Showing papers on "Precision rectifier published in 1971"

Temperature control circuit employing a variable resistance heating element

Abstract: The present circuit employs a heating element whose electrical resistance varies in response to the heat generated thereby. The heating element comprises one leg of a bridge circuit and the output signal from the bridge circuit is connected to fire a silicon-controlled rectifier. The silicon-controlled rectifier is connected to short out a leg of the bridge circuit which is serially connected to the heating element thereby providing full power for energizing the heating element when the siliconcontrolled rectifier is turned on and simply providing control current to the heating element when the silicon-controlled rectifier is turned off.

Regenerative pcm line repeater

Abstract: The line repeater operating on bipolar PCM signals includes substantially identical circuits for both directions of communication to provide line equalization, clock extraction, and pulse regeneration and retiming. A differential input, differential output operational amplifier has a line compensating network in a feedback path thereof. A peak detector coupled to both outputs of the operational amplifier and an amplitude comparator coupled to the output of the peak detector and a reference voltage produces a control signal to control the line compensating network and thereby compensate for line distortion of the received PCM signals and provide constant amplitude received PCM signals on both outputs of the operational amplifier. The clock extractor includes an average full wave rectifier coupled to both outputs of the operational amplifier, a tank circuit coupled to the output of the average rectifier and a 90* phase shifter and amplitude limiter to produce first square wave timing pulses prederminedly related to the bit rate and the zero crossings of the received PCM signals. The first timing signal has its negative going transistions differentiated and inverted to produce second timing pulses. The pulse regenerator includes a threshold voltage and two decision circuits coupled thereto and to the outputs of the operational amplifier, a different decision circuit being provided for each polarity of the received PCM signal. A different AND gate is coupled to the output of each of the decision circuits and are enabled by the second timing pulses. A different RS flip flop is coupled to the output of each of the AND gates and are reset by the positive going transistions of the second timing pulses. The output of the two RS flip flops are combined to provide regenerated bipolar PCM signals for transmission to the next line repeater. A direct current voltage coupled over the transmission line and a zener diode arrangement provides +V and -V power supply voltages at the repeater. A voltage of + OR - V volts is used in the operation amplifier of both directions of communication, a voltage of +V volts is used in the remainder of the circuits of one direction of communication and a voltage of -V volts is used in the remainder of the circuits of the other direction of communication.

Cycloconverter with rectifier bank control for smooth switching between rectifier banks

Abstract: The invention relates to a cycloconverter of the type utilizing phase controlled rectifier banks for generating a constant output frequency signal from a variable frequency input signal. Switchover from the positive to the negative phase controlled .rectifier. banks is controlled to minimize distortion of the output signal, while yet at the same time, protecting the system against circulating currents between the rectifier banks. The zero crossover point of the converter output current is sensed and utilized to change the programmed output level of the rectifier banks SOl that there is smooth transition from one bank to the other even though the output levels of the two rectifier banks are normally programmed for· different output levels to reduce or eliminate any circulating current between the rectifier banks. A further aspect of this invention lies in the manner in which the zero crossover of the converter current is sensed to minimize errors due to wave form distortion in the converter current. The converter current zero crossover is sensed indirectly by reconstructing the converter current from the load voltage and the load current and sensing the zero crossover of the reconstructed wave.

Zero-crossing silicon controlled rectifier control system

Abstract: A zero-crossing silicon controlled rectifier control system for single-phase, full-wave and three-phase operation. An error signal representing the difference between desired and actual load values in integrated to control a first switch constituted by complementary transistors. A second switch, in series with a pulse generator and the first switch, is conductive during portions of alternate half cycles. Concurrent conduction by both switches energizes the pulse generator which causes a pulse to be generated on the energization. This turns on a first silicon controlled rectifier at the beginning with the positive-going zero crossing. A second silicon controlled rectifier controlled by a trigger circuit conducts during the next half cycle in response to load energization.

