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Showing papers on "Relaxation oscillator published in 1972"


Journal ArticleDOI
TL;DR: An array of bidirectionally coupled relaxation oscillators is proposed as a model of gastric electric-control activity, and its characteristics, such as intact and intrinsic frequency gradients and phase-lag patterns, were studied in anesthetized dogs.
Abstract: An array of bidirectionally coupled relaxation oscillators is proposed as a model of gastric electric-control activity. The characteristics of relaxation oscillators simulating control activity, such as intact and intrinsic frequency gradients and phase-lag patterns, were studied in anesthetized dogs. A marked intrinsic frequency gradient was found along the axis of the stomach, and a slight intrinsic frequency gradient around the circumference. The phase lag/cm decreased distally from the body of the stomach to the antrum. The model showed all these characteristics. Each oscillator in the array was represented by a system of two first-order nonlinear differential equations. The model was programmed on analog and hybrid computers.

123 citations


Patent
20 Jan 1972
TL;DR: In this article, a triggered free-running multivibrator is synchronized to operate at a frequency equal to the spacing between adjacent channels of the FM receiver and an audio oscillator.
Abstract: Signal generator for use in testing FM communication receivers including a triggered free-running multivibrator which may be synchronized to operate at a frequency equal to the spacing between adjacent channels of the FM receiver and an audio oscillator. The outputs of the multivibrator and the audio oscillator are coupled to a step recovery diode which produces a spectrum of a plurality of harmonics of the frequency of the multivibrator, each of which is phase modulated by the output of the audio oscillator.

68 citations


Patent
J Fletcher1, S Feng1, T Wilson
18 Apr 1972
TL;DR: In this article, a closed-loop regulated dc-to-dc converter employing an unregulated two-winding inductive-energy storage converter is provided by using a magnetically coupled multivibrator acting as a duty-cycle generator to drive the converter.
Abstract: A closed-loop regulated dc-to-dc converter employing an unregulated two-winding inductive-energy storage converter is provided by using a magnetically coupled multivibrator acting as a duty-cycle generator to drive the converter. The multivibrator is comprised of two transistor switches and a saturable transformer. The output of the converter is compared with a reference in a comparator which transmits a binary zero until the output exceeds the reference. When the output exceeds the reference, the binary output of the comparator drives transistor switches, via a dc isolation circuit, which control the multivibrator to turn the multivibrator off. The multivibrator is unbalanced so that a predetermined transistor will always turn on first when the binary feedback signal becomes zero.

28 citations


Journal ArticleDOI
TL;DR: In this article, a simulation method which efficiently solves the complete Boltzmann transport equation has been used to analyse transferred-electron oscillators and four hitherto unrecognised relaxation effects have been identified, which are of major significance in characterising modes of operation.
Abstract: A simulation method which efficiently solves the complete Boltzmann transport equation has been used to analyse transferred-electron oscillators. Four hitherto unrecognised relaxation effects have been identified, which are of major significance in characterising modes of operation.

25 citations


Patent
18 Feb 1972
TL;DR: In this paper, a solid state electronic timer is used to control the time of load energization with a bidirectional solid state switching device, where a large capacitor is charged to provide a charge for a small capacitor in a relaxation oscillator circuit.
Abstract: The solid state electronic timer controls the time of load energization with a bidirectional solid state switching device. Upon the operation of a timer actuating unit, a large capacitor is charged to provide a charge for a small capacitor in a relaxation oscillator circuit. The relaxation oscillator output is supplied to gate the bidirectional solid state switching device. Since the current necessary to operate the relaxation oscillator is small, timing cycles in the range of many minutes are provided without resort to physically large capacitors.

20 citations


Patent
18 Dec 1972
TL;DR: In this paper, an integrator circuit coupled to a unijunction transistor functions as a relaxation oscillator to generate pulses at a rate proportional to the magnitude of the load current and pass them to a circuit for producing counter pulses.
Abstract: A submersible having a bank of storage batteries for power is provided with a circuit giving crewmen a real-time indication of power used or power remaining in the batteries. A sensor element interposed in series with the load created by the submersible's machinery bleeds off a small sample of the load current which is proportional to the power drain of the machinery. An integrator circuit coupled to a unijunction transistor functions as a relaxation oscillator to generate pulses at a rate proportional to the magnitude of the load current and to pass them to a circuit for producing counter pulses. Counter pulses are coupled to a digital read-out for providing a visual indication of power used or power remaining in the batteries and also are fed-back to the integrator circuit to repeatedly reset it during the integration sequence. Increased reliability is ensured by the provision of a biasing-circuitry arrangement which is "on" only during the period when load current is being drawn from the bank of storage batteries.

