Torrent of Tesla Coil Tutorials

Photo by Flickr user Pekar [source]

Tesla Coils are a special type of transformer originally intended to broadcast electrical power without the use of wires.  These days they're primarily used for special effects in TV and movies, electrical testing (why wait for lightning to strike? Make your own!) and plain old mad-scientist style geeky fun.

Instructables has a couple of excellent tutorials on building the Basic Spark Gap Tesla Coil, and a more advanced Solid State Tesla Coil that can be modulated to play music.

Get Cracking Roboteers!

Prizes for Electric Car Algorithms

The CREATE Lab at Carnegie Mellon University is sponsoring a contest to develop efficient battery-management algorithms for electric vehicles.  At the end of every month, high-performing entries will be awarded small prizes ($100 in Amazon gift cards), with a grand prize (possibly an actual electric vehicle) awarded at the end of the competition.  At the end of each monthly judging phase, entries are open-sourced for all to see and share.

The Guardian: Inexpensive AVR-based Cat Food Protection

Over 6 months ago we added two kittens (Duke and Ella) to our household, and we found out that our dog, Riley was eating their food.  To prevent this, I built the Guardian, an AVR-based protection system that humanely keeps Riley away from the cat food, but is not triggered by the cats themselves.

I wanted this setup to be cheap, so I decided to use an infrared "trip-wire" system.  On one side of the hallway is an always-on infrared emitter, and on the other side is an infrared receiver, an AVR ATmega8 microcontroller, and a buzzer.  The micocontroller continuously checks to see if the beam between the emitter and receiver has been broken - if it has, it sounds the alarm, which Riley hates, driving him away.  The microcontroller is programmed so that small, fast things (such as cat tails) do not trigger the alarm.  Also, the whole rig is place at Rileys shoulder height, which is much taller than the cats bodies.

This may not work for most dogs, as Riley is a pansy and afraid of loud noises, but here are the schematics, source code, and a rough bill of materials:

Schematics (Eagle, PNG)
Source Code
Bill of Materials

ArcAttack: Ride the Lightning

I've always been fascinated by Tesla Coils. The operating principle is so elegant - you set up one circuit (your power supply) that oscillates at some high frequency, and you set up another circuit that uses the earth to resonate with your power circuit. Energy is transferred and converted from current to voltage, and the end result is man-made lightning - an incredible display of light and sound.

Newer versions of the Tesla coil allow the control of the resonant frequency.  Have you ever noticed the sound that a flourescent light makes?  That kind of "buzz" ? You're hearing the frequency of the power that is coming into your house (around 60Hz).  When you control the resonant frequency of the Tesla, you control the tone that it generates, and thus the Singing Tesla Coil is born.  This is not lightning set to music - the sound is generated by the spark itself.

The band ArcAttack has integrated a pair of singing Tesla coils into their repertoire, with epic results:

Laser Command

Laser Command from Eiji Hayashi on Vimeo.

This awesome project was built by Eiji Hayashi at Carnegie Mellon University.  What stands out is the use of LED's as both display and input.  The full design is available here.

USB Oscilloscope on the cheap

Build your own tools!
This ATiny45-based dual channel oscilloscope is home-made, cheap and simple.  It doesn't capture at high sample rates, but it's neat nonetheless.

Design, source code and interface code available here.

Kohctpyktop: A logic design challenge

Feeling nostalgic for those frantic days in the digital design lab? Wish there were perhaps a game that put you in the place of an engineer, trying to design new ICs to meet the goals of some unspecified organization? Want to get your SI on? No idea what I am talking about?
Well then, let me introduce you to Kohctpyktop: engineer of the people, by Zachtronics Industries. It's the first game I've ever seen where you have to design integrated circuits as a challenge, sort of like pipe dream for electrical engineers.

Kohctpyktop via Make