Showing papers on "Relaxation oscillator published in 1979"

Dynamic properties of semiconductor lasers

Abstract: The dependence of relaxation oscillation on carrier diffusion length in AlGaAs lasers is analyzed using multimode rate equations containing carrier diffusion and spontaneous emission terms. A parameter representing coupling between carrier and light field distribution is introduced. The carrier diffusion shortens the delay time, the relaxation oscillation period, and the decay time constant and also makes spectral narrowing faster. The damping factor is enlarged and relaxation oscillation is suppressed as the carrier diffusion length becomes large. The diffusion length, normalized by stripe width L D /W, is estimated to be about 0.6 by comparing the numerical results with the experimental tendency of transient response. Furthermore, relaxation oscillation is suppressed as the oscillation beam spot size becomes smaller.

CMOS Schmitt trigger and oscillator

Abstract: A CMOS Schmitt trigger circuit displays a lower trigger point that is one N channel transistor threshold above the negative power supply potential and an upper trigger point that is one P channel transistor threshold below the positive power supply potential. Thus, the circuit hysteresis loop is related to supply potential and device threshold values. When the trigger circuit is employed in a relaxation oscillator configuration, the oscillator frequency is independent of power supply voltage and manufacturing variables in the CMOS process that vary transistor threshold values.

Energy extraction from a large‐volume HF laser amplifier

Abstract: Energy extraction from a large‐volume HF laser amplifier has been measured as a function of input intensity. Both the oscillator and amplifier were operated with similar gas mixtures of H2 and F2, which assured a good spectral match between the oscillator and amplifier. The amplifier input intensity was varied from 104 to 2×107 W/cm2. An input intensity of 2×107 W/cm2 extracted an energy equal to about 90% of the energy extracted from the amplifier when it was operated as an oscillator. The experiment also demonstrated that an input intensity of 104 W/cm2 decreased the amplified spontaneous emission intensity by a factor of 2 from the value with no input. Increasing the input intensity level above 104 W/cm2 did not further reduce the amplified spontaneous emission.

Low voltage fluorescent operating circuit

Abstract: A circuit for starting and operating a low-voltage fluorescent lamp from a 120 volt AC supply. The circuit includes a choke type ballast connected in series with the lamp and inductively coupled to a pulse train generator comprising an RC energy storage circuit connected across the line and a voltage sensitive transistorized relaxation oscillator having a divider network for sensing lamp voltage. In a preferred embodiment the circuit is employed in a preheat mode of operation in combination with an electronic starter circuit comprising a PTC resistor, silicon diode and SCR series connected across the lamp.

FET Relaxation oscillator with reduced sensitivity to supply voltage and threshold variations

Abstract: An MOS oscillator is provided which has reduced sensitivity to power supply voltage variations and to threshold processing variations. A plurality of field effect transistors are connected in series to provide reference voltages to establish two trip points for a comparator. A second input of the comparator is connected to a capacitor whose charging and discharging is controlled by the output of the comparator. The plurality of series connected transistors form unsymmetrical active device dividers. The unsymmetrical configuration is chosen such that power supply variations and threshold variations cancel much of the charge current variation due to these variations. Matched current sources are used throughout the oscillator circuit.

Resonator configuration for the suppression of relaxation oscillations in a long-pulsed Nd:YAG laser.

Abstract: A resonator configuration which couples out the Gaussian TEM00 mode was demonstrated to suppress low-frequency relaxation oscillations in the output from a long-pulse Nd:YAG laser. Experimental measurements of the spatial and temporal beam quality, the spectral bandwidth, and the depth of amplitude modulation were made for this and several other Nd:YAG laser resonator designs. The result of these measurements indicates that this resonator configuration can be used to generate a high-quality (TEM00) long-pulse laser output which is nearly free from relaxation oscillations.

Ignition device for oil burners

Abstract: An oil burner ignition circuit using a relaxation oscillator is disclosed. The step-up transformer has a tertiary winding magnetically coupled to a primary winding. The tertiary winding and a diode controls the dissipation in the circuit, and the recovery of energy to a capacitor of the relaxation oscillator.

Switch operated capacitive oscillator apparatus

Abstract: An oscillator circuit is disclosed using a capacitive voltage divider, the circuit being integratable in a monolithic integrated circuit chip. Currents are switched into and out of that one of the capacitors in the divider which is connected through inverters to the other capacitor in a feedback loop. Switching of the currents is controlled in another feedback loop involving a further inverter.

