Showing papers on "Relaxation oscillator published in 1973"

Apparatus for use by physicians in acupuncture research

Abstract: Apparatus for use in research into acupuncture anesthesia or analgesia and other acupuncture therapy having means to vary the amplitude, frequency and amperage of electrical impulses applied to pairs of acupuncture needles. A frequency variable relaxation oscillator is utilized to trigger at selectively variable intervals of time a monostable multivibrator which determines the output pulse interval. The multivibrator output pulse train is shaped and amplified before being applied to a separate pulse generator and isolation transformer for each output channel to generate the output waveform. Each channel includes an attenuator which is used to vary the amplitude of the output waveform and thereby vary the output current. Each channel is also protected against power surges thereby limiting the maximum output current. The output waveform which has been found to produce the most effective results is a steep positive-going pulse having a generally rounded crown followed in 0.5 millisecond by a steep negative-going pulse of approximately the same magnitude of negative voltage and abruptly decaying exponentially to zero in about the same time interval.

Audible signal generating apparatus having selectively controlled audible output

Abstract: A ceramic crystal transducer is connected to a direct current supply in series with a pair of transistors. A pair of independent multivibrator oscillators are connected, each controlling one of the transistors. Each oscillator establishes a rectangular wave and is provided with a continuously adjustable resistor for controlling the output frequency of the corresponding oscillator. The one oscillator is constructed to produce a frequency and a voltage to excite the crystal at the order of the natural resonant frequency and to thereby produce an audio output signal. The second multivibrator oscillator selectively controls the second transistor to control the on/off or pulsing rate of the tone related audible signal. The crystal is pulsed at the output rate of the tone oscillator and vibrates at the fundamental frequency of the rectangular wave as well as harmonics to either side of such fundamental frequency to produce a full and pleasant sound. Variation of the repetition rate of the output signal of the tone generator to either side of the natural resonant frequency of the crystal correspondingly varies the pitch and intensity of the emitted sound to distinguish adjacent alarms. The pulse rate oscillator permits further distinction by adjustment of the signal duty cycle.

Oscillator circuit for providing a conductivity ratio of sea water

Abstract: An oscillator circuit wherein two conductivity cells are arranged in a circuit to provide a conductivity ratio which is converted into a linear variation of the period or frequency of the oscillator.

The investigation of oscillatory processes by perturbation experiments i. the dynamical interpretation of phase shifts

Abstract: Publisher Summary The analysis of phase shifts resulting from discrete perturbation of biological rhythms has been developed By these methods, important insights have been achieved into the entrainment behavior of neural and circadian rhythms, respectively If not directly observable, the hypothetical oscillator projects a reliably periodic rhythm into some observable quantity There is experimental access to a quantity affecting the oscillator By manipulation of this quantity, the oscillator can be perturbed Following perturbation, the observable rhythm is generally deranged, but eventually returns to its normal period There remains an asymptotically constant residual phase shift with respect to a control not so perturbed For example, limit-cycle oscillators, relaxation oscillators, and linear oscillators would behave in this fashion Phase information is reliably transmitted after transients subside, at least as regards certain qualitative features of its dependence on parameters of perturbation

Temperature stable relaxation oscillator having controllable output frequency

Abstract: The disclosed oscillator configuration is suitable for being provided in monolithic integrated circuit form and provides a sawtooth output signal having a repetition rate which is controllable and which is substantially independent of temperature variation. The oscillator circuit includes a comparator which senses the voltage across a discrete timing capacitor and switches states to control the charge and discharge of the capacitor. The oscillator configuration insures that no conductive semiconductor devices are connected to the timing capacitor during the relatively long charge time of the capacitor and that all transistors connected to the capacitor during the short discharge time are saturated to minimize the effects of the thermal changes of the active devices on the capacitor charge and discharge times. Moreover, the oscillator circuit requires only two power supply levels and one timing control terminal to facilitate its use in minimum lead integrated circuit packages including other circuits.

Logarithmic resistance-to-frequency converter

Abstract: By including four resistors and a capacitor in a bridge and connecting the bridge to the input terminals and the output terminals of a comparator amplifier a relaxation oscillator is obtained the square-wave frequency of which depends logarithmically upon the ratio of two resistances. Linearization is obtained by using a measuring-value transducer the resistance of which depends exponentially upon a physical quantity, such as temperature, as one of the resistors. The converter may be used in frequency-analog transmission of measuring values and in measuring instruments for measuring-value indication without the need for linearizing steps.

