Patent ID: 7092268

Claim:
An isolating power supply for electrical equipment, comprising a transformer having an input for a mains alternating current (AC) power supply, a rectifier by which the output of the transformer can be rectified, a primary energy storage device for electrically smoothing the output of the rectifier, a switching device which is electrically connected to the output of the primary energy storage device and which can be switched between a conducting state and a non-conducting state, and a secondary energy storage device which is electrically connected to the switching device, and means for producing a switching device control signal so that in use when the switching device is in a non-conducting state the primary energy storage device stores the output from the rectifier and the secondary energy storage device is electrically isolated from the primary energy storage device and supplies an electrical output to associated electrical equipment, and when the rectifier is no longer charging the primary energy storage device the switching device is in a conducting state so that the primary and secondary energy storage devices are electrically connected and the secondary energy storage device stores the output from the primary energy storage device, and the associated electrical equipment is supplied with an electrical output.