Abstract: A method for simultaneously triggering a plurality of serially connected SCR's transfers energy from a relatively low voltage energy source to each of a plurality of energy storage devices which are coupled respectively to the gate of a corresponding SCR through a respective switching device. The energy from each storage device is simultaneously discharged into the gate of each respective SCR by a respective trigger signal from the low voltage energy source to each respective switching device.Apparatus for simultaneously triggering a plurality of serially connected SCR's comprises a pulse transformer for transferring energy from a relatively low voltage source of energy.

Abstract: A power converter adapted for use in a high-voltage circuit and equipped with a plurality of arms each comprising a plurality of thyristor elements connected in series, wherein an overvoltage limiter having an overvoltage limiting element and means for short-circuiting the ends of the overvoltage limiting element in response to flow of a load current therein are connected between the anode and the cathode of each thyristor element. The short-circuiting means has a gap between the two electrodes connected respectively to the anode and the cathode of each thyristor element, and also a metal layer of a low melting point which is molten by heat generated due to the flow of a load current in the overvoltage limiting element to fill the gap.

Abstract: There is disclosed an alternating current to direct current static converter which includes a three-phase transformer interconnected with two rectifier bridges to produce a twelve-phase connection for direct current output. The twelve-phase connection is provided by coupling input terminals of one of the bridges to corresponding primary input terminals of each of the three phases of the transformer, and coupling input terminals of the other of the bridges to corresponding phase terminals of the secondary of the three-phase transformer. The outputs of the rectifier bridges are then coupled to provide the DC output. The transformer is constructed such that there is a 150 degree phase shift between the primary and secondary voltages of each phase of the three-phase transformer and a 30 degree phase shift between the input voltages to the rectifier bridges.

Abstract: An optical gate signal generating apparatus for firing a plurality of thyristors in a thyristor converter apparatus, including a circuit for generating an electrical gate signal, a plurality of first light emitting elements, each being connected to receive the electrical gate signal for generating a first optical signal.

Abstract: A protective circuit for a plurality of series connected thyristors where each thyristor has in parallel with it a resistance, capacitance type snubber circuit and a metal oxide varistor. The arrangement of the series connected thyristors, snubber circuits and their metal oxide varistors has in parallel with it a main metal oxide varistor. The main varistor is responsive to external transient surges so as to conduct large currents. The outer varistors are selected to have values so as to conduct a much smaller or minimal current relative to the current conducted by the main varistor. In a preferred arrangement, a tuning inductor is in series with the thyristors, snubber circuits and parallel arranged varistors. Also, the main varistor is arranged in parallel with the series connection of thyristor, snubber, varistor combination and inductor, and in series with a bank of capacitors.

Abstract: A hybrid phase-controlled rectifying bridge includes both controlled and uncontrolled electric valves referred to as thyristors and diodes, respectively. Each of a pair of thyristors is periodically fired at an "angle" that can be advanced or retarded as desired, whereupon load current commutates to the thyristor from the corresponding diode. Subsequently the thyristor is turned off at a desired extinction angle by the action of cyclically operative forced commutation means. To avoid reverse recovery overvoltages across a diode when the desired extinction angle is only slightly larger than the firing angle, means is provided for temporarily preventing any turnoff action during the diode-to-thyristor commutation interval and for an additional interval that gives the diode sufficient time to fully recover its reverse blocking capability.

Abstract: An auxiliary thyristor control circuit inserts a zinc oxide varistor in series with the capacitor bank of a static VAR generator for discharging the capacitor bank when the static VAR generator is subjected to high transient voltages.

Abstract: A D.C. power supply (10, 44) having an auxiliary bridge rectifier (14, 38, 48) connected in series with a primary bridge rectifier (12, 46) is disclosed. The auxiliary bridge rectifier (14, 38, 48) "floats" above the potential of the primary bridge rectifier (12, 46) furnishing additional voltage at the D.C. power supply output (20, 22; 56, 58) whenever the A.C. mains voltage input to the main bridge rectifier (12, 46) drops below a predetermined value. In one embodiment of the present invention, a series of SCR's (26, 28) arranged in three-phase configuration perform the rectification and regulation functions of the primary bridge rectifier (12, 46) and the auxiliary bridge rectifier (14, 48). In an alternate embodiment of the present invention, paired SCR's (40) and diodes (42) are arranged in a half-controlled auxiliary bridge rectifier configuration (38). Individual firing angles for the various SCR's (26, 28, 40) are computed as a composite of several factors, including a firing delay factor .alpha..sub.

