Abstract: A fastener driving device such as a tacker, including an actuating circuit for producing a power stroke for substantially a complete half cycle of an AC potential supply and which occurs a fixed number of cycles following the actuation of a switch actuable at random times with respect to the cycles of the AC supply. The circuit features a decade counter clocked by the AC supply. One of the decade count outputs of the counter provides a signal for firing an SCR in series circuit with a solenoid for powering the tool. The counter is wired in circuit so as to latch at a predetermined count higher than the count output from which the firing signal is taken. Actuating the switch causes the counter to reset to zero, after which it counts positive half-cycles of the AC. When it reaches the count corresponding to the output from which the firing signal is taken, the tool is actuated. The counter continues to count until it relatches. It remains at the latched count until the switch is again actuated.

Abstract: A fastener driving device such as a tacker, including a silicon-controlled rectifier (SCR) actuating circuit for producing a power stroke for substantially a complete half cycle of an AC potential supply and which occurs following the actuation of a switch actuable at random times with respect to the cycles of the AC supply. The circuit features three functional stages. A firing synchronizer circuit is provided to inhibit firing at other than the beginning or end of a half wave cycle of rectified AC potential. A memory supporting circuit provides a high degree of switch bounce immunity. A protecting circuit prevents an accidental and undesirable firing of the SCR that might otherwise automatically occur when a sudden increase of voltage occurs at its anode such as might occur when power is first applied to the actuating circuit.

Abstract: An electrically operated fastener driving device comprising a housing structure providing a manually engageable handle for engaging a user to portably operate the device, a front wall disposed in vertically extending relation forwardly and below the handle and a vertically extending fastener drive track disposed closely adjacent the front wall. A solenoid is carried by the housing structure forwardly of the handle and rearwardly and above the drive track and includes an elongated plunger having a longitudinal axis inclined with respect to the vertical. A cam and cam track mechanism is disposed between the upper end portion of the fastener driving element slidable in the drive track and the lower end portion of the plunger for causing a downward stroke of the plunger in response to the energization of the solenoid to effect a drive stroke of the fastener driving element.