Even if when you can get these remotes really cheap, iwasz wanted to build them by himself. This way he’s got some valuable experience in dealing with IR signals and setting stable carrier wave frequency.
His design is based on Attiny2313 microcontroller. Being small size it is powered form coin lithium battery. Microcontroller sends signals with IR leds that is connected to MCU using transistor key. Remote is equipped with single push button which is used to control shutter trigger. And this is pretty much of it. Remote control works with Cannon cameras.