Showing papers on "Precision rectifier published in 1969"

Automatically resetting transient protection device

Abstract: Apparatus for protecting electrical circuitry from voltage transients in a power supply or the like connected to the circuitry. A plurality of diodes and a silicon controlled rectifier are connected in series across the output of the power supply. The silicon controlled rectifier is triggered by a predetermined transient voltage level, and the output voltage of the power supply is clamped at the sum of the forward voltage drops of the diodes and controlled rectifier, the sum being set above the normal output voltage level of the power supply. The silicon controlled rectifier then commutates as soon as the transient ceases and the voltage level drops to normal. Various configurations are provided for DC or AC systems, as well as for remote sensing, and additional compensating circuits are employed for various applications.

High d/d, fast turn-on darlington controlled semiconductor switch

Abstract: A high di/dt, fast turn-on Darlington controlled rectifier semithyristor semiconductor switch embodies a body of semiconductor material wherein two controlled rectifier switches are formed, each having a separate gate and a separate cathode but both sharing a common anode. The cathode current of one controlled rectifier switch is the gate current for the second controlled rectifier switch thereby enabling a small initial current to be amplified and turn-on a larger controlled rectifier switch whereby the overall effect is a fast turn-on gate controlled switch with a high di/dt rating.

Duty cycle control apparatus

Abstract: A duty cycle control apparatus for a traction motor or the like is provided which controls the mean voltage applied to an inductive load from a direct current source in response to an applied control signal. The apparatus includes a semiconductor controllable rectifier connected between the source and load, a control circuit for rendering the semiconductor controllable rectifier alternately conducting and nonconducting in accordance with a variable mark-to-space ratio, a unidirectionally conductive freewheeling current path around the load for enabling load current to flow during the time between ''''on'''' periods of the rectifier, and a current sensing device for producing a current-limiting signal indicative of mean current flowing from the source through the rectifier. The control circuit acts, responsive to the current-limiting signal, to impose a restriction upon the available maximum mark-to-space ratio so as to tend to maintain the mean current in the controllable rectifier within predetermined limits without correspondingly limiting the current in the load.

Circuit for the protection of monolithic silicon-controlled rectifiers from false triggering

Abstract: Power supply voltage transients are prevented from turning on a silicon-controlled rectifier by use of a dual-emitter current switch to short circuit a given PN junction within the siliconcontrolled rectifier for the duration of each transient.

Electric cranking motor automatic disconnect and lockout circuit

Abstract: An electric cranking motor automatic disconnect and lockout circuit. The normally open contacts of a cranking motor solenoid operated switch are connected in series with the electric cranking motor across a source of direct current supply potential. Upon the closure of an electric switch, the source of direct current supply potential, applied across the gate-cathode electrodes of a first silicon controlled rectifier, triggers this device conductive through the anode-cathode electrodes to establish a circuit for base-emitter current flow through a first transistor. The conductive first transistor establishes an energizing circuit for the operating coil of an electric relay which, in turn, establishes an energizing circuit for the operating coil of the solenoid operated switch. The output potential of an electrical generator driven by the cranking motor armature is applied across the gate-cathode electrodes of a second silicon controlled rectifier. When the generator output potential is of sufficient magnitude to produce gate-cathode current through the second silicon controlled rectifier, the resulting anode-cathode current flow therethrough shunts base current from the first transistor to extinguish this device, thereby interrupting the energizing circuit for the operating coil of the electric relay and, in turn, the solenoid operated switch to provide automatic disconnect of the cranking motor upon engine start. A vibration transducer mounted upon the cranked engine produces an alternating current potential signal which triggers a second transistor conductive to shunt gate current from the first silicon controlled rectifier thereby preventing the retriggering of the first transistor while the engine is running to provide a lockout of the cranking motor.

Dc arc welder

Abstract: A DC welding system wherein DC power is applied to an electrode through a rectifier and the output of the rectifier is controlled by a transformer tap-changing system supplying power from a supply transformer through a second transformer in series with the rectifier. The tap changing system is controlled by selectively applying power to controlling relay coils through a diode matrix.

