Showing papers on "RLC circuit published in 1982"

A complete DC analysis of the series resonant converter

Abstract: The dc-to-dc conversion ratio of the series resonant converter has been determined in the general discontinuous and continuous condection modes. This new analysis gives a complete description of the dc operation of the circuit for any load and for any switching frequency.

Energizing circuit for ultrasonic transducer

Abstract: An energizing circuit (10) for automatically driving a piezoelectric crystal transducer (Y1) at its resonant frequency includes a resonant circuit (12) of which the transducer (Y1) forms a capacitive element and the secondary winding (80) of a transformer (T2) forms an inductive element. In addition, the piezoelectric crystal itself acts as a series RLC circuit disposed in parallel with the parallel capacitive and inductive elements of the resonant circuit (12). Secondary winding (80) is inductively coupled with a primary winding (74) of the transformer (T2) which forms part of a driving circuit (14). The driving circuit (14) includes a switching circuit (20) connected between a power supply circuit (16) and the resonant circuit (12). Driving circuit (14) also includes a control circuit (28) which senses the difference between the vibrational frequency of transducer (Y1) and its resonant frequency and produces an appropriate level control signal which is transmitted to an oscillatory circuit (24) which in turn produces a switching signal of the desired frequency to actuate the switching circuit (20) at the proper rate to drive resonant circuit (12) at the resonant frequency of transducer (Y1) through the inductive coupling formed by transformer (T2).

Capacitance-type material level indicator

Abstract: A system and probe for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An rf oscillator has an output coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a function of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a predetermined level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. In the preferred embodiments of the invention disclosed, an automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit of the reference signal indicative of a predetermined reference material level.

Electronic ballast for a discharge lamp

Abstract: An electronic ballast for a discharge lamp (8) for restricting and stabilizing the lamps current. The ballast comprises a high frequency oscillator for connection to a D.C. supply which consists of two transistors (1,2) connected in series, with a base drive transformer (3) coupled between them to bring the transistors (1,2) into alternating phase operation. A resonance circuit connected in series with the primary winding (4) of the transformer (3), comprises an inductor (7), resonance capacitors (10 and 11) and a capacitor (9) coupled in parallel with the lamp (8). The lamp (8) is, in turn, connected in series with the resonance circuit. In addition, a filter capacitor (c) having a high charging ability is coupled between the terminals of the D.C. supply. The resonance capacitors (10 and 11) are connected in series between the terminals of the D.C. supply, and diodes (23, 24) are connected parallel to them, and the last part of the resonance circuit is connected to a point common for the capacitors and the diodes, e.g. by means of the electrode (8a) of the lamp (8).

Lamp driver circuits

Abstract: The invention provides a lamp driver circuit for discharge lamps, in particular fluorescent lamps. An inverter (12) receiving DC provides a high frequency AC output. A resonant circuit includes a capacitor (C25) connected across the lamp (13) and a ballast inductor (L2) in series with them. A control arrangement (15,16) causes the inverter (12) to operate at a frequency above the resonant frequency of the lamp when initially switched on. It is then caused to sweep down in frequency towards the resonance frequency so that the lamp strikes as a result of the magnified voltage applied to it. After the lamp has struck the frequency drops to a suitable running frequency. If the lamp strikes a circuit (L25, 201, 17) controls the frequency to limit the lamp voltage. Another circuit (DCT1, 203, P1, 17') controls the lamp frequency for dimming purposes. The circuit when operative at the initial higher frequency provides heating current through the filament before the lamp strikes since the capacitor (C25) shunts the lamp at such frequency.

