Showing papers on "Precision rectifier published in 1980"

Low-ripple power rectifier system

Abstract: To provide a power rectifier for connection to an a-c power network which has low ripple at the d-c output, and low harmonic content at the a-c side, particularly for feeding a d-c - a-c inverter frequency generator providing output in the audio or low supersonic range for supply of gas discharge or fluorescent lamps, a wave-shaping network is connected to the a-c side of a standard bridge rectifier unit such that the a-c power applied to the rectifier is of approximately trapezoidal or rectangular or square-wave shape; a suitable network is the combination of an inductance (D) and a storage capacitor(C1) in a T-network or in a series resonant circuit, in which the quadrature VA of the choke (D), at network frequency, is about 60% of the power to be supplied by the rectifier, with a capacitor (C1) in a T-network configuration of such value that the resonant frequency of the L/C circuit is about 2.2 to 2.6 times network frequency or equal to network frequency, when in a series resonant circuit. Splitting the inductance (D) into two winding portions, one in each one of the supply lines substantially reduces radio interference from a connected gas discharge lamp.

Apparatus for reproducing disc record

Abstract: Apparatus for maintaining a constant linear velocity for a PCM disc record which includes a detector for optically detecting the PCM signal on the record and supplies the output to a differentiating circuit and a rectifier circuit with the output of the rectifier circuit supplied to a peak detector circuit which supplies its output to a level comparator that also receives a reference level from a reference source. A first phase comparator also receives the output of the rectifier circuit and controls a voltage controlled oscillator through a low pass filter and the output of the voltage controlled oscillator is supplied to the phase comparator. A divider receives the output of the voltage controlled oscillator and supplies a first input to a phase comparator which also receives an input from a reference frequency generator. The outputs of the level comparator and the phase comparator are supplied to the motor drive circuit which controls the drive motor for the disc record.

X-ray diagnostic generator

Abstract: An inverter, with a frequency lying in the medium frequency range, and a mains rectifier are connected with the high-voltage transformer Between the X-ray tube and the high voltage transformer there is disposed a high-voltage rectifier with a high-voltage filter member There is likewise connected with the filament transformer an inverter with a frequency lying in the medium frequency range and a mains rectifier Filter members are connected between the mains rectifiers and the inverters Plural inverters with different phase may supply respective high voltage transformers, and each transformer may have a voltage doubler high voltage rectifier contributing to X-ray tube anode voltage

Knock detector for internal combustion engine

Abstract: A knock detector for an internal combustion engine comprises a resonantly tuned knock sensor mounted on the engine, a variable gain amplifier for amplifying the signal from the knock sensor, knock and reference channels which are operatively coupled with the output of the variable gain amplifier to develop respective knock and reference channel signals, and a comparator for comparing the signal of one channel against the signal of the other channel. The gain of the variable gain amplifier, in general, is an inverse function of engine speed. The amplified signal from the variable gain amplifier is gated to a peak detector of the reference channel circuit during absence of any appreciable engine knock to develop a reference signal representing background noise. The knock channel detects peaks of the amplifier output signal, and the comparator compares the two peak detected signals to provide a knock signal when a predetermined relationship between the two is attained.

Self-adjusting dual mode automatic gain control circuit

Abstract: An automatic gain control circuit comprising a gain-controlled amplifier for receiving a variable amplitude, pulse-type input signal to produce a substantially constant amplitude, pulse-type output signal which is applied to a feedback circuit for comparison with a predetermined reference voltage to generate a control voltage to set the gain of the amplifier. A voltage limiter included in the feedback circuit clips the pulse peaks of the output signal whenever the peaks exceed a predetermined amplitude so that the gain of the amplifier is reduced in a prescribed manner to preclude output signal dropout. A peak detector and a filter included in the feedback circuit are capable of operating in fast and slow modes. When operating in the fast mode, the peak detector responds essentially to each pulse peak of the output signal and the filter has a wide bandwidth so that the automatic gain control circuit operates with a prescribed fast time response. When operating in the slow mode, the peak detector operates to increase the gain of the amplifier slowly in order to limit output signal overshoot and preclude output signal dropout if the input signal reappears after an absence for some period. The filter, when operating in the slow mode, has a narrow bandwidth so that the automatic gain control circuit operates with a time response substantially slower than the fast time response. A controller circuit produces, in response to the output signal, a controller signal which causes fast mode operation of the peak detector and filter whenever the output signal is present and slow mode operation thereof whenever the output signal is absent for a predetermined time period.

