Showing papers on "Relaxation oscillator published in 1976"

Suppression of the relaxation oscillation in the modulated output of semiconductor lasers

Abstract: Practical rates of direct pulse modulation of semiconductor lasers have so far been limited to below several hundred megahertz, owing to serious distortion in the output signal caused by the relaxation oscillation of the light intensity. Based on theoretical analysis of the dynamic properties of lasing under constant injection of external radiation into the cavity modes, light injection is proposed as a method for suppressing the relaxation oscillation. The effectiveness of this method has been confirmed in a series of preliminary experiments which employed GaAs injection lasers both as the modulated laser and as the external source of the injected radiation.

Mathematical Modeling of the Colorectal Myoelectrical Activity in Humans

Abstract: Measurement of the colorectal myoelectrical activity in humans has revealed three basic patterns of behavior, comprising a lower frequency oscillation of about 0.05 Hz, a higher frequency of about 0.12 Hz and periods of zero activity. To simulate these myoelectrical patterns, the concept of linked relaxation oscillators is extended in this paper using three different mathematical model structures. In the three models two of the activity patterns are obtained as two stable limit cycle solutions produced by symmetrically coupling together two relaxation oscillators. The first model comprises a ring of interconnected oscillators which produces a third stable solution representing the higher frequency of oscillation. Summation of adjacent oscillator outputs reproduces the zero activity when the oscillators are in antiphase. By addition of an extra coefficient into the basic relaxation oscillator equation for the second model, the zero state becomes a stable condition and the three patterns are obtained without the necessity of a ring structure. The third model requires an in-situ change in a parameter value for the lower and higher frequencies to decay away to the zero activity condition.

Subscriber loop verification device and method

Abstract: A subscriber loop test device is connected across a subscriber loop adjacent a subscriber equipment and remote an associated switching office. The subscriber loop test device includes a relaxation oscillator and a connection circuit responsive to a predetermined high voltage applied at the switching office for connecting the relaxation oscillator to the subscriber loop. The relaxation oscillator responds by drawing an energizing current which it modulates at the operating frequency of the oscillator. Detection of this frequency in the switching office verifies the DC and the AC continuity of the subscriber loop. Additional contacts in the connection circuit are used to disconnect the subscriber apparatus for the duration of the operation of the test device so that faulty subscriber apparatus will not interfere with verification of subscriber loop serviceability.

Power supply unit for data viewing devices

Abstract: The invention relates to a power supply unit for data viewing devices, which, from a main alternating voltage produces at least one d.c. voltage for the operation of the data viewing device, where the power supply unit is in the form of a switching power supply unit and contains an oscillator which produces signals which determine the switching frequency of the switching power supply unit and where the data viewing device contains a pulse generator which, in order to produce an image on a screen, produces timing pulses of a given repetition frequency and a given duration. More particularly, the control stage for a switching power supply unit of a data viewing device having a display screen includes a free-running oscillator whose frequency is synchronized by timing pulses from a pulse generator. These pulses are of a predetermined repetition frequency and a given duration. The oscillator is preferably an astable multivibrator. The output signal of the oscillator is pulse modulated and fed to the base of a switching transistor in the power supply circuit. A separator stage such as an optical coupling element or transformer, is provided in the circuit between the pulse generator and the oscillator. The oscillator may contain an amplifier provided with a positive feedback and a negative feedback and which oscillator has its control input connected to the non-inverting input of the amplifier. The non-inverting input of the amplifier preferably includes a capacitor.

Stabilized crystal controlled oscillator

Abstract: The invention relates to an oscillator having a positive feedback amplifier circuit the gain of which is controlled in direct opposite relationship to the amplitude of the oscillatory voltage produced by the oscillator and is especially useful for crystal controlled oscillators. The controlled feedback amplifier comprises a differential amplifier one branch of which feeds a rectifier producing the control voltage and the other branch of which acts as the controlled feedback amplifier.

Regulated strobe with hysteresis

Abstract: A simplified voltage regulating circuit is provided for controlling the operation of a d-c to d-c converter oscillator as is commonly used in an electronic flash. The voltage regulating circuit controls the operation of the d-c to d-c converter so that the output voltage from the oscillator is maintained within a prescribed range. The voltage regulating control circuitry includes an ordinary transistor controlled by way of an output voltage sensing zener diode which operates to turn on the transistor and thereby terminate operation of the oscillator when the output voltage therefrom reaches its maximum value within the prescribed range. A capacitor is also charged by way of the transistor when it turns on and the residual charge of the capacitor thereafter operates regardless of the non-conductive state thereafter assumed by the zener diode and transistor to maintain the oscillator off until the output voltage from the oscillator decays to its minimum value within the prescribed range.

