Abstract: A voltage-controlled capacitor circuit and related circuitry. The voltage-controlled capacitor circuit includes a metal-oxide semiconductor (MOS) varactor, a diode varactor, and/or a capacitor with fixed capacitance. The MOS varactor, the diode varactor and the capacitor are electrically connected in parallel or in series to form a capacitor with a preferred characteristic of voltage-controlled capacitance.

Abstract: A method for monitoring an entrance to a hazardous area comprising sensing a signal pattern generated by light barriers when an object passes the entrance and comparing the sensed signed pattern with at least one predetermined signal pattern. The object is admissible if the signal patterns are identical and under certain other conditions.

Abstract: The invention relates to a surge arrester arrangement comprising a surge arrester with a number of ZnO blocks arranged between two end electrodes as well as a cut-out device arranged in series with the arrester for automatically disconnecting the arrester in the event of arrester failure. The central part in the cut-out device is a ZnO block (1) with a higher relative energy capability than the blocks in the arrester. In this way, the block in the cut-out device can only break if the arrester connected in series with the device has failed, whereby incorrect tripping of the device is prevented.

Abstract: A solid state machine controller for actuating a machine. The machine controller requires near simultaneous interruption of two photo-optic beams by fingers from both operator hands to actuate the machine. The beams are part of switches located at opposite ends of a tubular enclosure. The photo-optic beams are located in annular openings surrounded by embossed rings to prevent beam generator and receiver soiling as well as accidental machine actuation.

Abstract: An information carrier (17) has formations (20,21) which are engaged by contact elements (30,32) during insertion of the carrier into a receiving member (39) the movement of the contact elements is amplified and transmitted by levers (26,33) to respective means (25,34) for providing electrical signals representing movement of the contact elements.

Abstract: An electronic pressure responsive switch comprises an activating element and at least two sensors. The activating element and the sensors are arranged to be relatively displaceable with respect to one another whereby the sensors each generate signals when the activating element assumes a predetermined position relative to a respective sensor. The switch further has an elastic diaphragm having a first face exposed to pressure to be sensed and a reverse second face carrying either the activating element or the sensors. The diaphragm is deformable by the pressure whereby the relative position between the activating element on the one hand and the sensors on the other hand is varied as a function of the pressure.

Abstract: A light barrier system for monitoring the presence or absence of an obstacle in the monitored area and for simultaneously monitoring itself to detect contamination of the system. A photo-converter emits signals indicative of the light intensity of a light barrier beam and the signal is applied to a first, obstacle switch which is normally open but which closes at a relatively high level of darkness, i.e. when an obstacle is present. A converter signal is also applied to a second, contamination switch which is normally open but which closes at a lesser degree of darkness than the first switch so that both switches can be simultaneously closed. The outputs of the switches when closed are applied to relays to switch the relays between alternative position to indicate (a) the presence of an obstacle in the light curtain area and (b) the contamination of the light curtain system irrespective of whether or not an obstacle is present.

Abstract: A modular lighting control apparatus utilizes a housing having a plurality of total electric light centers mounted therein, such that the centers may be manually activated by light beams emanating from a hand held flashlight. The housing is provided with a utility outlet receptacle and is operated by a flexible line cord which is energized by a household utility current. Each light sensor controls a character of the outlet voltage available at the output receptacle. One light sensor provides a source of continuous full voltage at the light receptacle. Another light sensor de-energizes the voltage supply to the output receptacle. Still another light sensor causes the voltage, present at the output receptacle, to become intermittent. Yet another light sensor determines the amount of voltage available at the output receptacle.

Abstract: A circuit for controlling the energization of a night lighting load or the like, in which failure of the main circuit to control and shut off electrical supply to the load during daylight hours leads to permanent shutdown of the electrical supply to the load. Two photosensitive elements are provided in the circuit. One element, e.g. a photocell, is a main control which periodically operates a relay and supplies electricity to the load, i.e. at night. The second element, e.g. a second photocell, is connected in the circuit, together with a second relay, in such a manner that failure of the first relay to operate and open the load circuit during daylight hours will cause the second relay to operate and permanently open the load circuit.