Abstract: An improved color picture tube according to the invention includes a faceplate panel having a cathodoluminescent screen thereon. A low expansion color-selection electrode is mounted in the faceplate panel by a support structure including a bimetal element. The support structure is responsive to changes in temperature of the faceplate panel and moves the color selection electrode relative to the screen.

Abstract: Slotted shadow mask for a color picture tube mounted on an L-section frame having a lateral wall and a radial wall which are integral and extend toward the tube axis. The mask is bordered by a skirt having an axial generatrix, whose height is preferably between a third and a quarter the height of the lateral wall of the frame and whose thickness is less than ten times the thickness of the mask. The free inner end of the radial wall of the frame is bent in the opposite direction to the mask in order to form a stiffening lip and opening for the passage of electrons up to the edge of the metal surface of the mask.

Abstract: A spark plug having a center electrode comprises a ceramic insulator whose leg portion is shaped at the tip in a bag form so as to close the insulator bore. A firing tip is provided at the bag-shaped tip in a face-to-face relation with a side electrode by fixing an electrode element made of a sinter of a ceramic powder containing particles of a size between 10 and 200 .mu.m which are coated with a noble metal to a thickness of 0.1-20 .mu.m. An electrode axis extends from the top end of the plug and is inserted through the insulator bore.

Abstract: For use in an in-line electron gun of a cathode ray tube, a cup member comprises a planar plate having three apertures aligned with one another and a collar portion protruded from the planar plate. A height of the collar portion is between 2 mm and 6 mm, both inclusive. The collar portion may be either uniform in height or divided into a first pair of protrusions transversely of a predetermined straight line passing through the three apertures and a second pair of protrusions contiguous to the first pair of protrusions and lower in height than the first pair of protrusions.

Abstract: The low pressure discharge lamp has at least one glass tube containing therein mercury and a rare gas and provided with a fluorescent layer on its inner wall and electrodes set up in a single base plate in an airtight manner, each end of the glass tube is bonded with an adhesive to the base plate in a condition that each of the electrodes are received in each of the open ends thereby to form a sealed space by the glass tube and the base plate. With the structure, damage of the glass tube in sealing process is prevented and the structure of the lamp is made compact while manufacture of the lamp can be easy.

Abstract: Gas discharge display device having a vacuum-tight gas-filled envelope with a front plate and a back plate. A perforated control unit divides the interior of the envelope into a gas discharge space and a post-acceleration space and includes several electrode planes extending parallel to the plates. The gas discharge space has at least one plasma cathode and at least one plasma anode. The front layer carries on its back side a cathodoluminescent layer as well as an electrically conducting layer (post-acceleration anode). A spacer frame spaces the conductor as post-acceleration cathode in the foremost electrode plane of the control unit from the post-acceleration anode. In operation, a gas discharge burns at least temporarily between the plasmas electrodes. Electrons are pulled through selectively opened holes of the control unit into the post-acceleration space. The post-acceleration space which remains free of discharges is accelerated to several kV.

Abstract: A display tube comprising in an evacuated envelope (1) an electron gun system (6) for generating and focusing by means of a focusing lens at least two electron beams (28 to 35) on a display screen (5), which electron beams are deflected by deflection means and describe a frame on the display screen. The electron gun system (6) comprises at least two electron sources (20 to 26), the electrons in each electron beam being accelerated immediately after leaving the electron source by means of an electric field having a field strength exceeding 600 V/mm. The central axes (36) of the electron beam extend substantially parallel to each other, and all beams are converged by the focusing lens in the immediate proximity of the focus of the focusing lens, after which each separate beam is focused on the display screen by the focusing lens to form a spot.

Abstract: An electric discharge lamp has an arc tube within an outer gas filled glass envelope, and a thermal switching means is located within the outer envelope. The thermal switching means has a bimetal strip and a spring-like member each affixed to at least one of the electrical conductors, and upon application of heat the bimetal strip and spring-like member are flexed to short-circuit the electrical conductors and remove any DC potential between the main electrode and the starting electrode minimizing electrolysis.

