Showing papers on "RLC circuit published in 1978"

Intracranial pressure implant

Abstract: An implantable transensor device containing a passive RF resonant circuit having a natural frequency influenced by the pressure of the sensor's environment in a body cavity of a living entity. The circuit of the transensor includes an inductor and a capacitor, at least one of which varies in value in direct relation to variation of environmental pressure to change the resonant frequency of the circuit. The circuit can be externally interrogated to determine the resonant frequency thereof at any point in time by the imposition thereon of swept frequency electromagnetic radiation provided by a monitoring device which determines when some of the radiation is absorbed as a result of the frequency of the radiation being the same as the resonant frequency of the transensor circuit. An imposed relationship exists between the sensed environmental pressure, and the reactance of the reactive components of the circuit. A natural relationship exists between pressure sensitive reactance, and the resonant frequency of the circuit. As a result, an increase in environmental pressure causes a corresponding increase in frequency and a decrease in environmental pressure causes a decrease in frequency.

Reversal protection for rlc defibrillator

Abstract: REVERSAL PROTECTION FOR RLC DEFIBRILLATOR Abstract of the Invention A defibrillator, or alternatively, paddles therefor adapted with the wave-forming inductance of the discharge circuit disposed between the two paddles of the discharge circuit of the defibrillator and is so disposed in the paddles as to couple in a cancelling manner when the paddles are placed face-to-face. In a preferred embodiment, the waveform inductance is split substantially equally in each of the two paddles wherein each of the inductors have a value of substantially half the total necessary inductance for the forming of the waveform for the defibrillating wave. The respective coils of the inductors are wound in reverse directions, one with respect to the other so that the total inductance generated in a discharge directly through the paddles is substantially nil.

A 95-Percent Efficient 1-kW DC Converter with an Internal Frequency of 50 kHz

Abstract: A dc converter is described which processes 1-kW power with an internal frequency of 50 kHz at an efficiency of 95 percent and which provides ohmic isolation between its input and output ports. It was experimentally verified that the customary penalty of lowered efficiency at higher levels of frequency could be avoided by the use of series resonant circuits which favor the switching elements. The output characteristic of the system is that of a voltage limited current source. The road toward development of the technology of reliable and efficient dc converters with yet higher power densities appears possible.

An improved interpretation of Mason's model for piezoelectric plate transducers

Abstract: A new interpretation of Mason?s model (1948) for a piezoelectric plate transducer is presented. The network model emphasizes a series connection for the two acoustic loads while utilizing lumped impedance elements expressed 88 functions of the delay operator Z = exp ST. An exact analysis of the plate dynamics permits a simplifii resistive model for conditions of light asymmetry in acoustic loading. A simplified resistive structure provides transmission (reception) loss near the halfwave resonance. Air backed front loading b modeled. Finally, RLC lumped component models are provided fo1 evaluation of transducers as lumped-element filters.

Current control circuit for horizontal deflection coil of television receiver

Abstract: In a circuit for controlling the current flow through a coil, such as, the horizontal deflection coil of a television receiver, a first switching circuit including a first switching transistor and a first damper diode is connected in parallel with a first resonant circuit including a first capacitor and a first coil which is the coil through which the current flow is to be controlled, a second switching circuit including a second switching transistor and a second damper diode is connected in parallel with a second resonant circuit including a second capacitor and a second coil, a charging capacitor is connected in a common current path for the first and second resonant circuits, and switching signals of the same frequency, for example, the horizontal frequency of a video signal, are applied to the first and second switching transistors with the phase difference between such signals being controlled to vary the voltage across the charging capacitor and hence the current flowing through the first coil. The phase difference between the switching signals is varied or modulated by a parabolic correcting signal having the vertical rate or frequency of a video signal in the case where a side pin-cushion distortion of the raster of a cathode ray tube is to be corrected, or the phase difference can be modulated by a correcting signal corresponding to the electron beam current or anode voltage in the cathode ray tube so as to stabilize the horizontal dimension of the raster.

An Active Frequency Technique for Precise Measurements on Dynamic Microwave Cavity Perturbations

Abstract: A new method for the dynamic measurement of the passive parameters of a microwave cavity is described. Both the resonant frequency (f0s) and the loaded Q factor (QLs,) are measured simultaneously from active frequency signals generated by a closedloop circuit containing the test cavity. Resonant frequency deviations of up to 20 MHz are measured with an accuracy of better than ±0.25 percent, and loaded Q-factor variations (from 500 to 7000) are measured with an accuracy of better than ±1.2 percent. The unperturbed cavity resonance was at 2452.0249 MHz, and the time of measurement of each cavity parameter was < 1 s.

