace but were also better informed.

[via Schneier]

24kJ Capacitor Bank

September 20, 2008 by Jason Rollette 42 Comments

The Leyden jar capacitor posted the other day fails to compare to what [FastMHz], one of the members over at the 4HV.org forums, has been busy building, a 24kj capacitor discharge bank. This capacitor bank will be configured for 4500v @ 2400uF and can be charged up slowly using microwave oven transformers. It can then release all its stored energy in under a millisecond through a triggered spark gap. This allows for some pretty big sparks as seen in this video, we are not sure about the laughing in the video maybe the power has gone to his head? Continue reading “24kJ Capacitor Bank” →

Electromagnetic Aluminum Can Crushing

October 15, 2007 by Will O'Brien 15 Comments

This has been around for a while, but we never covered it – and it’s friggin’ awesome. [jesse] sent in this crusher, but I featured this one due to a sort of draconian copyright notice on the former. The latter also uses some easier to find, hackable parts. They’re both built on similar concepts – use a large bank of capacitors to store up the energy needed, and deliver it in one large pulse to a coil electromagnet. The resulting force lasts for a short time, but is enough to physically crush an aluminum can inward without touching it. Yet another one has some more dramatic examples of crushed cans.