18 citations


Journal ArticleDOI
01 Mar 1972
TL;DR: In this article, a general form of this function is introduced for RC oscillators of the second order, and expressions for the required maintenance gain and the oscillation frequency are derived.
Abstract: It is assumed that a sinusoidal RC oscillator consists of a linear, passive or active RC network and an amplifier. The properties of such an oscillator are primarily dependent on its open-loop voltage transfer function. A general form of this function is introduced for RC oscillators of the second order, and expressions for the required maintenance gain and the oscillation frequency are derived. It is shown that there exist four distinct types of 2nd-order oscillators. A set of basic building elements for the oscillators is proposed. This consists of some simple RC networks, a voltage divider, a buffer and two amplifiers. The theory and the building elements are used to develop 18 novel oscillator circuits. All these oscillators have either two earthed tuning capacitances or two earthed resistances. It is shown that six of them can be tuned by varying only one capacitance or resistance. Eight of the oscillators are tunable by varying a voltage parameter; in four of these, the voltage-tuning range can be very wide. 14 additional 2nd-order oscillators are suggested. A general 3rd-order RC oscillator is also considered, and it is shown that there exist 15 distinct kinds of this oscillator. The procedure used in the development of the 2nd-order oscillators can also be applied to the design of those of the third order. It is thought that this will lead to a very large number of different oscillator circuits.

18 citations


Patent
11 Jul 1972
TL;DR: In this article, the resistivity of a circuit path between sense electrodes in a volume of material and providing audio pulses of increasing frequency to cut-off where cutoff is indicative of a predetermined undesired quality of the volume of materials.
Abstract: System for monitoring the resistivity of a circuit path between sense electrodes in a volume of material and providing audio pulses of increasing frequency to cut-off where cut-off is indicative of a predetermined undesired quality of the volume of material. A unijunction transistor is utilized in a relaxation oscillator circuit and a predetermined value of resistance is connected in series path with a base electrode of the unijunction transistor to provide an alarm by oscillator cut-off when the current flow between probes becomes indicative that an undesired quality of the material has been reached, e.g., that saturation of soil by moisture is imminent or that drinking water has become polluted. A particular sense probe geometry provides accurate path measurements between the probes dependent upon the particular depth to which the probe tips have been inserted.

13 citations


Journal ArticleDOI
TL;DR: In this paper, the authors interpret measurements reported for thin film bridges in terms of a relaxation oscillation at the Josephson frequency, using an equivalent circuit including an intrinsic inductance.

13 citations


Patent
31 Jul 1972
TL;DR: A failure detection circuit for a power oscillator driven by a set of transistors which are switched to provide a square wave drive voltage to the oscillator comprises a narrow band pass filter and a voltage sensitive means.
Abstract: A failure detection circuit for a power oscillator driven by a set of transistors which are switched to provide a square wave drive voltage to the oscillator comprises a narrow band pass filter and a voltage sensitive means. The band pass filter is coupled for receiving the square wave voltage and permits the passage of a predetermined odd-harmonic signal to the voltage sensitive means. The amplitude appearing at the voltage sensitive means, such as a lamp, is indicative of the operation of the oscillator.

10 citations


Patent
Eric C Hopkinson1
30 Jun 1972
TL;DR: In this article, a variable D. C. voltage is used to control the pulsed acceleration voltage and hence neutron output by first feeding into a unijunction relaxation oscillator in combination with an SCR output which output is transformer coupled into a voltage multiplier circuit.
Abstract: A variable D. C. power supply and a variable A. C. power supply are coupled onto the upper end of a single conductor cable at the earth''s surface and from the lower end of said cable to a well logging instrument. The A. C. voltage is used to provide filament power for the ion source accelerator tube. The D. C. voltage is used to provide power to fixed D. C. loads maintained constant by regulators once a threshold is reached. The D. C. voltage is raised above the threshold to control the pulsed acceleration voltage and hence neutron output by first feeding into a unijunction relaxation oscillator in combination with an SCR output which output is transformer coupled into a voltage multiplier circuit. An antilatch feature is provided for the SCR by transformer coupling the pulses on the SCR anode back to the base of a transistor in series with the cathode of the SCR. Two outputs of the voltage multiplier circuit are connected to the cathode and anode, respectively, of an ion source accelerator tube, the cathode being connected through a resistor to retard the ripple pulsing of the cathode to allow ionization of the accelerator tube.