Power conserving blocking oscillator power supply circuit

Abstract: A power source circuit for a discharge type sensing circuit, comprising a blocking oscillator (1 ) and a feedback circuit (2) for changing the period of oscillation of the blocking oscillator (1). The sensing circuit as a load is connected to a secondary winding (L2) of a transformer (T) of the blocking oscillator (1). The base bias of a transistor (Tr1) of the blocking oscillator is controlled by the feedback circuit (2) to which is applied a negative voltage produced in the primary winding (L1) in an off state of the transistor (Tr1). As a result, when the sensing circuit is in the sensing mode of operation, the period of oscillation becomes shorter for rapid supply of electric power and, when in the waiting mode of operation, the period of oscillation becomes longer for reducing supply of power, so that the power consumption is reduced as a whole.

Temperature sensitive relaxation oscillator

Abstract: A temperature sensitive thyristor 10 is incorporated with a capacitor 4 in a relaxation oscillator to provide active temperature sensing. As temperature decreases, the breakover voltage VBO of the thyristor increases, and when VBO becomes greater than the supply voltage, oscillations will cease, thus providing a low temperature alarm point. As temperature increases, VBO decreases and the amplitude of oscillation diminishes, thus providing a high temperature alarm point. This is a "failsafe" arrangement because component failure also provides a warning condition (absence of oscillation). Frequency of oscillation may also be sensed as an indication of temperature.

Entrainment boundaries of relaxation oscillators coupled by low pass filters

Abstract: A simple electronic network employing unijunction transistors has been used to obtain qualitative information regarding the entrainment behavior of relaxation oscillators coupled by low pass filters. Using arbitrary criteria, entrainment boundaries have been determined over the frequency range from 0.14 to 0.5 Hz for filters having time constants of 0.55,1.1 and 1.7 s. It is shown that the efficacy of entrainment is related to filter time constant and the Fourier structure of the bilaterally coupled signals

Transistor resonant circuit power oscillators

Abstract: A power oscillator utilizing one or more field effect transistors in conjunction with a tank circuit.

Relaxation oscillators with electrical control of periodicities of oscillation

Abstract: In this relaxation oscillator first and second electrically controlled constant current generators are used to provide proportionately related first and second currents to first and second terminals, respectively, between which the timing capacitor is connected. Set-reset, or R-S, flip-flop means is set and reset by the voltage at the first and second terminals, respectively, departing in a first sense from the voltage at a reference voltage bus by a predetermined amount. First switching means responds to the R-S flip-flop reset condition to complete a connection of the first terminal to the reference voltage bus and responds to the R-S flip-flop set condition to interrupt that connection. Second switching means responds to the R-S flip-flop set condition to complete a connection of the second terminal to the reference voltage bus and responds to the R-S flip-flop reset condition to interrupt that connection. The rate at which oscillations proceed is linearly related to the amplitudes of the proportionately related currents supplied by the first and second constant current generators.

Electronic accelerator pump timing control

Abstract: Disclosed herein is an electronic timing circuit which can be incorporated in an accelerator pump timing control, also disclosed herein. The timing circuit is adapted to be connected to the first and second power terminals of a DC supply and for energizing a load, for example, a fuel pump solenoid valve, during a predetermined timed cycle. The circuit includes a thyristor having an anode-cathode path adapted to be connected to the load so that when the thyristor is rendered conductive by a trigger pulse applied to the gate, current flows from the DC supply through the thyristor to energize the load and start the timed cycle. A transistor control circuit including a transistor connected in series relation with the anode-cathode path is operable for controlling the energizing current flow through the thyristor, subject to a relaxation oscillator included in the timing circuit. The relaxation oscillator produces a stop pulse a predetermined time after the start of the timed cycle for rendering the transistor operative to interrupt the energizing current flow through the thyristor and to thereby deenergize the load and end the timed cycle.

A charge-flow transistor oscillator circuit

Abstract: The charge-flow transistor (CFT) turn-on delay time can be monitored with a two-inverter one-latch oscillator. Data are presented for a CFT oscillator incorporating the moisture-sensitive polymer film, poly (p-aminophenylacetylene). An instability of oscillator period is observed in certain bias conditions. The origin of this instability is shown to be charge-averaging the polymer film. The averaging time, which can be extracted from the transient behavior of the oscillator period after power-up, is identified as the bulk dielectric relaxation time of the polymer, and equals 130 s in the present case. A theory of oscillator operation that accounts for the observed behavior is presented, along with a brief illustration of the use of such devices in sensing applications.

