Intervalometer can be used in DSLR photography to take time-lapse shots.  You can buy one of these Intervalometers off the shelf for anywhere between $60 to $200+ but if you got some programming and soldering skills, you might be interested in learning to make one yourself.

Circuit schematics, code, and whole bunch of images are included in this DIY to help you make the intervalometer for your Canon or Nikon DSLR camera.

This instructable is teaches you how to make an intervalometer that can be used with virtually any camera.  It has been tested with Canon and Nikon cameras, but making adapter cables for other cameras is just a matter of figuring out the camera pinout.
It’s also available as a kit so you might want to go that route if you are not familiar with programming an AVR.

This intervalometer has the following features:

• Intervalometer mode with options to change delay time and exposure time
• Sensor mode with built in light sensor and connector for external sensor input
• Manual mode allows intervalometer to act like a simple remote cable
• Integrated 2×12 LCD display
• Fully optically isolated interface to camera
• Total package is roughly 1″ x 2.5″ x 3″ finished
• Electronics small enough to fit in a mint box
• Source code is available for download so that you can change programming as desired

Available as a kit from www.ottercreekdesign.com

via instructables