This is a quick ATtiny85 project to make an DIY intervalometer (Interval timer and remoter shutter release) for a canon 600d or other camera that uses a 2.5mm jack for the remote shutter release cable. I used a 3.5mm to 2.5mm adapter cable.
I got my ATtiny85 from here Farnell there are incredible good value. Loads of different options if you don’t want to use the 85 – http://uk.farnell.com/atmel
The initial interval is 1 second and each press of the (de-bounced) button adds 1 second to the time. This does mean that you would have to press it 60 times for a 1 minutes interval, changing the code or adding another button to add 10s of seconds would be a good addition.