Abstract: A thyristor matrix arrangement having four columns, each column being formed of n thyristors connected in series with each other. In one embodiment, the series connected thyristors in respective columns are coupled to one another via heat sinks. The thyristors in each column are poled such that forward conduction current cannot flow through only one of the columns. The heat sinks are cross-connected among the columns to form a current path which is formed of appropriately poled thyristors in different ones of the columns and the column cross-connections. The cross-connections are inductive so as to provide relatively large inductive voltage drops when the thyristors are fired, thereby enabling the firing of thyristors having relatively low firing and forward voltages.

Abstract: A flyback transformer is described for use in television receivers, video monitors, and the like in which a video display device is scanned in accordance with a horizontal retrace frequency. The transformer includes a primary winding for receiving horizontal scan rate pulses and a plurality of secondary windings. The latter windings are tuned to selected harmonics of the horizontal retrace frequency such that at least two secondary windings develop horizontal rate pulses whose peaks are complimentary. The pulses developed by the secondary windings are combined so as to develop a composite pulse whose peak is substantially flat.

Abstract: A high voltage converter converts an incoming high frequency pulse voltage to a direct voltage at a level which can be varied by varying the pulse width. The converter contains a transformer (T) with its primary side (p) connected to a pulse source (U) and to a controllable switch (K). The secondary side of the transformer is divided into two sections (s.sub.1, s.sub.2). One section (s.sub.1) is connected to a rectifier in the form of a conventional voltage doubler circuit (D1, D2, Cd1, Cd2) with capacitors in parallel with the secondary winding sections (s.sub.1, s.sub.2). The other section (s.sub.2) is connected to a rectifier bridge (D3-D6) and a smoothing filer (L.sub.f, C.sub.f). The converter output is the doubler circuit output in series with the smoothing filter output.

Abstract: A snubber circuit coupled across each thyristor to be gated in a chain of thyristors determines the critical output of a NOR LATCH whenever one snubber circuit could not be charged and discharged under normal gating conditions because of a short failure.

Abstract: A power converting device including at least one power converting element, and a protection circuit monitoring the switching characteristics of the power converting element and for protecting the power converting element during switching thereof, including a first circuit coupled to detect a reverse voltage applied to the power converting element, a second circuit coupled to the first circuit for receiving the detected reverse voltage and for integrating the detected reverse voltage to produce a reverse voltage/time integral signal, and a third circuit coupled to receive the reverse voltage/time integral signal for producing a decision signal only when the amplitude of the reverse voltage/time integral signal exceeds a first prescribed value, the decision signal indicates that the power converting element is extinguished.

Abstract: The proposed method consists in that a narrow control pulse is applied to the thyristors of the arrangement at the beginning of the conduction interval of the arrangement. The positive voltage across the monitored thyristors is measured and a monitor signal is formed at the point in time when the voltage reaches a preset level. Using the received monitor signals, one can count the number of the thyristors whose positive voltage exceeds a preset level. At the point in time when the number of the monitor signals reaches a preset value, additional narrow control pulses are applied to the thyristors.The proposed control system comprises devices for measuring the positive voltage across the monitored thyristors and an adder connected to the devices. The adder and a reference signal source are coupled to a comparison circuit which, like a sync pulse source, is connected to an AND gate. The AND gate and the sync pulse source are connected to an OR gate which couples an amplifier-former connected to the arrangement.

Abstract: A flyback transformer comprising a primary winding wound onto a core, secondary windings wound in magnetic coupling with the primary windings, and diodes connected to the secondary windings respectively, each diode being mounted on the peripheral surface of a bobbin on which the secondary windings are wound and supported thereto through lead wires fitted into grooves provided at supports projecting from the peripheral surface of the bobbin, thereby simplifying the manner in which the diode is mounted to the bobbin and making it easier to automate both the diode mounting and the connecting of terminals of the secondary windings with the lead wires.