Abstract: A rapid-start fluorescent lamp has a tubular envelope with a phosphor-coated inner wall surface, a pair of spaced electrodes and a pair of electrical leads sealed into each end of the envelope with one electrical lead connected directly to the electrode and the other electrical lead having an integral circuit breaker connected to the electrode and formed to disconnect the electrode from an energy source during lamp operation. Also, the rapid-start fluorescent lamp is fabricated by preparing a phosphor coated envelope, forming a pair of end members having a pair of leads and an integral circuit breaker with one lead connected directly to the electrode and the circuit breaker connecting the other lead to the electrode, sealing the end members into the envelope, heating and exhausting the envelope, heating the electrodes via the circuit breaker, dispensing a fill gas and mercury into the envelope and pinching off the exhaust tubes of the envelope.

Abstract: The present invention consists of a modulation circuit used in a digital application. The modulation circuit is designed to provide an LED with a more analog type signal. This in turn causes the LED to emit a signal that is peaked rather than a constant square wave providing a better conversion frequency to the fundamental frequency.

Abstract: Circuitry for automatically vertically centering a video display on the face of a CRT when deviations result from different raster scanning times. A comparator 12 having inputs flanking a resistor 11 connected in series with the vertical deflection coil 3 detects the zero or picture plane center crossing points of the deflection signal. The zero crossing points are then time compared with a pulse signal (FIG. 3(e)) whose width represents the overall time duration of each raster scan for the picture or image being displayed, and a d.c. correction component is applied as necessary to the deflection signal such that the adjusted zero crossing points bisect the duration pulses to thus vertically center the display.

Abstract: A controlled force variable reluctance actuator. A variable reluctance actuator having a moving element operated by a solenoid is provided in which the current in the solenoid is controlled by a signal representative of the flux density in the magnetic circuit of the actuator. The signal is produced by a Hall effect device placed in the magnetic circuit. Preferably, the Hall effect device controls the current in the solenoid by controlling its duty cycle; however, continuous control of the current may also be employed. Alternative embodiments are provided for a constant force actuator, an actuator whose force-displacement characteristic is altered, and an actuator in which the force may be selectively controlled. An embodiment is also provided for selectively controlling the position of the moving element based upon measured electric and magnetic parameters of the actuator.

Abstract: Automatic guided vehicles are commonly used in industrial material handling operations. Such vehicles must be accurately docked at predetermined stop locations without the guidance or assistance of human operators. The subject apparatus is used in conjunction with a vehicle having a vehicle drive circuit for controllably propelling the vehicle at a velocity responsive to a velocity command signal. At least one ground engaging wheel is equipped with a vehicle brake for controllably stopping the vehicle in response to a brake actuation signal. A position determining element produces a controlled stop signal in response to the vehicle being positioned a predetermined distance from the desired stop location, and an absolute stop signal in response to the vehicle being positioned at the desired stop location.

Abstract: A robot control system comprises a hand movable along a plane according to position command data determined based on an absolute coordinate system arranged along the plane, and rotatable around an axis vertical to the plane according to angular command data determined with respect to a base axis of the absolute coordinate system for working a workpiece at a certain working point thereof with a certain angular position of the hand. Input means inputs working point data representative of the working point in terms of a local coordinate system arranged on the workpiece, angular position data representative of the angular position of the hand at the working point determined with respect to a base axis of the local coordinate system, and position data of the workpiece located along the plane in terms of the absolute coordinate.

Abstract: This invention relates to a servo system for positioning and driving a movable member such as a pickup head of an optical reading system, for example. A sinewave signal is generated by a position detector in response to movement of the movable member. A first reference signal is used with the sinewave signal to position the movable member. A second reference signal is used with a modified signal which is generated by differentiating and rectifying the sinewave signal, to drive the movable member.

Abstract: A brushless exciter is provided for controlling excitation of a synchronous motor. The brushless exciter uses a center tapped rotating transformer, a discharge resistor, a field winding which has one end coupled to the ends of the rotating transformer and the other end connected to the discharge resistor and center tap of the rotating transformer. Four power SCR's are used in the brushless exciter. The electronics for controllably firing the SCR's and applying and removing the field are arranged in modules. A field current regulator module is located externally of the rotating apparatus for external control and contains circuitry for field forcing. The circuitry controls the application of field current and the level of excitation. The circuitry monitors the presence, frequency and phase angle of the discharge current and determines the time for field application and removal.