Electrooptical camera for registering high-speed processes

Abstract: An electrooptical camera comprises an image intensifier connected to a control system for gate and scanning, which system includes a serial arrangement of a trigger oscillator, a master oscillator and an amplifier unit, which comprises preamplifiers and output amplifiers for the gate and scanning channels. The trigger oscillator is a relaxation oscillator utilizing an avalanche transistor and a storage capacitor in its collector circuit. The master oscillator is a Marx oscillator with an optical input and with cable line timing sections of different lengths in its collector circuits. The output amplifier of the gate channel is coupled to the gate system of the image intensifier. The output amplifier of the scanning channel is electrically coupled, via integrators, to a load in the form of a wide-band two-channel cable transformer/shaper, which is coupled to the deflection system of the image intensifier. The integrators utilize RLC-elements and can be inserted between the output amplifier of the scanning channel and its load, via a scanning time selector which includes sealed terminals.

Power supply circuit with a self-oscillating blocking oscillator

Abstract: A power supply circuit is disclosed with a self-oscillating blocking oscillator. A switching transistor and a transformer connecting to a supply voltage produce a DC output voltage which can be obtained from the transformer via a rectifier arrangement. A regulating circuit in a control circuit of the switching transistor is provided which controls the switching transistor as a function of a comparison voltage which is drawn from a primary circuit of the transformer. An integration member connected parallel to the supply voltage produces a periodic, sawtooth-shaped signal which corresponds to the current in the primary circuit and with which the regulating circuit is driven so as to trigger the switching transistor.

Relaxation oscillator having switched current source

Abstract: Within a relaxation oscillator of the type having a capacitor that is recurrently charged from a current source and then discharged through a silicon controlled rectifier upon reaching a threshold voltage thereacross, a switch is disposed to interrupt current flow between the current source and the capacitor whenever the SCR is conductive.

Photoelectric camera for recording high speed process

Abstract: An electrooptical camera comprises an image intensifier connected to a control system for gate and scanning, which system includes a serial arrangement of a trigger oscillator, a master oscillator and an amplifier unit, which comprises preamplifiers and output amplifiers for the gate and scanning channels. The trigger oscillator is a relaxation oscillator utilizing an avalanche transistor and a storage capacitor in its collector circuit. The master oscillator is a Marx oscillator with an optical input and with cable line timing sections of different lengths in its collector circuits. The output amplifier of the gate channel is coupled to the gate system of the image intensifier. The output amplifier of the scanning channel is electrically coupled, via integrators, to a load in the form of a wide-band two-channel cable transformer/shaper, which is coupled to the deflection system of the image intensifier. The integrators utilize RLC-elements and can be inserted between the output amplifier of the scanning channel and its load, via a scanning time selector which includes sealed terminals.

Relaxation oscillator including an SCR and having switch means for interrupting current flow therethrough

Abstract: Within a relaxation oscillator of the type having a capacitor that is recurrently being charged from a current source and discharged through a silicon controlled rectifier upon reaching a voltage threshold thereacross, a switch is disposed to interrupt current flow through the SCR in response to the capacitor being discharged to a predetermined level.

SCR Relaxation oscillator with current amplifier in its gate circuit

Abstract: Within a relaxation oscillator of the type having a capacitor that is recurrently being charged from a current source and then discharged through a silicon controlled rectifier upon reaching a voltage threshold thereacross, the current flow to the gate of the SCR is amplified relative to that being supplied by the current source when the threshold voltage level is reached across the capacitor

Relaxation oscillations of a Josephson contact

Abstract: The Josephson equation with constant current input has been solved in the adiabatic approximation in the limit of vanishing capacitance. In analogy to dissipative mechanical models with zero mass, the system undergoes discontinuous relaxation oscillations, except for large currents. The change in the topology of the phase trajectories manifests itself as a voltage discontinuity at a finite current. Time-average voltage-current characteristics are reported for various temperatures.

Control pulse generator system - has programmable unijunction transistor followed by transistor amplifier, and RC timing circuit

Abstract: The generator has a relaxation oscillator and is intended for two-pulse static converters with thyristors or triacs. It consists of a programmable unijunction transistor (PUT) operated by a trapezoidal DC voltage derived from an AC voltage and of an RC timing circuit with a discharge resistor used as base resistor. A voltage divider delivers a constant gate voltage determined by the supply DC voltage, and a transistor amplifier following the PUT. The relaxation oscillator (1) resistances of the charging resistor (12, 12') of the RC circuit (11, 12) and of the discharge resistor (13) serving as the PUT (10) base resistor are so low, that the transistor amplifier (2) is controlled by the PUT until the AC Voltage next zero crossing.

A tunnel-junction relaxation oscillator: Application to thermometry

Abstract: A superconducting tunnel junction will undergo relaxation oscillations when biased with an active voltage source along the negative conductance portion of its I‐V characteristic. A simple calculation yields an implicit equation for this frequency f in terms of the circuit and junction parameters which is in qualitative agreement with experiment. Measurements on Al*‐Pb : Bi junctions with transition temperature Tc(Al*) ∼1.8 K, over the temperature range 1.3 K