Regulated AC-DC converter having saturation inductance in resonant circuit

Abstract: A switching power source device, in which a DC voltage obtained by rectifying an AC voltage is converted by switching elements into an AC voltage, which is subjected to voltage conversion by a transformer and rectified by a rectifier circuit to output a DC voltage therefrom In one embodiment, a resonance capacitor and a saturable transformer form a series resonant circuit, and switching elements are subjected to frequency modulation control In another embodiment, an inductor connected in parallel with a non-saturable transformer, and a capacitor connected in series to the same transformer, form a series resonant circuit, and the switching elements are subjected to frequency modulation control In each embodiment, the series resonant circuit is subjected to frequency modulation control, and the electric currents from the switching elements do not rise and fall suddenly Accordingly, switching losses and noise can be minimized, and the output voltages can be controlled easily

Transmitter/receiver circuit for signal transmission over power wiring

Abstract: A system transmits and receives control signals for various types of indoor devices using the existing power wiring in houses and buildings. The transmitter section of the power wiring transmission system is provided with a circuit in which the output of a sine wave oscillator is fed to an emitter-follower through a photocoupler and this output is then fed to the indoor power distribution line through a series resonance circuit after stepping down with a transformer; and the receiving section is provided with a circuit in which the signal from the distribution line is fed to a parallel resonance circuit after passing through a series resonance circuit. Moreover, the input and output sections are resistor terminated.

Quarter-Wavelength Coupled Variable Bandstop and Bandpass Filters Using Varactor Modes

Abstract: A quarter-wavelength coupled bandstop filter rising varactor diodes for the 6-GHz band has been proposed and tested. Frequency giving maximum attenuation varies from 4.4 GHz-7 GHz. A quarter-wavelength coupled variable bandpass filter using varactor diodes for the 4-GHz band is also proposed and tested. The passband width varies from 730 MHz-1.22 GHz. The center frequency of the filter can also be changed.

Electrostatic voltage detecting device

Abstract: An electrostatic voltage detecting device includes a detecting electrode for detecting an electrostatic voltage generated by charge on a recording medium, a variable capacitance diode whose capacitance changes according to an output signal applied from the detecting electrode, a primary coil combined with the variable capacitance diode to form a resonance circuit, an oscillator for supplying an oscillating output signal of predetermined frequency to the primary coil, and a secondary coil inductively coupled with the primary coil. The capacitance of the variable capacitance diode changes according to an output voltage applied from the detecting electrode to vary a resonance frequency of the resonance circuit and consequently a voltage induced in the secondary coil.

Multiple low-pressure discharge lamp operating circuit

Abstract: To operate at least one, and preferably a plurality of fluorescent lamps, aelf-oscillating transistor push-pull switching oscillator, using two similar transistors (T1, T2), is connected to respective lamps (3, 3', 3"), with an oscillatory circuit (4, 4', 4") to operate at audio, supersonic or low high frequency, for example in the 20 kHz range. Each lamp operating circuit has an individual series resonance circuit (4, 4', 4") which includes a ballast inductance (L1, L1', L1") and a capacitor (C1, C1', C1"). For multiple operation, the respective lamp operating circuits are connected in parallel. A special starting circuit (10) and a control circuit (9a, 9b; L2, L2', L2"; L3, L3', L3") for the switching transistors insures low-loss operation. The transistors (T1, T2) are the deenergized in case of malfunction by a monitoring circuit (11; L4, L 4', L4") which includes a thyristor (21) which fires to disable oscillatory operation of the oscillator circuit and thereby prevents over-voltage conditions upon electrical removal of a lamp load.

Protected low-pressure discharge lamp operating circuit

Abstract: A fluorescent lamp control circuit which provides power at high frequency,or example in the order of 35 kHz, includes a push-pull oscillator circuit having two transistors (T1, T2), an inductance element (L1, L1'), and a capacitor (C1, C1') to supply the lamps (3, 3'). To prevent dangerous high voltages upon removal of the lamp load, connected to the oscillatory circuit and to the series resonance circuit, upon removal of failure of a lamp, a protective circuit is provided formed by a thyristor (TH) connected to short-circuit at least one of the transistors (T1) of the oscillatory circuit. Control energy is derived directly from the high-voltage supply by a rectifier (D1, D1') connected to the inductance (L1, L1') of the series resonance circuit, so that sufficient and reliable switching energy for the protective thyristor (TH) is always available, the firing criterion therefor being determined by the breakdown voltage of a breakdown element such as a diac (22) connected to a voltage divider (20, 21) and receiving its control voltage also from the high-voltage connection of the series resonance circuit (4) including the inductance, which also feeds the power supply capacitor (C3) for the thyristor (TH).