Electronic system for determining blood sedimentation rate using a continually retuned resonant circuit

Abstract: A device for determining the blood sedimentation rate in a substantially vertical test tube, where the electrical or magnetic property of a given volume of liquid, which is changed by the settling of the erythrocytes in the test tube is measured as a function of time, by means of an oscillator with an output circuit which is completed via the column of liquid to be measured and by means of a measured-value pickup, having an output signal of which a pulse sequence of a definite frequency can be fed to a pulse counter with an indicating device. A coil-capacitor resonant circuit is coupled inductively with its coil or capacitively with its capacitor to liquid at a definite height in the test tube. An additional coil inductively coupled to the resonant-circuit coil serves as the measuring pickup. A retuning circuit is provided for the retuning of the resonance of the tuned L-C circuit which is detuned by the lowering of the boundary layer between the erythrocyte column and the plasma in the test tube. A pulse counter connected to the retuning circuit determines the number of retuning operations which correspond to the blood sedimentation rate. The electrical or magnetic property of the liquid, which changes due to sedimentation, causes the L-C oscillation range to be detuned, and can be the dielectric constant or the permeability of the liquid volume undergoing measurement.

Apparatus for determining the state of each of a plurality of bi-state devices

Abstract: In a system for determining the state of each of a plurality of bi-state devices located remotely from a central station, a group of resonant circuits is connected to a multi-frequency excitation source. A bi-state device is then connected to each resonant circuit. When a particular bi-state device is in one position and its corresponding resonant circuit is being excited by its resonant frequency, a maximum amplitude signal is produced by the resonant circuit. When the bi-state device is in the other position, a lesser amplitude signal is produced. The signal produced by each resonant circuit is fed to detection circuitry and in turn to display circuitry. Thus the state of each of the plurality of bi-state devices is indicated by the display circuitry. The two wire line in addition may serve as a transmission medium for a DC control signal used for controlling a remotely located process control valve or for controlling other final actuators.

Resonant circuit with two partial inductances

Abstract: A control circuit for measuring the distance between a workpiece and an electrode which is formed as inductance and is part of a resonant circuit as a frequency-determining element whereby the frequency variations of the resonant circuit for producing voltage and/or current changes which are proportional to a distance are connected to a measuring circuit and includes at least two partial inductances in the resonant circuit with one inductance being represented by the electrode and the other being a stationary resonant circuit arranged at a distance from the electrode and in the immediate influence sphere of the workpiece.

Coaxial type filter

Abstract: PURPOSE: To make a filter small-size, make adjustment needless for the filter and improve a vibration-proof property by using a dielectric substrate in inter-step connection parts in the filter constitution. CONSTITUTION: Dielectric substrate 500 provided to support one ends of plural resonance circuit elements 47 to 49 is provided, and conductor regions are formed on one face or both faces of this substrate 500 correspondingly to elements 47 to 49 and are matched to inter-step connections, and shielding plates 34 and 35 are provided between elements 47 to 49. As a result, the filter can be made small-size, and no adjustment is required for the filter, and the vibration-proof property can be improved. COPYRIGHT: (C)1980,JPO&Japio

Method and apparatus for investigating dielectric semiconductor materials

Abstract: A method and apparatus are disclosed for determining electrical properties of dielectric and semiconducting materials and devices by admittance measurement. According to the disclosed method, a sample contained between electrodes is subjected to an essentially sinusoidal radio frequency signal. Simultaneously, the sample is subjected to a perturbation as may be produced, e.g., by thermal, optical, or electron irradiation. Admittance is determined as a current-to-voltage ratio. According to the invention, signal-to-noise ratio in the output signal is enhanced by establishing a resonant circuit formed by the sample capacitor and an appropriately selected inductor element and pulsing the perturbation synchronous to the resulting resonant oscillation.

Parametric adjustment circuit

Abstract: An improved frequency sensitive circuit capable of adjusting one or more of its parameters in order to shunt an adjustable amount of electrical signal to a current sink, thereby controlling the amplitude of the signal. The frequency sensitive circuit is connected to the wiper of a potentiometer that is placed across the inputs of a difference amplifier in order to control the peak value of the cut or boost in the signal. The frequency sensitive circuit includes a shunt impedance connected between the wiper of the potentiometer and the current sink. A resonant circuit is connected to the impedance and is tuned to an adjustable resonant frequency. A compensation circuit, such as a difference amplifier referenced to the wiper, couples the output of the resonant circuit to the shunt impedance so that the impedance of the frequency sensitive circuit approaches infinity as the frequency of the electrical signal is displaced from the resonant frequency. As a result, the frequency sensitive circuit has substantially no effect on the overall amplitude of the electrical signal at frequencies widely displaced from the resonant frequency.

