Abstract: A circuit and method for controlling the application of a fastener to a surface and a support, for use with a support sensor and an automatic fastener applying device. In the circuit, a comparator receives a primary signal from the sensor and generates an intermediate signal when a preselected condition is satisfied between the primary signal and the predetermined value. A controller generates a control signal in response to receipt of a secondary signal from the sensor and the intermediate signal. An actuator operates the automatic fastener applying device to apply the fastener to the surface and support in response to the control signal.