Abstract: A control circuit is connected between a three-phase power supply and a motor and ensures the correct application of phase signals to the motor, regardless of the way in which the control circuit is connected to the power supply. A first output signal of the supply is connected directly to an input of the motor via the circuit. Supply of power to the other two inputs is controlled by four switches, two of which receive signals from the second supply output and have their outputs connected to respective motor inputs, and the other two of which receive signals from the third supply output and have their outputs connected to respective motor inputs. The switches are controlled such that two switches are on, and the other two switches are off if the third output signal is positive with respect to the first output signal when the second signal passes through zero with respect to the first signal in a positive sense.

Abstract: A remote speed controller for an electric motor, the controller comprising a switching unit having three switches. A capacitor pack incorporating two capacitors is connected to the switching unit such that different combinations of the capacitors can be selected by one switch. The controller is connected in circuit between an AC voltage supply and windings of a motor so that selective actuation of the one switch changes the speed of the motor in accordance with the values of the capacitors selected. Further switches are incorporated to provide reverse motor capability and remote sensor capability.

Abstract: The present invention relates to an electronic device that is used to calculate the actual torque being produced by an electric motor at any instant in time and comparing this value of torque ratiometrically either with the maximum (peak) torque that the motor could produce under the line voltage available at that instant or with rated motor torque, thus giving an indication of whether the motor is approaching stall or is under utilized or over utilized.

Abstract: A microprocessor-based electronic voltage regulation system for controlling the charging of the battery in a vehicle. The conventional voltage regulator is eliminated and the intelligence of the microprocessor already present on the vehicle for controlling engine operation is used to regulate the output of the alternator. The battery temperature signal from a temperature transducer and a battery voltage signal from a sense line connected directly to the positive terminal of the battery are supplied to the microprocessor through an analog-to-digital converter. The microprocessor is programmed to ascertain from the battery temperature signal the desired set point voltage based upon an inverse first order relationship between battery temperature and desired battery voltage with preset maximum and minimum voltage set point levels.

Abstract: Disclosed herein is a regulator circuit for regulating the charging of a battery from a source of alternating current wherein the regulator circuit includes a rectifier having first and second pairs of terminals. Alternating current, applied to the first pair of terminals, is converted to a unidirectional charge current for application to the battery through the second pair of terminals. Circuitry, responsive to the voltage at the first pair of terminals, inhibits the generation of the charge current when the voltage at the first pair of terminals reaches a predetermined threshold. Additional circuitry, also responsive to the voltage at the first pair of terminals, provides a low impedence path across the second pair of terminals. Upon the occurrence of an overvoltage condition, the production of charge current by the rectifier is inhibited and any capacitance coupled to the charge current output circuit is discharged through the low impedence path provided across the second pair of terminals.

Abstract: A high voltage constant current source circuit includes first transistor biased as a constant current source and a second transistor connected in series with the first transistor. The second transistor has a punch-through voltage that is substantially less than any breakdown voltage of the second transistor. The emitter of the second transistor is connected to the collector of the first transistor. The collector of the second transistor supplies the constant current, provides an increased high output impedance, and allows low voltage operation if the collector-to-emitter voltage of the second transistor is less than its punch-through voltage. If its punch-through voltage is exceeded, that punch-through voltage adds to the collector-to-emitter breakdown voltage of the first transistor, allowing high voltage operation.

Abstract: An input transformer circuit in which transformer-isolated, balanced inputs are provided operates with low distortion and employs a transformer that has an equal number of turns in the primary and secondary windings and which is operated in the current mode to drive the two inputs of an operational amplifier. One input of the operational amplifier is connected to ground and the circuit operates to drive the other input to virtual ground, so that by transformer action the signal voltage across the ends of the primary winding is essentially zero. Because the signal voltages across the primary and secondary windings of the transformer are both substantially zero, there is relatively no induced electromotive force and no signal distortion occurs in the transformer.

Abstract: This method of constructing microwave systems and processing the signal by correlation is applicable notably to tachometric, telemetric, directional and tracking control systems, to the detection of heterogeneousness and discontinuity in materials by using sensors of the direct-contact or contactless type.

Abstract: The inductors in an induction heating apparatus are arranged in parallel branches with an SCR in series with each inductor and an RC snubber circuit in parallel with each inductor. If an SCR becomes shorted the faulty SCR is detected by a method and apparatus for coupling a capacitor across the inductors one at a time, exciting the capacitor-inductor circuit with a frequency suitable to induce a resonant condition provided the inductor is in series with a normal SCR and whereby resonance will not occur if the inductor is in series with a shorted SCR, and sensing circuit resonance thereby detecting whether the SCR in series with the selected inductor is shorted.

