Abstract: A lightweight electrical assembly for vehicular application is virtually “fastenerless” and includes a fold-up case formed of polymer based material that is molded to provide details to accept electronic devices such as playback mechanisms and radio receivers, as well as the circuit boards required for electrical control and display. The case is of composite structure, including an insert molded electrically conductive wire mesh screen that has been pre-formed to contour with the molding operation. The wire mesh provides electromagnetic shielding and grounding of the circuit boards via exposed wire mesh pads and adjacent ground clips. Side wall closure members are extruded of aluminum defining self-engaging attachment features for affixing to the case, providing electrical self-grounding with the wire screen and thermal grounding with internal power devices.

Abstract: A VFD drive apparatus in which the filament of a VFD is coupled at a first terminal to an input voltage derived from a voltage source, and at a second terminal to a shunt voltage regulator that establishes a regulated filament current and a regulated cutoff voltage with respect to ground potential. Other electrical loads such as drive circuitry for the anodes and grid of the display are coupled between the second terminal of the filament and ground potential so that at least a portion of the filament current is supplied to such other electrical loads. Power dissipated by the shunt voltage regulator is thereby reduced, and the cost associated with providing additional voltage regulators for the other electrical loads is avoided.

Abstract: A VFD drive apparatus in which the filament of a VFD is coupled at a first terminal to an input voltage derived from a voltage source, and at a second terminal to a shunt voltage regulator that establishes a regulated filament current and a regulated cutoff voltage with respect to ground potential. Other electrical loads such as drive circuitry for the anodes and grid of the display are coupled between the second terminal of the filament and ground potential so that at least a portion of the filament current is supplied to such other electrical loads. Power dissipated by the shunt voltage regulator is thereby reduced, and the cost associated with providing additional voltage regulators for the other electrical loads is avoided.

Abstract: A filter board for filtering electromagnetic emissions from an electronic device couples to a conductive housing in the device. The filter board includes a plurality of filter components connected to a substrate, which is coupled to a continuous ground plane. Signal lines from the electronic device are coupled to the filter components and pass through the substrate and ground plane before being connected to other circuits. The filter board prevents high frequency noise and excessive emissions from exceeding required limits.

Abstract: A coolant shutoff valve is closed when a motor-operated temperature door is moved to full cold position to prevent heating of air due to radiation, conduction, convection, or leakage around the door. The motor moves the door to hot or cold limit positions and remains in a stall condition to maintain such positions. A motor control responsive to operator selected temperature moves the door to such limit positions. A shutoff circuit associated with the motor control senses whether a hot or cold mode is selected and detects from the motor current whether the motor is stalled. When the circuit determines both a cold mode and motor stall current an actuation signal is sent to the shutoff valve.

Abstract: An efficient power supply for a vacuum fluorescent display having a battery or other unregulated source supplies the grid voltage directly from the battery and supplies the anode voltage via a step-up regulator. To eliminate apparent display brightness changes upon variation of battery voltage, the battery voltage and the anode voltage are fed back to the regulator, adjusting the regulated anode voltage inversely to the battery voltage. The direct coupling of battery to the grid eliminates the necessity of regulating or converting the grid voltage, allowing a smaller power supply to be used and minimizing heat losses.

Abstract: A power supply for a VF display generates a DC filament voltage from a battery by either a switched transformer supply or a monolithic regulator circuit. Where a higher-than-battery voltage is needed for anode and grid voltages, another monolithic regulator circuit or the switched transformer is used. An H-switch develops an alternating voltage from the DC voltage and applies it to the display filament. A controller for the H-switch is a logic circuit including flip-flops which toggle in response to a low frequency pulsed dimmer signal to synchronize the filament half cycles with the dimmer phases. Slew rate control ramps the H-switch control signal to produce a trapezoidal waveform in the filament current having reduced radio frequency emissions.

Abstract: A governor circuit for limiting the maximum speed of an internal combustion engine is effective to minimize overshoot at all ranges of engine acceleration. The system includes a circuit responsive to the engine speed which provides control signals to a solenoid valve which, in turn, controls a vacuum actuator which can override a manual throttle control to move the throttle toward closed position when a governed engine speed is approached. A control circuit provides a signal having a lead component and an integrated signal which comprises a stabilizing component and an integrated speed component. The integrated signal is provided by an integrator having a low sensitivity and high gain at low engine accelerations and a high sensitivity and low gain at engine accelerations above a predetermined switch point. The resulting control signal controls a duty cycle oscillator which actuates the solenoid valve.