Self-oscillation mixer circuits

Abstract: A self-oscillation mixer circuit includes a cascade amplifier circuitry which is composed of a first transistor of a common emitter connection having a collector connected to an emitter of a second transistor of a common base connection, a filter circuitry for deriving an intermediate frequency signal and a resonance circuit adapted to resonate at a local oscillation frequency being connected to the collector of the second transistor and a feedback circuitry connected between the resonance circuitry and the emitter of the first transistor.

Regulated deflection circuit

Abstract: A deflection generator of a television receiver is coupled to a deflection winding for generating scanning current during a deflection cycle. The generator includes a retrace capacitor coupled to the deflection winding for forming a retrace resonant circuit therewith to produce a retrace pulse voltage during a retrace interval of the deflection cycle. An inductor and another capacitor form a second resonant circuit that is coupled to the retrace resonant circuit. A switching arrangement is coupled to a source of energy and the second resonant circuit in a push-pull configuration. The switching arrangement is responsive to a deflection rate switching signal to store during trace a controllable amount of energy from the source in the second resonant circuit. This stored energy is then transferred to the retrace resonant circuit during the retrace interval to replenish losses sustained during the deflection cycle.

Video signal play-back circuit

Abstract: In a video signal play-back circuit connected so that a play-back signal from a magnetic head may be applied to an amplifier circuit through a resonance circuit which consists of an inductance element and a capacitance element, a resistor for adjusting the quality factor Q of the resonance circuit is connected between one terminal of the resonance circuit and one output terminal of the amplifier circuit, thereby to reduce thermal noises which develop from the Q adjusting resistor.

Cycloconverter and method for its operation

Abstract: A method of operating a cycloconverter which is adapted for use with a load in the form of a parallel resonant circuit and for use with an intermediate d-c link supplied by an a-c voltage source and including a smoothing choke and a controlled rectifier, the cycloconverter including an inverter circuit comprising a bridge circuit having output terminals adapted to be connected to the load and input terminals adapted to be connected to the d-c link, in which starting of the cycloconverter is realized by firing the thyristors of an auxiliary commutating device for a time interval sufficient to charge commutation capacitors to a predetermined voltage and the thyristors of the inverter then fired for a time interval sufficient to result in a current of predetermined magnitude, the latter being held constant by controlling the rectifier in the d-c link, and, thereupon, prior to each zero crossing of the resonant circuit voltage, first firing the thyristors of the auxiliary device followed, after a predetermined time interval, by the firing of the thyristors of the inverter and continuing this until the resonant circuit voltage reaches a value sufficient for direct commutation.

Flyback type power supply

Abstract: A flyback type power supply in which dissipation losses associated with switch transition time are substantially eliminated by performing all switching operations at or near zero current by the use of a plurality of resonant circuits. In a first resonant circuit an intermediate storage capacitor is resonantly charged through an inductor and a first switch until, after a half sinewave of charging current, the voltage on the capacitor is twice the input supply voltage. The capacitor is then discharged through a second switch and the primary inductance of a flyback transformer having rectifiers on the secondary that are back-biased initially so as to provide a resonant current buildup in the primary winding with an amplitude that follows a sinewave function, the primary voltage following a cosine function. At the peak of the sinewave of current in the primary, the voltage across the transformer reverses in polarity, continuing to follow a cosinewave shape until the secondary voltage exceeds the voltage on the network to be charged. The primary current is then discontinued and the remaining energy stored in the transformer inductance is transferred to the circuit to be charged.

Tunable uhf oscillator with harmonic limitation

Abstract: In a tunable UHF transistor oscillator with a frequency determining resonating LC circuit reduction of the harmonic to fundamental ratio is obtained through the use of an output circuit consisting of an output resistor connected in parallel with a resistor voltage divider a part of which is used as a damping resistor for a second controllable tuned circuit comprising an inductor with a larger inductance than that of the frequency determining circuit and the same capacitance and a non linear circuit between the control voltage source and the adjustable capacitor of said second circuit. The output is taken across the second tuned circuit. Coupling between the transistor and the frequency determining circuit is low.

Antenna tuning circuit

Abstract: An antenna tuning circuit of the type having a first variable capacitance diode connected in parallel with a coil to form a resonance circuit and a second variable capacitance diode through which the resonance circuit is connected to an antenna, in which the connection position of the first variable capacitance diode to the coil is adapted to be changed for the reduction in the image interference ratio. Reductions in the maximum capacitance and the ratio between the maximum capacitance and the minimum capacitance required for the variable capacitance diodes are also intended by the connection of a third variable capacitance diode to the antenna side of the second variable capacitance diode.

