Showing papers on "Precision rectifier published in 1974"

Inverter fault protection and frequency limiting circuit

Abstract: An inverter fault protection and frequency limiting circuit for inverters having controlled rectifier and antiparallel diode pairs is described for preventing short circuits of the inverter power supply and for limiting the operating frequency of the inverter. An inhibit circuit is responsive to controlled rectifier forward blocking voltages and antiparallel diode currents to generate a gate inhibit signal for one of the seriescoupled controlled rectifiers when the other one of the controlled rectifiers is not forward blocking or if the time duration of the current through the antiparallel diode thereof is less than a specified controlled rectifier turn-off time. A frequency limiting circuit is responsive to the gate inhibit signal for limiting the maximum operating frequency of the inverter.

Current-supply arrangement for an electronic remote control receiver

Abstract: A current supply arrangement for an electronic remote control receiver, wherein a series circuit comprising a protective impedance, a capacitor and a full-wave rectifier is connected between two input terminals intended for connection to an alternating current network, a voltage limiter is operatively associated with the full-wave rectifier.

Circuit for supplying a dc load from an ac source through a rectifier

Abstract: An improvement A.C. a circuit for supplying a D.C. load from an A.C. source through an uncontrolled rectifier with a control element arranged between the output of the rectifier and D.C. load using a control unit synchronized with the A.D. source to keep the power factor at a predetermined value and the circuit including a capacitor associated with the DC control element and a by-pass diode bridged across the DC load in which, in order to suppress harmonics to the greatest degree possible, the DC load is bridged by two by-pass diodes connected in series in the same direction and the capacitor associated with the DC control element is connected between one input terminal and the center connection point of the two by-pass diodes. In a second variation, the same result is achieved with the capacitor and a first decoupling diode connected in series between the input terminals of the DC control element with one electrode of the capacitor connected with one input terminal of the DC control element and the other electrode of the capacitor through a second decoupling diode to an output terminal of the DC control element.

Dc arc welding apparatus by high-frequency pulse current

Abstract: A DC arc welding apparatus using a high-frequency pulse current is disclosed and includes a rectifier bridge for commutating AC voltage and for applying DC voltage having a substantially smooth waveform to a circuit including an electrode and a workpiece for welding. A first switch is connected between an arc load formed between the electrode and the workpiece and a positive output side of the rectifier bridge. A second switch is connected between the arc load and a negative output side of the rectifier bridge. A capacitor has one end connected to a contact of the rectifier bridge and the first switch and another end connected to a contact of the rectifier bridge and the second switch. First and second rectifiers are connected so as to charge energy accumulated in the inductance of the circuit including the electrode and the workpiece during the off state of the first and second switches to the capacitor so that the current passed through the arc load is controlled by an on-off control of the first and second switches.

Leakage and continuity tester

Abstract: A leakage and continuity test unit for checking the ground impedance and leakage current in a medical instrument to ensure that the medical instrument is properly grounded and does not conduct an excessive amount of leakage current through the chassis. The unit includes a test probe which is interconnected with the equipment under test, the unit including a continuity circuit having a comparator which compares a fixed voltage with a voltage representative of the impedance to ground of the equipment under test. The output of the comparator is fed to a flip flop circuit which, when an excessive amount of ground impedance exists, drives a warning lamp circuit. If the impedance is below certain set limits, the flip flop will drive a lamp which indicates that the ground of the equipment under test is proper. The unit also includes a leakage detector circuit which includes an upper and lower limit control circuit which establishes different standards for the equipment under test depending on whether the equipment is to be used in critical service or general service areas within the hospital. The leakage signal is fed through a precision rectifier which in turn feeds the signal to a dual input comparator which dual input comparator is capable of testing either a positive or negative signal. The output of the comparator is fed to a flip flop circuit which drives a set of lamps, one of which warns the user that an excess of leakage current exists and the other of which indicates to the user that the leakage current is within the limit set by the gain control circuit.

