Showing papers on "Relaxation oscillator published in 1981"

Class E high-efficiency tuned power oscillator

Abstract: The class E high-efficiency transistor tuned power oscillator, based on the class E power amplifier, is presented. Theoretical conditions for optimum operation of the oscillator are formulated. A new feedback-loop circuit is proposed and a corresponding oscillator design procedure is given. Experimental results show that the collector-voltage and collector-current waveforms and the collector efficiency of the oscillator are the same as in the class E amplifier with the same transistor and operating at the same frequency. The measured collector efficiency was over 95 percent with 3 W output at 2 MHz. The proposed oscillator is especially applicable at high frequencies because it minimizes the power dissipated during the transistor off-to-on transition, even if the switching time is an appreciable fraction of the signal period.

The intrinsic electrical equivalent circuit of a laser diode

Abstract: The basic electrical equivalent circuit of a laser diode is derived. The effects of spontaneous emission and self-pulsations are included. It is found that self-pulsations are represented by a negative resistance in the model. Application of this model suggests purely electronic methods of suppressing relaxation oscillations in laser diodes.

Electronic oscillation counting timer

Abstract: An electronic timer having an oscillator, a counter which counts outputs of the oscillator up to a predetermined count value and thereupon generates an output, and an output circuit for generating an output signal in response to the output from the counter, the oscillator comprising a first terminal for connection with a time constant circuit consisting of a resistor and a capacitor, a second terminal supplied with a reference voltage, a dividing resistance circuit for developing a first upper limit voltage and a lower limit voltage, a first upper limit comparator for comparing a potential at the first terminal with the first upper limit voltage, a second upper limit comparator for comparing the potential at first terminal with the reference voltage, an OR-circuit for receiving outputs from the first and second upper limit comparators, a lower limit comparator for comparing the potential at the first terminal with the lower limit voltage, a flip-flop which is set by an output from the OR-circuit and reset by an output from the lower limit comparator, and a transistor for discharging the capacitor in response to an output generated from the flip-flop.

A subharmonic Josephson relaxation oscillator—amplification and locking

Abstract: The inductance of the shunt loop in a resistively shunted Josephson tunnel junction may cause relaxation oscillations at subharmonics of the Josephson frequency. The relaxation period, the injection locking to a subharmonic of a strong external signal, and the amplification of weak signals were studied in detail. Gains up to 15 dB were achieved, but the noise temperature, which depended upon the harmonic of the relaxation frequency at which the amplification occurred, was high.

Regulated single-ended self oscillating, DC-DC converter

Abstract: A switching regulator having a blocking oscillator including a transistor, and a transformer with primary, secondary, and positive feedback windings. A rectifying and smoothing circuit is connected to the load and includes a photodiode coupled to a phototransistor connected to the blocking oscillator transistor in the feedback path for adjusting feedback to maintain output voltage at a constant level. A second positive feedback circuit connects between the phototransistor and the blocking oscillator transistor to assure stable oscillation of the blocking oscillator.

Analytical and experimental approaches for the design of low-distortion Wien bridge oscillators

Abstract: Although Wien bridge oscillators are commonly used as fixed-frequency generators of low distortion there has apparently not been suggested a simple systematic method based on nonlinear theory for reducing their distortions. This paper attempts at filling the gap. This is achieved by suggesting a network which is on the one hand a Wien bridge oscillator and it can be also regarded as a Van der Pol oscillator. Van der Pol oscillators, however, are well known and as a result the task of systematically reducing the distortion becomes a straightforward procedure which is demonstrated by a series of experiments. Additional improvements (in the economy of design and with regard to a further reduction of distortions) are attained by slightly modifying the basic Van der Pol type system. The small level of distortion achieved in the present work systems is explained as partly due to the deliberate generation of harmonic components which are then subtracted from the output signal to remove the distortion components which are added by the amplifier circuit.

A relaxation oscillator type spark generator

Abstract: The spark generator (10) includes a spark transformer 16, an energy storage capacitor 20 connected across an AC supply from terminals (11, 12), and an SCR (25) connected across the transformer capacitor circuit for discharging the capacitor and generating a spark (at 18). The transformer capacitor circuit is connected to the AC supply in series with diode circuit 31 through which the capacitor is charged to the peak voltage of the AC supply and the diode circuit is shunted by an SCR firing control circuit (21, 33, 28) through which current flows when the voltage across the diode circuit reverses to fire the SCR during the same half cycle as the capacitor is charged in.

