arduino module for time-lapse photography

There are already many instructables on time-lapse photography.

An easy way to do time lapse photography is to adapt an old photo device by welding wires on its main button.
Here is an instructable showing how to do it :
http://www.instructables.com/id/Time-Lapse-Photography/

Then to take picture at a certain period, it is very simple to use an arduino.
This instructable shows how to plug an arduino to the welded wire by using a simple NPN transistor in saturation mode.

To make this module you will need :
- a npn transistor BC546
- a 5KOhm resistor (or two of 10kOhms in parallel)
- a piece of protoboard
- 4 pins

Obviously you also need some tools like a welder, nippers, tin,...

All the detail to mount the module are shown on the picture.

Here is a time lapse video of my beta fish (1 picture every 30s)