Abstract: A passive, integrating electromagnetic radiation power dosimeter. A radiofrequency or microwave antenna is combined with a diode detector/rectifier, a squaring circuit, and a electrochemical storage cell to provide an apparatus for determining the average energy of electromagnetic radiation incident on a surface. After a particular period of irradiation, the dosimeter can be interrogated electrically or visually, depending on the type of electrochemical cell employed, to yield the desired information. The apparatus has a substantially linear response to the electromagnetic power density over a wide range of electromagnetic field, and all of the energy required to record the incident energy is supplied by the electromagnetic field.

Abstract: An electric watthour meter provides for selectively accumulating energy consumption in one of at least two registers according to the value of a parameter relative to a predetermined threshold level. The parameter may be a load current, a line voltage, a time of day or a combination thereof.

Abstract: To permit testing of electrical connectors mounted on a strip, a pair of jaws, similarly to substantially transversely extended clothespin jaws, are provided, the inside surface of one (A) of the jaws (A, B) carrying a conductive strip (4) adapted to be engaged by one terminal of elements to be tested, the other terminal of the test elements being connected to a test track (7), for example applied over the conductive strip with an intervening insulating layer; (20) individual components (2) can be tested by foreshortening one terminal pin (5b) of the components and extending electrically conductive fingers, preferably of resistance material (6) for spring-clip engagement (8) with the foreshortened pins. The conductive strip (4) and the track (7) are brought out to external accessible terminal connectors (9). Alternatively, the test track is applied to a support strip (1) on which the elements (2) are located.

Abstract: An improvement to electrical circuit test probes of the type wherein a socket tube having a cylindrical spring loaded plunger therein is mounted in a test fixture. Electrical contact is assured between the socket and the plunger as the plunger moves longitudinally by the plunger having a resiliently flexible wand extending inwardly therefrom at an angular offset to the longitudinal axis of the plunger and the wand terminating in a bulbous contact member. The contact member is disposed within a cylindrical plunger tube and passes through an opening through which the contact member cannot pass. As a result, the wand acts as a flexible resilient finger holding the contact member firmly against the inner wall of the plunger tube as the plunger is moved in and out through its limits of movement.

Abstract: Apparatus for measuring precise distances between the turbine shaft and the interior surfaces of the inner and outer cylinders of a turbine is disclosed. A mandrel carrying proximity transducers is placed inside the inner and outer cylinders and rotated to preselected points. A proximeter generates a radio frequency electromagnetic field which is radiated in the immediate area of the proximity transducers. Energy losses caused by eddy currents generated in the interior surface of inner and outer cylinders are converted into linear output by a computer. Distances between the interior surface of the turbine and the transducers are calculated from the linear output. Comparison of measurements made with the top halves of the turbine removed with measurements made with the turbine halves installed permit determination of the "sag" in the turbine spindle introduced when the turbine is assembled.

Abstract: Metal detection apparatus includes an oscillator coil 101 driven by an oscillator 101, which induces in detector coils 103,104 equal and opposite E.M.F.s such that a nominally zero output is produced at terminals D.E. When metal is detected the E.M.F.s in coils 103,4 move out balance to produce a voltage at D.E., which is detected by circuit IC11 and fed to output circuits 111. Drifts in the nominally zero output at D.E. are corrected by combining quadraphase balancing signals on lines 109,110 with the detector coil output by means of amplifier IC10. The combined signal from IC10 is fed to phase sensitive detectors IC1,2 which respectively detect the quadraphase components of the combined signal from IC10. The outputs of IC1,2 are stored by capacitor circuits 112,113 and used to adjust variable capacity diode bridges 106,7 which adjust the amplitude of the balancing signals to maintain a nominally zero output from IC10 when metal is not being detected.

Abstract: An eddy current testing system is disclosed in which a pair of thin one-layer windings are disposed against a pair of thin plates of high permeability magnetic material, about aligned openings in the plates through which a wire is passed, pits and inclusions in the wire being detected by comparing signals corresponding to the electrical impedances on the two windings. The plates of high permeability magnetic material operate to concentrate magnetic flux in small regions of the wire, to obtain a high resolution.