Safety device monitoring system

Abstract: For use in monitoring a safety device switch through which alternating current flows, monitoring means comprising a rectifier connected across such a switch to provide a direct current output when the switch is opened, a light and a capacitor connected in series across the output of the rectifier, a signal light, and a light-actuated silicon controlled rectifier. The silicon controlled rectifier is positioned and arranged to be actuated or rendered conductive by light from the light which is in series with the capacitor. When the safety device switch is opened, direct current provided by the rectifier charges the capacitor to a predetermined level. During this charging process, the light in series with the capacitor produces light for actuating the silicon controlled rectifier. The power source for the signal light and the silicon controlled rectifier may be a separate, low voltage direct current power source completely separate from the power source producing the current flowing through the safety device switch.

Static converter station for high voltage

Abstract: A converter station for high voltage is formed of a plurality of static converters with a direct current side directed in series Each converter is a full-wave rectifier bridge provided with a control device An additional control device is provided with a reserve control for one of the converters, which controls two series-connected rectifier groups of the bridge with different delay angles, one greater and the other less than 90* As a result the two series rectifiers in one phase of the bridge conduct simultaneously and current is commutated at a certain frequency from the rectifier in one phase of the rectifier bridge to the rectifier in a subsequent phase of the bridge

Laser energy monitor circuit

Abstract: A laser energy monitor circuit. A fixed fraction of the energy output of a laser is diffused and then directed to a photodiode, and the diode output current is integrated. The integrated signal is transferred to a peak detector which, in turn, drives an FET transistor. The output of the transistor, which may persist for many minutes even in the case of a nanosecond laser pulse, drives a meter and thus provides an extended visual indication of the energy in the pulse.

Ac to dc rectifier circuit with rapid turn-off in case of overcurrent through the load circuit

Abstract: A plurality of main rectifiers are connected to a transformer secondary with one terminal, the other terminal being connected to the load circuit. A sensing circuit is provided to detect over-current conditions. A rapid turn-off circuit is connected to provide reverse current to the rectifier elements, the rapid turn-off circuit being triggered by the sensing circuit and having a series connected control switch, typically a thyristor (SCR), an energy storage device (typically a condenser) and a pair of connections, one of which preferably includes a diode, and connects back to the load terminal of the main rectifier, the other connection, preferably including a smoothing choke, being connected back to the transformer, so that, when the thyristor is triggered, reverse current will be applied to the rectifier and, additionally, the thyristor will be held conductive by current through the transformer and the thyristor connection to the rectifiers.

Under-voltage protection device

Abstract: An under-voltage protection device including an AC source connected across a load; a series combination of a line switch and a control rectifier connected between the AC source and the load; and a series combination of a rectifier and voltage divider connected across the AC source; wherein the control electrode of the control rectifier is connected to an adjustable terminal of the voltage divider

Cycloconverter silicon controlled rectifier gate-cathode circuit signal and power system

Abstract: A system for producing properly timed gate signals and gate-cathode power for the silicon controlled rectifiers of a cycloconverter network, through which the phase windings of a three-phase alternating current motor are cyclically energized from an alternating current supply potential alternator, having two groups of three silicon controlled rectifiers for each motor phase winding. The properly timed gate signals are produced by a rotor position sensor including six circumferentially arranged phototransistors, each of which corresponds to a group of cycloconverter silicon controlled rectifiers, an axially aligned and spaced light-emitting diode corresponding to each phototransistor, a shutter disposed therebetween and rotated by the motor rotor of a configuration such that pairs of phototransistors are alternately exposed to and masked from the corresponding light-emitting diodes and three gate signal light-emitting diodes connected in series with each phototransistor across a direct current potential source. When any pair of phototransistors is exposed to the corresponding light-emitting diodes, a circuit is completed for the three gate signal light-emitting diodes in series with each. Each gate signal light-emitting diode produces a gate signal for a respective silicon controlled rectifier of the group to which the phototransistor with which it is connected in series corresponds. The gate-cathode circuit of each cycloconverter silicon controlled rectifier of each group is transformer coupled to a different phase output winding of a gate power three-phase alternating current alternator, mechanically coupled to and operated by the alternating current supply potential alternator, which produces a gate-cathode power potential which leads the alternating current supply potential alternator potential by a selected electrical angle. Included in each cycloconverter silicon controlled rectifier gate-cathode circuit are a light actuated silicon controlled rectifier, optically coupled to a corresponding gate signal light-emitting diode, and a gate-cathode circuit silicon controlled rectifier which are triggered conductive, respectively, by the light emitted by the corresponding gate signal light-emitting diode and the output signal of a zero crossover switch in the same gate-cathode circuit to complete the gate-cathode circuit for the corresponding cycloconverter silicon controlled rectifier.

