Showing papers on "RLC circuit published in 1968"

High-frequency lamp operating circuit

Abstract: Circuit operating from a low-voltage current source for applying high-voltage, high-frequency alternating current to a load such as a gaseous discharge lamp connected across the source includes a charging capacitor and a first induction coil connected across the source and forming a first resonant circuit, a second induction coil and a controlled rectifier switch connected in series across the capacitor forming a second resonant circuit when the controlled rectifier switch is closed, and triggering means connected to the source for operating the controlled rectifier switch in accordance with a predetermined rate, the second resonant circuit operating to close the controlled rectifier switch, and the first resonant circuit operating when the switch is opened to raise the voltage and apply it to the load in high-frequency pulses for starting and operating the same.

Frequency selectivity using positive impedance converter-type networks

Abstract: It is shown that positive impedance converter-type networks may be used to realize a driving-point impedance that is ideally a frequency dependent negative resistor. This concept may be used to realize new types of inductorless selective networks. A simple resonant circuit application is discussed.

Power system filter

Abstract: A harmonic filter for an AC power system, particularly for converter installations, which provides damping to diminish the effects of parallel resonance. The filter consists of a plurality of conventional LC shunt filters tuned to the expected harmonic frequencies. The power system may also include static capacitors for power factor correction. Since the power factor capacitors and the harmonic filters are effectively in parallel with the inherent inductance of the AC system, a parallel resonance, which may occur at one of the lower harmonic frequencies, results. In order to reduce the effects of a parallel resonance, there is provided an additional filter tuned to provide damping at the harmonic frequency at which parallel resonance may occur. This additional filter comprises an LC filter with a resistor connected in parallel with the inductance. This resistor is connected to a blocking filter which presents a high impedance to the system fundamental frequency. The effect of this resistor is to provide damping which will reduce the amplitude of oscillations under parallel resonant conditions. Since this resistor is connected through a blocking filter, it provides damping without providing excessive additional loading at the fundamental frequency.

Impatt oscillator performance improvement with second-harmonic tuning

Abstract: Improvements in power, efficiency, and FM sensitivity are achieved experimentally with Impatt oscillators which are operated so that the second harmonic lies in the frequency range for classical Read operation. The improvement in performance is accomplished by providing a trapped resonance at the second harmonic, in addition to the required tuning at the output frequency.

Near Resonant Coupling on EHV Circuits: I - Field Investigations

Abstract: Higher voltages than anticipated and large neutral currents were measured on 345-kV shunt reactors installed at each end of a 261.4-mile 345-kV circuit operated in close parallel with a 138- kV circuit. The phenomenon existed only when the 345-kV circuit breakers at both ends were open, the line ungrounded, and either or both of the EHV shunt reactors connected. Field investigations and measurements are presented.

A New Procedure for Calculating Varactor Q from Impedance Versus Bias Measurements

Abstract: The reasons for preferring the impedance versus bias method of measuring varactor Q at high frequencies are pointed out. To circumvent the circuit loss problem, a rigorous procedure has been developed, based on the Weissfloch equivalent circuit of a lossy two-port network, for extracting the varactor junction Q. Parallel circuit loss is automatically corrected for, but correction for series loss requires substitution of a dummy shorted varactor. The procedure is described along with an actual example of its use at 64 GHz. Simulated examples are also worked out to illustrate the effect of the initial reactance in series with the varactor junction, and to demonstrate the numerical correctness of the procedure.

Signal-seeking radio receivers

Abstract: In a signal-seeking radio receiver which includes an antenna, means for automatically and sequentially tuning to a plurality of predetermined radio frequencies, and means for reproducing the intelligence therein; a tuning circuit comprising local oscillator means for generating a plurality of discrete local oscillator signals individually in sequence, and first control signal-generating means including therein a resonant circuit, having predetermined impedance vs. frequency characteristics, coupled to the local oscillator means to receive the local oscillator signals for generating a pluralitly of first control signals in response to the local oscillator signals, there being one of the aforementioned controls signals generated in response to each of the local oscillator signals. The magnitude of each control signal is proportional to the impedance of the resonant circuit at that frequency. A second control signal-generating means is coupled to the first control signal-generating means to receive the first control signals for rectifying the same and adding thereto a selected direct current threshold signal thereby producing a plurality of second control signals each of which also has a magnitude proportional to the impedance of said resonant circuit at the frequency of the local oscillator. A radio frequency amplifier is coupled between the antenna and the reproducing means, the amplifier including at least one band-pass filter having a voltage-variable reactance device therein coupled to the second control signal-generating means to receive the second control signal. The reactance of the device corresponds to the voltage applied thereto, whereby the pass-band of the filter is automatically and sequentially tuned to pass a band of frequencies about each of the predetermined frequencies in synchronism with the tuning of the receiver thereto.