Adjustable waveform spark source

Abstract: A capacitor is charged to a high voltage, and then is discharged through a circuit comprising an analytical spark gap and first and second inductive elements, whereby the discharge current is oscillatory The waveform of the discharge current is modified by a diode rectifier shunted across the series combination of the analytical spark gap and the second inductive element To provide for adjustment of the waveform over a wide range, the second inductive element is adjustable in inductance The first inductive element is also preferably adjustable in inductance Provision may also be made for changing the capacitance of the capacitor A reversing switch makes it possible to reverse the polarity of the diode rectifier One or more control spark gaps may be connected in series with the analytical spark gap An electronic switching device may be connected across one of the control spark gaps to initiate the discharge of the capacitor Either or both of the inductive elements may be replaced with other reactances or impedances, such as transmission lines Coupling may be provided between the inductive elements Inductance or impedance may be provided in the diode circuit The capacitor may be replaced with some other source of alternating current or pulses The spark may be ignited by high voltage, developed at a radio frequency by a quarter wave line The diode rectifier may be replaced with a silicon controlled rectifier, silicon controlled switch, or some other active element

Precision rectifier circuits

Abstract: A precision rectifier circuit includes two differential amplifiers each having a negative feedback path including a diode. Two pnp transistors have their base-emitter paths connected in parallel with the respective diodes and their collectors connected together and via an output resistor to ground. An a.c. signal to be rectified is applied to non-inverting inputs of the amplifiers, whose inverting inputs are interconnected via a resistor in series with a capacitor, to develop a unipolar output voltage across the output resistor. The capacitor renders the output voltage independent of input offset voltages of the amplifiers. The transistors can comprise Darlington-connected transistors to avoid the need for matching.

Rectifier circuit diode array and circuit protector

Abstract: In a rectifier circuit structure, particularly for automative use, a diode array is in the form of a column and includes a Zener diode in the column which serves to protect the rectifier diodes of the arrangement and to protect an electrical load system coupled to the output of the diode array.

Method and means for an accurate wideband peak detector

Abstract: A peak detector is comprised of two related circuits having similar circuit parameters, each providing an output in response to a repetitive waveform applied to the detector. The two outputs are combined to eliminate the dependence on the circuit parameters to provide as an output of the detector an accurate, wideband peak voltage of the applied waveform.

Rectifier system with failure alarm circuitry

Abstract: A rectifier unit for supplying power to a D.C. load including a transformer having a primary, a secondary and a saturable core, the secondary defining an output section and a control section. A ferroresonance control circuit simulates saturation of the transformer core and includes an electronic switch for controlling the degree of simulated core saturation and thereby regulating the rectifier unit output. Rectifier failure alarm circuitry produces a failure alarm in response to a number of rectifier unit malfunctions. The rectifier failure alarm circuitry is coupled to the ferroresonance control circuitry and comprises a rectifier alarm element operable between the first condition wherein a rectifier failure alarm is produced and a second condition. The failure alarm element is operated from its first condition when the electronic switch minimizes the rectifier system output. The failure alarm element is provided with power from the secondary output section so that, if this output section fails to produce power, a rectifier failure alarm is also produced.

Cockcroft-Walton voltage multiplying circuit for slim hole well logging tool

Abstract: A Cockcroft-Walton voltage multiplying circuit constructed for use in a slim hole well logging tool includes a plurality of capacitor packages having a first capacitor package, adapted to receive an input voltage, and a last capacitor package. A plurality of high voltage rectifier packages of which each rectifier package, except for a last rectifier package, are physically as well as electrically interconnected with two capacitor packages. The last rectifier package is connected to the last capacitor package so that all of the capacitor packages and all of the rectifier packages form an inline rigid body. Output terminals are connected to the last rectifier package for providing the high voltage developed by the capacitor packages and the rectifier packages in response to a received input voltage.

