Exhibit: Circulating Circuits
Two pairs of hands are needed to complete the circuits and make this exhibit work. There are three circuits, one each for the train, the light and the bell.
The three circuits can be only completed by pressing four switches, two on each side of the exhibit. More switches can be pressed so as to run more than one device, although this may need the use of elbows and forearms, as well as hands.
The current is driven round a completed circuit by a low voltage transformer which is connected to the mains.