“G” By Free Fall

The apparatus consists of an electromagnet housed in a plastic case with connections provided for an external timer. It also contains a platform unit containing a switch and terminals for the external timer. The unit is supplied with a heavy steel sphere. With the upper and lower unit connected to the external timer, the sphere is released by moving the switch on the electromagnet to the upward position. This action simultaneously starts the timer. As the sphere hits the cork mat on the platform unit, it activates a switch to turn off the timer.