Frequency independent peak detector

Abstract: A frequency independent peak detector includes a circuit for differentiating the signal whose peak is to be detected, with the output of the differentiating circuit being applied to a high gain amplifier whose output is either in a high or low state, depending on what state the differentiated signal is in. The differentiating circuit is comprised of a capacitor and a diode operating as a resistance which varies inversely proportional to frequency by virtue of the fact it is biased to operate in the exponential region of its volt-ampere characteristic. This compensates for the change in capacitor reactance as the input signal frequency varies to maintain the frequency-RC time constant product of the circuit relatively constant.

Voltage control apparatus for an alternating current generator

Abstract: A voltage control apparatus for an alternating current generator comprising an alternating current generator which is self-excited, an electric motor for driving the generator, a control rectifier arrangement for exciting the field winding of the generator by rectifying the output voltage of the generator, a phase shifter for controlling the control rectifier, a saturable reactor excited by the output of the generator, a rectifier for rectifying the current flowing through the reactor to supply a control input for the phase shifter, and a resistor connected across the alternating current terminals of the rectifier to bypass the current of the reactor.

Automatic gain control circuit

Abstract: An automatic gain control circuit is provided with fast attack and slow release by the use of a capacitor of only 0.01 microfarads and a slow discharge path through the base-emitter circuits of Darlington-connected transistors. The capacitor is charged through a peak detector transistor circuit that also sets the d.c. reference (no signal) level for the control voltage. A low-level cut-off control circuit is similarly provided with a fast attack and slow release.

Scr phase control system

Abstract: A silicon controlled rectifier phase control system While a load-controlling silicon controlled rectifier is reversed biased, a capacitive circuit is charged and then discharges for a time including the succeeding half cycle when the silicon controlled rectifier is forward biased to generate a reference voltage This reference voltage is compared with a control voltage to cause the load-controlling silicon controlled rectifier to be turned on at an appropriate time Controls for single phase, half- and full-wave control and three-phase systems are illustrated Modifications to assure operation with overriding input signals and feedback circuit means to improve linearity and line voltage compensation are described

Diode monitoring systems

Abstract: An apparatus for monitoring a rectifier leg which forms a part of a system that is being supplied with electrical power from an external circuit. The rectifier leg has at least first and second series connected rectifier cells. The monitor apparatus includes a source of control power for supplying electrical power to the monitor apparatus as well as to the rectifier leg. The monitor apparatus provides an indication of open and short circuit failure of the rectifier cells while they are in use in the system and being supplied with electrical power from the external circuit or while they are being supplied with electrical power solely by external circuit or while they are being supplied with electrical power solely by the source of control power of the monitor apparatus.

Electronic device for controlling a silicon controlled rectifier in a capacitor discharge electronic ignition circuit

Abstract: A silicon controlled rectifier controls a capacitor discharge into an electronic ignition circuit for internal-combustion engines. Spurious signals are prevented from operating the controlled rectifier.

Shut-off arrangement for power controlled rectifiers in a dc to ac inverter

Abstract: An AC induction motor is supplied excitation current from a source of direct voltage through a three-phase inverter. Each of the power controlled rectifiers of the inverter is shut off by applying the voltage of a shut-off capacitor through a respective shut-off controlled rectifier to the series combination of the source of direct voltage and the power controlled rectifier selected to be shut off. Accordingly, at the time of commutation, the voltage of the shut-off capacitor opposes the source voltage and provides reverse bias for the selected power controlled rectifier terminating conduction therethrough. Current continuity is maintained for the induction motor during shut-off intervals since the shut-off capacitor and the shut-off controlled rectifier provide a current path for the motor windings. In addition to providing current continuity during commutation, the shut-off circuit provides a path through which magnetic field energy stored in the motor windings is extracted and transferred to the shut-off capacitor.

