I found this keychain LED flashlight at Lowe's, and it looked great for making a CHDK-compatible shutter button for my Canon digital camera. It was small, had a button, and had three 1.5-V batteries. 4.5 Volts is within the USB standard for voltage, so it should work for any CHDK compatible camera! Here is how I did it. It takes some minor soldering skills, but I could do it, so you can too!
- LED flashlight.
- USB Type-A to mini-A cord.
- Unscrew the flashlight front and remove the circuit board. Make sure you don't lose the blue button!
- Unsolder the LED and take it out.
- Cut the paths to the chip under the white epoxy.
- Remove the surface-mount resistor. Get some of the solder off and then chip at it.
- Cut off the Type-A part (the big side) of your USB cable. Put the end of the flashlight on the cable now! Make sure it's in the right direction. you won't be able to get it off after the next steps.
- Strip off about 3/8" of the outer insulation, and remove the loose wires and foil. Cut the white and green wires away.
- Solder on the black and red wires as shown in the photos.
- Take the batteries out of the light and put them in BACKWARDS.
- Put the whole thing back together.
A few notes:
- I couldn't figure out a way to do this that didn't involve reversing the batteries. There was a sticker on the battery end that indicated the direction of the batteries. I removed it.
- I superglued the USB cord to the end of the flashlight AFTER confirming it worked. This will make it nearly impossible to unscrew that end of the light, but hopefully will prevent the wires and solder from taking any stress from pulling on the cord.
- I have put "people" in the picture of the bottom of the circuit board indicating where to solder the wires and cut the paths on the board to take the chip out of the circuit. Apparently Google doesn't let you annotate pictures like Flickr does. Click here to see it.