Make your own bike light. The box I used for the simple Ipod amp project came with an army surplus survey lamp in it. My cruiser is army green. You see where this is going?

This uses a 555 timer and some transistors for the controls.

Step 1: Parts

Army Surplus "Army Survey Signal Lamp"
4AA Battery holder
Switch
Old Reflector
Army Survey Lamp ( from the simple iPod amp project...)
PNP Transistor (3906)
NPN Transistor (2222)
555 Timer
150k resistor
4.7k resistor
1uF Capacitor
160 Capacitor
220 Capacitor
Breadboard
Solderless Breadboard

Step 2:

Two screws hold on the old power connectors, remove them so we can fit in the AA holder.
Set those aside, they are very heavy duty and I'm sure they will come in handy for something.
Take the light bulb out of the assembly and unscrew the bezel on the front.

Step 3:

So I based my circuit on a 555 timer circuit, the one I like the most is on Bill Bowden's web site: http://ourworld.compuserve.com/homepages/Bill_Bowden/555.htm. Build it out on the breadboard and see how it works.

Step 4:

At this point you can solder the circuit up, or I just moved it up on a small solderless breadboard... guess I was lazy. but this one fits right in the light box.

Step 5:

Unscrew the front bezel of the lamp and trace the outside of the rubber gromet on the breadboard. Cut it out with a dremel.

Step 6:

Solder your LEDs to the breadboard. Hook them up so they light up in some kind of cool pattern, the two transistors will control your two sets of LEDs. I didn't end up using this set of LEDs in the end. I just had some brighter LEDs and used them instead.

Step 7:

Run the cables through the hole the old light bulb was using. click on the pic for a big picture

Here is a second shot, I used a different colored set of wires to distinguish which set of lights they go to..

Step 8:

Put your LED assembly back in to the lamp assembly and screw the bezel back down.

Step 9:

Drill a hole in the box for your power switch.

Step 10:

I use an old reflector to mount the light to the seatpost of the cruiser.
The light already came with a knob, use that to attach it to the reflector mount.

had to extend it out a little bit to pass the seat post, I just used a peice of metal I had in my parts bin.