Abstract: In order to place into operation a group of power converters which are connected in series as concerns the direct-current mode and in parallel as concerns the alternating-current mode, of a power or current converter operating in a rectifying mode of a high-voltage direct-current transmission installation, the control pulses of the group of power converters to be placed into operation are set at a range of approximately 100 to 115 electrical degrees. The bypass or shunt switch of such group of power converters subsequently receives an opening command. The control pulses, after accomplishment of opening of the bypass or shunt switch are shifted in accordance with a predetermined linear ramp function in the rectifying range and thereafter the control pulses are delivered by means of a pole current regulator. The placement into operation of a power converter operating in the inverting mode is accomplished in a similar fashion.

Abstract: In the propulsion system of an electric locomotive, a-c wayside power is converted to direct current for the traction motors by a plurality of phase-controlled rectifying circuits having serially connected outputs. To improve power factor, forced commutation means is provided for turning off the controllable valves in one of the circuits at a desired "extinction angle." This angle is varied with motor speed, but its effective range of variation is restricted so as to avoid undesired leading power factor at low speeds, to optimize power factor when the locomotive is running at full power, and to prevent misoperation when the level of load current is low.

Abstract: An arrester is provided including series connected first and second nonlinear resistance elements and a by-pass circuit. The by-pass circuit is connected in parallel with the second nonlinear resistance element and short-circuits the second nonlinear resistance element only when a voltage of a predetermined polarity is applied to the second nonlinear resistance element. An semiconductor circuit arrangement with a protection device is also provided, where the arrester is used for protecting a semiconductor device.

Abstract: In a television receiver having a picture tube that requires an ultor accelerating potential and an intermediate direct voltage, such as a focus voltage, a high voltage generator is provided that develops the two voltages. A source of alternating voltage is coupled to a primary winding of a transformer for developing an alternating polarity voltage across each of two high voltage secondary windings. A first voltage doubler is coupled to the first high voltage winding for rectifying the alternating polarity voltage developed across the winding during both polarity intervals thereof to produce a first direct voltage. The first direct voltage is applied to an intermediate voltage terminal to generate the picture tube intermediate direct voltage between that terminal and a reference terminal. A second voltage doubler is coupled to the second high voltage winding for rectifying the alternating polarity voltage developed across the winding during both polarity intervals thereof to produce a second direct voltage.

Abstract: An electrical converter equipment for providing a d.c. voltage from an alternating current source. The converter has a unique operating cycle wherein a variable control angle is effected. The operating cycle for the converter comprises a series of half periods of the alternating current source. During different periods of time, the converter operates with different control angles. The control cycles comprise n periods of the input signal, where n is an odd number not less than three. During two half periods of a cycle, the control angle is varied. During two other half periods of the cycle, the converter operates at a fixed control angle. The half periods during which the converter is controlled with a variable control angle are time equidistant.

Abstract: A high voltage converter apparatus having overvoltage protection circuits for thyristors is disclosed in which, in order to protect series-connected thyristors in the converter against overvoltage, the converter is stopped when the overvoltage is generated by a trouble in the primary circuit of a pulse transformer, which is included in a gate circuit for the thyristors, and one of the overvoltage protection circuits, each of which is connected between an anode and a gate of a corresponding thyristor, is prevented from being operated when the overvoltage is generated by a trouble in the secondary circuit of the pulse transformer.

Abstract: A static high voltage switch which can be constructed in miniaturized form and having a high degree of reliability, it comprises a bridge of switches, such as thyristors, each controlled by a secondary winding of a transformer whose single primary winding is connected to the secondaries by toroidal cores. Each toroidal core comprises a secondary winding. The primary winding is constituted by a high voltage cable element, which passes axially through the cores.

Abstract: Thyristors included in circuit configurations are, in turn, connected in series circuit fashion such that n circuit configurations are so interconnected, where n is a real integer equal to or greater than 2. The circuit configurations provide a combination of functions such as current limiting, voltage distribution, assumption of storage load, limitation of commutation voltage and limitation of search voltage. The combined circuit configurations provide the most practical arrangement of desired characteristics to meet the requirements for specific applications.

Abstract: A power converter includes a plurality of thyristors, each of which is controlled by a control circuit. A multi-section voltage divider is connected in parallel with a thyristor and provides the control circuit with power as well as means for measuring voltage across the thyristor. The present voltage divider components minimize the space required and cost of fabrication.