Patent
15 May 1972
TL;DR: In this paper, a siren system with a semi-conductor device, which acts as a variable resistance, is coupled to the basic oscillating circuit and is modulated by a relaxation oscillator.
Abstract: A siren system in which a sound producing transducer is coupled to a basic oscillating circuit through a push-pull amplifier and a semiconductor phase inverter. The basic oscillating circuit is modulated by a relaxation oscillator. A semi-conductor device, which acts as a variable resistance, is connected in a resistance-capacitance circuit of the basic oscillating circuit and is coupled to the relaxation oscillator.

Patent
C Lai1
26 Oct 1972
TL;DR: In this paper, an analog-to-pulse-width converter (A2PWC) is proposed, where an analog voltage representing the oil pressure of an internal combustion engine is applied at the input of the circuit to charge the capacitor of the multivibrator to the voltage level of the analog voltage.
Abstract: An analog to pulse width converter circuit includes a monostable multivibrator. The circuit is maintained in a first stable state by a constant current source. An analog voltage representing, for example, the oil pressure of an internal combustion engine is applied at the input of the circuit to charge the capacitor of the multivibrator to the voltage level of the analog voltage. A sample oscillator applying pulses periodically to the circuit triggers the latter to operation in a second, active state, whereby an output is provided from the circuit. Upon operation to the active state, the constant current source charges the capacitor in the opposite direction; the reverse charging time being determined by the original charge on the capacitor at the time of application of the trigger pulse. The duration of the circuit output is thus equal to the reverse charging time and directly related to the voltage level of the analog voltage. Additional circuitry including a clock oscillator, AND gate and pulse converter may be employed in conjunction with the analog to pulse width converter circuit to provide an analog to digital converter.

Patent
L Bellocchio1
16 Feb 1972
TL;DR: In this article, an R-C oscillator controls a transistor switch between a D.C. input voltage and an inductive coil, which is stored in the coil during switch ON time and is transferred through a diode to an output capacitor during switch OFF time.
Abstract: An R-C oscillator controls a transistor switch between a D.C. input voltage and an inductive coil. Energy is stored in the coil during the switch ON time and is transferred through a diode to an output capacitor during the switch OFF time. The D.C. output voltage, across the capacitor, is used as a feedback voltage to control the frequency of the oscillator. The frequency is increased or decreased as a function of a change in the input voltage or output, and the switch is switched ON as a function of the oscillator frequency to maintain a constant output voltage.

Patent
W Camp1
03 Apr 1972
TL;DR: In this paper, the output of a high or low pass filter receiving the oscillator RF output is retified to trigger a monostable multivibrator whose output pulse width is controlled by an RF discriminator circuit.
Abstract: To compensate for changes in the output frequency of an LSA mode oscillator, the bias voltage pulse applied to the oscillator is varied by means of a feedback circuit. The output of a high or low pass filter receiving the oscillator RF output is retified to trigger a monostable multivibrator. In an advantageous technique, the pulse output of the multivibrator is integrated, amplified and applied to a Zener diode which is connected to the bias voltage input of the oscillator to provide a clipping voltage to the oscillator responsive to changes in the RF output. A constant voltage is applied to the integrator along with the monostable output to prevent low repetition rates of the multivibrator from introducing a significant AC component in the integrator output. Different rates of convergence are provided in the feedback loop by employing a monostable multivibrator whose output pulse width is controlled by an RF discriminator circuit. To determine more precisely the frequency at which the multivibrator is triggered, a differential amplifier system is added to compare the power in the filter output with the power in the unfiltered RF output.

Patent
P Zanini1
17 Jul 1972
TL;DR: In this article, a circuit for supplying a progressively increasing amount of power to a plural phase motor during rotor acceleration employs a relaxation oscillator to vary the effective conduction angle for each applied line voltage phase.
Abstract: A circuit for supplying a progressively increasing amount of power to a plural phase motor during rotor acceleration employs a relaxation oscillator to vary the effective conduction angle for each applied line voltage phase. Circuitry is provided to restore an oscillator timing capacitor to a reference condition at a like point during each power phase cycle such that each phase supplies essentially the same monotonically increasing motor accelerating energy. In accordance with varying aspects of the present invention, overload and undervoltage protective circuits remove power from the motor responsive to abnormal operating conditions.