Abstract: A magnetic device for nondestructively inspecting elongated objects such as wire cables and the like, for loss of metallic cross-section due to abrasion and corrosion and internal defects has magnets which induce a saturated magnetic field axially through a short section of the cable as the device and the cable move relative to one another. A sensing coil located in close proximity to the cable between the magnetic field poles detects small changes in leakage flux at the surface of the cable in the saturated condition. The sensed flux changes are applied to an integrator to measure the net variation in flux and correspondingly the total change in cross section. Multiple sense coils mounted on core pieces conforming to the external surface of the cable ensure complete continuity of the inspection process and allow the magnetic device to be installed and removed at intermediate stations along the cable.

Abstract: The disclosure is directed to an improved method and apparatus for subsurface electromagnetic logging in a borehole wherein means are provided to detect transverse magnetic mode components and to either correct for these spurious components in the processing of the received signals or to generate suitable cancelling signals.

Abstract: An apparatus and a method are disclosed wherein simultaneous electrical well logs can be made with a plurality of focused currents emitted from a plurality of electrodes located along a single equipotential surface of a housing. The focused currents are generated in response to a single voltage signal from a single power supply connected between the housing and a single current return electrode. A voltage reference is located on a cable which suspends the housing and the current return electrode in a well borehole, and a voltage detection circuit detects a voltage offset between the voltage reference and the housing.

Abstract: An improved battery tester for determining the acceptability of a Lithium lfur Dioxide (LiSO.sub.2) storage battery at a given temperature and with one or more cells therein. The tester is generally made up of a first comparison circuit having a series of series interconnected components, namely a comparator, first and second flip-flops, and an AND gate. A first resistor is parallel connected to the first comparison circuit. A second comparison circuit is also parallel connected to the first comparison circuit and is generally made up of a series of series interconnected components, namely a second resistor, a capacitor, a buffer, and a second comparator. A first switch is connected to the first resistor and a second switch is parallel connected to the second comparison circuit between the capacitor and the buffer.

Abstract: An active filter element of the fourth degree, to be connected in series with other such elements in forming a band-pass or band-stop filter of adjustable bandwidth, is a four-terminal network with three cascaded operational amplifiers interconnected by two mutually identical series resistors each inserted between the output of one amplifier and the noninverting input of the next one. The first operational amplifier, serving as an inverting adder, has its inverting input connected by two resistors to its own output and to the output of the third amplifier; the second and third operational amplifiers have their inverting inputs directly connected to their respective outputs to act as voltage followers. The two series resistors are longitudinal branches of respective frequency-dependent voltage dividers each further comprising a transverse branch connected to the junction of the corresponding resistor with the noninverting input of the next-following operational amplifier.

Abstract: A switched capacitor filter system is provided which is programmed to filter a predetermined sequence of tone signals. The filter system is de-rung after each selected tone signal is detected by increasing the clock frequency of the switched capacitor from the programmed value corresponding to a tone signal up to a center frequency substantially greater than that of the tone signals. Energy stored in the filter system is thus quickly dissipated. Rapid sequences of sequential tone signals are thus filtered without the problems associated with ringing of the filter.

Abstract: Apparatus for measuring the difference between two voltages in which a first current proportional to the voltage difference is generated at a first point, and there is circuitry for delivering at a second point a second current that is based on the first current and is indicative of the voltage difference; the circuitry includes an uninterrupted current path from the first point to the second point and the current path has a circuit element across which at least a portion of the common mode voltage appears; and the circuit element provides an output current to the path which is independent of the voltage across the circuit element.

Abstract: For a voltage follower unity gain amplifier, used, for instance, as a buffer in a transceiver associated with a data bus, the input signal is fed forward to a comparator (T2-T3) to which the output is also applied. The input is also applied via an amplifier stage (T5-T6) to a transistor (T4) in the commoned circuit of the comparator, which is a long-tailed pair. Thus, with a connection from the output of the circuit which includes another transistor (T9), provides negative feedback round the comparator, gives a highly stable current.

Abstract: In a signal generator based on Direct Frequency Synthesis, a first reference frequency generator generates a signal of a reference frequency. A plurality of second reference frequency generators, respectively, generates K signals with different frequencies Asin(.omega..sub.1 t+.psi.), Asin(.omega..sub.2 t+.psi.) . . . Asin(.omega..sub.K t+.psi.), which are in phase at time point (t=0), in response to the output signal of the first reference frequency generator. A switching circuit selectively switches the output signals from the plurality of said second reference frequency generators. A timing pulse generator generates timing pulses to operate said switching circuit at time T as given by .vertline..omega..sub.i+1 T-.omega..sub.i T.vertline.=2l.pi. (l:integer) where i=1, 2 . . . K-1.

