Abstract: An improved temperature control circuit having a controller portion with an inhibit input and a temperature responsive circuit portion that includes a resistive portion connected in series with a sensor portion which establishes the control point for the control circuit, the improvement including a semiconductor switch in series with the sensor portion, the semiconductor switch having two electrodes between which a resistor is connected. The resistor is also connected to the inhibit input of the controller to present a signal to inhibit operation of the temperature control circuit when the sensor portion and semiconductor switch is not conducting.

Abstract: A device for dispensing molten thermoplastic material comprising a barrel member having an internal melting chamber communicating with an outlet opening through a nozzle, and a sleeve having one end secured at the barrel member and a through opening communicating with the end of the melting chamber opposite the outlet opening. The sleeve is adapted to receive a rod of solid thermoplastic material with one end portion of the rod in the melting chamber and the rod projecting through the sleeve along a predetermined path. The barrel member is heated to melt the end portion of the rod therein, and a drive adapted to be switched between a deactivated state and an activated state is provided for driving the rod of solid thermoplastic material into the melting chamber at a predetermined rate to expel molten thermoplastic material through the nozzle.

Abstract: A hot melt adhesive applicator operable at a number of selected temperatures having a portion of the circuitry for control of the applicator temperature at a point remote from the applicator body. The remotely located circuitry employs a differential amplifier and a zero crossing detector for controlling the operation of a triac which, when turned on, increases the temperature at the applicator. The operational amplifier is protected by a clamping circuit from receiving a signal, when a temperature setting is changed from a high to a low setting, that would otherwise cause the differential amplifier to provide an output required for turning on the triac which would cause a run away condition to exist.

Abstract: A transistorized amplifier includes an active network having a succession of DC coupled transistors, a load resistor across which an output voltage is developed in response to current flowing through the active network and a voltage divider network for distributing an applied DC potential equally across the active network. Each stage in the active network is thereby allowed to operate over only a restricted voltage range, while yet operating cooperatively to control high voltages, using inexpensive low voltage rating components. The amplifier preferably includes at least two sets of active networks, load resistors and voltage divider networks, each set being responsive to a complementary input signal current to provide complementary output voltages useful in driving a pair of electrostatic deflection plates.

Abstract: An improved temperature control circuit having a controller portion with an inhibit input and a temperature responsive circuit portion that includes a resistive portion connected in series with a sensor portion which establishes the control point for the control circuit, the improvement including a semiconductor switch in series with the sensor portion, the semiconductor switch having two electrodes between which a resistor is connected. The resistor is also connected to the inhibit input of the controller to present a signal to inhibit operation of the temperature control circuit when the sensor portion and semiconductor switch is not conducting.