Patent
06 Mar 1972
TL;DR: In this paper, a free-running unijunction transistor relaxation oscillator was used for firing a controlled rectifier, the period of oscillation being a multiple number of half cycles of the line frequency and obtained by the selection of several resistors switched into the emitter circuit.
Abstract: An induction motor speed control circuit which creates submultiples of the power line frequency by selective switching of the line voltage to allow certain cycles representative of a bilateral network in the form of a frequency lower than that of the power source to pass through and operate the motor. The circuit employs a free-running unijunction transistor relaxation oscillator for firing a controlled rectifier, the period of oscillation being a multiple numberof half cycles of the line frequency and obtained by the selection of one of several resistors switched into the emitter circuit. A pulse generated by a zener diode at each of the zero crossings of the line voltage is superimposed by a transformer upon the sawtooth waveform generated by the relaxation oscillator with the result that the oscillator is synchronized to fire the rectifier precisely at the start of a new one-half cycle of the power line frequency. The circuit performs the conversion of the frequencies of large amounts of power at lower power levels and with inexpensive circuit components.

Patent
Visioli A1, Wittlinger H1
29 Mar 1972
TL;DR: In this article, an illumination activated circuit for supplying power from an oscillatory source to a load is presented, where a light sensitive device is arranged in the output circuit of the source such that the signal provided by the source to the load is initiated only when illumination above a certain intensity is received by the device.
Abstract: An illumination activated circuit for supplying power from an oscillatory source to a load. A light sensitive device is arranged in the output circuit of the source such that the signal provided by the source to the load is initiated only when illumination above a certain intensity is received by the device, the device being in effect a dynamic load for the source.

Patent
19 Apr 1972
TL;DR: In this paper, a battery discharge indicator incorporating a battery voltage sensing circuit which responds to the fall of battery voltage below a predetermined value to actuate an indicator, the system incorporating a switch which is actuated by a magnetic field generated by the battery current when this is above a given value so as to prevent actuation of the indicator.
Abstract: 1,271,497. Preventing over discharge of batteries. SEVCON ENG. Ltd. 30 April, 1969 [17 May, 1968], No. 23636/68. Heading H2H. [Also in Division G1] A battery discharge indicator incorporates a battery voltage sensing circuit which responds to the fall of battery voltage below a predetermined value to actuate an indicator, the system incorporating a switch which is actuated by a magnetic field generated by the battery current when this is above a given value so as to prevent actuation of the indicator. This ensures that the indicator will not be operated during temporary voltage drops due to heavy surge currents. In one arrangement (Fig. 1) a determined proportion of the voltage of battery 4 being monitored is tapped from resistor 15 and applied to one transistor 9 of an emitter coupled pair 7, 9. The other transistor 7 has a standard voltage from a Zener diode 1 applied to its base. Any changes due to temperature effects in the base-emitter voltage of 9 are compensated by similar changes at 7. If the battery voltage falls below a predetermined level, transistor 9 is switched off, current through the winding 13 ceases, and a pair of reed relay switch contacts controlled by the winding open. If however, there is a high current surge in the battery circuit to the load 6, a large field is produced in the winding 21 to hold the contacts closed. The contacts are used to control the operation of an indicator. In a second embodiment (Fig. 2) fall of the battery voltage is used to set a relaxation oscillator into operation. A proportion of the battery voltage is applied to the base of a transistor (37) whose emitter is normally held at the potential across a capacitor (43) charged from a Zener diode circuit (45). When the base voltage falls below the emitter, the transistor conducts and switches on a second (39) coupled back to the first so that the capacitor discharges and eventually prevents the first transistor conducting again. These oscillations are amplified and applied to a warning lamp (57). Heavy current flow in the battery circuit is used to operate a pair of contacts (61) across the warning lamp so that it is by-passed under surge current conditions. The first arrangement may be incorporated in a battery operated fork lift truck, operation of the contacts preventing the lift circuit from being operated.

Patent
03 Jul 1972
TL;DR: In this article, an electronic switching arrangement for an electronic pulse generator, which has a condenser and a resistor as pulse frequency determining members, was presented, where a series connection of a second transistor and a second resistor was connected in parallel with the time determining resistor associated with the first transistor.
Abstract: An electronic switching arrangement for an electronic pulse generator, has a condenser and a resistor as pulse frequency determining members, the condenser and the resistor being controlled by an active electronic element such as a first transistor. A series connection of a second transistor and a second resistor is connected in parallel with the time determining resistor associated with the first transistor and the pulse generator. A Zener diode is connected to the base of the second transistor to provide a predetermined voltage-dependent control of the second transistor.

