Showing papers on "RLC circuit published in 1977"

A general unified approach to modelling switching DC-tO-DC converters in discontinuous conduction mode

Abstract: A method for modelling switching converters in the discontinuous conucction mode is developed, whose starting point is the unified state-space representation, and whose end results is a complete linear circuit model which correctly represents all essential features, namly, the input, output, and transfer properties (static dc as well as dynamic ac small signal). While the method is generally applicable to any switching converter operating in the discontinuous conduction mode, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The outlined method lends itself easily to investigation of the discontinuous conduction mode in more complex structures (cascade connection of buck and boost converters, for example), in which more thean one inductor current may become discontinuous. As opposed to other modelling techniques, the new method considers the discontinuous conduction mode as a special case of the continuous conduction mode.

Field intensification in radio frequency thermotherapy

Abstract: A technique in the treatment of tumors in humans utilizing radio frequency electromagnetic radiation to produce necrosis of the tumors by which intensification at the situs of the tumor of a radio frequency field applied across the portion of the body containing the tumor is obtained by positioning a small inductance element preferably in the form of a closed resonant circuit such that the inductance is in or adjacent to the tumor tissue and thus functions to concentrate the field at that location. Alternatively, rather than utilizing a resonant circuit, the inductance can be coupled to the output of the radio frequency generator utilized and applies the radio frequency electromagnetic field.

High-Frequency Link Power Conversion

Abstract: A class of electrical power conditioners incorporating an intermediate variable high-frequency link concept is introduced by considering a converter with dc source and variable voltage and frequency polyphase output, then extending the concept to polyphase ac source voltage The ac 60 Hz -ac high-freq -ac output-freq system is essentially comprised of two cascade 12-thyristor cycloconverters separated by a parallel resonant tank circuit The tank circuit provides commutation means for both cycloconverters Normally, the input cycloconverter operates in the inverting mode and the output cycloconverter in the rectifying mode, although during regeneration their roles are reversed For static var control applications, the output cycloconverter is not required The input cycloconverter separating the 60-Hz supply from the resonant tank circuit can be envisioned as a ``solid-state synchronous machine'' capable of controlling real and reactive power independently Various control strategies for doing this is discussed The design and potential performance characteristics for a 50-kVA system suitable for motor drives is illustrated with regard to power capability and tank frequency versus tank-to-supply voltage radio, input power factor setting, load voltage, and power factor

High voltage signal coupler for a distribution network power line carrier communication system

Abstract: A high voltage signal coupler couples carrier communication signals between a distribution network primary conductor and communication elements located at spaced intervals on the distribution network. A single bushing, high frequency, coupling capacitor communicates the carrier communication signals between one of the distribution network primary conductors and a conductor which is at ground or real earth potential with respect to power current frequencies. A parallel resonant circuit, formed by a tuning capacitor and a hollow core of magnetic material inductively surrounding the power frequency ground conductor, couples the carrier communication signals to the communication elements connected thereto at a predetermined frequency without interfering with the operation of the ground conductor at the frequency of the power current.

Detection plate for an identification system

Abstract: A detection plate for an identification system, comprising a resonant circuit, a switching device, and coding means, characterized in that the coding means comprises a digital circuit and is arranged to receive, in operation, supply voltage from the resonant circuit via rectifier means.

Position detecting system

Abstract: The position or presence of a metallic object is detected by an electronic circuit which senses a shift in phase between a first cyclic signal and a second cyclic signal which shifts in phase in response to movement of the object. An oscillator produces the first cyclic signal which is used as the reference signal and as the excitation for a parallel resonant circuit which produces the second signal. The phase of the second signal is shifted in response to movement of a metal plate or a shorted coil in an electromagnetic field produced by an inductor in the resonant circuit. The degree of the phase shifts may be used to detect the position of an object in the electromagnetic field or rate of the phase shifts may be used to detect the velocity of an object. An exclusive-or gate senses the changes or differences in phase between the two cyclic signals and produces an output signal representative of the changes or differences in phase. The output signal of the detector may be used with a digital counter to produce a digital output or with a smoothing filter to provide an analog output.

Suppression of relaxation oscillation in light output of injection lasers by electrical resonance circuit

Abstract: It is shown that relaxation oscillation in the light outputs of injection lasers can be suppressed by an external electrical circuit. This method can be applicable to high-speed pulse modulation. For this purpose, an electrical resonant circuit connected to the laser diode (LD) and tuned to the relaxation oscillation is considered as an example. Frequency response of direct modulation and the device-transient characteristics are analyzed. These results were verified experimentally. A brief discussion on the upper limit of the repetition frequency of pulse modulation is given and it is shown theoretically that stable pulse modulation of an LD up to a few Gbit/s may be obtained by applying this method.