Varactor-tuned integrated Gunn oscillators

Abstract: Electronic tuning of Gunn diodes in hybrid integrated circuits has been studied. Microstrip transmission lines were used to form resonant circuits into which a Gunn diode and a varactor diode were mounted to provide the microwave power and frequency tuning, respectively. Basically, two types of circuits have been investigated. The first is a half-wavelength open-circuited microstrip `cavity' with this transmission line and the varactor diode attached between the end of the cavity and an RF ground. The second is a lumped LC circuit in which the inductance of a short high-impedance microstrip line is resonated with the lumped capacitance of the varactor diode. The latter circuit provides a tuning range of over 10 percent at 7.5 GHz. The power output varies within 2 dB in the tuning range.

Apparatus for monitoring the response of a resonant circuit

Abstract: An oscillator circuit applies variable-frequency test signals to a resonant circuit in a manner to sweep across the band-pass of the resonant circuit. A control pulse is generated while the resonant circuit transmits the test signals above a preset amplitude. The control pulse is processed to provide an indication of the response of the resonant circuit to the test signals.

Closed loop parametric voltage regulator

Abstract: A parametric voltage regulator in which the inductance component of the resonant circuit of a parametric device is varied in response to changes in the output voltage, caused for example by changes in line frequency, to maintain the output voltage constant. The inductance is preferably changed by providing an external flux generator on the core of the parametric device to vary the reluctance of a part of the core, but can also be accomplished by the use of a separate inductor in the resonant circuit.

Simultaneous oscillations at two frequencies in RLC circuits

Abstract: It is shown under which conditions two parallel high-Q resonance RLC circuits connected in series to a voltage-controlled active device, described by an instantaneous characteristic of fifth degree, can oscillate simultaneously at two frequencies.

Timing of regenerator and receiver apparatus for an unrestricted digital communication signal

Abstract: A dedicated burst of timing pulses is multiplexed in each frame of an unrestricted digital signal to supply timing information to receiver and regenerator circuits in a time division communication system. When the burst appears in the received signal the output of a tuned RLC circuit builds up to a threshold level. A threshold detector then triggers a time control circuit, which in one embodiment of the invention is a counter circuit and in another embodiment of the invention is a pair of monostable multivibrator circuits, to gate the digital signal to a timing recovery circuit for the duration of the burst.

Selective radio receiver system

Abstract: The disclosure shows a remotely controlled radio receiver circuit which may be used to control a garage door operator, for example, from a low-power remote transmitter. The signal emitted by the transmitter includes a carrier as modulated by a lower frequency, for example an audiofrequency, which signal is amplified in the receiver, detected and supplied to an audiofrequency resonant load and to a resistance load. These two loads are connected in opposition so that if the received signal is of the proper carrier frequency to be amplified and passed through the first stages of the receiver and if the audiofrequency is of the proper preselected frequency to be resonated by the audiofrequency resonant circuit, a resonant voltage signal is passed. A first time delay capacitor is connected in a circuit to give only time delay of turn turn-on of a load relay, and a second time delay capacitor is connected in circuit to give only time delay of dropout of the relay, and in this manner telemetering or other relatively rapid pulsed signals, even of the proper carrier and audiofrequencies, do not actuate the relay. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

Rectangular pulse modulator

Abstract: Discharge of a RLC network is controlled with a siliconcontrolled rectifier to provide a rectangular pulse for pulsing GaAs lasers.

Two Worst-Case Insertion Loss Test Methods for Passive Power-Line Interference Filters

Abstract: The feasibility of two methods for determining the worst-case insertion loss of power-line interference filters is demonstrated. The first method makes use of injection and detection probes (transformers) which introduce an extremely small impedance (L ?50 nH, R ? 3 m?) into the test circuit. The second method does not use injection and detection probes, thus eliminating their problems. Both methods maintain the high Q of the test circuit and permit interfacial resonances to occur between the power-line and filter interface impedances. A conventional filter and a lossy filter were measured by both methods. Large resonances, including a negative insertion loss at 150 kHz, were measured in the stopband of the conventional filter. No resonances were detected in the stopband of the lossy filter. Measurements with the two test methods differed by only a few dB.

Ac regulator employing a control rectifier switching circuit

Abstract: An AC regulator which employs inductance, a resonant circuit and controlled rectifier switching between the input terminals connected to the AC voltage to be regulated, and the output terminals which supply the regulated AC output The controlled rectifier switching circuit is regulated by a control system which monitors the output voltage and controls the firing of a pair of oppositely-polarized parallel controlled rectifiers connected in serial relationship between the input (line) and output terminals

Automatic frequency control for an oscillator in a chroma demodulation circuit

Abstract: In the chroma channel of a color television receiver, a demodulator circuit for the chroma subcarrier component and an oscillator circuit for producing a control signal having the frequency and phase of the chroma subcarrier component, wherein the demodulator circuit and the oscillator circuit except for the resonant circuit portion thereof have been designed to be capable of incorporation in an integrated circuit on a single wafer of semiconductor material.

