Abstract: A self-regulating heating element comprising a tubular body closed at each end and containing two longitudinal electrically and thermally conductive flat strips arranged parallel to and spaced from each other. Each flat strip is provided along at least one longitudinal edge thereof with an abutting longitudinal resilient heat-conductive strip conforming with the adjacent surface of the inner wall of the tubular body so as to be in resilient heat-exchange contact with such inner surface for conducting heat from the flat strip to the tubular body. At least one PTC resistor is positioned between and in electrical and heat-exchange contact with the parallel flat strips, electrical terminals extending through the tubular body into contact with the flat strips. Such heating elements find particular use as immersion heaters for liquids and as the heat source in hair-curling devices.

Abstract: A device for the acquisition and storage of an electrical signal.The signal is divided into adjoining elementary time intervals of specific duration. During each of them the amplitude minimum and amplitude maximum of the signal are established, which values are first stored in analog form and subsequently in digital form.The device may be utilized in oscilloscopes, in particular those of the type comprising a matrix display panel.

Abstract: A line sawtooth deflection current generator with modulating means for the purpose of correcting the amplitude variations of the current produced, the said modulating means including a stage operating in the switching mode.

Abstract: When a color television signal is recorded on a video disc and said signal is read a complication arises owing to the asymmetry which is produced in the signal by the various process steps. This gives rise to spurious components whose influence should be minimized by a suitably selected coding system. The invention proposes a device with which the influence of this asymmetry is automatically reduced. This device comprises two separator stages for supplying two sub-signals which respectively represent the rising and falling edges of the information signal. The phase relationship between these two sub-signals is controlled with the aid of a phase shifter. The control signal required for this is produced with the aid of a detector which responds to an asymmetry component in the information signal. The two corrected sub-signals are subsequently recombined to the information signal.

Abstract: A .sup.3 He-.sup.4 He dilution refrigerator is provided with two interconnected mixing chambers arranged at different levels. One end of a superleak opens into concentrated .sup.3 He contained in the upper mixing chamber, while the other end opens into a portion of the apparatus containing dilute .sup.3 He for the supply of superfluid .sup.4 He, via the superleak, to the upper mixing chamber under the influence of the osmotic differential pressure prevailing across the superleak.

Abstract: A variable resistance device utilizes a control signal variable resistor and a first fixed resistor connected in series as a voltage divider as well as a second fixed resistor and an operational amplifier having an input connected between the first fixed resistor and one side of the variable resistor and an output connected through the second fixed resistor to the other side of the variable resistor, as a substantially linear variable resistance device where the variable resistance is obtained across the voltage divider.

Abstract: An optical scanning device which scans a rotary video disc with the aid of a light beam comprises an objective which performs focussing movements, for focussing a light spot on a recording surface of the video disc, as well as tilting tracking movements and time-error correction movements. Near its lower end the objective is suspended in an impregnated corrugated loudspeaker diaphragm of fabric fibre which enables the various movements of the objective to be made without giving rise to annoying resonant effects. The tracking movements and the time-error correction movements are obtained with the aid of coils which are connected to the objective near the upper end and which are disposed in air gaps of associated permanent magnetic stators.

Abstract: An optical scanning device scans recording tracks on a record carrier with the aid of a beam of radiation, while an objective, which concentrates the beam of radiation to a scanning spot, performs automatic electrically controlled movements in a direction perpendicular to the plane of the record carrier with the aid of a focussing bearing arrangement, so as to ensure a continuous focussing of the scanning spot on the recording tracks. Moreover, in order to follow the oscillations of the recording track, the objective also performs electrically controlled movements which are such that the scanning spot moves at least substantially parallel to the plane of the record carrier.

Abstract: Electric network for use in a subscriber's loop, comprising at least two connecting terminals for supplying thereto a current flowing in the subscriber's loop, the network comprising the series arrangement of a capacitive element and a switching device and a threshold device coupled to the connecting terminals and the switching device for either coupling or not coupling, depending on the polarity and the value of said current, said capacitive element to the terminals of the network. This results in a network whose pattern of behavior is optimum for the various signals which are exchanged in the loop.

Abstract: An apparatus is described for reading an optically encoded radiation-reflecting information carrier, using an opto-electronic focussing error detection system. The path of the read beam which is directed towards the information carrier includes a radiation-deflecting element producing a narrow focussing beam that co-operates with two focussing detectors to produce an error signal.

Abstract: A solar collector comprising an elongate solid cylindrical body extending lengthwise into an elongate cylindrical Dewar-type vessel in a manner to form annular-shaped supply and outlet ducts for a heat-transport medium, the sum of the cross-sectional areas of the supply and outlet ducts being less than one-quarter of the inner cross-sectional area of the vessel.

Abstract: A television camera having a camera tube provided with centering means for centering the camera tube in a coil former. One type of camera tube is thus suitable for a plurality of types of camera and can be made suitable for the relevant camera by a suitable choice of the centering means to be provided at a later stage.

Abstract: A three-output level logic circuit in which in addition to zero and one binary logic levels a third off-logic level is provided in which the output impedance is relatively high to in effect isolate the switching circuit from a common line to which it is connected thereby allowing several switching circuits to be used in common without deleteriously affecting switching speed in an overall computer or calculator unit.