In order to encourage us to play with electronics more, JWA and I have begun doing monthly challenges. For our inaugural challenge, we decided upon an LED Birthday Candle. This is my entry to that challenge.
You blow the center pole towards one side, and the LED shuts off. To turn it back on again, blow it the other direction. It’s a circuit known as a bistable multivibrator, or “flip-flop”.
I do like that it’s so simple and cheap, though.
My parts list is simply:
2 – 10k ohm resistors
1 – 1k ohm resistor
1 – 220 ohm resistor
2 – 2n3904 NPN Transistors
1 – LED
3 – AAA batteries (this thing’ll last forever!)
Not including the batteries, this thing costs less than 15 cents in parts. If I could work out the “blow” mechanism a little better, I think this would be a marketable product.
Okay, now for some photos:
On the breadboard:
Before being shoved in the pill bottle:
I had originally wanted to be able to shove this thing into a fat straw, like you get with a bubble tea, so I made it as small as possible, and soldered the pieces together straight rather than using protoboard:
Next: Brighter LEDs!
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Wiichuck adaptor arrived a couple of days ago, and I just hooked it up.  As my first project, I’ve written this, which uses the Wii nunchuck as a musical instrument.
Source code: Freqin’ Wii
Hook a speaker to the output pin (defined below, 13 by default), and hook the Wii adapter up to analog pins 2-5, preferably using the Wiichuck adapter. Tilt the wii from side to side to adjust the tone, and tilt forward and back to adjust  the octave.  Push the joystick forward and back to adjust the length of the note.  Push the Z button to play the note.
I’m trying to think of what else I could do with this. Â There’s just not a lot of data out there that can use three dimensions of acceleration data and two dimensions of joystick data.
 The electronic man holds his joy aloft.  He loves it, because he was built to love it.  It shines with the energy that courses through his body.  He wants to share his Light with the world, but fears that if he lets it go, he’ll never know it’s glow again.Â