Showing papers on "Precision rectifier published in 1986"

Synchronous power rectifier

Abstract: A synchronous power rectifier incorporating a bipolar power transistor operable in a switching mode to rectify the energy from a secondary winding of a power transformer. The synchronous rectifier reduces or eliminates the need of rectifier diodes, which provides power rectification without the power loss associated with the rectifier diode voltage drops. Moreover, the present invention includes further refinements of the circuit, including adjustment of the rectifier switching time to accommodate delayed turn-off times of bipolar power devices, and adjustment of the switching signal duration to provide output voltage regulation independent of the excitation of the transformer primary. The resulting embodiments of the present invention provide a modular switching power supply circuit of high efficiency, which may be operable together in combination to provide multiple output voltages.

Adaptively stabilized RF amplifier

Abstract: An output transistor of an RF power amplifier remains stable so that it does not generate subharmonic spurious outputs. An adaptive stabilization network maintains the stability of the output by decreasing the impedance presented to the output transistor when voltage levels at the output transistor exceed a predetermined level. A combination consisting of a peak detector coupled to a Zener diode senses the predetermined level. A PIN diode couples to the Zener diode and to the output transistor so that the PIN diode becomes forward biased when the predetermined level is exceeded.

Two transistor full wave rectifier

Abstract: An integrated circuit two transistor full wave rectifier suitable for fabrication in a CMOS, NMOS or PMOS process and characterized by a high level of integration based upon shared utilization of doped regions. In one form, the full wave rectifier is configured from two diode connected field effect transistors and two parasitic p-n junctions, all formed in a substrate region of common impurity type.

Surge current-limiting circuit

Abstract: There is disclosed a surge current-limiting circuit including a current-limiting means connected in series with a load; a controlled rectifier connected in parallel with the current-limiting means; a photocoupler; and a delay circuit having a time constant, connected through the photocoupler with the gate of the controlled rectifier.

Multirate automatic equalizer

Abstract: An automatic amplifying and equalizing circuit for bipolar data signals has first and second voltage controlled amplifiers controlled by the output of a peak detector. The first amplifier provides even amplification of frequency spectrum components of the data signals while the second amplifier provides amplification of only higher frequency spectrum components of the data signals to compensate for losses of differing length transmission lines. Switches in filtering and frequency dependent circuits provide for operation at several data rates.

Apparatus for limiting surge currents in dc-illuminated incandescent lamp

Abstract: Surge currents which may arise in dc-illuminated incandescent lamp can be effectively limited by an apparatus comprising a low resistance (first resistance); another resistance (second resistance); a diode rectifier, the input terminal being connected in series to an ac source through the first resistance, and the output terminal being connected in series to an incandescent lamp through the second resistance; a voltage regulator diode connected in parallel with said diode rectifier; a capacitance (first capacitance) connected in parallel to the input terminal of said diode rectifier; another capacitance (second capacitance) connected in parallel to the output terminal of said diode rectifier; a switching device connected to the second resistance; and a timing circuit connected to said switching device in a manner that the switching device shorts the second resistance after a lapse of a prescribed time upon switching-on of the ac source.

Receiver for amplitude-modulated time signals

Abstract: In this receiver, a tuned aerial circuit (1), a control amplifier (2), a filter (3), a post-amplifier (4) and a rectifier (5) are provided and connected to one another in the order mentioned. The control voltage (12) supplied to the control amplifier is formed from the difference of the signal (10) of the rectifier (5) and of the signal (11) of a reference source (7) and averaged by a storage capacitor (8). In addition, a decoding unit (9) is provided which determines the envelope curve of the amplitude modulation from the control voltage (12).

Peak detector circuit for FM measuring apparatus

Abstract: A peak detector circuit comprises a peak detecting diode circuitry for detecting peaks in an input FM demodulated signal, a capacitor connected to the output of the diode circuitry, a first resistor connected in parallel with the capacitor, and an amplifier connected to the output of the diode circuitry and having a high input impedance A second resistor is connected to the first resistor in parallel therewith through a turn-on/off switch for discharging and subsequently charging the capacitor within a short time in response to detection of decreasing in the level of the input FM demodulated signal

