Pinball solenoid power control system

Abstract

A pinball machine is provided and generally includes a power supply for supplying unfiltered, unregulated DC voltage, a solenoid for activating a play feature device such as a flipper, a microprocessor for controlling game play activities, a clock associated with the microprocessor for supplying a first interrupt signal thereto, a memory device associated with the microprocessor having stored therein a plurality of duty cycle settings, each of the duty cycle settings comprising a predetermined pattern of ON and OFF states, a voltage detection circuit linked to the microprocessor and connected to the power supply for providing to the microprocessor a voltage value indicative of the level of the DC voltage, wherein the microprocessor utilizes the voltage value to select one of the plurality of duty cycle settings, and a driver, responsive to the microprocessor, connecting the power supply to the solenoid for controlling the flow of current thereto based upon a corresponding one of the states of the predetermined pattern of the select one of the plurality of duty cycle settings as determined by the first interrupt signal. Preferably, a zero-voltage detect circuit is also provided and used to detect when the DC voltage level approaches zero for signalling the microprocessor to reset or synchronize the clock.