Imaged impedance through frequency conversion

Abstract: THIS APPLICATION DESCRIBES THE MANNER IN WHICH A FREQUENCY CONVERTER CAN BE USED AS A BRIDGE BETWEEN DIFFERENT FREQUENCY DOMAINS. IN PARTICULAR, A FREQUENCY CONVERTER IS USED TO IMAGE LOW FREQUENCY CIRCUIT COMPONENTS AT A HIGHER FREQUENCY, THEREBY PRODUCING CIRCUIT RESPONSES AT THE HIGHER FREQUENCY THAT COULD NOT ORDINARILY BE PRODUCED DIRECTLY. FOR EXAMPLE, A RELATIVELY MODERATE Q RESONANT CIRCUIT IS IMAGED AT A HIGHER FREQUENCY WITH A Q THAT IS INCREASED BY THE FREQUENCY TRANSFORMATION RATIO. A NEGATIVE RESISTANCE DIODE IS IMAGED AT A HIGHER FREQUENCY THEREBY PRODUCING AMPLIFICATION AT A FREQUENCY AT WHICH SUCH A DIODE COULD NOT NORMALLY OPERATE.

Parametric amplifier nonresonant gain maximum

Abstract: Parametric amplifier analysis, taking exact account of the frequency dependence of the parametrically induced impedance in the signal circuit, indicates that maximum gain occurs at a signal frequency slightly below that at which the signal and idler circuits are resonant.

Improvements relating to high voltage generators

Abstract: 1,130,082 Rectifying ASSOCIATED ELECTRICAL INDUSTRIES Ltd 1 June, 1967 [31 March, 1966], No 14285/66 Heading H2F A rectifier circuit is characterized in that a series resonant circuit L1, C1 is connected between the AC supply and the rectifier, this serving to reduce the ripple in the DC output and to improve the voltage/current relationship In Fig 3 there are three rectifier bridges D1- D3 arranged in cascade to provide three times the DC output voltage, AC being supplied to one bridge from the preceding bridge through two tuned circuits With this arrangement the bridges D2 and D3 are supplied with almost a square wave, which is advantageous and the input AC may also be a square wave A simpler circuit (Fig 1, not shown) omits the bridges D2 and D3 A modified circuit (Fig 6, not shown) has capacitors C2 and C3 1 moved to the other side of their associated inductances so that the paired inductances, L1, L2 and L2 1 , L3 1 may be housed together In a three-phase system three columns of tuned circuits may be connected to a plurality of bridges arranged in cascade, the bridges being either three-phase (Fig 4, not shown) or single-phase (Fig 5, not shown) In the latter case if the secondary of the input transformer is star connected, earthing the star point increases the output voltage and decreases the ripple voltage The inductances may be protected against excess currents by shunting them with a spark gap or a non-linear resistance, or by arranging that they saturate if the maximum rated current is exceeded

Multiband varactor tv tuner

Abstract: A MULTIPLE BAND TUNING CIRCUIT HAVING RESONANT CIRCUITS FOR EACH BAND THAT ARE CONNECTED TO BE TUNED BY SEPARATE VOLTAGE DEPENDENT REACTANCES. THE HIGHER FREQUENCY RESONANT CIRCUITS ARE TAPPED, AND ARE CONNECTED IN THE CIRCUIT TO FORM SEPARATE BRIDGE CIRCUITS, WITH THE TAPS BEING POSITIONED SO THAT EACH BRIDGE IS IN BALANCE AT THE TUNING FREQUENCIES OF THE RESPECTIVE BAND. EACH LOWER FREQUENCY RESONANT CIRCUIT IS CONNECTED TO THE TAP OF THE NEXT HIGHER FREQUENCY RESONANT CIRCUIT.

Oscillator circuit with series resonant coupling to mixer

Abstract: An oscillator circuit tuned by a voltage dependent variable capacitance diode is coupled to a mixer stage by a wide band injection circuit which includes a series connected inductor and capacitor adapted to series resonate at a frequency within the oscillator tuning range. A resistor interconnects the voltage dependent variable capacitance diode and a tuning bias potential supply. The resistor is of a value to cause the tuning of the oscillator circuit to track the tuning of the other circuits controlled by the bias supply.

