Abstract: A power actuated door opener is disclosed with a beam break system for detecting obstructions in a door opening. A transmitter includes a beam emitter and emitter drive circuit for transmitting a train of emitter pulses to a receiver. The receiver includes a pulse detector circuit with a beam detector for producing detector pulses in response to emitter pulses impinging on the detector. The emitter drive circuit and the pulse detector circuit are synchronously coupled with each other and the pulse detector circuit produces a normal output signal only if the detector receives a pulse which is in synchronism with an emitter pulse. The receiver includes an annunciator which produces an audible and a visible warning signal when the pulse detector circuit produces a fault output signal. The audible annunicator is a piezoelectric crystal mounted in the receiver housing with a cover plate operating as a sounding board.

Abstract: A power actuated door opener is disclosed with a beam break system for detecting obstructions in a door opening. A transmitter includes a beam emitter and emitter drive circuit for transmitting a train of emitter pulses to a receiver. The receiver includes a pulse detector circuit with a beam detector for producing detector pulses in response to emitter pulses impinging on the detector. The emitter drive circuit and the pulse detector circuit are synchronously coupled with each other and the pulse detector circuit produces a normal output signal only if the detector receives a pulse which is in synchronism with an emitter pulse. The receiver includes an annunciator which produces an audible and a visible warning signal when the pulse detector circuit produces a fault output signal. The audible annunicator is a piezoelectric crystal mounted in the receiver housing with a cover plate operating as a sounding board.

Abstract: A method and system are provided for controlling the energization of at least one glow plug in an internal combustion engine wherein a solid state drive circuit, including a semiconductor switch, is utilized for applying an energizing current to the at least one glow plug from a voltage source based on a control signal to electrically heat the at least one glow plug. The control signal is preferably a 50 Hz switched ground duty cycle signal from an electronic control module (ECM). Based on the duty cycle input, the drive circuit for each of the glow plugs supplies current from a main feed bus. A glow plug current monitoring circuit is provided for each of the glow plugs to detect whenever an open or short circuit condition appears in any of the glow plugs. The semiconductor device preferable is a current sensing type of MOSFET called a SENSEFET. Each SENSEFET internally monitors individual current draw of its respective glow plug to verify its proper operation.

Abstract: A tone generator for producing an audible sound for a predetermined time period in response to the occurrence of one or more predetermined conditions. The tone generator comprises a diaphragm mounted within a resonant sound cavity that is activated by an electromagnetic assembly which is in turn driven by the output signal from an oscillator circuit. The control logic and timing circuit for the tone generator includes a unique PTC subassembly that provides a timed logic signal for controlling the activations of the diaphragm, as well as an independently generated signal for contemporaneously activating a lamp which provides a visual indication of the detected predetermined condition. The control logic and timing circuit is adapted to produce the proper timed logic signal despite the absence of a lamp in the circuit or a lamp failure.

Abstract: A tone generator for producing an audible sound for a predetermined time period in response to the occurrence of one or more predetermined conditions. The tone generator comprises a diaphragm mounted within a resonant sound cavity that is activated by an electromagnetic assembly which is in turn driven by the output signal from an oscillator circuit. The control logic and timing circuit for the tone generator includes a unique PTC subassembly that provides a timed logic signal for controlling the activations of the diaphragm, as well as an independently generated signal for contemporaneously activating a lamp which provides a visual indication of the detected predetermined condition. The control logic and timing circuit is adapted to produce the proper timed logic signal despite the absence of a lamp in the circuit or a lamp failure.

Abstract: A tone generator for producing an audible sound for a predetermined time period in response to the occurrence of one or more predetermined conditions. The tone generator comprises a diaphragm mounted within a resonant sound cavity that is activated by an electromagnetic assembly which is in turn driven by the output signal from an oscillator circuit. The control logic and timing circuit for the tone generator includes a unique PTC subassembly that provides a timed logic signal for controlling the activations of the diaphragm, as well as an independently generated signal for contemporaneously activating a lamp which provides a visual indication of the detected predetermined condition. The control logic and timing circuit is adapted to produce the proper timed logic signal despite the absence of a lamp in the circuit or a lamp failure.

Abstract: A tone generator having a diaphragm and an electromagnet for vibrating the diaphragm to produce sound, the bobbin of the electromagnet being held in a fixed, predetermined relation to the diaphragm and connected to the retaining ring which holds the diaphragm by resilient spring arms that are stressed automatically by assembly of the tone generator to clamp the diaphragm, the pole piece of the electromagnet being held by flexible and resilient supports that are flexed automatically to retain the pole piece when the generator is assembled and to hold an end of the pole piece precisely spaced with respect to the diaphragm.