Showing papers on "Relaxation oscillator published in 1982"

PLL for regenerating a synchronizing signal from magnetic storage

Abstract: A phase-locked loop circuit, which obtains a signal synchronized with a phase of an input signal, including a synchronizing portion, and a data portion having a voltage controlled oscillator, a frequency phase comparator, a phase comparator, and a control circuit. The frequency phase comparator detects the phase difference and the frequency difference between the input signal and the output of the voltage controlled oscillator and the phase comparator detects the phase difference between the input signal and the output of the voltage controlled oscillator. The control circuit controls the voltage controlled oscillator, at least during a portion of the synchronizing signal portion, in accordance with the output of the frequency phase comparator, and, during the data signal portion, in accordance with the output of the phase comparator.

Longitudinal mode competition in semiconductor lasers: Rate equations revisited

Abstract: Multimode rate equations have been used to investigate the response to a step current pulse of a semiconductor laser with built-in lateral waveguide. General expressions are given for the frequency and damping time of relaxation oscillations allowing for both gain and total spontaneous emission rate to have arbitrary dependences on carrier concentration. The exchange of power between dominant longitudinal modes, which occurs as a result of the peak gain shift with oscillating carrier concentration, is shown to occur on a time scale controlled by the damping time. The power exchange and the eventual domination by one or other mode are extremely sensitive to one key parameter – the wavelength displacement between peak gain and the adjacent Fabry-Perot mode.

Singular perturbations and a mapping on an interval for the forced van der pol relaxation oscillator : (preprint)

Abstract: Abstract This paper deals with the Van der Pol relaxation oscillator with a large sinusoidal forcing term. By using singular perturbation techniques asymptotic solutions of such a system are constructed. These asymptotic approximations are locally valid and may take the form of a two time scale expansion in one region and a boundary layer type of solution in a next region. Integration constants are determined by averaging and matching conditions. From these local solutions a difference equation is constructed. There is an equivalence between solutions of the difference equation being an iterated mapping on a compact interval and solutions of the system itself. This equivalence makes it possible to analyze subharmonics and chaotic type of solutions to the full extent. As a result of this we find domains in the parameter space, where regular subharmonics exist. These domains overlap so that for some parameter values different subharmonics coexist. For parameter values in this range chaotic type of solutions are found as well. They are described by using concepts of symbolic dynamics.

Voltage controlled oscillator with linear characteristic

Abstract: A voltage controlled oscillator is provided with an LC parallel resonance circuit connected to the collector of one of a differential pair of transistors, and an amplifier and a capacitor which are connected between the collector of the one transistor and the base of the other transistor. The bases of the differential pair of transistors are equally biased. The emitters of the transistors are connected to a variable current source. The variable current source produces a current proportional to the square of control voltage. The frequency of the VCO can be changed by the control voltage with good linearity over a wide dynamic range. The variable current source causes the VCO characteristic to be linear. The value of the capacitor can be small, making the oscillator circuit well suited for integrated circuit fabrication.

Tuning apparatus of phase-locked loop type

Abstract: A tuning apparatus of phase-locked loop type having a voltage controlled oscillator which is working as a local oscillator of a tuning circuit, a programmable divider supplied with the output signal from the voltage controlled oscillator, a reference frequency signal generating circuit, a phase comparator supplied with the output signal from the voltage controlled oscillator and the output signal from the reference frequency signal generating circuit, and supplying the output signal to the voltage controlled oscillator, the programmable divider, the reference frequency signal generating circuit and the phase comparator being formed in a single integrated circuit, and a control circuit formed separately from the integrated circuit for supplying a control data to the programmable divider in the single integrated circuit is disclosed, in which the integrated circuit further comprises a memory for memorizing the control data which is serially supplied from the control circuit and supplying the control data to the programmable divider in parallel.

