Abstract: A contactless motion detector responsive to the approach of a ferromagnetic element, including an oscillator with a sensing coil, has an output lead connected to one input of a first Exclusive-OR gate having another input connected to a square-wave generator whose pulses appear in the output of that gate with or without phase inversion depending on the output voltage of the motion detector. These pulses are fed, via an amplifier, to one input of a second Exclusive-OR gate whose other input receives the output pulses of the square-wave generator directly but with a delay compensating a lag introduced by the first gate and the amplifier. In the absence of a malfunction, the inputs of the second gate are energized either cophasally or antiphasally to produce either a low or a high output voltage of substantially constant magnitude fed to a load; in the event of a malfunction interrupting the pulse transmission to either input of this second gate, its output becomes a pulsating voltage.

Abstract: A contactless motion detector is energized from a source of current via a pair of supply leads and delivers an output signal by way of a further lead through an Exclusive-OR gate to a control electrode of a binary electronic switch in circuit with the source and a load to modify the flow of load current upon the approach of a metallic element, for example. The Exclusive-OR gate, having one input connected to that further lead, has another input connected to an ancillary lead which in turn is connected to the other supply lead through a decoupling diode. A selector switch enables completion of the load circuit directly via the latter supply lead, thereby causing inverted transmission of the output signal of the detector to the control electrode, or by way of the ancillary lead to prevent the inversion of that output signal, whereby the load current can be either increased or reduced upon the occurrence of the event to be detected.

Abstract: A contactless motion detector, specifically an oscillator whose signal amplitude is attenuated or enhanced by the approach of a monitored metallic element, is periodically switched for brief periods into its alternate state by a train of short test pulses giving rise to corresponding checking pulses that are superimposed upon the integrated output voltage of the oscillator whereby that voltage is intermittently increased when at low level and/or intermittently reduced when at high level. These checking pulses, whether of the voltage-increasing or the voltage-reducing kind, are integrated to provide an enabling signal allowing a controlled load to be energized or de-energized according to the mean value of the output voltage; an absence of the enabling signal indicates a malfunction.

Abstract: Electrical components of an electronic switching device, such as a motion sensor of a monitoring system, are mounted on a dielectric carrier film covering opposite surfaces of a flat non-conductive support. The several components, disposed on the outer surfaces of the carrier film, are electrically interconnected by leads in the form of conductor strips on the inner film surfaces. A coil constituting such a component is embedded in a ferrite pot which is pasted onto an extension of the film and has a central pin with an end insertable into an aperture in an edge of the flat support after that extension is bent around the edge. The surfaces of the support may be pitted to provide recesses for an adhesive designed to bond that support to the film.

Abstract: A signal detector of a contactless proximity sensor feeds three voltage comparators with reference inputs connected to points of different threshold potentials. When the incoming signal exceeds only the lowest threshold, a light-emitting diode is flashed at a low frequency; when the intermediate threshold is surpassed, the diode flashes at a higher frequency, whereas its light emission is continuous in the presence of a signal level above the highest threshold. Only in the last two instances will a load-control circuit be switched.

Abstract: A contactless motion detector, including an oscillator sensitive to an approaching metallic element, includes an electronic switch such as a thyristor triggerable by an output signal from a demodulator comprising a storage capacitor which is alternately chargeable and dischargeable, preferably with constant current, during each cycle of a high-frequency voltage generated by the oscillator. The oscillator voltage is compared with a reference voltage by means of a differential amplifier causing the flow of a charging current into the capacitor when the oscillator voltage exceeds the reference voltage whereas a discharging current flows out of that capacitor in the opposite case. The reference voltage is so chosen that the capacitor charge rises in the course of a few cycles above a predetermined threshold when the oscillator voltage is high but remains below that threshold when it is low.

Abstract: A switch assembly, especially for electronic contactless or proximity switches comprises a substantially two-part housing including the housing bottom and housing top which are separable from one another. The housing parts interfit to form a generally rectangular parallelepipedal structure provided at one end with a threaded connection for a threaded connector, pipe or conduit through which conductors may be passed to connect to the electronic device within the housing. The bottom housing portion is provided with the connecting circuitry while the top housing portion, interfitting with the bottom housing portion, has a part overhanging the latter and provided with the plug connectors forming a detachable electrical connection with the connecting circuitry permanently received in the lower housing portion. The upper housing portion contains all of the switch circuitry in its receptacle.

Abstract: A contactless motion detector, such as an oscillator sensitive to an approaching metallic element, is connected across a storage capacitor which can be charged from a source of pulsating direct current through a constant-current unit whose current flow is throttled when the charging voltage of the capacitor reaches a predetermined level. A thyristor connected across the series combination of storage capacitor and constant-current unit has a gate connected to a tap on a voltage divider lying in parallel with the capacitor so as to fire when the capacitor voltage rises substantially above the aforementioned level in order to break down a Zener diode forming part of that divider. Such a rise occurs when a transistor, inserted between the capacitor and a higher-voltage output of the constant-current unit, is turned on by a switching transistor responsive to a trigger signal from the detector.

