Abstract: A pair of microswitches are mounted in the housing of an automatic screwdriver in the path of relative movement of the barrel thereof as it is urged rearwardly to activate a throttle valve and thus operate the drive mechanism of the screwdriver. Closure of both microswitches, which occurs during the driving of a fastener, resets the entire control circuit in readiness for the automatic emplacement of a new fastener upon completion of one driving operation. Release of one of the microswitches, as when the driving is completed activates a timer and air cylinder to drive the barrel forward into an extended receiving position. At the receiving position a new fastener is emplaced in the chamber of the mechanism. On completion of a predetermined time cycle, the barrel is returned to its normal position with one microswitch engaged, one not engaged, and a fastener in the barrel against the kit ready for the driving operation.