Switching regulated power supply apparatus including a resonant circuit

Abstract: A switching regulated power supply apparatus, comprising: an alternative current power source, a first rectifier for rectifying the alternate current output, a high frequency reference pulse generator, a pulse width modulator for modulating the pulse width of the reference pulse output as a function of a control signal, a switching transistor for on/off controlling the output from the first rectifier as a function of the pulse width modulated output, a high frequency transformer connected in series with the first rectifier and the switching transistor, a second rectifier for rectifying the output from the high frequency transformer, and a smoothing circuit for smoothing the output from the second rectifier, the output from the smoothing circuit being applied to the pulse width modulator as a control signal, characterized in that the said apparatus further comprises a resonance capacitor coupled to the said high frequency transformer for causing resonance cooperatively with the said high frequency transformer when the said switching transistor is turned off, and a switching device coupled to the output of the second rectifier to be turned on responsive to a flyback pulse obtained from the smoothing circuit when the switching transistor is turned off, whereby the said resonance is suppressed by means of the second rectifier and the switching device in the latter half cycle of the resonance during the off time period of the switching transistor.

Induction heating apparatus

Abstract: An induction heating apparatus comprises a DC power source, a series resonant circuit of a heating coil and capacitance connected between the terminals of the DC power source, a diode connected in parallel with the capacitor and in polarity-reversed relation to the DC power source, a transistor having a collector-emitter path connected in parallel with the capacitor, and a control circuit for controlling the conductive state of the transistor in accordance with the magnitude and direction of a current flowing through the heating coil.

Pulse power source

Abstract: In a pulse power source for applying a pulse voltage to a capacitive load; a series resonance circuit capable of generating transient oscillation is formed of the capacitive load adapted to be applied with the pulse voltage, an inductance for generating transient oscillation and a power source capacitor; the capacitive load is charged from the power source capacitor by first closing one of two switch elements provided in the midway of the resonance circuit, that is, a load charging switch element to make the voltage across said capacitive load rise up to about twice the voltage across the power source capacitor after a period equal to about 1/2 of a transient oscillation period of said series resonance circuit, to form a rising edge of the desired pulse voltage; then reversely, the power source capacitor is charged from the capacitive load by closing the other switch element, that is, a charge recovering switch element after first said one switch element has been closed to make the voltage across said capacitive load fall down, to form a falling edge of the desired pulse voltage; and further a residual charge on said capacitive load is discharged by closing still another switch element provided in parallel to said capacitive load, to improve the falling edge of the desired pulse voltage; whereby a steep pulse voltage can be applied to said capacitive load with a low power loss.

Series resonant battery charger and control therefore

Abstract: An inverting circuit of the series resonant type and including a pair of SCR's operated at variable off-times for controlling the charging of a battery A control circuit is provided for gating the SCR's at appropriate times in response to sensed circuit current, and battery voltage Instantaneous resonant circuit current is monitored to derive timing information for firing the SCR's and for anticipating commutation failures

Theory and Practice of Geophone Calibration In Situ Using a Modified Step Method

Abstract: The transfer function of a moving coil electromagnetic geophone requires up to six constants: the suspended mass, the natural resonant frequency, the mechanical and the electrical damping factors, the inductive time constant of the coil-damping resistance circuit, and the coil transductance. If the mass is known, the remaining constants may be satisfactorily determined by displacing the mass with a known dc current, and observing the time varying output potential on removal of the steady current. The techniques outlined are suited to in situ calibration, and have a minimum equipment requirement of a CRO and a small battery. Improved accuracy is possible using a precision signal generator and a quality CRO, if the geophone natural and upper resonant frequencies are measured by the phase ellipse method. Calibration is possible for both under- and over-damped systems, using either the derived formulas or accompanying graphs. The accuracy attainable is dependent on the geophone damping and frequency range of operation, but is typically 2 percent in absolute amplitude and 2° in phase for 0.7 critical damping.