D-c voltage control with adjustable pulse width and repetition rate

Abstract: A d-c voltage control circuit provides a controlled rectifier in series with a motor and battery and provides gating pulses to fire the controlled rectifier at an adjustable pulse repetition rate. A turn-off circuit for turning off the controlled rectifier is adjustable independently of the pulse repetition rate adjustment to adjust the length of time the controlled rectifier conducts after firing.

Reverse current protective means for rectifier output circuits

Abstract: A direct current circuit including a pair of ground electrodes and an electrolytically conductive earth formation therebetween is normally fixedly connected to the high voltage direct current output terminals of a power rectifier. The unidirectional voltage supplied to the terminals through the power rectifier is variable and the power rectifier may be disconnected by control means in its alternating current input circuit. A bias voltage of normal polarity and predetermined low magnitude is supplied to the output terminals by a low voltage battery and blocking rectifier in series circuit relation connected directly across the terminals in opposing relation to the voltage supplied through the power rectifier. Battery charge is maintained through a current limiting impedance of high resistance connected across the blocking rectifier.

Stabilized power supply systems

Abstract: A D.C. power supply employs shunt stabilization of the output of a full-wave rectifier for an A.C. source. The A.C. source is a low-loss, high impedance type and a shunt stabilizer can be connected across the source output and/or the rectifier output.

Electronic flashlight units

Abstract: In an electronic flashlight unit, a controlled semiconductor rectifier is ignited simultaneously with the ignition of flash tube and power from a first capacitor flows therethrough. A voltage of one polarity thereby appears across the rectifier. The discharge causes a voltage drop across a resistor and that voltage drop is used to charge an integrating capacitor in correspondence with the integral of the flash light flux as detected by a photoresistor. At a predetermined integral value a switching action applies the voltage of a quenching capacitor across the rectifier in a manner such that the polarity is opposite to said one polarity. The rectifier is thereby turned off to ensure that the flash tube is quenched. In one embodiment two semiconductor rectifiers each connected in series to a reactor are provided in the flash discharge circuit and a second pair similarly connected in the quenching circuit to enable the use of inexpensive low-power semiconductor rectifiers protected from overloading.

Apparatus for controlling the operating potential of a vidicon

Abstract: The video signal derived from a vidicon target electrode, after preamplification, is applied to the control gate input electrode of a field effect transistor where it is clamped by a pair of diodes and where combined horizontal and vertical blanking pulses are added to it by another diode at the transistor drain electrode and a pedestal component derived from a pedestal control circuit is added at the transistor source electrode to produce a clamped composite signal. The composite signal is clipped at a fixed level by a series diode coupled between the drain electrode of the field effect transistor and the base electrode of an emitter follower transistor, the emitter electrode being coupled to an output amplifier and to the input transistor of a peak detector including a diode and a second field effect transistor, the source output electrode of which is coupled to a transistor which supplies the operating potential for the vidicon target electrode through a coupling circuit comprising a capacitor and having a first branch including a relatively small value resistor and a diode which is forward biased for operating potential decreases, thereby forming with the capacitor a short time constant, fast reacting circuit; the coupling circuit having a second branch including a relatively large value resistor which forms with the capacitor a long time constant, slow recovery circuit for operating potential increases which reverse bias the diode. The vidicon target electrode operating potential also is applied to the input gate electrode of a third field effect transistor having an output source electrode which is coupled to the pedestal control circuit.

Voltage multiplying rectifier device

Abstract: A voltage multiplying rectifier device for use as a high voltage power supply for a cathode-ray tube in a television receiver in which silicon rectifier elements are used for rectifying the high voltage.

High arrangement frequency scr gating

Abstract: A semiconductor controlled rectifier being particularly suited for high power, high frequency applications is disclosed. The rectifier includes at least two gates which are spaced from each other. One gate is triggered with positive signals to initiate current conduction through the rectifier for one cycle of operation and the other gate is triggered with negative pulses to initiate the immediately succeeding cycle of operation.

