Abstract: A filament lamp outage indicator system in which the actuation of an on/off switch to its on position is sensed to enable a logic circuit in the event a current flow increase is not inductively detected in a conductor in series with the switch and a corresponding filament lamp.

Abstract: A microprocessor circuit employed to control the on/off switching of a filament lamp in series with a power switching device and a single conductor is programmed to periodically cycle the filament lamp between its deenergized and energized state at a rate above that which would be humanly perceptible. A toroidal ferrite core surrounds the conductor between the lamp filament and the switch and picks up current changes which occur due to the cycling. The absence of current changes during cycling are perceived by the microprocessor as a lamp failure and appropriate signaling is made to indicate the lamp failure.

Abstract: Apparatus for generating an electrical signal indicative of the level of a liquid stored in a reservoir. The apparatus includes first and second probes spaced from one another and extending into the reservoir. Each of the probes includes a metal electrode surrounded by a preferably dielectric material. The liquid to be measured contacts the dielectric material, but does not directly contact the electrodes. A preferably alternating voltage is applied across the electrodes and the impedance therebetween is sensed. The impedance between the electrodes varies as a function of the level of the liquid in the reservoir and this impedance is substantially greater than the impedance between the probe areas of contact with the liquid. In effect, the liquid is treated as a conductor because its impedance is negligible as compared to the impedance between the probe electrodes, this impedance varying as a function of liquid level.

Abstract: A control circuit for a variable reluctance motor. A solid state switching device has its output circuit connected in series with the electrical winding of the motor. Circuit means are coupled to the motor winding and to the control electrode of the solid state switching device. The circuit means senses the EMF induced in the motor winding while the motor is rotating and while the switching device output is nonconductive. The switching device output circuit is rendered conductive when the EMF attains a predetermined level. The EMF induced in the winding of the rotating motor results from residual magnetism in the magnetic circuit of the motor or from such residual magnetism in addition to a bias current supplied to the motor winding. The variable reluctance motor acts as its own position sensor.