Abstract: A method and apparatus for controlling power delivered to a fastening machine solenoid comprises a half wave rectifier, a filter network, an adjustable frequency generator and a pulse conditioning circuit. The frequency of the frequency generator is varied in accordance with fluctuations in peak AC line voltage and is input to driving circuitry which engages a solenoid at a predetermined time and for a specific amount of time. By increasing or decreasing the solenoids on time in accordance with power line voltage fluctuations, a pulse of constant power will be received by the solenoid, regardless of fluctuations in power line voltage.