Circuit for compensating harmonic currents in an electric consumer arrangement

Abstract: To improve the effect of a filter circuit for the harmonics, which contains an L-C-R series resonant circuit in at least one loop, a variable supplementary current excitation which compensates the residual harmonic current in the consumer arrangement at least approximately, is coupled into the series resonant circuit, the supplementary current excitation preferably being supplied by a compensation transformer which is controlled by the current in the loop, the compensation transformer being excited by a source and controlled by an auxiliary transformer arranged in the loop.

Automatic warning system for tyre pressure - includes resonant circuit on tyre valve and tuned detector circuit on chassis

Abstract: The tyre pressure monitor has a resonant circuit(5) on the wheel, operated when the tyre pressure falls below the set value This provides a strong signal which is detected by an oscillator circuit(10) on the chassis, which in turn operates the warning circuit (12) on the dashboard The system is highly sensitive and is unaffected by outside interference, such as from the ignition circuit The resonant circuit is tuned to the oscillator

Signal generator, especially for ringing current in telecommunication system

Abstract: A circuit arrangement for feeding a sinusoidal signal current to a wide range of loads, such as ringing current transmitted over subscriber lines from a telephone exchange, comprises a modulator which converts a rectified sine wave into a sequence of unipolar constant-amplitude pulses of varying width controlling, through a logic network, the energization of a load impedance via a resonant circuit from a d-c source. A switchover unit, including a transistor bridge having a diagonal connected across the d-c source, receives command signals from the logic network in response to the control pulses and to the outputs of two sensors determining the instant polarities of the load voltage and the load current in the output of the resonant circuit. The switchover unit produces a train of bipolar driving pulses, of constant amplitude and synchronized with the control pulses, whose polarity changes with alternate half-cycles of the sine wave fed in rectified form to the modulator.

Induction heater with power transistor switches - supplying resonant circuit containing heating coil and controlled, current-limiting choke

Abstract: The induction heater has the oscillator's induction coil acting as the heating coil for the cooking utensil A parallel resonant circuit is connected in series with a controlled, current-limiting choke This series circuit is connected via controlled power switches to a current supply The switches are opened and closed alternately so that the series circuit is supplied with an alternating current When the switches are being turned-off this current passes via a shunt path comprising capacitors and diodes The advantage lies in causing no rf interference and in being efficient whilst needing relatively few components

Lower bounds on the summed absolute and squared voltage transfer sensitivities in RLC networks

Abstract: Simple lower bounds are presented for the summed absolute and summed squared sensitivities of voltage transfer to components in passive RLC networks. Those bounds are functions of the voltage transfer only, and independent of the circuit configuration.

Hydrogen and oxygen prodn. cell - with rectifier fed by parallel resonant circuit with inductance and capacitance

Abstract: Cell for the decomposition of water to produce H2 and O2 is fed from a rectifier which is connected to the power supply through a parallel resonance circuit, consisting of resistances, inductances and capacitances. Arrangement enables several electrolytic cells to be connected in series. The active current flowing through the circuit is increased only little by the series connection.

Microwave low-pass band-pass filter circuit - has several longitudinal and lateral branches and has parallel and series resonant circuits

Abstract: A low pass or bandpass filter consists of a number of longitudinal branches which have lateral branches between them. The longitudinal branches contain one or more parallel resonant circuits, in which when designed as a low pass filter the lateral branches consist of a series resonant circuit (Pk), and when designed as a band-pass each lateral branch consists of a pair of series resonant circuits. The filter circuit is intended especially for use in a microwave network with very small insertion loss.

Basic Operating Characteristics of a High-Frequency Inverter with Capacitive Voltage Multiplier

Abstract: The integrodifferential equations of the equivalent circuit are solved, and the operating characteristics are derived for a currentfed thyristor inverter. This inverter can be especially useful as a highfrequency power source for induction heating.

Stabilisation circuit for microwave oscillator - has high Q resonant circuit coupled to waveguide via slot at one sixth wavelength from active device

Abstract: The stabilisation circuit is used with a microwave oscillator whose active device, e.g. a negative resistance device is located between the broad faces of a section of rectangular waveguide operated below its cutoff frequency. The distance between the active device and a coupling slit in the narrow face of the waveguide is roughly 6. The coupling slit between oscillator and resonator is chosen so that the latter determines the former's frequency.

Signal detector circuit for video disc player

Abstract: PURPOSE:To secure an accurate detection for the recorded signal, by containing the variable capacity diode into the UHF resonance circuit to vary the DC bias and the resonance frequency and also measuring the diode DC output component for signal detection.

Constant current power supply circuit for magnetron

Abstract: PURPOSE:To linearly adjust the output of magnetron by controlling the trigger phase of a thyristor in the control circuit according to a variation of high frequency current flowing in the resonance circuit.