I've decided I want to play with time lapse photography. The first thing I need it an intervalometer, and rather than buy one, I decided to start out by making one. I built an IR blaster from 2 940nm infrared LEDs and an old headphone plug:
I've covered this up with heatshrink. Of course, I soldered it wrong first time, and had to take it to pieces and redo it.
I didn't seem to work with the Android app I was planning to use on my Nexus, so I tested it with an AA battery - connecting the battery one way would light up one LED, and the other way would light up the other, so the connections would seem to work fine. I couldn't see anything using my camera (CCDs can see infrared). I then tried my cell phone, and that worked just fine in that I could see the lights lighting up on the camera. So I tried the DSLR again, and that worked just fine. Doy.