Tone control circuit

Abstract: A tone control circuit for stereophonic amplifiers, guitar amplifiers and the like is disclosed. The tone control circuit includes a bass circuit having a first variable resistor whose movable contact is connected to an output terminal of an amplifier circuit, two resistors equal in resistance connected respectively to two end terminals of the variable resistor, and a capacitor shunting the variable resistor. The tone control circuit also includes a treble circuit having a second variable resistor, a resistor, and a capacitor. The treble circuit is connected in parallel to the bass circuit in such a manner that the gain in a particular frequency range of the amplifier circuit can be changed by varying the resistances of the two variable resistors.

A circuit technique for broadbanding the electronic tuning range of Gunn oscillators

Abstract: A circuit technique is described whereby the electronic tuning range obtained by varactor tuning solid-state oscillators, such as Gunn oscillators, can be improved. The principle of the technique has been demonstrated by doubling the tuning range obtained from a coaxial X-band Gunn oscillator using distributed circuit elements. An analytical expression for the improved tuning range is presented and predictions for the improvement in an existing microstrip X-band oscillator using chip devices given.

Circuit for providing saw-tooth current in a coil

Abstract: A circuit for providing a saw-tooth current in a coil is described. The circuit comprises a trace condenser and a retrace condenser which form together with the coil a resonant circuit during the retrace interval, a diode connected parallel to the retrace condenser, a controllable switch connected to a supply source through an inductor and to the retrace condenser through a second diode. The main feature of this circuit is to comprise a condenser connected on one hand towards the controllable switch and the first inductor and, on the other hand, to a circuit comprising a second inductor and, through a third diode, towards the retrace condenser. The condenser and the two inductors are sized in such a manner that when the controllable switch is not conductive, energy is supplied to the condenser and that successively, when the controllable switch is conductive, the condenser is completely discharged through the second inductor. The energy thus stored in the second inductor is then supplied to a storage device.

Helix traveling wave tubes with resonant loss

Abstract: To suppress spurious oscillations in a helix-type traveling wave tube (TWT), frequency-sensitive loading is produced by a lossy resonant circuit attached to a dielectric support and coupled to the fields of the interaction circuit. The lossy circuit is resonant near the band-edge frequency. It may be a section of delay line with reflective terminations. In one embodiment, it is a metallized pattern on a dielectric rod used to support the helix.

Remote supervisory equipment

Abstract: PURPOSE:To be able to pick up the signal on the required frequency with changeable resonance circuit with small sized circuit, when signal number of different frequency is transmitted on a transmission line.

U-shaped microstrip resonant circuit

Abstract: In one embodiment, a resonant circuit comprising a ground-contacting conductive member, a dielectric layer provided on the ground-contacting conductive layer, a ground-contacting member provided on the dielectric layer and electrically connected to the ground-contacting conductive member, and a U-shaped microstrip line formed on the dielectric layer. Both ends of the U-shaped microstrip line face the ground-contacting member. One of them is connected to the ground-contacting member through a lumped capacitor, and the other end is directly connected to the ground-contacting member.

Circuit and method for controlling reactive load currents of a three-phase system

Abstract: Circuit for controlling reactive currents of a three-phase network, having three converters with forced commutation connected in parallel with the loads of the three-phase network, at least one energy accumulator connected to the d-c side of the converter, and a closed control loop having measuring transformers for input currents of the converter, for the load currents and for the conductor voltages of the network, means for evaluating required compensation currents and means for controlling firing pulse formers for the converters to adjust the waveform of the currents on the three-phase side, including capacitors shunted across the loads in three phases, the compensation control element being a three-phase four-quadrant control element, the energy accumulator being an additional capacitor and a resonant circuit tuned to twice the network frequency, the resonant circuit being connected in parallel to the additional capacitor, the control loop including means for controlling the mean voltage on the d-c side of the four-quadrant control device, a conductance measuring converter connected to the measuring transformers for the load currents and an active-current reference-value generator connected to the conductance measuring converter.

Thin film microwave voltage controlled oscillator

Abstract: A microwave oscillator including a tuning varactor and a transistor in a thin film series resonant circuit.

Compact microwave distributor circuit - has shared transformer between signal source and node input to all parallel branch paths

Abstract: The compact microwave distributor is constructed with relatively few components. It has a shared transformer (L1) between the signal source and the sum point (S) connected to the inputs of the parallel transformers (L) in the branch paths. In addition, or alternatively, each paralle transformer consists of series and parallel quarter-wave lines. the shared transformer consists of at least one quarter-wave line. the decoupling impedances (K) between the branch paths consist of RLC circuits.