Tracking servo circuit

Abstract: PURPOSE:To attain tracking stable against various external disturbances without complicated operation by adding a signal corresponding to the polarity of an external disturbance and an error signal to the same amplifier in the same system so as to adjust automatically unstable operation of a servo system due to the external disturbance. CONSTITUTION:When an external disturbance is applied, a selection circuit 26 selects a contact (c) of a switch 20 by using an output signal of a bottom detector 27, a tracking error and a polarity signal to apply a signal pulse of the same polarity as that of the tracking error signal to a summing amplifier 19. If any flaw exists, the circuit 26 selects a contact (b) of the switch 20 by using the output signal of a peak detector 29, the tracking error signal and a polarity signal to apply the tracking error signal and a signal pulse of opposite polarity to the amplifier 19. Thus, the tracking error signal level is changed depending on the type of the external disturbance and the servo loop gain is adjusted automatically to an optimum value so as to attain stable tracking against various external disturbance without complicated operation.

Development of an Efficient, Lightweight Switched-Mode Power Supply for Telecommunications Network Use

Abstract: This paper discusses the development of an efficient, lightweight switched-mode power supply (SMPS) for reducing cost and energy consumption and for simplifying essential maintenance procedures at small telephone offices. This SMPS consists of a voltage regulator, control circuits, protection circuits and five rectifier units including one redundant unit. Each rectifier unit weighs only 9 kg and can be handled by one person during maintenance. These features are realized through the employment of a single-ended forward-type 20-kHz conversion circuit. Furthermore, an effective decrease in rectifier unit weight and power loss is accomplished by designing the input filter to suppress high-frequency voltage ripple only, while designing for low-frequency voltage ripple to be absorbed in the conversion circuits. The efficiency of each rectifier unit is maximized by developing and using a new high-speed, high-voltage transistor for the conversion circuit and by improving the winding methods used in fabricating the transformer and the inductor, as well as by a loss reduction technique for the input filter. Accordingly, this SMPS can convert 200-volt, three-phase AC power to 48-volt DC with better than 90% efficiency, and it can supply output power up to 5 kW.

Analog modulation circuit for laser diode

Abstract: PURPOSE:To drive a laser diode under a stable and constant high frequency superimposing condition by controlling a sperimposed high frequency current amplitude in response to the temperature change in the differentiation quantum efficiency of the laser diode and applying amplitude limit so that the negative peak of a high frequency current is not below a prescribed positive current. CONSTITUTION:The amplitude of an analog signal current inputted to the laser diode 1 from a laser diode drive circuit 2 is increased/decreased in inversely proportion to the change in the differentiation quantum efficiency. Thus, after a voltage across a monitor resistor 6 is amplified by a differential amplifier 7 and the amplified result is fed to a peak detector 8. A differential amplifier 9 outputs a voltage difference between an output voltage of the peak detector 8 and a reference voltage Vr to a variable attenuator 11, which changes a high frequency current amplitude fed from a high frequency signal generator 4 to the laser diode 1. Thus, the amplitude of a superimposed high frequency optical signal is constant even when the differentiation quantum efficiency is changed. On the other hand, a high frequency amplitude limit circuit 12 clips the peak value of the superimposed high frequency voltage (current) inputted from the variable attenuator 11 so that the peak is not smaller than a prescribed positive clip voltage (current) inputted to a reference voltage (current) input terminal 13.

Recording and reproducing device

Abstract: PURPOSE:To shorten the non-recorded sound reproducing time by limiter-amplifying a signal from a reproducing head, inputting it to a comparator circuit after peak detection, delaying a voltage which causes a peak detection output to rise below the prescribed level during the prescribed period by means of a time-limit circuit to energize a mode switching circuit and switching it to a rapid traverse function. CONSTITUTION:Signals recorded on a magnetic tape are converted into electrical signals by the reproducing head 1, amplified by a reproduction signal amplifier circuit 2, further amplified up to a certain width value by a limiter amplifier circuit 3, and detected by a peak detector 4, thereby obtaining DC signals in proportion to their amplification values. Then they are inputted to the comparator circuit 5, and compared with a reference voltage below the prescribed level to detect the presence or absence of the reproduction signal. When the input signal goes below the prescribed level, the signal for rising at the point can be obtained. This signal is impressed to a time constant circuit 7, and the voltage for rising by the prescribed time constant from the point when the impressed signal rises can be obtained and compared with the reference voltage in the comparator circuit 8, thereby obtaining the voltage signal for rising at the point beyond said voltage. Thus the reproduction/rapid traverse mode switching circuit 9 is switched in a rapid traverse mode to raise the speed of a motor 10.

