There's nothing nicer than having one of these things on your desk that you give a push and they take ages to stop moving, like the typical dolphin or the little balls that hit each other.
They are very pretty and all that you want, but if you don't push them every now and then they end up stopping. Not like this project I'm going to show you now, the solar pendulum. As the name itself indicates, it is a pendulum that, thanks to the energy of the sun, we achieve a perpetual movement.
The circuit in question is the following, which does not look very complicated, consisting of a mini solar panel, two transistors, resistors, capacitors and an LED:
Here is also a video of how the device works:
Seen on Ikkaro from Make and created by Accomplished.