A few weeks ago I thought it would be nice to try out time-lapse photography. I searched for ways to trigger my DSLR in given inverals and found, that the plug for wired remotes was some proprietary Nikon thing and timer remotes cost 40€ upwards.
Fortunately, DSLRs can also be triggered using an infrared signal. I already owned an Nikon ML-L3, a normal IR remote compatible to my Nikon D80. So what I did (and what you can also do to have fun with IR devices) was this.
Simply connect an IR LED to an audio cable and use it to record and send IR signals. It's that easy. : )
If you're interested in further information on this topic have a look at the following links:
Jim Watters - Nikon D70s MC-DC1 remote
www.doc-diy.net :: camera remote release pinout list
DIY Infrared transmitter for iPhone, iPod
Arduino – IR remote/ intervalometer for Nikon D80 DSLR (that means timelapse photography yarrr!)
bigmike.it - infrared remote control for Nikon