Pulse width modulator having nonlinear transfer function

Abstract: A pulse width modulator circuit for use with DC power converters The circuit contains an oscillator having a nonlinear output, a first comparator for comparing the output of the oscillator with an input voltage, and a second comparator for selecting portions of the output waveform of the first comparator for supplying to the output of the modulator

Precision differential relaxation oscillator circuit

Abstract: A relaxation oscillator which is suited for fabrication as a monolithic circuit and which uses a parallel resistive capacitive frequency determining network wherein a capacitor is charged and discharged between an upper and lower voltage level As the capacitor is charged to a potential exceeding a first threshold voltage level supplied to a comparator switch, the operating state of the comparator is caused to switch A current detecting circuit is included which detects a current that is proportional to the charging current supplied to the capacitor from a charge circuit As the proportional current decreases in value below a predetermined level due to the capacitor being charged to the upper voltage level the current detecting circuit is disabled which actuates a control circuit for switching the threshold voltage applied to the comparator to a lower level The actuated control circuit also disables the charge circuit such that the capacitor discharges to the lower voltage level at which time the comparator switches states to disable the control circuit whereby the threshold voltage level is switched to the first level Thereafter, the charge circuit is enabled to enable the current detecting circuit and to charge the capacitor to the upper voltage level

Circuit for cancelling the resetting of a microprocessor

Abstract: A semiconductor element handling the resetting is switched by the charge of a capacitor (3). This charge is periodically changed after a limit value has been reached and, as a result, the reset signal (R) of a particular period is generated in the semiconductor element. After the period has elapsed, the reset signal (R) is suppressed by a disturbance voltage opposing the charging-up of the capacitor (3). The circuit comprises a disturbance-signal circuit (1) and an oscillator circuit (2) containing the capacitor (3). The disturbance-signal circuit (1) is activated by squarewave pulses (UE) generated by the microprocessor and outputs differentiated and rectified disturbance voltages to the oscillator circuit (2). The oscillator circuit contains a multivibrator circuit, activated by the capacitor (3) and containing a comparator (7). The threshold voltage (US) for the non-inverting (+) input of the comparator (7) is generated from the supply voltage (VCC) by means of a voltage divider. The oscillating frequency and the period of the reset signal (R) is determined by the time constant of the capacitor (3) together with the resistance (13) and the threshold voltage of (US).

Ultrasonic wave circuit

Abstract: PURPOSE:To improve the pulse response at pulse drive of an ultrasonic oscillator, by connecting a coil oscillating a parallel resonance frequency being approximate to a resonance frequency of the ultrasonic wave oscillator in parallel with the ultrasonic oscillator by means of the static capacitance of the ultrasonic wave oscillator. CONSTITUTION:The ultrasonic wave oscillator 1 has a static capacitance C0, the C0, a capacitor C1 and the inductance of coils L1, L2 consitute a parallel responance circuit and the resonance frequency is designed so as to be close to a resonance frequency f0 of the ultrasonic wave oscillator 1. Since the impedance at a frequency (f) viewed from both ends of the ultrasonic wave oscillator 1 is minimized at the f0, the echo time is reduced remarkably. The capacitor C1 is for temperature compensation and connected in parallel with the ultrasonic wave oscillator 1 so as to reduce the change in the total capacitance and to eliminate the change of the resonance frequency of the parallel resonance circuit comprising the coils L1, L2 due to temperature. Since the transmitted signal is large, diodes D1, D2 are low in the impedance, and since the received output signal is small, the D1, D2 are high in the impedance, and the single ultrasonic wave oscillator 1 is used in common for the receiving and transmission.

Electronic drive circuit for discharge lamps

Abstract: A fluorescent lamp is started and subsequently driven by a circuit having an inductor and a transistor connected in series with one another across a D.C. supply , the transistor being turned on and off at a high rate (15-35 kHz) such that current flows from the inductor through the lamp when the transistor is off. The transistor may be part of a two transistor astable circuit (Fig 2) or may be driven by an R-C relaxation oscillator including a disc (Figs. 4, 7). The inductor may be coupled to a feedback winding (Figs. 3, 7, 10), and a resistor RF and capacitor CF may be connected in series with the lamp to allow current flow therethrough when the transistor is on whereby the lamp is not subjected to unidirectional current. The inductor may form part of an autotransformer (Fig. 9) or may be the primary of a transformer having a secondary connected in parallel with the lamp (Fig. 3). The lamp may be dimmable (Fig. 10). A ceiling mounted lighting unit incorporating the circuit is described (Fig. 13).