Abstract: A static electrical converter equipment has a plurality of controllable converter bridges connected to a common a.c. supply source. Control pulse devices supply control pulses to the controllable valves of the bridges. The converter equipment comprises members arranged to prevent a control pulse from being supplied to a valve in one of the bridges, for initiating a commutation in this bridge, until a corresponding commutation in another bridge is completed.

Abstract: A high-voltage transformer-rectifier device comprising a step-up three-phase transformer with a spatial magnetic circuit made up of three vertical stacks (7) of closed cores (9) insulated from one another and secured in an insulating frame (8), having a common window and carrying the sections (10) of a secondary winding (2). A primary winding (1) comprises three flat rectangular coils (11) whose vertical parts are arranged to lie pairwise along the axis of the common window in each stack (7) of the cores (9). A bridge rectifier section comprises individual bridge rectifiers connected to the sections (10) of the secondary winding (2), and each of the potential screens is formed by ring sections (6 and 20) arranged one on top of another along the stacks (7) of the cores (9).

Abstract: An apparatus for simultaneously firing a plurality of series-connected thyristors having a control pulse transformer for each thyristor. Each transformer has first and second primary windings, with the first windings being connected in series with each other, and the series combination being connected through an auxiliary thyristor to a capacitor which is charged from a DC voltage source. The second primary windings are also connected in series with each other with the series combination being connected to a DC source through a transistor switch means. In half of the transformers the two primary windings have the same polarities, while in the other half they have opposite polarities. To fire the thyristors, the auxiliary thyristor is caused to be fired causing the transformers to provide a steep pulse with a high amplitude to the thyristors.

Abstract: A device and method for converting electrical energy into heat energy including a cascade connection of bidirectional thyristors, such as triacs, operated from an alternating current power supply. The thyristor are submerged in oil which is thermally conductive but electrically insulative, the oil being in initimate contact with the thyristors junctions. The heat energy at the junctions flows to the oil, from there to a heatsink (radiator), and from the radiator to the surrounding atmosphere.

Abstract: A high voltage power converter has a number of thyristors interconnected. Symmetrical voltage dividers maintain equal voltage distribution across the thyristors. Each thyristor has a plurality of inductors associated therewith for reducing rapid current increases through the thyristors during firing which might injure the components and generate radio frequency interference.

Abstract: A converter transformer for an AC-DC converter is assembled by connecting three transformer units at an installment site. In the respective transformer units, first, second and third iron core legs are received in oil tanks. On the first and second core legs are mounted series-connected first and second primary windings, respectively. On the second and third legs are mounted first and second secondary windings respectively. Coupling windings connected in parallel are mounted on the respective legs. The primary windings and the secondary windings are electromagnetically coupled.

Abstract: A gate controlling circuit for a thyristor converter having a forward/reverse bias voltage detecting circuit connected between the anode and the cathode of one of a plurality of serially connected thyristors in a thyristor arm of the converter for determining whether the thyristor is forward or reverse biased. The output of the forward/reverse bias voltage detector is utilized to control the gate control signals supplied to the thyristors in the thyristor arm.

Abstract: In a gate control circuit for a thyristor converter, in which thyristor valves each having a plurality of series thyristors are connected to form a bridge, a detector for detecting a forward voltage applied across one of the thyristors and a circuit for supplying a gate signal to the gate of that thyristor valve are provided. The gate control circuit further comprises a circuit for supplying, when a bypass pair operation of the thyristor converter is switched over to a deblock operation, a signal to the gate of a continually conductive thyristor valve according to a control signal to a thyristor valve to be operated in deblock with the continually conductive thyristor valve and also a gate signal to the continually conductive thyristor valve.

Abstract: A gate controlling circuit for a thyristor converter having an inverse bias voltage detecting circuit which detects the inverse bias voltage across a thyristor and is connected between the anode and cathode of serially connected thyristors in a thyristor valve. A gate signal to all of the thyristors is supplied when the output of the inverse bias voltage detecting circuit drops or becomes zero after all of the thyristors are turned off.

Abstract: The two secondary windings of a transformer the primary winding of which is connected to an AC power supply are each provided with a controlled rectifying circuit. The DC sides of the rectifying circuits are connected in series to supply power to DC motors. One of the secondary windings is detachably connected with a capacitor bank. The capacity of the capacitor bank is selected so that the power factor of the converter can be improved to a satisfactory value when the two rectifying circuits are both controlled to produce output voltages. The capacitor bank becomes connected in response to the fact that the current in the primary winding of a transformer has arrived at a predetermined value.

