Abstract: A sensing circuit system including circuitry for sensing impedance variations of a variable impedance element. As disclosed, a bridge circuit system includes a bridge circuit to which the variable impedance element is couplable. The bridge circuit system further includes circuitry for detecting open circuit or short circuit fault conditions of the variable impedance element. The variable impedance element is coupled to the bridge circuit by a connector, having two connector components, which is also operable to couple the fault detection circuitry to the bridge circuit only when the two components of the connector are connected together.

Abstract: A hot melt adhesive dispensing system including a hot melt adhesive dispenser, a hot melt adhesive tank, and a hose for coupling hot melt adhesive from the tank to the dispenser. The dispenser, the tank and the hose are heated by electrical heaters to maintain the adhesive in a suitable molten condition for dispensing and for flowing from the tank to the dispenser. When the hot melt adhesive system is first energized, the hose and tank heaters are coupled to a source of electrical power and the temperature at either the tank or the hose is sensed. When the sensed temperature reaches a suitable preselected level, the dispenser heater is then energized by coupling the heater to a source of electrical power. In this way, as the adhesive in the dispenser is heated from a solid to a molten form, it is free to expand into the hose, with the adhesive in the hose adjacent the dispenser having already been heated to a molten state.

Abstract: A power controller for placement between a source of electricity and a user of electricity such as heaters for heating thermoplastic material. The controller comprises a normally closed switch allowing electrical communication between the source and user. An electrical control circuit including a coil which is connected to the normally closed switch.The control circuit further includes a switch assembly operable between an on and off condition. The switch assembly prevents or allows the energization of the coil when in the on or off condition, respectively. A first timing assembly causes the switch assembly to be in the on condition for a first selected duration after energization of the control circuit. A second timing assembly causes the switch assembly to be intermittently placed in an on condition after energization of the control circuit.