Inverter circuit with symmetry control

Abstract: An inverter circuit having transistor switches connected to alternately and repetitively apply a-c electrical energy to a load such as a fluorescent lamp. An oscillator control circuit supplies control pulses to the transistor switches in a manner to control their switching to insure a symmetrical waveform at the load. D-C power for the oscillator control circuit is obtained by rectification of the a-c load energy, and the oscillator frequency is adjustable by means of a control voltage.

Tunable Magnetostatic Surface Wave Oscillator At 4 GHz

Abstract: An oscillator tunable from 1.8 GHz to 4.0 GHz has been fabricated using a Magnetostatic Surface Wave (MSSW) 2-port etched groove resonator as the frequency selective element, and a bipolar transistor amplifier for gain in the feedback loop. The theory for a resonator based oscillator is summarized, including the effect of loop gain, amplifier noise loop power, and resonator Q on oscillator noise. Noise and amplitude characteristics of the oscillator are reported over the tuning range. FM phase noise is comparable to YIG sphere oscillators and optimization should yield significant improvement.

Color synchronizing circuit

Abstract: A color synchronizing circuit comprises a phase locked loop which includes a voltage controlled oscillator including a ceramic vibrator. Phase comparison is made of an intermittent color burst and the output of the voltage controlled oscillator and the phase comparison output is applied to a low pass filter. The low pass filter provides a control voltage associated with the phase difference of these two signals to the voltage controlled oscillator. The frequency variable range Δf of the voltage controlled oscillator is selected such that a relation Δf<±f H is met with respect to the repetition frequency f H of the color burst. The low pass filter comprises a dual time constant circuit, which sufficiently attenuates a beat signal from the phase comparator, thereby to make narrow the pull-in range of the phase locked loop. On the other hand, a sawtooth waveform voltage of a stepwise fall is obtained from a sweeper circuit and is applied to the voltage controlled oscillator together with the output voltage from the low pass filter as a control voltage.

Horizontal deflection circuit with a start-up power supply

Abstract: In a horizontal deflection circuit, a horizontal oscillator, energized by a supply voltage, develops a horizontal frequency switching signal. A deflection outputs stage is responsive to the switching signal and generates scanning current in a horizontal deflection winding. After commencement of oscillator operation, the voltage developed across a secondary winding of a flyback transformer is rectified and filtered and applied to the horizontal oscillator as the oscillator energizing supply voltage. A start-up supply for developing the oscillator supply voltage during an initial interval includes a source of voltage that is available for use prior to the commencement of oscillator operation, a capacitor, a charging circuit for charging the capacitor from the available voltage source, and a controllable switch coupled to the capacitor and to the oscillator. After the charging circuit has charged the capacitor to a predetermined threshold voltage level, the controllable switch is made conductive to apply the capacitor voltage to the oscillator to commence oscillator operation. The switch is arranged with the capacitor as a relaxation oscillator to begin discharging the capacitor by the load current drawn by the horizontal oscillator. Should the capacitor discharge to a lower threshold level before the flyback-derived supply voltage is developed, the relaxation oscillator changes states to disconnect the horizontal oscillator from the capacitor to initiate a capacitor recharging cycle.

Phase-locked loop oscillator circuit utilizing a sub-loop with a second phase comparator

Abstract: A phase-locked loop oscillator circuit having a reference signal generator, a voltage-controlled oscillator and a phase comparator comprises a second phase comparator. The first phase comparator is supplied with an output of the reference signal generator whose frequency has been lowered and also an output of the voltage-controlled oscillator whose frequency has been lowered. The second phase comparator is supplied with a signal which has been derived from an intermediate position of a higher-frequency path extending from the reference signal generator to the first phase comparator and also a higher-frequency signal which has been derived from an intermediate position of a path extending from the voltage-controlled oscillator to the first phase comparator. Outputs of the first and second phase comparators are added and applied to the voltage-controlled oscillator to reduce residual FM noise.