Measurement of parameters in a mode‐locked and frequency‐doubled Nd : YAG laser using relaxation oscillations

Abstract: The behavior of relaxation oscillations in the presence of a nonlinear loss was used to determine the relevant parameters of an intracavity frequency‐doubled and mode‐locked Nd : YAG laser The acousto‐optic mode locker was used in a controlled manner to excite the relaxation oscillations which allowed the measurement of the damping time and frequency Laser output power at 053 μm and damping time is consistent with recent theory

DC to DC converter with isolated output - suitable for aircraft control panel illumination and uses relaxation oscillator which triggers transformer input

Abstract: The secondary winding of the transformer(22) supplies an amplifier(25) connected to an isolating transformer(30) whose output is rectified filtered and fed to the output via a current measuring resistance(37) Another rectifier(40) provides a reference to a threshold circuit(45) whose other input is from the current measuring resistance Its output is connected to an OR gate A comparator(50) sensing the reference voltage and the output voltage, is also connected to the OR gate The gate output provides negative feedback to the relaxation oscillator via a photo-diode and transistor pair The circuit gives a totally isolated output suitable for use in aircraft control panel illumination circuits

Variable on-and off-time relaxation oscillator

Abstract: A relaxation oscillator comprising three cascaded operational voltage comparators is described. The on-time of the inventive circuit is established in accordance with a variable input element to the first operational comparator. The off-time is established by an RC network in the input circuit of the second operational comparator. The first and second operational comparators are interconnected so that the turning on or off of the second operational comparator affects the first operational comparator to cause it to also turn on or off.

Voltage controlled Clapp oscillator having output isolated from tuned circuit

Abstract: A voltage controlled oscillator arrangement having improved characteristics is shown to include a Clapp type oscillator utilizing a transistor as the active element, the electrodes of such transistor being connected to an electronically tunable resonant circuit and to a load in such a fashion as to effectively separate the two.

Supply cct. for incandescent lamps in battery-driven vehicle - has astable multivibrator reducing supply to power low-rated lamps

Abstract: The supply circuit for incandescent lamps in a battery-driven vehicles has the lamp (13) supplied from an astable multivibrator (10) whose duty cycle is determined by the lamp rated voltage and the supply voltage, the latter being generally greater than the lamp rated voltage. The multivibrator consists of two complementary transistors (20, 21), whose one collector is coupled over a capacitor (27) to the other transistor base. A protection circuit (14) is connected across the lamp and blocks the astable multivibrator transistors in case of a short circuit. Using a multivibrator as voltage divider avoids providing the battery with a tapping.

A constant flux rate variable-frequency hysteresis loop generator having wide dynamic range

Abstract: The circuit described generates a constant alternating-polarity time-rate-of-change of magnetic or electric flux. Commutation is performed automatically when a prescribed degree of saturation has been attained. The circuit has been operated over the frequency range 1 μHz to 1 kHz.

Frequency stabilising circuit for oscillator - has phase locked loop remaining within tolerable swing-out range during interruptions

Abstract: The frequency stabilising circuit, for an oscillator, has a phase locked loop designed to remain within a tolerable swing-out range during brief interference -- such as interruptions to the supply voltage or control frequency changeover. The outputs of the crystal oscillator (or control frequency) (ST) and the varactor-tuned oscillator (0) are frequency divided and applied to the phase discriminator (PD). The phase discriminator output is LP filtered and compared (VV) with the LP filtered output of a monostable multivibrator (M1) following the output of the tunable oscillator. The comparator output is coupled to a store (SP) together with the delayed output of a voltage discriminator (SD). The store is connected to the multivibrator and its contacts are held during interruptions.

Monolithic integrated circuit for an rc oscillator

Abstract: A monolithic integrated circuit for an RC oscillator includes a differential amplifier acting as a switching stage for comparing a threshold voltage corresponding to the maximum oscillator voltage with the capacitor voltage of the RC circuit. An output of the differential amplifier is connected to the S input of an R-S flip-flop which is set when the capacitor voltage reaches the threshold voltage. A switching transistor has its collector and emitter connected across the capacitor and a base connected to the output of the R-S flip-flop for discharging the capacitor when the flip-flop is set. A second transistor has its base-emitter junction connected across the base-collector junction of the switching transistors so that when the switching transistor has discharged the capacitor to a point that only its collector-to-emitter saturation voltage dropped across it, the second transistor is turned on to provide a signal to the reset input of the flip-flop, thereby inhibiting the discharge of the capacitor and allowing the capacitor to recharge through a current source.

Constant current supply for gas discharge lamps - uses relaxation oscillator and is independent of number or length of discharge tubes in circuit

Abstract: The current supply is used for illuminated letters, where a constant intensity is required. The circuit consists of a relaxation oscillator, containing a transistor (1), a transformer (4, 5, 10) a timing circuit and a current discriminator. The transistor in the oscillator switches repeatedly from fully conducting to fully cut off and vice versa, with the lengths of time in either state defined by the discriminator and timing circuit respectively. The discriminator detects when a particular current in the transistor has been attained and then forces it into the cut off condition. This defines the current in the transformer secondary circuit (10) which in turn feeds the gas discharge lamp (11) or lamps.