Vehicle blink pulse generator manufacturable on an integrated circuit basis

Abstract: An emitter-coupled differential amplifier has its inputs connected to the extremities of the diagonal of a bridge comprising resistors and a capacitor, while its output controls a Darlington circuit switch which when operated practically short-circuits the other diagonal of the bridge and causes the capacitor to charge and discharge between two limiting potentials and to make the differential amplifier operate as an astable multivibrator. The Darlington switch also controls the blinker relay. A stabilizing switching circuit controlled by the current flow through a series resistor in the lamp circuit is arranged normally to short-circuit, during the flash period of the lamps, one element of a voltage divider to which the bridge capacitor is connected so as to lengthen the multivibrator period, but if one lamp in the circuit has failed, this switching circuit will not operate, the voltage divider will not be short-circuited and the flash frequency will be increased, warning the driver of the vehicle by the usual pilot light. The circuit is designed for utilization of integrated circuit techniques.

Wide-band, voltage controlled oscillator utilizing complimentary metal oxide semiconductor integrated circuits and a constant current MOS-FET field effect transistor

Abstract: A wide-band, voltage controlled oscillator is described which has a frequency range of six decades. The voltage controlled oscillator (VCO), which uses complementary metal oxide, semiconductor field effect transistor elements (C-MOS-FET''s), is basically an astable multivibrator which is operated from a voltage controlled, variable amplitude, constant current source. The constant current source includes a p-channel MOS-FET operated in a saturated mode to provide a constant current which may be selectively varied as a function of the gate to source voltage. The current source is coupled to a capacitor storage element through a pair of C-MOS-FET''s which selectively establish a conducting path between the capacitor and the constant current source to charge and discharge the capacitor. The C-MOS-FET elements through which the capacitor charges and discharges are controlled by a C-MOS-FET switch means which is actuated in response to the voltage level on the capacitor. By utilizing a constant current source to charge the capacitor, linear charging is easily achieved. Furthermore, the rate at which the capacitor is charged, and hence, the oscillator frequency, may be readily varied over a wide range of values by varying the current level as a function of the input voltage applied to the gate of the constant current p-channel MOS-FET. In one example, a VCO is described which is capable of operating over a frequency range from 5 Hz to 5.5 MHz, and may, in one application described herein, form part of a Phase Locked Loop which is capable of operating over a dynamic frequency range of five decades, i.e., 50 Hz to 5 MHz.

Comparator-keyed oscillator

Abstract: A dead-zone comparator includes first and second voltage comparators used respectively to compare an input signal to a high reference level and to a low reference level, which reference levels can be programmed. A bistable memory element is set by the output signal of one comparator and reset by the output signal of the other. These SET and RESET signals are opposite polarity currents, one of which is more severely constrained in value than the other, and are applied via a common SET-RESET buss to the memory element. When the memory element is in its SET condition, a relaxation oscillator is permitted to deliver output pulses of sufficient magnitude to trigger SCR''s or triacs directly. When the memory element is in its RESET condition, the relaxation oscillator is prevented from furnishing any output pulses.

D. C. power supply for arc welding with SCR controlling three-phase power

Abstract: A D.C. arc welding power supply is supplied with three-phase power through a three-phase transformer. The secondaries of the transformer are connected to a three-phase rectifier bridge with an SCR connected in each phase. A timing pulse generator receives phase reference from the secondaries and produces timing pulses at a controlled time in each phase. A firing signal generator responds to such timing pulses by generating firing signals and applying them to the respective gate electrodes of the SCR''s. A torch switch turns the timing pulses off and on to turn the welding arc off and on, even though full voltage is applied to the primaries. The timing circuit preferably comprises a relaxation oscillator circuit. Multiple torches may be supplied with controlled power simultaneously from the same transformer. A hot start circuit provides greater voltage for a predetermined interval at the beginning of a weld. A MIG spot circuit turns the arc off at the end of a predetermined time for spot welding.