Abstract: A contactless motion detector is energized from a source of direct current via a pair of supply leads and delivers an output signal by way of a further conductor to a control electrode of a binary electronic switch, such as a thyristor, in series with the source and a load to modify the flow of load current upon the approach of a metallic element, for example. An Exclusive-OR gate is inserted in the further conductor to act as a selective signal inverter, one input of this gate being permanently connected to one supply lead while being also selectively connectable to the other supply lead whereby the load current can be either increased or reduced upon the occurrence of the event to be detected.

Abstract: A contactless motion detector, such as an oscillator sensitive to an approaching metallic element, is connected across a storage capacitor which can be charged from a source of pulsating direct current through a constant-current unit with two parallel branches, one of them including a voltage divider controlling an emitter-follower transistor in the other branch. A Zener diode, shunting the storage capacitor and part of the constant-current unit in series therewith, throttles the flow of charging current through that unit by stabilizing the base voltage of the emitter-follower transistor when the capacitor reaches a predetermined charging voltage. Connected across the series combination of storage capacitor and constant-current unit is an ancillary thyristor forming part of a firing circuit for a main thyristor in parallel therewith; that firing circuit further includes another Zener diode and a stabilizing resistor in series with the ancillary thyristor.

Abstract: A contactless motion detector, such as an oscillator sensitive to an approaching metallic element, is connected across a storage capacitor charged from a source of pulsating direct current through a current-limiting device and shunted by a Zener diode. Connected across the series combination of storage capacitor and current-limiting device is an ancillary thyristor, triggerable by the detector, forming part of a firing circuit for a main thyristor in parallel therewith; that firing circuit further includes another Zener diode and a stabilizing resistor in series with the ancillary thyristor. Conduction of the main thyristor, upon the triggering of the ancillary thyristor, reduces to near-zero the resistance in series with a load, such as a relay, which is traversed by the current drawn from the source.

Abstract: A contactless motion detector, such as an oscillator sensitive to an approaching metallic element, is connected across a storage capacitor which can be charged from a source of pulsating direct current through a constant-current unit. A Zener diode, shunting the storage capacitor and part of the constant-current unit in series therewith, throttles the flow of charging current through that unit when the capacitor reaches a predetermined charging voltage. Connected across the series combination of storage capacitor and constant-current unit is an ancillary thyristor, triggerable by the detector, forming part of a firing circuit for a main thyristor in parallel therewith; that firing circuit further includes another Zener diode and a stabilizing resistor in series with the ancillary thyristor. Conduction of the main thyristor, upon the triggering of the ancillary thyristor, reduces to near-zero the resistance in series with a load, such as a relay, which is traversed by the current drawn from the source.

Abstract: A contactless proximity sensor includes an oscillator which generates an output damped by the presence of a metal part whose approach is to be detected. The operating voltage for the oscillator is developed across a capacitor, in parallel with a Zener diode, whose charging circuit includes a high-ohmic resistance connected in series therewith across a supply of pulsating direct current. The flow of charging current into the capacitor is controlled by a thyristor adapted to be fired by means of a trigger transistor upon a critical reduction in the amplitude of the oscillator output. The trigger transistor, upon conducting, lowers the cathode potential of the thyristor whose gate is connected, via a resistor and/or a diode, to the junction of the capacitor with its charging resistance; in one embodiment this gate is driven positive through an inverter upon the conduction of the trigger transistor.

Abstract: A contactless motion detector, including an oscillator and an amplifier, has an energizing circuit connected across an electronic breakdown device lying in series with a contant-current unit, this series combination receiving pulsating direct current from a supply circuit in parallel with an output thyristor which bridges either the entire series combination or only the constant-current unit. The output thyristor is controlled by a switching transistor responding to an output signal from the motion detector; even when the output thyristor fires to actuate a load in the supply circuit, a sufficient voltage drop is maintained across the breakdown device to keep the oscillator and the amplifier operating.

Abstract: A contactless motion detector, including an oscillator and an amplifier, has an energizing circuit connected across a Zener diode in a section of a voltage divider also comprising a current-sensing resistor, another section of this divider comprising an output thyristor in parallel with a resistive branch which may be a constant-current unit. The voltage divider receives pulsating direct current from a supply circuit including a load; an ancillary thyristor has its gate and cathode connected across the current-sensing resistor so as to fire when the load current exceeds a certain limit, the two thyristors being so coupled to each other that conduction of the ancillary thyristor cuts off the output thyristor.