Showing papers on "RLC circuit published in 1975"

Resonant tag circuits having one or more fusible links

Abstract: A planar resonant tag circuit especially useful in electronic security systems wherein the value of a circuit component can be electrically and selectively altered by one or more fusible links integrally formed with the planar circuit. At least one fusible link is formed in bridging relationship with one or more turns of a planar inductor and which can be selectively fused by application of an energizing field to activate the resonant circuit or to alter the resonant characteristics of the circuit.

Radio frequency detection system and method for passive resonance circuits

Abstract: A system for detecting passive resonant circuits in which bursts of swept radio frequency are transmitted to excite passive resonant circuits. If a circuit is resonant at a particular burst frequency, it is excited, rings and emits a radio frequency signal. Following each transmitted burst, a receiver is turned on to receive energy emitted by a resonant circuit so that if a resonant circuit is excited, its emitted energy is received and the particular resonant circuit identified.

Cautery protection circuit for a heart pacemaker

Abstract: A cautery protection circuit is disclosed for use with a heart pacemaker and comprises circuit elements for preventing those signals induced within the output portion of the heart pacemaker circuit by an electric field established by cautery procedures, from being rendered unsymmetrical in wave form, thereby minimizing the possible adverse effects of such induced signals, e.g. fibrillation of the patient's heart. In one embodiment, a diode is disposed from the emitter to the collector of a pacemaker output transistor to offset the unsymmetrical conduction of the output transistor. In another embodiment, a capacitor of a value presenting an effective short circuit to the frequencies of interest, is inserted across the output transistor to shunt thereabout signals induced by cautery procedures. In addition, the cautery protection circuit includes a suitable inductive element to reduce the high frequency current flow to the pacemaker electrodes to a level below that at which the patient's heart may be excited and further, a capacitor to detune the resonant circuit established by the capacitances of the diodes and the transistor junction, and the inductive element, from the frequencies of interest.

Linear oscillator for proximity sensor

Abstract: A proximity sensor oscillator, having a resonant circuit in which the power loss is inversely related to the distance of a conductive body from a probe containing a part of the resonant circuit, produces an oscillating output signal in the resonant circuit with a peak amplitude that varies with power loss and distance. A power source provides either the current or the voltage component of electrical power at a substantially constant value independent of changes of resonant circuit power loss and is periodically switched to the resonant circuit to provide an average input power thereto. The power loss of the resonant circuit loads the source, and thus the other component of power oscillates within the resonant circuit at a peak amplitude linearly related to the inverse of the power loss. A control circuit is responsive to the phase of the oscillating component to maximize power input to the resonant circuit by applying the fixed power component substantially only throughout each alternate half wave of the oscillating component having the same polarity sense as the one component. Over the operating range where the inverse of the power loss has a linear variation with distance, the peak amplitude of the oscillating component varies linearly with distance. A detector circuit responsive to the amplitude of the oscillating component provides an indication of distance.

Voltage regulating transformer

Abstract: A ferro-resonant, voltage-regulating transformer. The transformer has a primary winding formed about a portion of each leg in each of two spaced, juxtaposed cores. A regulated output voltage is produced at a resonant circuit formed by a capacitor and a secondary winding around another leg of the first core. The flux variations in the two cores are continuously out of phase with each other. As the primary voltage changes the magnitude of the total flux in the system, the flux in the second core can vary in magnitude and phase thereby to maintain the flux in the first core at a constant level. Thus, the output voltage at the resonant circuit is substantially constant.

Self-tuning filter

Abstract: A self-tuning filter is provided through the employment of a voltage tunable filter circuit which simulates a series resistor-inductor-capacitor (RLC) circuit and which is tunable to vary or adjust its resonant frequency in response to the value of an input control voltage. The filter is made self-tuning through the provision of suitable circuitry, responsive to simulated inductance and capacitance voltages, to generate the input control voltage and hence render the voltage tunable filter circuit resonant at the frequency of an applied input signal.

Circuit arrangement for tuning and range or band switching of an RF resonant circuit

Abstract: A television tuner features a switching voltage generator that resets the voltage across the varicap tuning diodes to about zero voltage when a new tuning range is switched on. This allows the full steepness of the capacitance-voltage characteristics of the diodes to be used in each range. This in turn allows more ranges to be tuned and reduces the effects of stray capacitances.