Variable frequency power converter for ac motor drive

Abstract: In a variable frequency power converter of a current type for driving an AC motor including a rectifier, an inverter, and a smoothing reactor disposed on a DC transmission line between the rectifier and the inverter, there are provided a series circuit having a switching circuit and a smoothing capacitor on the DC input side of the inverter and a feedback circuit having controlled rectifier elements and commutation reactors for feeding back the reactive power of the AC motor. The power converter operates as a current type converter until the output frequency of the converter reaches a predetermined value under the condition that the switching circuit and the controlled rectifier elements are non-conductive, and operates as a voltage type converter when the output frequency has reached the predetermined value under the condition that the switching circuit and the controlled rectifier elements are conductive.

Polyphase rectifier system for providing two output current-voltage ranges

Abstract: A polyphase rectifier system which provides two output current-voltage ranges upon the system direct current output circuitry. Each phase of a polyphase potential source is rectified by a respective rectifier circuit having the alternating current input circuit thereof electrically connected to the output electrical coil of the corresponding phase of the polyphase potential source and the direct current output circuit thereof connected in parallel with the direct current output circuit of all of the other rectifier circuits. An electrical switching means operable to the electrical circuit open and closed conditions is provided for electrically interconnecting one terminal end of all of the output electrical coils of the polyphase potential source when operated to the electrical circuit closed condition.

Self powering temperature compensated rectifier for measuring current

Abstract: The current measuring device provides for measuring the power in radio frequency waves without requiring any source of power for the measuring device except the radio waves themselves, and the device includes a rectifier to change alternating current to direct current by a solid state diode, but a solid state diode has an offset voltage of approximately 0.4 volt and to provide compensation for this offset a second diode is used in opposed relation to the first diode and the second diode is powered from the source of alternating current by a third diode so the resulting voltage from the device is linear and the extrapolation of the linearity passes through the origin of the graph thereby providing for measuring currents with extreme accuracy over a large temperature range without requiring an additional source of power and without requiring thermisters or bolometers. The output of the circuit can be directly applied to an analog/digital converter (A/D converter) to obtain a digital reading of the analog of the circuit.

Control system for brushless motor

Abstract: A control system for a brushless motor is disclosed which comprises an AC power supply, a rectifier circuit including controlled rectifier elements for converting the alternating current supplied by the AC power supply into a direct current, an inverter circuit including controlled rectifier elements for converting the direct current produced by the rectifier circuit into an alternating current, a motor driven by the inverter circuit and a position detector for detecting a signal representing rotational positions of the motor. The controlled rectifier elements of the inverter circuit are fired in predetermined sequence in response to detection signals from the position detector, while the DC output current of the rectifier is continually controlled at each commutation of the inverter circuit at low motor speeds. A predetermined number of signals in synchronism with each commutation of the inverter circuit are included in one cycle, so that the DC output current of the rectifier circuit is controlled for continual operation by the use of signals with different delay times behind the aforementioned signals concurrent with the commutation of the inverter.

Linear ECL distance measuring gauge

Abstract: A linear eddy current loss (ECL) proximity distance measuring gauge comprising an ECL oscillator and a linearizing DC feedback circuit is disclosed. As the distance between a magnetic target and the ECL coil increases and changes the impedance of the ECL tuned circuit, the linearizing DC feedback circuit shunts current away from the tuned circuit and controls the rate at which oscillation amplitude varies with a change in target distance. The amplitude control created by the linearizing DC feedback circuit results in oscillation amplitude being linearly related to the distance between the target and the ECL coil. A peak detector circuit detects oscillation amplitude and applies a directly related DC voltage to a buffering emitter follower output circuit. Thus, output voltage is linearly related to target distance.

System for monitoring and indicating peak values of a time varying signal

Abstract: This invention relates to a system for monitoring and indicating peak values of an audio signal. The system is especially useful in replacing the standard VU-meter presently used on the audio mixing and recording consoles of movie and television editor desks. The VU-meter has the disadvantage of monitoring and displaying average values. The inventive system monitors and displays peak audio values. The system consists of a balanced input amplifier for receiving and amplifying the monitored signals. The amplified signals are fed to a rectifier circuit which supplies a rectified output of the signal, and the rectified signal is fed to a peak detector means which retains the peaks of the rectified signal. The output of the peak detector means is fed to a comparator which compares the peak values with reference sources, and the output of the comparator drives a display means. Preferably, the display means includes a first numerical display for indicating the highest peak value attained in a series of observations, as well as a moving dot display for indicating ongoing peak values in the series.