Focus detection circuitry

Abstract: The focus meter is an electronic circuit that is responsive to a video sil input to provide an output signal which indicates the degree of focus on a target. Imaging systems require alignment or focusing of the imaging sensor aimed or directed toward a target. The image sensor is aimed at the target and the degree of focus on the target is varied. As the maximum point of focus is reached a peak signal output results. The input video is coupled to an amplifier. The input signal is then processed through a differentiator to a peak detector. A portion of the signal is coupled from the amplifier to a sync separator circuit which causes a gate signal to be generated to an electronic switch during undesirable portions of the input video signal. This allows the differentiator output to be short-circuited to ground when undesirable signals are present. When the desired video lying between the blanking pulses are present, the differentiated signals are coupled to the detector. The detector measures the peak values. For a typical viewed scene wherein the target being tracked or sensed has reasonable detail, the peak detected value provides an easily measured maximum at the best point of focus.

Telephone privacy controller

Abstract: A telephone privacy controller for connection in series with a telephone set having steering diodes that direct current through a silicon controlled rectifier which is activated to conduct current by a zener diode connected between the current input and the gate input of the silicon controlled rectifier. The telephone privacy controller may be adapted to include a privacy release feature by addition of a capacitor and resistor connected to the gate input of the silicon controlled rectifier wherein the discharge from said capacitor may provide an input to the gate of the silicon controlled rectifier.

Earth leakage protection devices

Abstract: An earth leakage protection device comprises a core balance current sensing transformer 1 having a secondary winding 2 in which a fault signal is generated in response to leakage from AC supply lines forming primary windings of the transformer 1, an operational amplifier OA1 for amplifying the fault signal, a precision rectifier circuit 8 comprising a pair of operational amplifiers OA2 and OA3 for performing full wave rectification of the amplified fault signal, a delay circuit 9 in the form of a two stage RC network which delays the rectified signal according to an IDMT characteristic, and a trigger circuit 10 in which the delayed signal is compared with a preset reference signal by an operational amplifier OA4 to provide a control signal which actuates a sagety device in the AC supply lines via a relay 11 when the reference signal is exceeded. Within its operating range the device actuates the safety device much more slowly for lower leakage currents than for higher currents, and since it is operative on both halves of the AC leakage current signal the device provides reliable protection against the possibility of dangerous electric shocks while avoiding spurious tripping.

Linear full wave rectifier and method for providing full wave rectified signals

Abstract: A circuit and method for producing a signal that is nearly a perfect full wave rectified version of an applied alternating signal. The circuit comprises first and second identical non-linear symmetrical rectifiers each having a respective output coupled to a current mirror circuit. In response to the alternating signal being applied to the input of the first rectifier a full wave rectified signal is produced at the output thereof to drive the current mirror such that at the output thereof, which is coupled to the output of the second rectifier, there appears a signal identical to the output from the first rectifier. This signal is utilized to produce an input signal to the second rectifier to constrain the output signal therefrom to be identical to the output signal from the current mirror circuit. The input signal to the second rectifier is thus a perfect full wave rectified version of the input signal applied to the first rectifier.

Apparatus for converting an A.C. input signal to a rectified and smoothed D.C. signal

Abstract: Offset voltages of a precision rectifier circuit, buffer amplifiers, and an input comparator of a log converter are compensated for by charging a coupling capacitor to the combined total offset voltage of the apparatus. The charging is effected by causing the comparator to operate as a unity gain inverting amplifier during part of the operating cycle of the log converter when the comparator output signal is not used, so that the log converter operation is not adversely affected. During such charging the input of the precision rectifier circuit, to which the a.c. input signal is normally applied, is grounded. Throughout the charging and associated switching operations a capacitor of a smoothing filter connected following the precision rectifier circuit is disconnected from ground to isolate the smoothing filter output from ground and to prevent switching transients from affecting the charge of this capacitor.