An improved method of resonant current pulse modulation for power converters

Abstract: Presented is a converter philosophy for controlled transfer and transformation of electric energy through internal series resonant circuits at high internal power frequencies in excess of 10 kHz. Control of the continuously oscillating high Q series resonant circuit is attained by adjustment of the phase angle ψ r between the exciting voltage and the resonant current. Only a very small fraction of the energy transferred to the load is absorbed by the resonant circuits to replace the power dissipated therein. Moderate and unconditionally predictable voltage and current stresses on components result from definite control of static and dynamic behavior of the system. This system is suited for construction of failsafe and highly efficient, low cost, submegawatt, single module converters with use of currently available components.

High voltage generating circuit

Abstract: A high voltage generating circuit for a television receiver including a flyback transformer having primary and secondary windings which are loosely coupled to achieve substantial operational isolation therebetween. The secondary winding has a diode rectifying circuit coupled thereto for developing the high voltage signal which is applied to the anode of the television receiver. A tertiary winding is provided which is tightly coupled to the secondary winding and which has a capacitor in parallel therewith to form a resonant circuit which is resonant at a frequency somewhat higher than the horizontal sweep frequency applied to the deflection coil of the television receiver.

Method and apparatus for non-destructively measuring internal film resistance in a fluorescent lamp

Abstract: The resistance of a conductive film coating on the interior bulb wall of a fluorescent lamp is measured by capacitive coupling from the exterior bulb wall. A pair of metal bands engage the exterior bulb wall, with one band being connected to ground through a sensing resistor and the other band being connected through a series inductance to a variable frequency signal generator. The sinusoidal voltage output of the generator is set to a fixed frequency equal to or less than 15 KHz, and the series inductance is selected to provide a resonant circuit during lamp testing. The voltage across the sensing resistor is measured and compared with a predetermined reference voltage or a measurement of the generator output voltage to provide an indication of the internal film resistance of the tested lamp.

Resonant circuit using variable capacitance diode

Abstract: A resonance circuit having an inductor, a capacitor and a semiconductor with a junction, and means for applying a signal to the semiconductor junction. The semiconductor junction satisfies the equation: ##EQU1## where C represents the capacitance of the semiconductor junction when a voltage V is applied thereto and the junction of the semiconductor is reverse biased, C' is a constant, and the inductor and capacitor are connected in series.

Variable reactance circuit including differentially-connected transistor device providing a variable reactance input impedance

Abstract: A variable reactance circuit is composed of a differential amplifier having first and second emitter-coupled transistors, a reactance element, such as a capacitor, connected between the collector and base electrodes of the first transistor, and a control signal source connected to the emitter electrodes of the transistors by which the input impedance of the first transistor is effective as a variable reactance which is changed in accordance with the level of the control signal. Such variable reactance circuit may be used with an oscillator or resonance circuit to constitute a frequency modulator controlled by the control signal source.

Transient processes in gunn diodes

Abstract: The influence of transient processes on the parameters of Gunn logic devices and Gunn generators is considered. For Gunn logic devices the dependence of the switching time on the load resistance R1 is calculated and the criteria limiting the possible values of R 1 R 0 (where R0 is the low field resistance of the Gunn diode) are derived. The simple criterion of the Gunn generation modes is obtained. This criterion allows the prediction of what mode of generation (transit, hybrid or LSA) should take place if the oscillation frequency and the diode parameters are known. For the transit modes in a parallel resonant circuit the change of the resonant frequency due to the diode connection is estimated and the criterion which should be met by the diode parameters and the load resistance is derived. In particular this criterion sets up a limitation of the maximum diode length for the quenched mode at a given frequency. The simple calculation of the basic generation parameters is presented for the case when the Gunn diode operates in a series resonant circuit.

Contactless ignition system utilizing a saturable core transformer

Abstract: A contactless ignition system includes a free running oscillator which generates an output timing pulse to a pulse generator and an ignition coil whenever the oscillations of a saturable core transformer and a series resonant circuit which is driven by the feedback voltage induced in the transformer secondary winding cease. In the free running state, the feedback voltage sustains the oscillator operation at a frequency fixed by the resonant circuit. A disk, having a plurality of permanent magnets evenly spaced around its periphery, is affixed to the distributor shaft and disposed within the vicinity of the saturable core of the transformer. As the disk rotates, the magnetic field of each magnet, as it passes the vicinity of the core, momentarily saturates the transformer core. Saturation of the core reduces the feedback voltage below the oscillation sustaining level and, consequently, causes the oscillator to generate an output pulse which is synchronous with the engine speed. Means are provided for making the rise time of the output pulse independent of the engine speed, thereby facilitating the use of this system at extremely low cranking speeds.