Circuit arrangement for combined regenerative and resistive braking operation for a d-c series machine operated as a generator

Abstract: A circuit arrangement which provides for combined regenerative and resistive breaking operation in a D-C series machine which is operated as a generator in which a D-C control element having a main controlled rectifier and associated quenching capacitor are connected in parallel with the motor and wherein there is provided a return diode, a braking resistor and a controlled braking rectifier. In addition, an overflow diode is provided to bypass the return diode and field winding of the machine. The requirement for a separate extinguishing circuit for the breaking rectifier is avoided by providing an auxiliary rectifier which is fired at the same time as the main controlled rectifier and provides therethrough an extinguishing current from the quenching capacitor of the main controlled rectifier to extinguish the controlled braking rectifier.

Controllable and quenchable rectifier circuit for high direct current values

Abstract: A controllable and quenchable rectifier circuit for high d.c. current values, which is fed from an alternating or three-phase current main and includes a plurality of controllable rectifier elements each having associated therewith quenching devices to reduce feedback to the main. A plurality of like controllable and quenchable partial rectifier circuits are provided which are connected in parallel on the a.c. or input side in a rigid and low impedance manner and which are each connected on the d.c. or output side via impedances to two bus bars which feed a load. The current conducting controllable and quenchable rectifier elements of the rectifier circuits are quenched in a stepped sequence.

Solid state touch operated switch

Abstract: A solid state touch operated electrical switch using a low voltage source of AC power supplied to a load and comprising a silicon controlled rectifier, connected at its anode to the output of the load, with a touch plate connected to the gate of the silicon controlled rectifier and the cathode of the silicon controlled rectifier at ground, whereby human contact with the plate causes current to flow across the silicon controlled rectifier thereby driving the load. A latching circuit which rectifies the low voltage AC to DC may be used so that once current flow across the silicon controlled rectifier is commenced, being initiated by touching of the plate, continued touching is not necessary.

Shunt A.C. voltage regulator with modified full-wave bridge

Abstract: A semiconductor switching device is connected in shunt with an AC voltage source to be regulated A modified full-wave bridge rectifier is connected across the voltage source by a first pair of diagonally opposite nodes A control circuit including a capacitor is connected across the output between a second pair of diagonally opposite nodes of the bridge rectifier to control a gate electrode of the switching device to control the triggering of the switching device in response to the voltage across the bridge rectifier output The triggering of the switching device regulates the voltage supplied by the voltage source The bridge rectifier includes an impedance network comprising first and second resistors branching from one of the nodes of the second diagonal pair, each resistor being connected via a diode to a different node of the first diagonal pair The impedance network also includes a third resistor coupled between the junction of the first resistor and corresponding diode and the junction of the second resistor and corresponding diode

Bridge rectifier circuits using transistors as rectifying elements

Abstract: Two full-wave bridge rectifier circuits embodying the invention are disclosed. In each rectifier circuit four transistors and four sets of transformer windings for controlling base current are connected in a bridge configuration. Each transistor is connected in an inverted mode so that voltage blocking is performed by its collector-base junction. High efficiency is achieved by controlling the base current of each transistor in response to the emitter current thereof so that the base current is proportional to the emitter current so as to minimize circuit losses.

AM/FM radio receiver

Abstract: An AM/FM radio receiver has an FM input circuit and an FM amplifier connected to a rectifier circuit and has an AM input circuit and an AM intermediate frequency amplifier also connected to the same rectifier circuit. Either AM intermediate frequency signals or FM intermediate freuqency signals actuate the rectifier to produce a direct current signal, and the rectifier is connected to a tuning indicator so that the direct current signal actuates the indicator to identify correct tuning of either the AM input circuit or the FM input circuit. The rectifier is also connected to another circuit to control an automatic mono-stereo switching circuit in the FM portion of the receiver to allow stereo operation if the incoming signal has a sufficiently high amplitude. The signal from the rectifier is also connected to a muting circuit to mute the output of the FM section of the receiver in the absence of any FM signals. The output of the rectifier is also connected to a gain control circuit in the AM intermediate frequency amplifier to provide automatic gain control of the AM section of the receiver.