Abstract: In a high voltage rectifier for use in a television receiver set, a resistor block is incorporated therein to produce focusing and screen voltages, and a focusing voltage feeder for supplying the focusing voltage to a cathode ray tube is covered by a screen voltage feeder for supplying the screen voltage to the cathode ray tube to form a unitary high voltage insulated cable.

Abstract: In an electric power converting apparatus comprising a plurality of branches each including a plurality of serially connected semiconductor switching elements, a non-linear resistor is connected in parallel with each semiconductor switching element, and a voltage division element including serially connected capacitor and a resistor is connected in parallel with each semiconductor switching element. A reactor is connected in series with each one of the branches and an arrestor is connected in parallel with a serially connected reactor and an associated branch.

Abstract: Electrical apparatus such as a VAR generator or convertor is taught for high-voltage application. The electrical apparatus includes series stacked silicon controlled rectifiers, some of which operate at high electrical potential. Switching information is provided to the thyristors by way of insulating light pipes. The energy for actuating the gate of the thyristor in each case is provided by a current transformer which in some instances is interconnected with the anode of the thyristor in question to monitor the anode current thereof in a previous half cycle of conduction. In other instances, anode current of another thyristor are monitored. The anode current is converted to stored charge which is later released through a light actuated switch to the gate for energization of the thyristor in question. This means that a thyristor may be repeatedly energized even after many intervals of full cycle conduction where no anode to cathode potential is available for charging a capacitor.

Abstract: A coil bobbin for a fly-back transformer or the like having a bobbin proper. A plurality of partition members or flanges are formed on the bobbin proper with a slot between adjacent ones. At least first and second coil units are formed in the bobbin proper, each having several slots, formed between the flanges, and first and second high voltage coils are wound on the first and second coil units in opposite directions, respectively. A rectifying means is connected in series to the first and second coil units, and a cut-off portion or recess is provided on each of the partition members. In this case, a wire lead of the coil units passes from one slot to an adjacent slot through the cut-off portion which is formed as a delta groove, and one side of the delta groove is corresponded to the tangent direction to the winding direction.

Abstract: A multilayer-winding fly-back transformer is provided with first, second, third, fourth, fifth and outermost cylindrical bobbins made of dielectric material and arranged concentrically. A magnetic core is inserted in the first or innermost bobbin, and a primary winding is wound in layers on the outer periphery of this bobbin. The first, second, third and fourth secondary windings are wound in layers round the second, third, fourth and fifth bobbins, respectively. First, second, third and fourth diodes are connected between the first and second secondary windings, the second and third secondary windings, the third and fourth secondary windings, and between the fourth secondary winding and an output terminal, respectively. A capacitor is formed between the cathode of the fourth diode and the anode of the third diode.

Abstract: A power converter apparatus for an a.c. electric rolling stock comprising two transformers, each including a primary winding and a plurality of secondary windings generating the same output voltages but having different internal reactances; a pair of phase-controlled bridge rectifier circuits, each being connected to one secondary winding of each transformer; and diode bridge rectifier circuits connected to the other secondary windings, wherein the windings connected to the pair of phase-controlled bridge rectifier circuits have different internal reactances, and the phase-controlled bridge rectifier circuits are simultaneously controlled, and when the maximum output voltages from the phase-controlled bridge rectifier circuits are reached, the output voltages from the diode bridge rectifier circuits (non-phase-controlled) are increased to their maximum values, then the output voltages from the phase-controlled bridge rectifier circuits are decreased to their minimum values.

Abstract: A thyristor valve includes a plurality of thyristors connected in series and series circuits each including a capacitor and a resistor and connected in parallel with each thyristor. A pulse from a pulse generator for firing the thyristors is applied to them at the beginning of a prescribed period of conduction of the thyristor valve when voltage across the selected one of the thyristors is forward. An output signal of a current detector provides a firing pulse to all thyristors when the valve current exceeds a predetermined current value during the prescribed period of conduction of the thyristor valve.

Abstract: A flyback transformer comprising a magnetic core and primary and secondary windings wound around the magnetic core, the secondary winding being divided into a plurality of coil units and alternately connected in series with the same plurality of rectifying diodes, the coil units being wound around individual layer bobbins, the bobbins being assembled in layers and fitted alternately and the outermost layer bobbin being mounted with a support on which a plurality of diodes are fixed, whereby the whole flyback transformer obtains a compact structure.