Patent
25 Aug 1972
TL;DR: A key actuated electronic musical instrument of the type suitable for use with piano or organ keyboards, or the like, has a single relaxation oscillator circuit for producing melody tones from selected keys of a keyboard.
Abstract: A key actuated electronic musical instrument of the type suitable for use with piano or organ keyboards, or the like, has a single relaxation oscillator circuit for producing melody tones from selected keys of a keyboard, and three relaxation oscillator circuits for producing chord tones from other selected keys of the keyboard. A delta pitch circuit which produces a sawtoothlike output signal is coupled to one of the inputs of the single oscillator to provide a rapidly changing sound going from a flat tone to a natural tone. The signals for producing melody sounds are delivered through a selective filter circuit which will selectively simulate the sounds of, for example, a saxophone, brass, horn, or a string instrument. The sound signal from the filter circuit is then delivered to an audio amplifier and loudspeaker system. The three oscillator signals for producing chord sounds are mixed together in a transistor buffer stage and then delivered to the audio amplifier through a gate circuit formed by a light-emitting diode and a light-dependent resistor. The gate circuit is responsive to an automatic rhythm generator so that chord sounds may have a selected rhythm. Also connected to the audio amplifier is the automatic rhythm sound generator which can play one of several rhythms utilizing desired percussion sounds. An adjustable vibrato circuit is connected to the melody oscillator to produce a pulsating sound that can be varied in frequency.


Patent
29 Mar 1972
TL;DR: In this article, Person et al. presented a circuit for flashing vehicle direction indicators using transistors oscillators, where the base of a transistor oscillator is connected through a resistor to a relaxation oscillator circuit comprising a unijunction transistor 30, resistors 31... 34 and a capacitor 35.
Abstract: 1,268,372. Transistor oscillators. L. PERSON & SON Ltd., and FLEXIBLE LAMPS Ltd. 16 May, 1969 [17 May, 1968], No. 23581/68. Heading H3T. [Also in Division G4] A circuit for flashing vehicle direction indi. cator lamps 10 or 11 in dependence upon the position of a selector switch 14 connected between the lamps and D.C. supply 13, comprises a power transistor 20 in series with the lamps and cyclically switched on and off by a driver transistor 23. The base of transistor 23 is connected through a resistor 27 to a relaxation oscillator circuit comprising a unijunction transistor 30, resistors 31 ... 34 and a capacitor 35. A drive capacitor 40 in series with a resistor 41 are connected between the + ve line 36 and return line 24 in parallel with the relaxation oscillator circuit to ensure the continued energization of the oscillator circuit after the transistor 20 has been rendered conductive in each cycle. Initially, the transistor 20 is " off " and the voltage of supply 13 causes a current to flow from line 36 to line 24 through three parallel paths and to return to earth 12 through a diode 25. The first path includes capacitor 40 whereby this capacitor is charged, the second path includes capacitor 35 whereby this capacitor is charged, and the third path includes the ohmic junctions B1 B2 of unijunction transistor 30 and resistors 33, 34. The voltage drop across resistor 34 is insufficient to turn the transistor 23 " on ". As capacitor 35 charges, the potential at the + ve end of resistor 32 becomes sufficient to bias the emitter junction of transistor 30 forwardly so that current flows via resistor 31 in the emitter-base B1 circuit of the unijunction. The potential at the + ve end of resistor 34 now becomes sufficient to turn on the transistor 23 which in turn switches on the transistor 20 and the lamps 10 or 11 are illuminated. When transistor 20, conducts the voltage thereacross is so small that capacitor 40 discharges through the relaxation oscillator circuit and also through transistor 23, resistor 21 and the base-emitter junction of transistor 20. This discharge keeps the unijunction transistor 30 and driver transistor 23 conductive and keeps the base current flowing in transistor 20 whilst the capacitor 35 discharges until the valley point is reached where transistor 30 ceases to be conductive whereupon transistor 23 turns " off " and turns off transistor 20. Thus the indicator lamps are switched off and the cycle then repeats. A solenoid 45 in series with the indicator lamps 10, 11 operates a reed relay 43 to flash a monitor lamp 42 in unison with the indicator lamps. However, should a lamp 10 or 11 fail, the reduced current through the solenoid is insufficient to operate the relay.