Capacitor test apparatus and method

Abstract: A method and apparatus for the high-speed testing of capacitors. A computing amplifier is connected with the capacitor under test to form an integrator which integrates a known excitation signal. The integration is initiated with no charge stored by the capacitor and at a zero crossing of the excitation signal. The integration occurs over a period which produces the maximum voltage across the capacitor. A peak detector measures the maximum voltage across the capacitor to produce a peak detection voltage inversely proportional to the value of the capacitor and directly proportional to a predetermined nominal value of the capacitor. The reciprocal of the output from the peak detector is formed to provide a measurement directly proportional to the capacitor value and inversely proportional to the nominal value of the capacitor.

Differential current protective device

Abstract: A differential current protective device comprising a responsive unit, current transformers feeding a polyphase bridge rectifier, a single-phase bridge rectifier connected to the secondary of a differential transformer, a circuit including two resistors connected across the responsive unit, one of said resistors being connected to the single-phase bridge rectifier pole terminals and the other to the polyphase bridge rectifier pole terminals, and a single half-bridge. The device is distinguished from the prior art in that the single half-bridge is connected in a parallel opposed relationship to the polyphase bridge rectifier via a resistor of equal resistance in each arm.

Start-up control for DC motors

Abstract: Start-up power control of a full wave rectifier supply to a DC permanent magnet motor is provided by an SCR full wave rectifier bridge and a start-up control circuit for the SCR's comprising an independent rectifier for charging up a capacitor through a high impedance path to produce a start-up ramp voltage, a UJT relaxation oscillator powered by the independent rectifier bridge to trigger the SCR's through a transformer, and a series transistor control circuit for the UJT responsive to the ramp voltage to advance the firing angle of th UJT and thereby advance the firing angle of the SCR's as the ramp voltage increases fron 0 to a maximum.

Cycloconverter controlled rectifier protection circuit

Abstract: In a cycloconverter system, a circuit for maintaining the gate drive signal on the gate of each controlled rectifier when the gate drive command for the controlled rectifier terminates prior to the time when the controlled rectifier would normally become conductive Voltages across the controlled rectifier are monitored by voltage sensors Logic circuits are provided which are responsive to the outputs of the voltage sensors and the presence of gate drive commands for maintaining a gate drive signal on the gate of a controlled rectifier when the gate drive command for the controlled rectifier terminates after the controlled rectifier reverse blocks and until it becomes conductive

Low voltage supply circuit for solid-state t.v. receiver, with feedback inhibitor

Abstract: To prevent feedback of inductive peaks in low-voltage supply circuits of solid-state television receivers, in which a low-voltage supply circuit is energized during the retrace interval from the line deflection circuit, and in which the line deflection circuit includes controlled rectifiers, which controlled rectifiers might be triggered spuriously by such feedback peaks, an inhibiting circuit is connected to the rectifier circuit of the low-voltage supply, which is fed from an inductance, to suppress feedback through the inductance upon sudden drawing of current by the supply circuit; this inhibit circuit may be an inductance connected in series with the rectifier of the low-voltage supply, or an additional source of direct current which pre-charges the smoothing capacitor of the rectifier circuit; such low voltage d-c can be obtained, for example, from the filament transformer for the cathode ray tube, with a half-wave rectifier, the voltage being delivered to the low-voltage supply being less than that normally required by the low-voltage supply so that, when the low-voltage supply draws current, the half-wave rectifier will block and prevent power from being fed from the supply into the power transformer.

Triggering means for silicon controlled rectifier circuit

Abstract: The circuit for controlling the power supplied to a load from an alternating source in which a silicon control rectifier is connected in series with the source and the load. The particular silicon control rectifier used is one in which the impedance between the cathode and the gate is sufficiently high so that a simple RC firing circuit can be connected to the gate and the capacitor charged periodically to a value sufficient to effect conduction of the SCR.