Quadrature oscillators with extended time period using grounded capacitors

Abstract: The paper presents a quadrature oscillator with extended time constant. The circuit uses a pair of grounded capacitors. The timing components are scaled by a resistance ratio. The circuit offers desirable features for IC implementation. It can be made into a voltage controlled oscillator by replacing the controlling resistance by FET. An expression of quadrature error is derived, and the circuit is modified for amplitude stabilization. This is carried out at the cost of an additional operational amplifier which incorporates an automatic gain control circuit.

A proposed new method for damping relaxation oscillations in laser diodes

Abstract: A new concept of damping relaxation oscillations in injection laser diodes is described. This method involves the operation of the laser as a part of a bipolar transistor, and the damping is accomplished by reducing the carrier lifetime in the laser active region only at frequencies near resonance. The advantage of the proposed method is that the damping mechanism does not affect the laser operation at any other frequency range.

The Janet/Busch Oscillator: A Multivibratory Dissipative Structure Relevant to Dynamo Theories of Geomagnetic Flux Reversals

Abstract: A dynamo model of geomagnetism displaying multivibratory flux reversals is presented. This model employs a little-known but century-old motor/ generator system; it can be obtained from Bullard's original series dynamo model by replacing his short-circuit with a virtual loaded capacitor, realized by a separately-excited motor. This resulting system furnishes a dissipative structure whose symmetry-breaking instability corresponds precisely to that of the Rayleigh/Van der Pol relaxation oscillator. Motor field strength determines the vibratory frequency. If the field varies, so does the frequency, yielding an infinite reversal period for a field becoming sufficiently weak.

Temperature-period converting device

Abstract: PURPOSE:To make it possible to produce a small and light converter with good temperature-period conversion characteristics, low cost and higher reliability, by inserting property various circuit elements in a discharging circuit of a relaxation oscillator using a negative resistance element as an active element. CONSTITUTION:A temperature sensor is provided by using temperature dependency of the negative resistance element using the relaxation oscillator as the active element, and further into the discharging circuit, a circuit element to improve temperature-period conversion characteristics is inserted. For example, as the active element, a programmable unijunction transistor PUT is used, and when DC voltage +V1 is applied via resistances R3 and R5 to a capacitor C1, if the voltage exceeds peak voltage of the PUT, discharge occurs via the PUT, and the so-called relaxation oscillation is generated. At the time, if in the discharge circuit, for example, an inductance L1 with an appropriate magnitude is inserted, linearity of temperature-period conversion characteristics can be largely improved.

Electronic switching device operating without contact.

Abstract: An electronic switching device (1) operating without contact is represented and described, which comprises an oscillator (10) which can be influenced from the outside, a switched-mode amplifier (11), an electronic switch (12) which can be controlled by the oscillator (10) via the switched-mode amplifier (11), and a feed circuit (13) for generating the feed voltage for the oscillator (10) and for the switched-mode amplifier (11). In such switching devices (1), the oscillator (10) must start again after each damping action and the subsequent removal of the damping. The time needed by the oscillator (10) for coming from the non-oscillating state into the oscillating state, the starting time, is a criterion of the maximum switching frequency permitted by such a switching device (1). To reduce the starting time of the oscillator (10) in switching devices (1) of the type being discussed, a starting generator (14) is provided which generates a starting voltage containing the oscillating frequency, which voltage is coupled into the oscillator (10). According to the invention, a starting aid is thus provided to the oscillator (10) for the starting, which is immediately available in the form of the starting voltage immediately after each removal of the damping of the oscillator (10).

Integrated injection logic time-base oscillator circuit - uses constant current source and large switched current to produce large swing linear sawtooth voltage across capacitor

Abstract: The oscillator consists of a capacitor and an integrated current injection logic module It contains a transistor which forms a switch with a current input from a current source whilst the emitter is connected to a common point (5) One injection logic module (A) is connected to the output of a controlled current generator along with the capacitor (10) The common point (5) is connected to the negative supply through a resistor (R1) The current generator consists of a fixed current generator (14) a current mirror (T4,T5) The control transistor is connected to the common point or to a potentiometric tap on the supply resistor Other modules are connected in the circuit to produce a relaxation oscillator or monostable with a linear sawtooth voltage across the capacitor with a wide voltage swing The logical and analogue components are realised using the same technology The time base circuit is used to use two current generators one giving a fixed current and the other a much larger current The larger one is switched on and off to periodically charge and discharge the capacitor with a sawtooth voltage