Apparatus for measuring and controlling the level of molten steel in a continuous-casting mold

Abstract: An apparatus for controlling the level of liquid steel in a continuous-casting mold wherein the position of the molten steel level within the mold is detected by a coil juxtaposed therewith and forming part of a resonant circuit controlling an oscillator. The capacitor portion of this resonant circuit is formed at least in part by a coaxial cable connecting the coil to the balance of the oscillator circuit. The output frequency of the oscillator is combined with the signal of a reference oscillator in a modulator, the low-frequency passband of this signal is then transformed into an analog voltage proportional to frequency and is used to control a servomotor which regulates the feed of molten metal to the mold.

Phase-shifting multiplication type FM signal demodulation circuit

Abstract: A phase-shifting multiplication type FM demodulation circuits comprises a gate circuit including a first and a second switching circuit adapted to be switched for an FM intermediate frequency signal, a resonance circuit and a phase-shifting element. The FM intermediate frequency signal is phase-shifted for about π/2 (or 90°) and the phase-shifted signal (frequency) is fed to the second switching circuit of the gate circuit after the phase-conversion of the phase-shifted FM signal by means of a phase-shifter device. The demodulation circuit further includes a bias resistor for the second switching circuit which resistor serves also as a resonance resistor of the resonance circuit, a substraction circuit for detecting output signal from the gate circuit, an output resistor for determining magnitude of the output signal from the subtraction circuit, and a lowpass filter for eliminating higher harmonics from the output signal appearing across the output resistor thereby producing a demodulated output.

Microwave network with frequency determining resonant circuits - compensates for temperature coefficients of circuit with dielectric or magnetic elements positioned in magnetic or electric fields

Abstract: The microwave resonant circuits have elements compensating for the temperature coefficients of the circuits components. The compensation elements consist of at least one dielectric or magnetic element with a positive or negative temperature coefficient. They are placed in the resonant circuit's magnetic or electric fields, so that the temperature coefficient of the resonant circuit, together with any active or passive components connected to it, is compensated by frequency detuning as accurately as required.

Charge transfer filter with wide dimension tolerances - can be readily integrated by forming specified resonant loops

Abstract: The charge transfer filter can be readily integrated and has attenuation independent of dimensional tolerance. It also requires fewer charge transfer elements by a factor of c. 10. The charge transfer elements are connected into a resonant loop (5) to give a resonant circuit (6) with two inputs (1, 4) and two outputs (2, 3). At the loop's resonant freq., the signal at the first input (1) appears exclusively at the first output (3). As the frequency deviates more and more from the tuned frequency, more and more of the input signal begins to appear at the second output (2). The reverse applies when the signal is applied to the second input (4).

Broadband microwave oscillator with IMPATT diode - has rectangular waveguide with decoupling point in middle remote from ends

Abstract: The broadband microwave oscillator consists of a negative impedance device (e.g. tunnel diode or IMPATT diode) in a resonant circuit comprising a section of rectangular waveguide operated below its cutoff frequency. The coupler (3) that couples energy out of the waveguide (2) is located far enough from the ends of the guide to prevent the fundamental wave being affected by the guide terminations. The negative impedance device (4) with an additional capacitance (5) is located near the coupling out point.

Thyristor static inverter for induction heating - has inductor transferring stored energy to capacitor using repeated current pulses

Abstract: The thyristor static inverter, for induction heating, has an inductor, in a resonant circuit, supplied with pulses and periodically discharging its stored energy into one or more auxiliary capacitors. One or more rectifier diodes (9) are connected in parallel with these auxiliary capacitors (4) and are poled in the opposite direction to the charging voltage. The energy retained by the auxiliary capacitors is transferred by current pulses which repeat themselves every half period, or every integral number of periods.

Surge absorbing element

Abstract: PURPOSE:To make a varister applicable also to VHF and UHF lines while securing required surge-proof and voltage of the varister, by connecting a coil which forms a resonance circuit in cooperation with the capacitance of the varister in parallel with the varister, and incorporating them into one.

Microwave oscillation unit

Abstract: PURPOSE:The oscillation element within waveguide and integrated resonance circuit outside the waveguide are combined with use of the post one end of which is linked to strip conductor of resonance circuit and the other end positions inside waveguide. In this way, compactness of the equipment as well as its mass production program can be facilitated.

Staticcelectric power converting device

Abstract: PURPOSE:In a static frequency converting device which is composed of a semiconductor switching block, a current limiting inductor, and a series resonant circuit, devised is to place the current limiting inductor which has a mutual inductance so that the current limiting inductor can be made into a small-size.