Showing papers on "Inductive sensor published in 1979"

Proximity sensing system and inductance measuring technique

Abstract: A proximity sensing system including an improved variable inductance measuring technique to provide an indication of the proximity of a target object to a remote sensor unit 10 which includes a sensor inductor. A variable inductance measuring apparatus measures the inductance of the sensor inductor, which inductance corresponds to the proximity of a target object. The variable inductance measuring network includes a sensor current pulse generator 20 which, in each of successive system periods, establishes a time-varying current through the sensor unit 10. A sensor control loop stage 30 senses when the resulting sensor voltage reaches a predetermined level and then captures the sensor current so as to clamp the sensor voltage at this level. A retrieval stage 40 then determines the rate of change of the sensor current at the time the sensor current is zero, establishing a calibrated analog voltage of the inductance of the sensor inductor which is substantially temperature independent. The inductance analog voltage is applied to a proximity detection and switching stage 50 which provides a quantized target-near detection pulse if the inductance analog voltage corresponds to a threshold proximity of the target object. Integration over successive system periods then provides a time-average proximity voltage which is applied to a Schmitt trigger and proximity switching network 58, the output of which indicates the proximity of the target object to the sensor inductor with respect to a threshold actuation gap.

Magnetic field intensity measuring device with frequency change indication

Abstract: A device powered by a DC source produces an output signal the frequency of which changes as a function of changes in external magnetic fields sensed by such device. A pair of non-linear amplifiers are interconnected so that the output of one amplifier is the input of the other amplifier. An inductive sensor is connected between the outputs of the amplifiers. The inductive sensor has an elongated magnetic core and a coil is wound on the core. The voltages at the outputs of the amplifiers, across the inductive sensor, switch between zero and the full voltage of the DC source.

Proximity sensor for alarm system - has tuned oscillators to detect presence of object and uses Schmitt rigger

Abstract: An inductive proximity sensor is used to trigger a relay in an alarm circuit The sensor is designed to be insensitive to external disturbances The main stage has an oscillator stage (7) coupled to a Schmitt trigger and output stage, with output connecting wires (6) The oscillator is positioned (a) such that sufficient damping is obtained A trigger stage (9) with coupled oscillator (10) is located in a separate housing and activates the relay by interacting with the main stage

Arrangement for measuring the distance between a metallic workpiece and a tool

Abstract: In the case of an arrangement for measuring the distance (h) between a metallic workpiece (6, 6a) and a processing tool (5) moved relative to this, in particular for controlling the distance of oxy-fuel, plasma and laser cutting machines, the tool (5) has at least one the surface of the workpiece to be machined (6, 6 a) facing capacitive and / or inductive sensor device (2, 4) is assigned, the electrical properties of which are reduced. or increasing the distance (h) to the workpiece (6,6a) can be influenced. Furthermore, the sensor device (2,4) is connected to an electrical circuit (1,7) for evaluating the changes in the electrical properties of the sensor device (2,4). In order to improve this arrangement in such a way that workpieces with an irregular surface can also be machined perfectly, a compensation sensor arrangement (3) is provided in addition to the sensor device (2, 4), which arrangement is influenced by an elevation () 6a) of the workpiece (6) is arranged on the side of the tool (5). In addition, the sensor device (2.4) and the compensation sensor arrangement (3) each have at least one reactance (3, 4) which can be influenced by the workpiece, one of the reactances being inductive (3) and the other capacitive (4), and that the reactive resistors (3, 4) are dimensioned and electrically connected to one another in such a way that a predetermined lateral approach of the workpiece (6, 6 a) to the electrodes (8), or the tool (5), by approximately the same amount, but electrically opposite changes of the inductive or capacitive reactance (3,4) can be compensated.

Circuit for low power, contactless switching of electrical loads - has electronic switch with connected by low power single core cable to inductive trip

Abstract: A mains terminal is connected to a switch and the load, e.g. a domestic light. A switch trip is connected to the switch through a low power line. The switch (4) includes a contactless electronic circuit with a power supply. The trip is a non-mechanical inductive sensor (7), and the low power line (6) is a single wire screened cable with a cross-section of less than 0.5mm2. The switch may include an amplifier and an integrated circuit switching unit with a triac and an opto-coupler.

Pressure indicator including diaphragm and two chambers - has metal plate fastened to diaphragm and inductive sensor at one of walls (SW 31.1.77)

Abstract: A pressure indicator of the kind comprising a diaphragm box containing two chambers which are completely separated by a resilient diaphragm, each of the chambers communicating via a connecting channel with an associated one of two fluid sources between which a pressure difference is to be established A met al plate is fastened to the diaphragm and an inductive sensor is disposed at one of the walls of the diaphragm box, so that a pressure change in at least one of the chambers causes a change in distance between the metal plate and the sensor and, consequently, an output signal from the sensor