This is the setup that I used for my first experiments:

The Bolex is controlled by a server motor that is activated with the switch located at the back of the dolly. Below you can get a closer look at the switch and also at the server motor:

The switch is activated by the little piece of wood and is active for the whole length of it which makes for the distance the camera shoots in a long time exposure.

The server motor that executes the cable release of the Bolex.