Shading correction circuit

Abstract: PURPOSE:To secure the correction for the luminance without any expertness by providing the saturation region to the gain control amplifier of the device and then giving a comparison between the saturation level and the shading correcting waveform. CONSTITUTION:The HD (horizontal drive) and VD (vertical drive) pulses turn into the saw-tooth waves through saw-tooth wave formation circuits 1 and 2 to form the parabola waveforms through parabola wave formation circuits 3 and 4 each. These parabola waves are compounded at 3rd compounding circuit 11 via 1st and 2nd compounding circuits 9 and 10 to be led into signal correcting amplifier 20. And the output of the waveform the upper areas of which near the rise and fall reached the gain saturation region are cut off is applied to gain control amplifier 8. In this connection, amplifier 8 is controlled by the output of amplifier 20 and then controls the contrast component of the video signal to lead out the correcting video signal. On the other hand, the output of amplifier 20 is applied to peak detector circuit 23, and the peak level is given to comparator 21 as the reference level for the comparison with the output of circuit 11. And in case the peak level is higher than the output, analog switch 22 is closed. Then the peak level is applied to 4th compounding circuit 7 to obtain the correcting output.

Rectifier power-supply circuits

Abstract: The invention provides a rectifier circuit, particularly suitable for use with inverter and transformer power supplies, stabilised against a fall in input voltage. The supply is applied through inductors (L1.L2) to a full wave diode bridge rectifier (CR1, CR2, CR3, CR4) having a pair of capacitors (C1, C2) connected across its DC output and a controllable bi-directional current device (CR5) connected between the common point of the capacitors, and at least one of the bridge inputs. A control circuit 21 switches on the bi-directional current device for part of each cycle in response to a drop in output voltage causing the circuit to function at least partially as a voltage-doubler rectifier. The control circuit may compare an error voltage derived from the output with the voltage from a ramp generator to provide pulses for switching the bi-directional devices. In a three-phase version of the circuit (not shown in Figure 3) inhibit circuits are provided to prevent more than one of the bi-directional devices becoming conducting at any one time.

Method and apparatus for controlling an output current of a controlled rectifier

Abstract: In a method and apparatus for controlling an output current of a controlled rectifier connected to an AC power supply, by firing angle control of the controlled rectifier in accordance with the result of comparison of a value corresponding to the rectifier output current with a predetermined reference value, an average value of a detected rectifier output current over a period having a length equal to an integer multiple of the average period of the firing angle control is calculated, and a signal for firing the controlled rectifier is produced at an angle determined in accordance with comparison of the calculated average value with the reference value.

Thyristor-controlled in-phase boosting for h.v. d.c. convertors

Abstract: An alternative scheme to the conventional h.v. d.c. rectifier station is proposed. The transformer on-load tap-changer and convertor controls are replaced by a thyristor-controlled regulating transformer, the rectifier bridges consisting of pure diodes. Fast and continuous voltage control is achieved with improved displacement factor and reduced harmonic content.

Improvements relating to earth leakage protection devices

Abstract: And earth leakage protection device comprises a core balance current sensing transformer (1) having a secondary winding (2) in which a fault signal is generated in response to leakage from AC supply lines forming primary windings of the transformer (1), an operational amplifier (OAI) for amplifying the fault signal, a precision rectifier circuit (8) comprising a pair of operational amplifiers (OA2 and OA3) for performing full wave rectification of the amplified fault signal, delay means (9) in the form of a two stage RC network which delays the rectified signal according to an IDMT characteristic, and a trigger circuit (10) in which the delayed signal is compard with a preset reference signal by an operational amplifier (OA4) to provide a control signal which actuates a safety device in the AC supply lines via a relay (11) when the reference signal is exceeded. Within its operating rangs the device actuates the safety device much more slowly for lower leakage currents than for higher currents, and since it is operative on both halves of the AC leakage current signal the device provides reliable protection against the possibility of dangerous electric shocks while avoiding spurious tripping.