High frequency series resonant dc-dc converter

Abstract: A dc-dc converter employs a series resonant circuit which is driven by square waves of current. By adjusting the frequency of the square waves of current above the resonant point or by holding the frequency constant and varying the current supplied to the converter, the voltage on the resonant components can be stepped up and controlled. Switching losses in the inverter gate turn-off devices are low since the inverter feeds a lagging load which allows the use of lossless snubbers.

The generalized Lagrange formulation for nonlinear RLC networks

Abstract: Based on the concept of generalized Euler-Lagrange equations, this paper develops a Lagrange formulation of RLC networks of considerably broad scope. It is shown that the generalized Lagrange equations along with a set of compatibility constraint equations represents a set of governing differential equations of order equal to the order of complexity of the network. In this method the generalized coordinates include capacitor charges and inductor fluxes and the generalized velocities are comprised of an independent set of capacitor voltages and inductor currents. The generalized Hamilton equations are also developed and the connection with the Brayton-Moser equations is established.

The Generalized L,agrange Formulation for Nonlinear RLC Networks

Abstract: Based on the concept of generalized Euler-Lagrange equations, this paper develops a Lagrange formulation of RLC networks of considerably broad scope. It is shown tbat the generalized Lagrange equations along with a set of compatibility constraint equations represents a set of governing differential equations of order equal to the order of complexity of the network. In this method the generalized coordinates include capacitor charges and inductor fluxes and the generalized velocities are comprised of an independent set of capacitor voltages and inductor currents. The generalized Hamilton equations are also developed and the connection witb the Brayton-Moser equations is established.

Object displacement sensor and device for measuring the rotation speed and vibration frequency of a rotor

Abstract: An object displacement sensor specifically adapted for high speed counting of passing nonmagnetic objects is disclosed which has a resonant circuit made up of at least one inductive element 2 and a condensor whose one plate consists of a conductive surface 3 and whose other plate is successively formed by each object 4 passing close to this surface 3. The resonant circuit is connected to a first oscillator 6 which determines the functioning frequency such that the signal issued from the first oscillator 6 is modulated in frequency to the rhythm of the passage of the objects 4.

A New Current Mode Sine Wave Inverter

Abstract: A new sine wave inverter topology is presented. Its current mode operation is described, and its performance is compared to that of the more conventional series, or voltage mode, inverter. It is shown that higher frequency and more efficient operation is possible. A parity simulation of the new circuit is performed and parametric operating data are presented in a form useful for design purposes. The simulation results are verified on a 250 W 10-20 kHz hardware version of the current mode sine wave inverter.

Method of manufacturing capacitance-type material level indicator probe

Abstract: A system and probe for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An rf oscillator has an output coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a function of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a predetermined level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. In the preferred embodiments of the invention disclosed, an automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit of the reference signal indicative of a predetermined reference material level.

Ground fault detection circuit

Abstract: A current monitoring circuit of a ground fault detector which receives its input from the secondary winding of an annular core transformer through which extends the current carrying leads being monitored. A resistor and capacitor are connected in series between the secondary winding and an AC amplifier to form an RLC band pass filter to minimize the circuits sensitivity to noise outside of the band of frequencies of interest. The sensitivity of the circuit to temperature changes due to fluctuations of the inductance is reduced by choosing an inductance value sufficiently high to ensure that it is not reduced to below a critical level at which sensitivity is effected.

Band pass filter

Abstract: A band-pass filter circuit has series elements, comprising a parallel resonant circuit and a first inductance, and shunt elements comprising a series resonant circuit and a second inductance, the resonant circuits comprising variable capacitances to permit variation of the frequency over a frequency band. The second inductance may be a transformer. The variable capacitances may be constituted by a plurality of switchable component capacitances, having switches connected between the capacitances and ground.