Tracking device for signal detector

Abstract: PURPOSE:To obtain a tracking device of a signal detector that can make positioning at maximum step of output of a magnetic head by providing a controlling circuit that controls a driving mechanism to stop the detector at a position where output of an information detector becomes maximum. CONSTITUTION:When a display part indicating section 18 designate a track to be sent to a microcomputer 16, a driving circuit 19 rotates a motor 2 based on sequence stored in a ROM 17. When the motor 2 passed a point before designated track, output from a head 4 becomes an envelope signal 28 through a head amplifier 12 and an envelope detector circuit 13, and simple held in a sample and hold circuit 14 by PG pulse from a rotation system 11. The output signal 30 is inputted to a peak detector circuit 15, and a pulse 31 is inputted to the microcomputer 16 at a point where the signal becomes maximum, and the step motor 2 is stopped.

Automatic linear compression circuit

Abstract: An automatic linear compression circuit for a telephone "handsfree" loudspeaker is provided. The circuit consists of a variable attenuator the level of attenuation of which is controlled by the input signal level. The input signal is passed through a positive peak detector to obtain a time averaged signal corresponding to the average positive peak values of the input signal and this time averaged signal is compared against a time increasing reference voltage. As long as the reference voltage is below the value of the time averaged signal a positive attenuator control signal is derived. This positive control signal keeps the attenuator portion of the circuit operative. In the attenuator the input voltage is sampled to a first capacitor. The first capacitor is subsequently connected to and disconnected from a second capacitor a number of times as long as the positive attenuator control signal is present. Each time this is done the voltage on the first capacitor is reduced by a factor depending on the capacitances of the two capacitors. After a predetermined time the voltage remaining on the first capacitor is passed through buffers and another capacitor to provide an attenuated output. The circuit is simple and flexible, permitting wide ranges in the operating parameters to be achieved simply by including one or more variable capacitors.

Turn-off circuit for gate turn-off thyristor

Abstract: A turn-off circuit for GTOs has a three-phase, full-wave rectifier. The output voltage of the three-phase, full-wave rectifier is applied as a turn-off power source to a charge/discharge capacitor.

Circuit responsive to fault current.

Abstract: A fault current protection circuit (1) with a summing current transformer (4) having two primary windings (5, 6) and one secondary winding (7) is shown and described, which circuit (1) has one trip circuit (8), which has a trip transistor (9) and two control inputs (10, 11) and is connected downstream of the secondary winding (7) of the summing current transformer (4). In the fault current protection circuit (1) according to the invention, the response sensitivity is increased in that a rectifier circuit (12) is connected to the secondary winding (7) of the summing current transformer (4), in that the rectifier circuit (12) contains a semiconductor valve (13) and a storage or smoothing capacitor (14), in that the positive pole (15) of the rectifier circuit (12) is connected to the first control input (10) of the trip circuit (8), and in that an auxiliary impedance (17), through which an auxiliary current flows, is provided between the negative pole (16) of the rectifier circuit (12) and the second control input (11) of the trip circuit (8). The rectifier circuit (12) is preferably configured as a Villard circuit and the auxiliary impedance (17) is preferably an auxiliary diode.

Horizontal synchronizing signal separator circuit

Abstract: PURPOSE:To prevent a horizontal synchronizing signal from being omitted even when there is an extreme level change in an input video signal by comparing the video signal with a peak detecting signal of the video signal obtained by a time constant circuit to separate the horizontal synchronous signal. CONSTITUTION:An input video signal is reversed and amplified by a reversing amplifier 1 and this output is branched into two, one is inputted to a negative input terminal of a comparator 2 and the other is inputted to a peak detector composing of a Schottky diode D1, capacitor C1 and a resistance R4 to detect the peak, inputted to a positive input terminal of the comparator 2 and separates the horizontal synchronous signal by comparing therewith. A reference voltage follows an end level of the horizontal synchronous signal of the video signal, compares therewith, thereby separates the horizontal synchronizing signal. Therefore, even if there is a rapid level change in the input video signal or there is a sag wave shape, the horizontal synchronizing signal is not omitted nor the synchronization is shifted in the television and the cause of the level change in a clamper is eliminated.