Current output relaxation oscillator

Abstract: An integrated circuit current-output relaxation oscillator utilizes an internal or external capacitor which is alternately charged from +V BE to a predetermined upper trip point and then discharged to +V BE . A control current proportional to the voltage across the capacitor is generated and compared with a reference current. When the control current achieves a predetermined value with respect to the reference current, a transistor is turned on permitting the capacitor to discharge to +V BE . The control current is generated by the same current mirror circuit which generates the oscillating output current and is either equal or proportional thereto. Therefore, the magnitude of the oscillating output current is dominantly proportional to the magnitude of the reference current, and the frequency of oscillation is dominantly dependent on passive components; i.e. a resistor and a capacitor.

Electronic monitoring system stabilized against accidental triggering

Abstract: A contactless motion detector, including an oscillator sensitive to an approaching metallic element, includes an electronic switch such as a thyristor triggerable by an output signal from a demodulator comprising a storage capacitor which is alternately chargeable and dischargeable, preferably with constant current, during each cycle of a high-frequency voltage generated by the oscillator. The oscillator voltage is compared with a reference voltage by means of a differential amplifier causing the flow of a charging current into the capacitor when the oscillator voltage exceeds the reference voltage whereas a discharging current flows out of that capacitor in the opposite case. The reference voltage is so chosen that the capacitor charge rises in the course of a few cycles above a predetermined threshold when the oscillator voltage is high but remains below that threshold when it is low.

Electronic ballast for at least one fluorescent lamp

Abstract: The ballast comprises a series resonant circuit (17, 18), dessem capacitor (18), the fluorescent lamp (14) is connected in parallel The power supply to the series resonant circuit (17, 18) via a coil (22) under the control of a single electronic switching element that opens in response to the resonant circuit current and locked (21)

Coupling element between an oscillator and a mixing stage

Abstract: As a coupling element between an oscillator and a mixing stage, an inductor (28, 19) is provided in a receiver input circuit. In order to achieve optimum coupling between the oscillator and the mixing stage, the impedance of the coupling element is reduced in the upper frequency range. For this purpose, the inductor (28, 19) is connected in series to a capacitor (28) and a switching diode is inserted in parallel with the capacitor (28) and a part (29) of the inductor (28, 29) which is through-connected above a selectable oscillator frequency in the flow direction.

Capacity type displacement transducer

Abstract: PURPOSE:To eliminate the influence exercised by a distributed capacity, by a method wherein a capacity type sensor is used as a feedback capacity of an inversion amplifier to form a Miller integrator. CONSTITUTION:A capacity C1, in which an electrostatic capacity changes in proportion to a displacement of a process amount, is connected as a feedback capacity between an input and an output of an inversion amplifier Q1, and a resistor R1 is inserted in series into the input of the inversion amplifier Q1 to form the Miller integrator. Simultaneously, a trigger circuit Q2, having a hysteresis property, is inserted in series between the Miller integrator and the resistor R1 to form as a whole a relaxation oscillator which charges and discharges for the duration of a period corresponding to values of the resistor R1 and an electrostatic capacity C1. If the gain of the inversion amplifier Q1 is extremely large, the input potential of the inversion amplifier Q1 is kept constant through the integral action, whereby charging and discharging toward a distributed capacity CS1 are not conducted, and the presence of the distributed capacity CS1 can be ignored. Additionally, of the output impedance of the inversion amplifier Q1 is extremely small, the presence of a distributed capacity CS2 can also be ignored.

Control circuit for phase controlled oscillator - with pull-in range increased by positive and negative feedback with diode switching

Abstract: The range of this control loop circuit for a phase controlled oscillator is increased by employing a combination of positive and negative feedback to an amplifier which produces a sawtooth waveform output for tuning the oscillator until it locks to a predetermined frequency. This circuit maintains a constant feedback current and eliminates the need for critical or frequency dependent feed back. The output voltage of an amplifier (3) is fed back to its inverting and its non-inverting inputs (12,11) via a capacitor (5) in a positive sense (5,6) and a negative sense (5,7,8) respectively. The negative feedback via diodes (7,8) comes into effect when these diodes conduct at a predetermined threshold voltage.