Line operated fluorescent lamp inverter ballast

Abstract: Ballast circuit for fluorescent lights made up of the combination of a source of electrical energy (32, 33), a resonant circuit (18, 22), a switch means (11, 12) for connecting the source of electricity (32, 33) to the resonant circuit (18, 22), means (20) to connect the resonant circuit (18, 22) to a load (55), a resonant current monitor (13) controlling the switch means (11, 12) in synchronism with the resonant current so that the switch means (11, 12) switches the resonant current when the resonant current passes through zero. The resonant current monitor (13) is a current transformer having a primary winding (14) connected in series with the resonant circuit (18, 22) and two secondary windings (15, 16) connected to the bases (35, 43) of the two switching transistors (11, 12) in a two transistor inverter circuit at a polarity that will switch one of the transistors (11, 12) on and the other off at the time current passes through zero. This is the optimum time to switch the transistors (11, 12) since the current flowing through the transistors (11, 12) is passingthrough zero at that time and therefore the transistors (11, 12) operate at maximum efficiency and there are minimum switching losses and improves the efficiency of the circuit. The circuit will automatically adjust the switching frequency to the changed resonant frequency should the value of the inductor or the capacitor degrade and therefore change, and the switching losses will therefore be maintained at minimum.

Television receiver standby circuit

Abstract: A deflection generator of a television receiver includes a trace switch that during normal mode of operation is switched at a deflection rate to generate scanning current in a deflection winding. The deflection generator includes a retrace capacitance for forming a retrace resonant circuit with the deflection winding to produce a retrace pulse voltage. A load circuit is coupled to the deflection generator and is energized by the retrace pulse voltage during normal operation. A remote control circuit develops a remote ON-OFF command signal. A standby circuit is series coupled with the deflection generator and is responsive to a remote ON-OFF command signal for producing a substantially short circuited trace switch upon receipt of the OFF-state of the command signal. The retrace pulse voltage collapses and places the load circuit in a standby mode of operation.

Ripple determination for switch-mode DC/DC converters

Abstract: The state-space average model of a DC/DC convertor is used directly to obtain expressions for the ripple in any state or output of the model. This is used to rederive the current-ripple trade-off conditions in the Cuk convertor in a more straightforward fashion. In addition, it is shown that the buck convertor with input filter inductor and storage inductor coupling, and boost convertor with output filter inductor and storage inductor coupling, have similar ripple behaviour to the Cuk convertor at one port when the other port ripple is zero. For the case of equal input and output current ripples, the coupled inductor boost and buck are shown to be superior to the Cuk convertor.

Variable horizontal deflection circuit capable of providing east-west pincushion correction

Abstract: A controllable switch operated at the horizontal deflection rate is coupled to a horizontal deflection winding to generate scanning current during a trace interval of a deflection cycle. A deflection retrace capacitor forms a retrace resonant circuit with the deflection winding during the retrace interval. A supply inductance such as a winding of a horizontal output transformer is coupled either conductively or magnetically to a source of supply energy. A second capacitor is coupled to the supply inductance and to the controllable switch and forms a second resonant circuit with the supply inductance within the retrace interval to generate a pulse voltage. The pulse voltage energizes a load circuit such as the ultor high voltage circuit. A modulation inductance is coupled to a source of modulation signals and to the deflection winding and supplies a modulation current to the retrace resonant circuit to modulate the amplitude of the scanning current without modulating the amplitude of the supply inductance pulse voltage. The modulation may occur at a vertical rate to provide east-west pincushion distortion correction.

Parametric electric machine

Abstract: A parametric electric machine consists of a series resonant circuit, which has a capacitance (C) which is adapted to be mechanically varied, an inductance (L) and a resistance (R). The no-load values of the capacitance (Co), inductance (Lo) and resistance (Ro) fulfill the threshold condition ##EQU1## and at least one of the parameters L, R and C of the resonant circuit is a function of the current flowing in the resonant circuit.

Proximity switch with oppositely polarized coils

Abstract: A proximity switch comprising a detection coil, a first capacitor connected in parallel with the detection coil for forming a resonant circuit, an auxiliary coil, a second capacitor connected in parallel with the auxiliary coil for forming a resonant circuit, an oscillation circuit connected to the detection and auxiliary coils which are connected in series and in reverse winding directions, and an output circuit connected to the oscillation circuit for receiving variations in output generated from the oscillation circuit, the second capacitor having a capacitance larger than that of the first capacitor so that the second capacitor has a reduced low impedance at an oscillation frequency determined by the detection coil and the first capacitor.