Bar code reader

Abstract: PURPOSE:To decrease the electric power consumed by a bar code reader, by constituting it of a photodetector, an amplifier connected to said detector,a peak detector containing a transistor connected to said amplifier, and a digital circuit connected to said detector CONSTITUTION:A transistor 506 is a pnp transistor, therefore, the collector can be fluctuated nearly up to a power supply voltage, and the amplitude of a detecting signal becomes maximum An output signal is obtained from the collector, therefore, an amplifier stage 8 is an inversion gain amplifier, and the gain is set by resistors 613, 614 which have been connected to the base of the amplifier transistor 506 The resistor 614 and the base resistor 613 of the series transistor 506 set an operating voltage of the collector of the transistor 506 When a detecting diode is used for a circuit of preceding technique in order to detect the peak, the diode makes the transistor 506 drive a peak holding circuit capacitor 204 and lowers a load of the transistor 506 In this way, a bar code reader of low power consumption type is obtained

Bias controlling device

Abstract: PURPOSE:To prevent destruction of a voltage control amplifier or while of a bias controlling device in the bias controlling device in which output of the voltage control amplifier is applied superposing on recording signals to a recording head by connecting a limiter to the voltage control amplifier. CONSTITUTION:In a normal state, current that flows in the recording head 1 is detected by a low-pass filter 4, and the quantity of effective bias is detected by a peak detector 5. The quantity of effective bias is compared with voltage of a reference voltage source 9 by a comparator 6, and output of the comparator 6 controls gain of the voltage control amplifier 10 to keep the quantity of effective bias constant. Output of the voltage control amplifier 10 is superposed on signal current applied from a signal input terminal 13 by an adder 14 and applied to the recording head 1. In the case where gain control of the voltage control amplifier 10 becomes impossible due to, for instance, the grounding of the inputting section of the peak detector 5, the generation of excessive output of the voltage control amplifier 10 is prevented by the limiter 17.

Phase-controlled automatic switching circuit

Abstract: There is disclosed a phase-controlled switching circuit, comprising a controlled rectifier (e.g. bidirectional triode thyristor); an amplifier connected at its output terminal to the gate of the controlled rectifier; an ac Wheatstone bridge having at one of its arms a variable resistance (e.g. thermistor to CdS photoconductive cell), said ac Wheatstone bridge being connected at one branch to the input terminal of the amplifier and at its other branch between the cathode and anode of the controlled rectifier through a load; a time constant circuit connected with the variable resistance; a pair of mechanical contacts (e.g. relay) connected in parallel with the controlled rectifier and a dc source for electrifying the whole circuit.

Rectifier circuit for providing limited output voltage range

Abstract: A rectifier circuit connected with a variable voltage AC source for providing a range of DC output voltages narrower than the range of AC voltage input by controllably switching between half-wave and full wave rectification

Circuit detecting open fiber transmission line

Abstract: PURPOSE:To acquire suitably hit of an optical input signal by connecting a detection circuit having a small time constant in the midpoint of an AGC circuit to extract a signal while not adopting the conventional method in a conventional system such that an output of a timing circuit is supervised. CONSTITUTION:The time constant of a peak detector 10 is selected to a value sufficiently larger than the time of the maximum consecutive 0 signals and sufficiently smaller than the time constant of a conventional peak detector. When the optical signal reaches an interrupting state (a), the input waveform of the detector 10 is decreased suddenly once, the gain is increased (b) according to the time constant of the feedback system and an output waveform of the detector 10 is as shown in a figure (c). A discrimination circuit 11 compares the said waveform with a reference voltage to output a pulse signal (d) and a leading/trailing detection circuit 12 outputs two pulse signals (e). A signal interruption detecting circuit 14 consists of two D-FF circuits, the 1st FF circuit is turned on by the first pulse of the pulse signal (e), and when the next pulse comes in this state, the light signal interruption is detected by turning on the 2nd FF circuit.

Input characteristics of the capacitor-input rectifier filter

Abstract: An extension of the fundamental theory of the capacitor-filter rectifier is presented. Expressions are obtained for the calculation of input power factor. Single-phase and three-phase circuits are considered. The input power factor is shown to be leading.