Parallel connected controlled rectifier switching circuit

Abstract: A switching system is constructed using a plurality of modules. Each module controls the power to a separate load and includes a capacitor, a silicon controlled rectifier, and a switch. In each module the gate of each of the controlled rectifiers is connected, through a switch, to a common lead line which line is also connected to one side of the capacitor.

Analog storage arrangement using transfluxor

Abstract: A rectifier is connected to transfluxor output winding. A first feedback circuit is connected between rectifier output and setting winding, a second feedback circuit between rectifier output and blocking winding. The first and second feedback circuits have first and second three-stage amplifier respectively. The operating voltage for one stage of first or second three-stage amplifier applied selectively to produce increase or decrease of stored analog value respectively.

Static on delay circuit with improved holding means

Abstract: A two-terminal transformerless switching circuit adapted to be connected between a load, such as a relay coil, and a source of alternating current. When the switching circuit is energized by connecting it to the source of alternating current through an actuating means, such as a pushbutton switch, energization of the load is delayed by a timing and triggering circuit, the output of which is connected to the gate of a silicon controlled rectifier. The silicon controlled rectifier is connected across the output terminals of a full wave bridge rectifier in such a manner that when it is energized, alternating current will flow into the bridge and through the coil of the relay in sufficient magnitude to energize the relay and complete the switching operation. The complete switching action is delayed for a period of time determined by the charging of a capacitor through a variable resistor network. In addition, a diode array is connected in parallel with an energy storage capacitor so that the capacitor charges to a voltage generally equal to the maximum possible voltage drop across a conducting diode array. When the full wave rectified pulses of current which are applied to the silicon controlled rectifier approach zero the diode array is reverse biased and the capacitor discharges through the then marginally conducting silicon controlled rectifier to sustain conduction in it until sufficient energy from the next half wave of current flows through the silicon controlled rectifier or thyristor. Both the timing and triggering circuits and the holding circuit are initially empowered from the output terminals of the full wave bridge rectifier upon actuation of the timing cycle by closing the previously mentioned pushbutton switch, for example. The amount of current necessary to initially empower these circuits being insufficient to actuate the connected load coil.

Apparatus for control of the rotary rectifier of a synchronous machine

Abstract: An apparatus for controlling rotary rectifiers of a synchronous machine, which has an exciter in the form of a polyphase a.c. generator based on semiconductor devices and designed to supply the field winding of the machine via the rectifiers. The apparatus ensures contactless generation of peak-shaped e.m.f. pulses in the control circuits of the semiconductor devices of the rectifier, distributed in time and number according to the number of phases and semiconductor devices of the rectifier and having the required slope, on/off time ratio and controlled phase of each pulse with respect to the supply voltage of the corresponding phase of the rectifier. The apparatus is designed as a polyphase pulse generator having a stator with non-salient poles and distributed field windings which are electrically perpendicular to one another, and a rotor with teeth whose heads have a maximum cross-sectional area and roots have a minimum cross-sectional area, with windings provided thereon and connected to the control circuits of the semiconductor devices of the rectifier.

Single silicon-controlled rectifier reversible drive motor control†

Abstract: A simple adjustable speed reversible drive d.c. motor control system is described. For the purpose of control only one silicon-controlled rectifier is used in conjunction with a single reactor reversible output magnetic amplifier firing circuit. For reliability and long life magnetic amplifier's are incorporated for amplification of the error signal. Reversal of rotation is done by a differential potentiometer and the speed is adjusted to any value from about 10% to rated value by a simple potentiometer. The speed is observed to remain within 2% irrespective of load and line voltage fluctuation

Protection means for rectifiers upon the occurence of undesired discharge currents

Abstract: For protecting a rectifier unit including a control pulse amplifier composed of a monostable multivibrator and an OR-gate, the gate being controlled by control pulses to cause the amplifier to transmit a signal to the control electrode to render it conducting, a transformer in the conductor for the rectifier is provided which makes the control pulse amplifier operative to emit a control signal in response to a flow of current in the conductor produced by an external flashover occurring when the rectifier is not conducting.