Clock drive apparatus

Abstract

Apparatus for driving a timing device from an external AC power source and, in the event that the AC power source fails, from an auxiliary DC source. The driving apparatus includes a pulse producing circuit which produces periodic pulses in response to timing pulses. A timing pulse circuit, including an oscillator which produces an oscillating voltage having a frequency substantially proportional to the AC power source frequency, applies the timing pulses to the pulse producing circuit. A DC power supply receives the voltage which is supplied by the AC power source and generates a DC energizing voltage to energize the various circuits of the apparatus, including the pulse producing circuit and the oscillator. In the event that the AC power source fails, the voltage produced by the auxiliary DC source is used to energize the various circuits of the apparatus. A storage device is included in the DC power supply for receiving and storing the generated DC energizing voltage so as to maintain a sufficient energizing voltage during the interim between the failure of the AC power source and the time that the auxiliary DC source reaches a satisfactory energizing level. A driving circuit responds to the periodic pulses produced by the pulse producing circuit to supply driving energy to the timing device. The timing device comprises a single clock or clock system or, in the alternative, a master clock which is used to drive and control one or more slave clocks.