Watch this video to see how it works. Then flip through the steps to find out how to make one using the Arduino controller.
Step 1: Parts and schematic
To successfully complete this project, you will need to know how to solder, how to build simple electronic circuits, and have experience programming the Arduino microcontroller.
Pictured are some of the parts you will need. Here's a complete parts list:
1 ea Arduino Duemilanove or equal ( Radio Shack 276-128 Arduino Uno REV3 will work also) with power adapter
1 ea Arduino Proto Shield (Radio Shack 276-140 is slightly different but will work)
2 ea Phone jacks (Mouser 161-3508-E)
1 ea Terminal block, 5.08mm (Mouser 651-1935561)
1 ea Tactile PB switch (DigiKey SW407-ND)
1 ea 10K ohm variable resistor (DigiKey AAS14CT-ND)
1 ea 2N3904 transistor (Radio Shack 276-2016)
1 ea 47mf 16v electrolytic capacitor (Radio Shack 55047407)
1 ea 1K ohm, 1/4w film resistor (Radio Shack 271-1321)
2 ea 10K ohm, 1/4w film resistor (Radio Shack 271-1335)
1 ea 22K ohm, 1/4w film resistor (Radio Shack 271-1339)
1 ea PowerSwitch Tail II (Adafruit .com ID 268 or Sparkfun.com COM-10747)
And finally, the schematic diagram of the circuit.