Circuit for determining a measure value of a rectified a-c voltage

Abstract: A circuit for determining a measured value of a rectified a-c voltage of the type having at least one compensation diode for compensating the diode threshold values in the rectifier and which is connected in series therewith, in which the diode is connected in series with the same polarity as the rectifier diodes, a compensation resistor shunted by a voltage divider is connected in series with the compensation diode and an operational amplifier is connected in parallel to the diode and compensation resistor such that the desired compensation voltage always appears across the compensation resistor

Electronic circuit for exciting asynchronous-start slipringless synchronous motors

Abstract: In order to excite the field winding on the rotor of an asynchronous-start synchronous motor which has a resistor connected in parallel with the winding, the alternating current output from an exciter winding mounted on the rotor shaft is converted in a rectifier bridge of the semiconductor type also mounted on the rotor shaft and fed to the field winding through a direct current circuit which includes a thyristor for interrupting the flow of direct current to the field winding when the motor is operating in its asynchronous state. For this purpose, a pair of series-connected resistors extend between the positive side of the rectifier bridge and the control electrode of the thyristor, and a diode has its anode side connected to the junction between the series-connected resistors and its cathode side connected to the negative side of the rectifier bridge. The thyristor for interrupting current flow from the rectifier bridge to the field winding can either be an auxiliary thyristor unit, in which case the semiconductor elements of the rectifier bridge can consist entirely of uncontrolled diodes, or the function of the thyristor in disconnecting flow of direct current to the field winding can be performed by so constructing the rectifier bridge that uncontrolled diodes make up the positive half of the bridge and thyristors the negative half.

Method and apparatus for determining resistance at radio frequencies

Abstract: The radio frequency resistance between a pair of conductive elements, for example, adjacent pipe sections of a pipeline, which are coupled together through an insulator, may be determined by contacting each pipe section with one of a pair of probes or electrodes connected across the output of a radio frequency oscillator which is coupled to the input of a rectifier and filter circuit. The probes are connected across the oscillator output through a resistor which insures that the direct current output of the rectifier is directly proportional to the RF resistance between the pipe sections. The output of the rectifier is coupled to a meter through an operational amplifier. The meter, which provides a direct readout of the resistance being measured, may be provided with a current limiting circuit which protects the meter from excessive DC current. Calibrating means may be provided to enable adjustment of the gain of the operational amplifier for resistance readings within several ranges.

Constant voltage device for a magneto alternating current generator

Abstract: A constant voltage device for a magneto alternating current generator comprises a silicon controlled rectifier and a trigger signal generator circuit which comprises a voltage divider, a constant voltage element connected between the voltage divider and a gate of the silicon controlled rectifier and further a capacitor for forming a series-parallel delay circuit together with the voltage divider and for phase controlling the silicon controlled rectifier.

Converter-regulator circuit arrangement

Abstract: This disclosure relates to a converter-regulator circuit which has high immunity to transient voltages and which employs a feedback controlled operational amplifier at the input end for controlling the conductive condition of an intermediate transistorized inverter which supplies feedback signals from the output end of a bridge rectifier to provide a regulated d.c. output voltage.

Solid state rectifier control unit

Abstract: A circuit for controlling the rectifier circuit in an electrostatic dust precipitator, the circuit being an oscillator circuit utilising a pair of alternately conducting transistors and a timing circuit controlling conduction of one of the transistors, the other transistor controlling the circuit output.

High-voltage circuit for post focusing type color picture tube

Abstract: A high-voltage circuit for post focusing type color picture tube is disclosed in which a high voltage and a higher voltage are produced respectively from the middle and final stages of a voltage-multiplying rectifier circuit connected to the output winding of a fly-back transformer. The voltage-multiplying rectifier circuit comprises a plurality of rectifier elements and a plurality of capacitor elements. The fly-back transformer has its leakage inductance and the like adjusted so as to be tuned to the 7th or higher-order harmonic of fly-back pulses.