Before the construction took place a 2-metre prototype-pendulum was built, where for example the electronics to the electromagnetic driving was tested out. The prototype electronics is today in a pendulum appropriate to have for example in a sitting room. Actually in my house :).  The suspension is about 2 metres and the bob weighs 1 kg and the pendulum acts fairly well.

Below the compass card you can see the coil that gives impulses to keep the pendulum in motion. The electronics that generates the impulses is in the box in the background.