Dynamic time/voltage test system

Abstract: The test system characterizes a unit under test (UUT) by measuring on repetitive waveforms either the voltage level of the output waveshape at a specific time or the time required for the output waveshape to reach a specific voltage level. The system includes three main assemblies, a measuring assembly, D/A converter and controller. The measuring assembly employs a strobed tunnel diode as a voltage sampler for making all voltage and time measurements. The D/A converter functions as an interface device between the system and an external control means or computer. The controller extends the capabilities of the measuring assembly and includes: a countdown circuit to allow the system to handle high repetition rate signals; a delay circuit to assure proper time position of the measuring assembly with respect to the waveform being measured; a time calibrate subassembly which operates in conjunction with an A/D/A subassembly to allow for automatic calibration of the system; a peak detector subassembly which permits the system to make peak and valley measurements and allows preconditioning of the voltage sampler in the measuring assembly to make speedier measurements; and, a DC multiplex circuit card to allow for differential measurements and filtering the measurement to increase its precision. In addition, the system can be used as a sampling head for a real time oscilloscope.

Dark current compensation circuit

Abstract: A dark current compensation circuit for a television camera features a switch for controlling an X-ray tube located in front of the camera, a video amplifier is coupled to the camera and a peak rectifier circuit is in turn coupled to the amplifier output. A switch synchronized with the first switch connects the rectifier to a capacitor to establish a dark current bias voltage which is applied to the amplifier.

Absolute magnitude peak detector

Abstract: An absolute magnitude peak detector having a pair of operational amplifiers with only a single additional diode and only a single pair of matched resistors. The input signal is coupled to a different polarity input of each amplifier. The amplifier outputs are tied together and coupled through the diode to an output capacitor. The potential of the junction of the diode and the capacitor is fed back to an input of each amplifier, with the same diode thus being included in both feedback paths.

Electrical chopper regulator circuits

Abstract: An electrical chopper regulator circuit comprises a main controllable rectifier device connected in a current path between input and output terminals and a commutating capacitor connected in a second current path. Second and third controllable rectifier devices control connection of the commutating capacitor with appropriate polarity to opposite sides of the main controllable rectifier device so as to interrupt current flow in the main controllable rectifier device. A charging circuit for controlling charging of the commutating capacitor includes a switching device and an inductance through which current flows to charge the commutating capacitor to the correct polarity for commutating the main controllable rectifier device before firing of that device.

Precision rectifier with fet switching means

Abstract: A PRECISION FULL-WAVE RECTIFIER USES A SINGLE OPERATIONAL AMPLIFIER WHICH IS OPERATED SIMULTANEOUSLY AS A LINEAR AMPLIFIER AND A SWITCH DRIVER. A PAIR OF FETS ARE UTILIZED AS VOLTAGE RESPONSIVE SWITCHES FOR EFFECTING THE RECTIFYING OPERATION AND ARE GATED IN RESPONSE TO THE OUTPUT OF THE OPERATIONAL AMPLIFIER.

Automatic trigger level control circuit

Abstract: A circuit is disclosed for automatically varying the trigger level of a trigger circuit in order to maintain this level substantially proportional to the amplitude of a series of similar waveforms of an input signal. A peak detector provides a voltage substantially proportional to the peak voltage of the input waveforms. A manually adjustable fraction of the detected voltage is delivered to a control circuit as a control voltage to cause selection of increments of the input waveforms crossing a signal voltage level of these waveforms corresponding to the control voltage. The control circuit supplies control signals corresponding to such increments to a trigger circuit at a signal level which causes the trigger circuit to produce trigger pulses when the varying voltages of the input waveforms cross a signal level within the selected increments. This signal level remains substantially proportional to the peak voltage of the input signal waveforms even though this peak voltage changes.

Electrical power supply system for automotive vehicles and particularly polyphase bridge-type rectifier therefor

Abstract: To prevent transient overvoltages in automotive-type power supply systems using three-phase alternators and full wave rectifiers connected thereto, at least one of the rectifier pairs connected to an output winding of the alternator uses breakdowntype power rectifier diodes having a breakdown voltage at least 5 percent above the nominal voltage set by the voltage regulator of the system. Connection of breakdown diodes to further, or preferably all phases provides still better protection at greater expense, however.

High-speed precision rectifier

Abstract: This invention relates to a high-speed, full-wave rectifier having two parallel forward paths, one for transmitting positive input signals and the other for inverting and transmitting negative input signals to a common output. Each path includes a gate for passing signals in response to a command. A comparator which generates a first voltage in response to a positive input and a second voltage in response to a negative input cooperates with the gates to enable the gate in the first forward path when the input is positive and to enable the gate in the second forward path when the input is negative. Thus, positive signals are passed through the first forward path to the output and negative signals are inverted and passed through the second forward path to the output thereby converting an arbitrary input waveform to full-wave, rectified output waveform.