Distance measuring device - uses only one oscillator for comparison method of measuring and reference frequencies

Abstract: The distance measuring device has a measuring resonant circuit whose reasonant frequency depends on the measured distance, a frequency generator controlled by the resonant circuit, a second frequency generator producing a reference frequency, and a comparator for the measured and reference signals. The two frequency generators are formed by a single oscillator (5) which is connected alternately to the measuring resonant circuit (1/6) and to a reference resonant circuit (2/6) with constant resonant frequency. Pref. the two resonant circuits are LC-circuits and have a common capacitor (6) connected to one control input (4) of the oscillator, and separate coils (1, 2) connected by a common changeover switch (3) to the capacitor.

Tunable resonant circuit for several ranges - has variable inductance in region of junction point of inner conductor and tuning elements

Abstract: The resonant circuit is intended for at least two frequency ranges, such as VHF and UHF ranges and is preferably of half-wave length type The variable inductance (24) is connected in the region of the junction point between the inner conductor (16) and the tuning element (17) to frame through a capacitor (25) The inductance serves for the line circuit alignment at the high frequency end of the highest frequency range The inductance (24) and capacitance (25) are so designed that the whole circuit oscillates in a lower frequency range When used in an oscillator circuit, it oscillates above the next lower frequency range, and is tuned to this lower frequency range by an extension inductance

High voltage generating circuit

Abstract: A high voltage generating circuit for a television receiver which includes a horizontal oscillator and a switching circuit operating at the horizontal sweep frequency of the television receiver and being coupled to a flyback transformer which has an input resonant frequency in the vicinity of but higher than the horizontal oscillator frequency. The output of the flyback transformer is coupled to a rectifier circuit which in turn is coupled to the high voltage anode of the television receiver. The flyback transformer also has an input resonant circuit which includes a capacitor which is serially connected to the primary winding of the flyback transformer. This series resonant circuit is resonant at a frequency in the vicinity but less than the frequency of the horizontal oscillator with the result that improved voltage regulation is obtained while avoiding excess high voltage which otherwise would be caused by a shift in the output frequency of the horizontal oscillator.

Local oscillation circuit for tuner having reduced inter-channel deviation in AFC sensitivity

Abstract: A local oscillation circuit for a tuner having a reduced inter-channel deviation in AFC sensitivity. The local oscillation circuit comprises a resonance circuit capable of varying a tuning frequency by means of a variable capacitive element additionally provided with a variable capacitive diode which is applied with a control voltage in dependence upon variation in the frequency detected from the output signal of the tuner, thereby to effect an automatic frequency control. A single variable capacitive diode is coupled to the variable capacitive element of the resonance circuit in a parallel and a series connections.

Circuit to achieve low noise figure

Abstract: A circuit comprising the first stage of a multi-stage amplifier is described, incorporating a plurality of networks connected between the input stage transistor emitter and ground. The networks are connected in parallel; each comprises a series resonant circuit, the resonant frequencies and component values of which have been chosen to provide wideband impedance-matching to the base of the transistor while achieving a low noise figure.

High power remote control ultrasonic transmitter

Abstract: A wide bandwidth, high gain ultrasonic frequency transducer drive circuit utilizes a relatively low voltage source of supply voltage. A first signal path from a source of drive signals includes circuitry resonant with the transducer for providing a relatively high signal voltage across this transducer. A second signal path from the source of drive signals includes a resonant circuit mutually coupled to the first resonant circuit for inducing signal energy into the first path and increasing the signal voltage across the transducer.