Video signal processor

Abstract: PURPOSE: To minimize focal blur by dynamically emphasizing the luminance level of intermediate amplitude, as compared with that of high amplitude as a function of a mean value of luminance signals processed by a contrast controller. CONSTITUTION: The automatic contrast controller includes a white peak detector 29 for detecting the peak of a white direction part in an output luminance signal YOUT, in addition to a contrast processing part 9. When the signal YOUT exceeds focal blur threshold reference voltage VRP, an amplifier 31 is constituted so as to reduce a contrast control signal VC as the function of the peak of the signal YOUT, and a diode 31 is connected by a polarity satisfying the amplifier 31. A mean value detector 35 detects the mean value of the processed luminance signal YOUT. A DC signal obtained as the result of the detection is connected to one input of an amplifier 37. The other input of the amplifier 37 receives reference voltage VRA. Control voltage VC for a white-extension processing part 5 is generated from the output of the amplifier 37. When the mean value of the processed luminance signal YOUT is lower than the voltage VRA, the detector 35 and the amplifier 37 are constituted, so that the level of the voltage VC is reduced in direct relation with the mean value.

Distance measurement using ultrasonic wave

Abstract: PURPOSE:To provide an accurate measurement by a method wherein a compression amplifier is used to control a large variation in the receiving level and clock pulse counting is used to obtain the period from the transmission of ultrasonic wave to the generation of peak in the received signal CONSTITUTION:A compression amplifier CA having a logarithmic compression characteristics, for example, is inserted in the output side of the receiving amplifier RA in the receiving system The received signal is suppressed in its level variation and fed in the peak detector PD, which generates output corresponding to the peak value The calculator circuit AC, controlled by this output, provides output corresponding to the distance to the object to be determined

Correction device of fabryyperot interferometer

Abstract: PURPOSE:To obtain a drift correction method that the correction of drifts is accurate and the drifts can continually be corrected even when the quantities of the drifts become larger, by using alternating currents, which have no noise and possess arbitrary wave-forms, as integral input. CONSTITUTION:Voltage with positive chopping waves is applied to an electric distortion element from a drive voltage source 10, and photoelectric output a is gained, shaped to gate pulses b through an amplifier 11, a peak detector 20 and a pulse shaping circuit 21 and applied to a gate 13. The drive voltage of the voltage source 10 is converted into alternating signals through a negative direct current bias circuit 22, and applied to the gate circuit 13 as integral input signals. Thus, the integral input signals C are gated by the gate pulses b, and applied to an electric distortion element 23 for correcting drifts through an integrator 14 and an amplifier 23. Consequently, correction is accurate, and drifts can continually be corrected even when the quantities of the drifts become larger.

Fluorescence measuring instrument

Abstract: An onboard power supply and metering unit is connected, via an overboard cable e.g., 1000 meters long, to an underwater light-pulse projecting unit and a fluoroescence-sensing receiver unit. The operating power is transmitted to the underwater units by an onboard constant-current source, instead of a voltage source. Likewise, the output signal of the receiver unit is transmitted through the cable in the form of a current, not a voltage. The current of the receiver's photodiode is integrated, the peak value of the integral determined and held, this held value logarithmized, the logarithmized value sampled and held, and the held voltage converted to a current constituting the output signal. The offset of the peak detector and the input stage of the log amplifier are balanced automatically, by a balancing signal applied during pulse measurements, but derived between pulse measurements. The balancing signal is derived by integrating a signal derived from the log amplifier's output signal, and is applied to the input of the peak detector, with the peak detector converted to simple voltage-follower operation during the deriving of the balancing signal.

