Electromagnetic solar clock built in 2001. It was designed to fit inside a window and to let the maximun of light go through. We can see the 4 solar panels on the bottom: they charge a battery and one sunny day gives enough power for six month of use. The motor is magnetic. the time is given by the lengh of the pendulum. The frame is made of inox steel and the pendulum is in invar, as usual.
BELOW: data given by the controller Microset of Bryan Mumford, Santa Barbara, California.