Nonlinear Analysis of a Family of LC Tuned Inverters

Abstract: four widely used self-oscillating dc-to-square-wave parallel inverters which employ an inductor-capacitor tuned network to determine the oscillation frequency are reduced to a common equivalent RLC network. The techniques of singular-point analysis and state-plane interpretations are employed to describe the steady-state and transient ient behavior of these circuits and to elucidate the three possible modes of operation: quasi-harmonic, relaxation, and discontinuous. Design guidelines are provided through a study of the influence of circuit parameter variations on the characteristics of oscillation and on frequency stability. Several examples are provided to illustrate the usefulness of this analysis when studying such problems as transistor emitter-to-base junction breakdown during oscillations and the design of starting circuits to insure self-excited oscillations in these inverters.

Method of induction heating for range

Abstract: PURPOSE:To allow an unstable operation of a series resonance circuit to sag by switch controlling according as the quantity of load.

An Inexpensive Pulsed Power Supply for a Septum Magnet

Abstract: A 16 ?H, 6 m? septum magnet load must be pulsed while extracting beam from the 200 MeV booster of the Zero Gradient Synchrotron (ZGS). A power supply was designed for this purpose that can deliver ~ 2 ms wide, half sine wave pulses with a PRF of 30 pulses per second. The peak current is adjustable from 3 kA to 10 kA and repeatable within ± 0.05% by means of a novel charging circuit. By providing a transformer between the magnet and the capacitor bank, the overall cost of the system was reduced to less than onehalf of that of a conventional capacitor discharge system. A high-Q choke shunts the negative half wave of the current around the transformer, thereby extending the life expectancy of the magnet and increasing the circuit efficiency.

Parallel resonant circuit with feedback means for increasing Q

Abstract: In a parallel resonant circuit having an inductor connected in parallel with a capacitor, a sensing resistor is connected in series with the inductor to sense the current in the resonant circuit. The voltage drop across the sensing resistor is applied to an operational amplifier and the amplified output voltage is fed back to the circuit loop out of phase with the sensed voltage drop so as to reduce the effective circuit resistance and thereby increase the circuit Q.

Single frequency elimination filter - consists of bridged T section with series resonant circuit in shunt arm

Abstract: The series circuit may be tuned to the frequency to be eliminated, and the filter comprises further an inductance in each series arm bridged by a circuit adjusted for maximum attenuation of the frequency to be eliminated. The bridging circuit is a series resonant circuit whose resonant frequency is outside the frequency to be eliminated and on the side of the useful frequency band to be transmitted; the shunt arm contains a series circuit consisting of a capacitor in series with a parallel LC circuit. A sharp trough in the frequency transmission curve may be produced, and the shape of the trough may be a symmetrically, with the slope of the higher frequency flank (22a), being steeper than that of the lower frequency flank (22b).

Information from measured current in exploding wires

Abstract: Measured current waveforms in an RLC circuit are used as a basis for obtaining information on the behavior of wire material at various stages of the explosion. In the premelt region, there is, as expected, complete agreement between measured current and current calculated on the assumption that temperature and resistivity are linear with energy input. After absorption of an energy which under static condition leads to solid−liquid transition, the fit is unsatisfactory but can be improved by treating the wire as a superheated solid for a period of about 20 nsec. During the vaporization stage, resistance and energy are derived from the measured current. If all the energy input is assigned as latent heat of vaporization, the calculated current deviates drastically from the measured current, indicating that for all capacitor voltages used in this study, the process is far from static condition. Furthermore, the higher the energy input rate, the greater the containment forces and the more energy is required to...

Broadband electroacoustic delay lines

Abstract: In a broadband microwave acoustic delay line, two or more transducers are used for energy translation from electromagnetic into acoustic (one type) and reverse (the other type) which are mechanically independent and resonant at acoustic frequencies different from one to the others. Each transducer of one type is connected to a first end of a matching section which constitutes a series resonant circuit tuned at a frequency within the band different from the frequency corresponding to any other transducer. The second ends of the two or more matching sections are connected at the same end of a wideband impedance transformer.

Running up circuit for centrifuge driving hysteresis motor - has transformer matching load to give constant ratio between timing and resonant frequencies

Abstract: The running up circuit for hysteresis polyphase motors in centrifuge drives maintains a constant ratio between the resonant inverter timing frequency and the resonant circuit resonant frequency with the compensation capacitance being constant, by using a transformer to match the load circuit inductance. The timing frequency can be altered in steps, as can the transformer ratio. The motor is supplied from the transformer, and the compensation capacitors are connected between the inverter output and the transformer. The running up circuit enables all motors supplied from the same inverter to be started simultaneously and driven up to full speed together.