DC operated filament lamp - has built in rectifier and is operated in DC mode with rectification from AC supply

Abstract: An electric lamp with a built in rectifier allows the filament to be energised with a dc supply, while coupled to the ac mains Experimental tests indicate that while the filament is subjected to a higher voltage with some 70% increase in current drawn, the developed illumination is increased by 170% As a result of operating on a dc supply, the filament exhibits a greater load carrying capacity resulting in an improved operational life In addition to the built-in rectifier is a transformer to allow the lamp to be operated at a lower voltage

Photo receiver circuit

Abstract: PURPOSE:To prevent the runaway and oscillations of an AGC loop system by limiting a bias current by inserting a resistance into the bias supply circuit of a DC/DC converter which supplies a bias voltage to an avalanche photo diode CONSTITUTION:This photo receiver circuit consists of DC/DC converter 5 which applies a bias voltage to avalanche photo diode APD1, amplifier 2 which amplifies the output of APD1, and peak detector 3 which detects the peak value of the output of this amplifier 2 Further, operational amplifier 4 is provided which compares the peak value detected by detector 3 with reference voltage Ref and then applies this comparison output as a control voltage to the input of converter 5 Resistance R is inserted into the bias supply circuit of converter 5 of this constitution and a voltage across this resistance R is fed back to amplifier 4 by way of amplifier 6 and non-linear response circuit 7 to limit a current flowing through APD by way of resistance R, thereby preventing the runaway and oscillations of loop 2

Agc circuit of receiver

Abstract: PURPOSE:To increase the virtual sensitivity as well as to secure an automatic sound volume control effect to the AGC circuit to compensate the modulation factor by making the output of the detection circuit rectifying the intermediate frequency control the gain of the intermediate frequency amplifier circuit via the peak detector. CONSTITUTION:The input high-frequency signals sent from the antenna are selected through tuning circuit 1, converted into the intermediate frequency at mixture originating circuit 2, amplified through intermediate-frquency amplifier circuit 3, and then detected and amplified through detection/amplification circuit 9. The minimum level of the voltage is detected at peak detection circuit 14 for output terminal 6, and the output is supplied to circuit 3 in the form of the AGC voltage via Zener diode 13. At the early stage of reception, the voltage of terminal 6 lowers down, but the AGC voltage supplied from diode 13 does not change. While with the input field intensity higher than the fixed level, the circuit 3 gain lowers down by the AGC voltage. Thus, the sensitivity can be compensated virtually at the weak field time.

Bias circuit of amplifier

Abstract: PURPOSE:Not only to make an amplifier perform class A amplification but also to elevate its efficiency, irrespective of magnitude of the load impedance, by deciding the bias depending upon the signal current component of the amplifier output. CONSTITUTION:The transistors 4, 5 are subjected to class A bias, perform a complementary action mutually, and AC voltage applied to the load 14 is produced between the terminals 15, 16. This AC voltage is applied to the differential amplifier 10 and is amplified furthermore, after it has been amplified, it is applied to the peak detector 11, and it is converted to a DC signal after both the wave peaks have been detected. This DC signal becomes a differential output by being amplified by the differential amplifier 12, and is applied to the base of the transistors 4, 5. Resulting from the foregoing, DC voltage is produced between the terminals 17, 18. This DC voltage is fed back as negative to the inverted input terminal of the differential amplifier 12 after it has been amplified by the differential amplifier 13. The bias voltage is controlled depending upon the signal level by the aforesaid negative feedback action.

Automatic threshold value control circuit

Abstract: PURPOSE:To improve the S/N as a whole, by fixedly giving the threshold value to the signal less than a given amplitude and giving variable the threshold value depending on the amplitude to the signal having more than a given amplitude. CONSTITUTION:The signal inputted to the buffer amplifier 1 is level-shifted with the DC voltage VB fed via the resistor 12 and fed to the operational amplifier 13. The amplifier 13 provides the peak detector consisting of the diode 2 and capacitor 3 at the output terminal and the peak value detected is fed back to the amplifier 13. Further, this peak value is divided with the divider consisting of the resistors 4,5 and fed to the comparator 6. Further, the input signal is level-shifted with the DC voltage VC fed via the resistor 15 and inputted to the comparator 6. The comparator 6 discriminates the input signal to the said threshold value and performs signal repeoduction. The voltage VC is set as the fixed threshold value when the signal amplitude is small and the voltage VB is as the voltage specifying the amplitude level performing variable measurement of threshold value.