Low frequency band-pass filter for use in failsafe applications

Abstract: A LOW FREQUENCY BAND-PASS FILTER IS OF A CONSTRUCTION INHERENTLY PROVIDING A SINGLE PREDETERMINED OUTPUT MODE UNDER ANY CONDITIONS OF FAILURE OF ITS INDIVIDUAL COMPONENTS OR COMBINATIONS THEREOF. THE FILTER EMPLOYS COOPERATION BETWEEN THE Q OF A RESONANT CIRCUIT, A RESISTIVE DIVIDER, AND A THRESHOLD CIRCUIT TO DEFINE PASS BANDWIDTH.

Comments "On the intrinsic time variance of fast timing circuits using tunnel diodes"

Abstract: An analysis is presented for the lntrfztiic time variance originating from thermal noise and finite capacitances in high-speed timing circuits using tunnel diodes. The nonlinear differential equation of the transition is solved numerically for a wide range of circuit parameters,and limitations on the minimum attainable time variance are derived. (Submitted as a letter to the Proceedings of the IEEE) *Work supported by the U. S. Atomic Energy Commission. In many high-speed timing circuits significant time variance is contributed by the triggering jitter of the tunnel-diode discriminator. Even when the input waveform to the circuit is deterministic, there always exists a superimposed thermal noise which results in a finite time variance if the tunnel diode has a finite capacitance. This variance is c(~mputea her’i: for the circuit configuration of Fig. 2a. A representative current vs voltage characteristic of the tunnel diode is shown in Fig. 1. The device is biased initially at v = Vi, Ii = I p IO and transition to v > Vv will take place if the voltage across the diode is increased above V . The P time variance of this transition will be analyzed cncier the following assumptions: (a) The dc i vs v characteristic of the tunnel diode in the vicinity of the peak current can be approximated by the quadratic i = I where P IO 0 (v Vi Vo)2 /Vz , V. will be determined later. (b) The tunnel diode is imbedded in the circuit shown in Fig. 2a. (c) The tunnel diode can be represented by its dc i vs v characteristic of (a) parallel with a fixed capacitance C (see Fig. 2b). (d) The drive current is is a ramp function: is = Ii + Vi /R for t < 0 and is = IiiVi/R + kt for t > 0,’ Writing the current sum for node X in Fig. 2b, one obtains the nonlinear differential equation Defining S = 1 + Vo/(2RIo) as a measure of the source impedance, x E IoSt/(CVo) as the normalized time, y = (v Vi)/(VoS) as the normalized voltage, and A E k C Vo/(IfS3) as the normalized slope of is, Eq. (1) becomes dy/dx y2 + 2y -Ax=O. (2) This nonlinear differential equation was solved numerically for y and dy/dx with -2values of A ranging from 0.01 to 1000. 2 The results, summarized in Fig. 3, show the expected behavior. 3 In the limiting case of a slow-rising drive current 1 A<< 1, y z 1 (1 Ax)’ for 0 < y c 1, thus following the dc characteristic; while at y = 1, transition to v > Vv takes place. In the other extreme, when A>> 1, y M Ax2/2 for all x > Oa4 It wee a%c found that 1 (dY /WY = 1 : z A (l+A/8)? (3) with an error of less than 5% for 0.01 5 A 5 1000, The time jitter of a regenerative circuit, although its origin is superimposed thermal noise, is independent of the temperalure and depends only on the time derivative of the damping rate (characteristic root) o. For the circuit of Fig. 2b, Q! = -l/(C 0 dv/di)(r = o , (4) and the time spread can be written as 5 24 ‘Gj : = 0.61 (do,‘dtj; = o . (5) Here (dcddt)a =. = (ddWa, =. 0 (dddt)a r. o With Eq, (4) and assumption (a), (dcr/dv)o =. = (l/C) p (d2iidv2)@ =O = (6) where V1 is a property of the tunnel diode: for germanium devices Vl x 70 mV. From Eq. (3) with the definitions of x and y,

Over-frequency alarm

Abstract: An electrical circuit adapted to compare an externally sensed frequency with a reference frequency for giving an indication when the former exceeds the latter via voltage and current phase relationship utilizing a phase shifting inductance, a resonant circuit and a transformer having a core of square loop material, a dual primary winding and an alarm connected to its secondary winding.

Frequency-sensitive circuit

Abstract: An AC input signal is divided between two branch circuits, one comprising an LC series resonance circuit in series connection with a first unidirectional current device, and the other comprising a resistor in series connection with a second unidirectional current device poled opposite to the first unidirectional current device. The two branch circuits are connected in parallel to a common output terminal. A nonpolarized capacitor is connected between the output terminal and an electrical reference or ground to bypass to ground the AC voltage component that otherwise would exist at the output terminal, and to provide a smooth DC signal having one polarity when the frequency of the AC input signal is within a predetermined frequency range and an opposite polarity when the frequency is outside the predetermined frequency range.