Abstract: An electrical heating apparatus such as an electrically heated bedcover protected against an overheating condition by an overheat protective circuit which utilizes a pair of solid state switching devices in the heating element circuit. The solid state switching devices are so connected that should one switching device fail in a shorted or closed mode, a second switching device will be in the circuit to control the heating element and provide normal protection against an overheating condition. The solid state switching devices are employed in a manner which permits the use of relatively small light weight temperature sensors in the form of positive temperature coefficient devices such as PTC resistors, which avoids the need for using relatively bulky bimetallic thermostatic switches as are conventionally employed for sensing overheating conditions.

Abstract: A power converter is disclosed which is used for converting an a.c. power to a d.c. power or vice versa, and which comprises a first converter unit operated at a variable control angle with phase advanced to an input a.c. source voltage, and a second converter unit operated at a variable control angle with phase lagged to the input a.c. source voltage and having a d.c. side terminal connected in series to that of the first converter unit. At least one additional converter unit having a d.c. side terminal connected in seriesto those of the first and second converter units is further provided in accordance with the invention. The additional converter unit is operated at its bypass mode or a fixed control angle corresponding to the maximum forward or reverse conversion limit. The power converter of the above-mentioned construction enables its output level to be controlled continuously over a wider range without degrading its electric property than the conventional power converter.

Abstract: A voltage multiplier of the Cockroft-Walton type in which the ac-- and dc-- operated capacitors are arranged in respective separate capacitor winding rolls, the two rolls being arranged side by side on a common axis and the diodes being arranged between the two rolls.

Abstract: A power converter control system for use with a power converter of the type which comprises a plurality of cascade-connected converter units of which at least one converter unit is subjected to continuous control of its conduction phase angle and the remaining converter units are subjected to on-off control of their conductivity is arranged to include a master controller for instructing the number of the converter units to be rendered operative, a reversible counter operative to change its content in response to a phase controlling command applied to the continuously controlled converter unit indicating a maximum or minimum conduction phase angle or delayed phase angle in conduction, a unit change control unit for producing unit changing operation signals to be applied to the respective converter units for controlling the operation of the same, by using one of the binary bits derived from the counter without modification and decoding the remaining bits, and a comparing and identifying circuit which compares t

Abstract: A voltage regulator for providing a predetermined output voltage from an unregulated voltage input is described where the output voltage is compared with a reference voltage to generate one or more control signals which in turn activate boost regulators which inject voltage onto the output. Each boost regulator utilizes a transformer for injecting the voltage onto the output and a bypass diode across the transformer to permit the input voltage less the diode voltage drop to appear at the output when the boost regulator is not activated.

Abstract: This invention is applied to a power converter with a converting apparatus comprising one or more units including only controlled rectifiers or combination of controlled rectifiers and non-controlled rectifiers, said converting apparatus being connected with an AC power source, whereby high harmonic currents generated in the AC circuit during commutating periods are reduced.In the present invention, at the commutating period of the converting apparatus, the reactance in the AC circuit of the converter is changed to increase in accordance with change of the AC current of the converting apparatus, so that the change of the AC current during the commutating period is made more slowly thereby reducing high harmonic currents.

Abstract: A gate controlling apparatus for a thyristor valve including a plurality of series connected thyristors controlled by a narrow gate pulse. The apparatus includes means for judging whether the thyristor valve is to be in the conductive state or not, means for detecting a forward voltage across at least one of the thyristors in the thyristor valve, and an AND circuit for generating an output at a time when an AND condition between the respective outputs of the judging means and the forward voltage detector means is satisfied. The apparatus further includes means for detecting a period of inverse voltage across at least one of the thyristors in the thyristor valve. The forward and inverse voltages may be, respectively, detected by detecting the forward and inverse voltages of specified thyristors.

Abstract: In a fly-back transformer, the tertiary winding for obtaining the secondary B power source is wound in a position where the coupling with the primary winding is weak and where it interlinks the leakage flux of the secondary winding with the primary winding, and the output of the tertiary winding is rectified during the scanning period of a horizontal deflection circuit of a television receiver. Accordingly, only the wave crest value of the ringing is made smaller, regardless of the shot pulse to be obtained within the secondary winding.