METHOD AND APPARATUS FOR PROVIDING AUTORANGING FOR AN AC/DC POWER MANAGEMENT CIRCUIT FOR DC SOLENOID ACTUATORS

A method for providing a power management for a DC solenoid actuator includes the steps of initially supplying a first number of DC current pulses to the actuator and after a first time interval reducing the number of pulses applied to the solenoid in direct proportion to an output voltage of a source of the DC power. The method further includes the step of changing the duration of the first time period in direct proportion to the output voltage of the source of the DC power. An apparatus utilizing this method includes a timer for selectively providing a sequence of current pulses, circuit means for applying the pulses to a DC operated electromagnetic solenoid, power supply means responsive to an input voltage for supplying DC power to the timer means and compensating means for controlling the timer means to reduce the number of pulses applied to the solenoid after an initial maximum number of pulse applications during a first time period by changing the off time between the reduced number of pulses in direct proportion to the magnitude of the input voltage to maintain a predetermined average current in the solenoid during the time of the reduced number of pulses and being responsive to the input voltage for changing the duration of the first time period in direct proportion to the magnitude of the input voltage to maintain a predetermined average current in the solenoid during the first time period.