Dynamic gate bias for controlled rectifiers

Abstract: A pickup circuit connected to the main power circuit of a controlled rectifier generates an output signal responsive to the forward rate-of-change-of-voltage across the main terminals of the controlled rectifier. This output signal is then connected to the gate of the controlled rectifier as a negative gate bias, the magnitude of which is related to the rate-of-change-of-forwardvoltage across the controlled rectifier device.

Time-domain pitch detector and circuits for extracting a signal representative of pitch-pulse spacing regularity in a speech wave

Abstract: A time-domain detector circuit for producing a signal representative of the pitch pulses of a speech wave. The circuit comprises two peak detectors having two different time constants to which the input speech wave is supplied. The output of the shorter-time-constant detector is supplied to an isolating stage (e.g., an emitter follower network). The output of the longertime-constant peak detector is connected, via a zener diode, to the output terminal of the emitter-follower network. A differentiator circuit is connected to the output terminal of the longer-time-constant detector. When the potential difference across the zener diode rises to a sufficiently high value, the zener-diode conducts, enabling the emitter follower network to load the longer-time-constant peak detector. The shorter-timeconstant peak detector detects the pitch pulses and supplies them to the output terminal of the longer-time-constant detector. When the amplitude level of the speech wave is relatively constant, the zener diode isolates the output of the shorter-time-constant detector from the output terminal of the other detector and only the long-time-constant detector supplies an output signal thereto. One circuit includes an input speech wave, a clipper, ramp generator, peak detector and low-pass filter connected in series. Another circuit includes pitch pulses, a pulse width-to-amplitude converter, a sample-and-hold circuit, a differentiator and a second sample-hold circuit connected in series with delayed pitch pulses timing each sample and hold circuit.

Electronic delay multiperiod initiating system

Abstract: A device for providing electronically delayed multiple point initiating current to electrical initiators in blasting circuits is provided. The device has a plurality of firing circuits each of which employs a firing capacitor connected to a silicon controlled rectifier. A plurality of buffer circuits connected in parallel are provided, each buffer circuit having at least one capacitor which is connected to the control gate of a silicon controlled rectifier of a firing circuit. A timing circuit sequentially actuates discharge of each buffer capacitor into the gate of the silicon controlled rectifier of a corresponding firing circuit whereby the silicon controlled rectifier is made conductive allowing the firing capacitors to discharge into the firing circuit.

Bistable multiemitter silicon-controlled rectifier storage cell

Abstract: This specification discloses a storage cell which employs a single dual emitter silicon-controlled rectifying device as a storage element. This silicon-controlled rectifier device is biased to have two stable-operating states and is addressed by a word line connected to one of its emitters and a bit line connected to the other of its emitters. A transistor is formed by these two emitters and the gating layer of the silicon-controlled rectifier. By application of half select pulses to the word and bit lines this transistor is broken down so as to cause current to flow in the gating region or layer of the silicon-controlled rectifier. When current flows in the gating region the operating characteristic of the silicon-controlled rectifier changes so that the silicon-controlled rectifier switches from a highvoltage, low-current stable state to a low-voltage, high-current stable state along the operating curve of the silicon-controlled rectifier. To increase the turnoff speed of the silicon-controlled rectifier a Schottky Barrier diode is connected between the gating layer and the other intermediate layer of the siliconcontrolled rectifying device to discharge charge stored in the junction between the two layers.

Motor control circuit with semiconductor switching means and transformer and capacitor biasing means

Abstract: An electric motor is connected to a direct current electrical power source through a silicon controlled rectifier that is cyclically turned on by a triggering circuit and turned off by a commutating circuit A semiconductor diode is connected in parallel with the silicon controlled rectifier in a reverse biased direction relative to the direct current source The motor power circuit operates so that the diode is forward biased during part of the switching cycle by the action of a capacitor and transformer, and then, upon being reverse biased, momentarily carries part of the motor current in its reverse current direction thereby sharing the load current with the silicon controlled rectifier

Controlled rectifier arc welding supply having improved positive firing characteristics

