Step 6: Activate the Camera Shutter with a 555 timer
This circuit is a little different from regular 555 timer circuits. Pin 3 is used to charge and discharge the capacitor and pin 7 is the output. I chose this layout because during the discharge cycle pin 7 is shorted to ground through an internal transistor. This is the ideal way to activate the shutter of the camera.
You can power the circuit with anything from 4.5V to 18V. The timing is controlled by the resistor and the capacitor according to the formula:
Time interval (secs) = 1.386 * R * C
I used a 680µF capacitor and a 100k variable resistor. This let me adjust the picture interval from every few seconds to every 94 seconds.
To connect it to your camera, connect the ground line to the ground on the camera. Then connect pin 7 to the shutter function.