Abstract: An electromagnetic drive circuit comprises a coil for detecting and driving a permanent magnet; a comparator for generating an output when the induced voltage of the coil exceeds a reference voltage; a pulse generator for generating a drive pulse train in response to generation of the output of the comparator; a driver responsive to the drive pulse train for feeding a drive current to the coil; and a controller responsive to interruption of the output of the comparator for interrupting generation of the drive pulse train of the pulse generator. The permanent magnet is detected and driven by the single coil so that the output may be generated by the comparator when the induced voltage of the coil exceeds the reference value, and the drive pulse train is generated during generation of that output to feed the drive current to the coil. The coil can always be efficiently driven at the maximal point of the induced voltage, and the permanent magnet can be driven with a stable amplitude.

Abstract: Herein disclosed is an electromagnetic drive circuit for driving a pendulum or the like, comprising: a coil for detecting and driving a permanent magnet; a reference voltage source having a variable reference voltage; a comparator for generating an output when the induced voltage of the coil exceeds the reference voltage; a pulse generator for generating a drive pulse in response to generation of the output of the comparator; a driver responsive to the drive pulse for feeding a drive current to the coil; and a controller responsive to the output of the comparator for controlling the reference voltage in accordance with the amplitude of the induced voltage. It is possible to integrate the most of construction and to eliminate the disadvantage of generating the drive pulses at the level of the induced voltage other than its maximal point so that the automatic control can be accomplished to effect the drive efficiently at the maximal point of the induced voltage at all times.

Abstract: An electromagnetic driving circuit for driving a pendulum comprises a coil for detecting and driving a permanent magnet, a comparison circuit for comparing an induction voltage induced in the coil with a reference voltage, a generating circuit for generating driving pulses of a predetermined pulse width in response to outputs of the comparison circuit, and a driving circuit for flowing a driving current through the coil in accordance with the driving pulses. The timing at which the driving pulses are generated and/or the pulse width of the driving pulses are automatically adjusted to optimum values to improve the driving efficiency of the pendulum.