Abstract: Electrical switch circuitry including a relay with contacts and a transistor. A control circuit switches the transistor ON in response to a voltage difference across the relay contacts reaching a predetermined value, such that in use, electrical current is caused to flow through the transistor while the electrical contacts of the relay are closing or opening. This reduces electrical arcing across the contacts of the relay.

Abstract: A control system comprising a control input device having a movable magnet, a pole-piece frame arrangement positioned about the magnet and positioned therein at least two magnetic flux sensors for sensing movement of the magnet in a given direction. The control system further comprises a monitoring arrangement for monitoring the output signal of each of the sensors and permits the input device to control the system only when the output of the sensors are within a predefined range. This multiple sensing provides a fail-safe in the event that one of the sensors generates an erroneous signal.