Time Lapse Camera

The project is born from an idea of Michele G. The (first but not last) purpose is to take a time-lapse-shot of the traditional bonfire preparation (3-4 days) and burning (1-2 days).

For the purpose we needed something cheap, but powerful. There were many options, this is not the better, simply the one we used.

The system consists of a camera + a controller/timer circuit + power supply circuit.

If you use a Canon camera take a look at CHDK. Using this hack firmware you probably won't need building a timer/controller. We used a Nikon because was the only affordable and reperible at the time.

You should then take the camera apart and see how the switch works, and take some wires out of it. In our case the switch connects the signal wire to the ground so the interface to the controller-timer was very simple to make. In other cases may be more complex.

The whole system, under testings, looks like this:

The simple controller goal is to take a photo at regular intervals.

It should trigger the autofocus switch first, and then the shutter switch to take the photo.

As mentioned above, the camera switch connects the wire to the ground, and there are two wires one for focusing one for the shot. The controller will have to do the same.

• Issue #1: The timer. An atmega8 microcontroller (or any other) would be fine. Must draw the smallest current possible. The lapse-interval is set through six dip-switches with weight 2, 4, 8, 16, 32, 64 seconds. A led is for test purposes, it may be disabled removing a jumper. 8 Mhz quartz is optional, actually the internal oscillator would have been enough.
• Issue #2: Power. I've used a pre-built module that converts 9-12V into 5V through an LM2576 based switching step-down converter, and a 7585-3.3 linear regulator that provides 3.3v. An additional diode provides about 0.6v drop, so the camera is powered at about 2.7v. Other cameras may need different power requirements.

Simple C-written code provides timer routine. Features:

• A photo must be taken every N seconds. You select N in the range of 4 to 126 seconds.
• The interval set over the dip-switches is read only at startup (reset) to avoid current dissipation on the pull-up resistors.
• The focus signal is first driven low, then after 2 seconds the shutter signal is driven low, another second and both are released to hi-z state.
• An optional led shows when the photo is being taken (lits up when focusing, turns down a second after the shot).

The images below show the working timer. (green trace is focus, active low; yellow trace is shutter, active low)