Abstract: A three phase transformer and a full wave rectifier unit including silicon controlled power rectifiers A feedback control system includes a pair of separate and cascaded summing differential amplifiers to control the firing circuits for the related pairs of rectifiers Each firing circuit includes a unijunction transistor oscillator having a gate circuit including a small trim potentiometer for adjusting the pulse time A capacitor in series with a resistor is connected in parallel with the oscillator to a bridge rectifier A silicon controlled rectifier in series with a resistor is connected across the capacitor to form a firing pulse for the related pair of power rectifiers

Peak detection circuit

Abstract: A peak detector circuit having an output proportional to the most recently assumed peak value of an amplitude varying input signal is disclosed. In the described embodiment the circuit includes an input stage, a diode-storage capacitor series combination, a variable impedance path across the capacitor, and an output stage. The impedance of the variable impedance path is controlled by the form of the input signal and is such that when no input signal is applied it has a relatively high value but when an input pulse is applied it has a relatively low value for at least part of the duration of that pulse.

Accurate square-law detector circuit

Abstract: A silicon diode is connected in series with the input of an operational amplifier having a feedback resistor, and the modulated ac signal to be detected is fed to the input side of the diode. The signal current through the diode is an accurate function of only the voltage across the diode, and the output voltage of the operational amplifier is proportional to such diode current.

Automatic saturation control for a color television receiver

Abstract: A color television receiver using direct demodulation of the color and brightness signals is provided with an automatic chroma control circuit for controlling the gain of the color IF amplifier stage in order to prevent the saturation of the demodulated color signals from exceeding the peak brightness signals. The output of the video amplifier is supplied through a peak detector to one input of a differential amplifier, the other input to which is obtained through a second peak detector from the outputs of the color demodulators. The output of the differential amplifier is used to control a switching transistor, which supplies D.C. control signals to the color IF amplifier to control the bias on the final stage thereof. A pair of comparison circuits of the same type are provided, with the second circuit being responsive to the peak blackness signals and the saturation of the color components occurring during the black-going portions of the video signals, while the first comparison circuit compares the white-going peak portions of the video signal with the saturated color appearing during the white-going portions. The blanking circuit operates to disable the comparison circuits during the blanking intervals, so that the automatic chroma control circuit is responsive only to the video signals present during the trace portion of the video signal.

Electrical circuit for controlling the time duration of current application to an external load

Abstract: This is an electrical circuit for time limiting the application of current to an external load. A charging network is fed by alternating current having a capacitor charged through resistance means and a diode when a switching element is positioned conductive between the capacitor and resistance means. A pulsing network is fed by the alternating current which network has a transformer, resistance means, diode and Zener diode providing a pulse to a first silicon controlled rectifier on the half-cycle when the switching element is positioned nonconductive between the capacitor and the resistance means and is positioned conductive between the capacitor and the first rectifier. A second silicon controlled rectifier receives the potential of the capacitor through the first rectifier in its conducting state which in turn allows the second rectifier to conduct and thus permit the capacitor to discharge through said second rectifier to the external load to be controlled. This circuit is particularly adapted to the firing of electrically activated delay blasting caps without arcing when using high voltage.

Dc motor controllers with ir compensation for extended speed range

Abstract: In a standard speed control circuit for DC electric motors, such circuit generally being comprised of an external speed command potentiometer electrically connected to an amplifier, a negative feedback loop indicating motor armature voltage electrically connected to said amplifier, and a positive IR compensation loop electrically connected to said amplifier, which amplifier feeds a signal to a triggering circuit which in turn is electrically coupled to a silicon controlled rectifier circuit, such rectifier circuit being the final resolver of motor speed, means are provided to reduce progressively the effect of the IR compensation input to the amplifier as speed command is increased.

Rectifier bridge type wattmeter

Abstract: A wattmeter of the rectifier bridge type using a four-arm diode bridge having input and output circuits into which current and voltage signals are introduced. A squaring network comprising parallel connected resistors and diodes permits the product of the voltage and current signals to be read out by a milliammeter in the input circuit.

Frequency-sensitive triggering techniques

Abstract: A reliable trigger signal may be produced from a periodic electrical signal having several voltage peaks in each cycle by providing a controlled rectifier that is switched to its conductive state by the receipt of one of the voltage peaks The switching of the controlled rectifier energizes a signal generator that returns the controlled rectifier to its nonconductive state only after the occurrence of all voltage peaks in each cycle As a result, only one trigger signal is produced in each cycle The signal generator is controlled by a timing circuit that is charged to a progressively higher voltage as the cyclical repetition rate of the periodic electrical signal increases, thereby decreasing the time in each cycle in which the controlled rectifier conducts