Self-tuning narrow-band receiver

Abstract: To implement a narrow-band receiver with extremely high quality factor and, respectively, narrow bandwidth, it is proposed to use a circuit capable of resonating which can be adjusted by electrical quantities with respect to the frequency of resonance and quality factor, that a microcomputer continuously measures the frequency and bandwidth and, on the basis of these measurement results, outputs the electrical adjusting quantities for the resonant circuit in such a manner that the desired frequency and bandwidths are obtained accurately.

Phase-locked loop circuit with variable bandwidth filter

Abstract: A phase-locked loop circuit comprises an oscillator, a phase comparator which compares the phase of an input signal with the phase of an oscillator signal, a detector which detects when the phase-locked loop circuit is locked within a predetermined frequency range and produces a corresponding lock detecting signal, and a filter circuit including a variable current source which produces a variable current in response to a change of state of the lock detecting signal to control the bandwidth of the filter circuit, a filter element which receives the variable current, a differential amplifier which receives the phase-compared signal, a current mirror circuit which receives the variable current from the variable current source, and a buffer circuit connected to the filter element which supplies an output signal to the oscillator to lock the frequency of the oscillator signal to the frequency of the input signal.

Magnetically tuned resonant circuit

Abstract: A magnetically tuned resonant circuit for selectively coupling radio frequency (r.f.) energy between an input coupling circuit and an output coupling circuit through a resonant body disposed between such coupling circuits. Each coupling circuit includes a plurality of spaced conductors which are arranged to selectively spatially distribute r.f. energy fed thereto in order to provide, in the region where the resonant body is disposed, a magnetic field having a predetermined spatial distribution. Such magnetic field distribution is selected in accordance with characteristics of the resonant body to reduce coupling of unwanted spurious r.f. energy through the magnetically tuned resonant circuit. Further, a ground plane conductor associated with such coupling circuits has a selected portion thereof removed to provide a void therein, and a portion of the resonant body is disposed within the void provided in the ground plane. The size of the void is selected to increase coupling of r.f. energy through the resonant body, between the input and the output coupling circuits and to reduce coupling of r.f. energy between the body and the ground plane conductor and hence the r.f. energy loss concomitant therewith, without substantially affecting the desired coupling between the coupling circuits.

Dc-ac conventer

Abstract: 1. A d.c./a.c. converter for feeding one load circuit or a plurality of load circuits connected in parallel, where each load circuit has a series resonant circuit and a discharge lamp (E, E') with heatable electrodes, and the electrodes are arranged in the load circuit with the capacitor (C2) of the series resonant circuit arranged between the two electrodes of the discharge lamp ; with two switches (T1, T3) which switch periodically in alternation, of which one (T1) is arranged between the load circuit or load circuits and a direct voltage source and the other one (T3) is arranged parallel to the load circuit ; with a bistable switching device (T4) having an operating state and a blocking state ; with a control circuit for the bistable switching device, wherein an RC-element (R3, C9) is arranged as a parallel combination coupled to the load circuits and dimensioned such that in the event of a discharge lamp (E, E') not igniting, the switching device trips into the blocking state and disconnects the d.c./a.c. converter ; and with a holding circuit which maintains the bistable switching device in its blocking state ; characterised in that the holding circuit is passed via one of the electrodes of the discharge lamp of each load circuit.

Tuning system for a high frequency receiver utilizing a controllable inductor

Abstract: The tuning system for a high frequency receiver, particularly an AM receiver for vehicles, comprises a tunable input resonance circuit having a variable inductance formed by the signal winding of a controllable inductor. The control winding of the inductor is supplied with a control current. The control winding is simultaneously used as the frequency determinative element of an auxiliary oscillator. A frequency control loop is used to adjust the oscillating frequency of the auxiliary oscillator by adjustment of the control current. The tuning system allows a selective coupling between the tuned antenna input circuit and the rf front end of the receiver.