Abstract: A high frequency oscillator is provided by connecting two amplifier circuits in parallel where each amplifier circuit provides the other amplifier circuit with the conditions necessary for oscillation. The inherent noise present in both amplifier circuits causes the quiescent current, and in turn, the generated frequency, to change. The changes in quiescent current cause the transconductance and the load impedance of each amplifier circuit to vary, and this in turn results in opposing changes in the input susceptance of each amplifier circuit. Because the changes in input susceptance oppose each other, the changes in quiescent current also oppose each other. The net result is that frequency stability is enhanced.

Abstract: Three-terminal negative admittance networks are disclosed. The preferred networks include either a bipolar junction transistor or a field-effect transistor phase shift mechanisms are used to generate a negative admittance. Various biasing schemes for proper operations of the network are also explained.

Abstract: A high frequency oscillator having an oscillation transistor connected to a resonant strip line unit consisting of a main strip line member and an auxiliary strip line member. The auxiliary strip line member is connected in parallel with or isolated from the main strip line member by a switch diode for switching the characteristic impedance of the strip line unit so as to generate a reception or transmission carrier wave output. A varactor diode connected to the strip line unit has its capacitance changed through an applied control voltage for channel switching. A modulating signal input terminal is directly connected to a portion of the auxiliary strip line member for modulating an FM transmission signal independently of the value of the control voltage applied to the varactor diode.

Abstract: The device for limiting the transmission power of radiowave transmitters comprises a limiting stage for attenuating the signal to be amplified before applying it to the input of the amplifying chain. A coupler collects part of the signal in order to apply it to the input of control means. A delay device is coupled between the coupler and the limiting stage and delays the signal to be amplifed before applying it to the input of the limiting stage. The control means block the limiting stage in order to prevent transmission of the signal to be amplified to the input of the amplifying chain when the level of the signal to be amplified overshoots a predetermined amplitude and hold the limiting stage in the blocked state after the level of the signal to be amplified has fallen back below the predetermined threshold during a sufficient period of time which is calculated so as to prevent any power overshoot.

Abstract: A duplexer includes an integral interdigital transmitter filter and parallel interdigital receiver filter in a common housing. A three-quarter wavelength antenna transformer section couples rf energy from the transmitter filter to an antenna and also couples rf energy from the antenna to the receiver filter and to an antenna cable connector.

Abstract: An h.f. electrical network consists of a transmission line device in the form of a closed cavity having two end plates between which extend four quarter wave resonators positioned symmetrically about an axis passing through both end plates. The device is provided with four ports connected to two pairs of transmission line loops each of which couple equally into two adjacent resonators. The device exhibits frequency selective properties and can be used to couple two carrier frequencies into a common antenna while maintaining electrical isolation between the two signal sources.

Abstract: A radio frequency multiplier circuit includes a first plurality of non-linear devices, each device having an input electrode and an output electrode. The input electrode of each one of the first plurality of non-linear devices is successively interconnected via a first input coupling means to a first input terminal. The multiplier further includes a second like plurality of non-linear devices, each device having an input electrode and an output electrode. The input electrode of each one of the second plurality of non-linear devices is successively interconnected via a second input coupling means to a second input terminal. A common output coupling means is provided to interconnect the output electrode of each one of the first plurality of devices with the output electrode of a corresponding one of the second plurality of devices. The multiplier further includes means for coupling a pair of signals having a 180.degree. differential phase shift to the pair of input terminals.

Abstract: A graded leaky coaxial cable comprised of a center conductor, a dielectric surrounding the center conductor, and a braided conductive shield woven around and surrounding the dielectric. The shield has progressively fewer ends along its length, whereby progressively larger non-conducting gaps are formed separated by closely woven groups of carriers, thus facilitating controlled penetration of a radial frequency field through the shield.

Abstract: A millimetric electromagnetic waves switch is constituted by a ridged waveguide associated to a PIN diode of which the layers P.sup.+ and N.sup.+ are very thin, of about 2 to 5 microns thickness. The width of the diode is inferior to that of the ridged part of the guide and its dimension according to the longitudinal axis of the guide is a multiple of the half-length of the guided wave.