Light effect
All castles have a radar sensor build-in which will switch the lights on when somebody is close to the castle. The lights will stay on for a few minutes and then switch-off when there is no movement anymore. The energy consumption in the idle state is minimal (micro watts). The website example will show the idle state for 10 seconds and then will illuminate for 40 seconds.
On the left you see an old fashion handmade printed circuit from a Physio practise device with a electronic clock added to it. The pendulum has 2 powered leds activated by a reed contact and a magnet to minimize the friction.