Capacitor discharge ignition testing apparatus

Abstract: Capacitor discharge ignition analyzer includes a pulse source operable to generate electrical signals related to the inputoutput signals of various capacitor discharge ignition systems including battery driven and alternator driven systems. The pulse source may include a relaxation oscillator and switching transistors to generate appropriate initial charging pulses and delayed triggering pulses. Individual load matching circuit are provided to match the load normally applied to the trigger circuit of breakerless ignition systems. An on-off indicator is connected to be driven from the matching circuits. The analyzer also includes an electronic circuit generating an output signal approximating that of the permanent magnet alternators for charging of alternator driven systems. The circuit also includes means to generate a trigger pulse a predetermined time after the charging pulse. The analyzer also includes a self-testing circuit, and may be powered from a conventional battery. A polarity sensitive circuit indicates proper and improper battery connections. The analyzer includes a converter for generating alternating polarity signals, with the circuit connected to provide individual signals matched to selected types of ignition systems. A selection switch means provides for selected connection between an input-output tap means on the analyzer and the ignition circuits. The output of the capacitor is analyzed by a spark gap with an outer enclosure having a small opening. This permits direct testing of the ignition system on the engine without any practical danger of generating explosions as a result of surrounding gas fumes. A separate meter is provided to permit static testing of the output of the voltage and resistance characteristics of the several circuits, with a special energy adaptor being provided to permit selected connection of the ignition capacitor outputs into the meter.

Independently variable on-time and off-time pulse generator circuit

Abstract: A pulse generator for use in an EDM power supply or the like wherein the pulse-on time and pulse-off time are each adjustable, substantially independently of the other The circuit contains a pair of relaxation oscillators, one of which is associated with the on-time and one with the off-time of the output pulse train The timed signals produced by the oscillators are shaped by respective Schmidt triggers for controlling a flip-flop which thereby generates the output pulse train The flip-flop outputs are fed back to the oscillator inputs so as to allow only one of such oscillators to be active at any given time thereby allowing the on-period and off-period to be each independently timed

Dc-to-ac-to-dc-inverter

Abstract: Dc-ac-dc inverter with galvanically separated input and output circuits by means of a transformer and having only two input terminals and two output terminals, further having a rectifier for connecting the transformer secondary to the output terminals, and switching transistors connecting the transformer primary to the input terminals; circuit includes specifically: a selfstarting - self-sustaining relaxation oscillator which is connected for controlling the transistors, and having a pair of power input terminals; impedance means such as forwardly biased diodes or a Zener diode are connected serially between one of the input terminals and to the transformer primary for developing a voltage drop upon flow of current into the inverter, that constant voltage drop is applied to the input terminals of the oscillator to provide power thereto. The inverter may include a starter circuit for providing for a temporary shunt and by-pass for the input current, so that the voltage drop can be developed even if the switching transistors are all off.

Control for electromechanical brake having transistorized timing reset means

Abstract: A static brake controller for an electromechanical brake initially supplies direct current voltage from a first bridge rectifier, energized from a power supply transformer, to the brake magnet coil to release the brake and then supplies reduced direct current voltage from second bridge rectifier, energized by a reduced voltage tap on the power supply transformer, to the brake magnet coil to maintain the brake released while preventing coil overheating The first bridge rectifier has SCR''s in the legs thereof and a relaxation oscillator energizable from the transformer and including a unijunction transistor and an emitter capacitor connected thereto, applies gating pulses to the SCR''s to render them conductive Oscillator disabling means, including a timing capacitor energizable from the transformer and dischargeable to operate a first transistor to short-circuit the emitter capacitor, are provided to disable the relaxation oscillator a predetermined interval of time after the power supply transformer is energized A solid state logic reset circuit, including a normally reverse-biased transistor which becomes forwardly biased in response to deenergization of the power supply transformer, is provided to operate a second transistor which short-circuits the timing capacitor to effect reset thereof and to operate said first transistor which shortcircuits the emitter capacitor to disable the relaxation oscillator

Voltage converter and regulator

Abstract: Voltage converter and regulator circuits are disclosed for converting a relatively low direct current input voltage to a higher output voltage for use in photographic flash equipment, power supplies and energy discharge applications. A battery supplies starting current for a transistor oscillator which provides current through a drive circuit to energize the primary winding of the transformer, during the ''''on'''' portion of the oscillator cycle. During the ''''off'''' portion of the oscillator cycle, no energy is supplied to the primary transformer winding, and the secondary winding provides charging current for a storage capacitor. While energy is being supplied to the storage capacitor, the circuit is maintained in the ''''off'''' condition by a second secondary winding through which current simultaneously flows and is used to energize a transistor to shunt battery current away from the oscillator. Voltage regulation is accomplished by a neon lamp and zener diode which are serially connected with a resistor, across the storage capacitor. While excess energy is being discharged from the storage capacitor the oscillator is maintained in the ''''off'''' condition by a feed-back connection responsive to current flowing through the neon lamp and zener diode to energize a switching transistor to shunt the starting current away from the oscillator. The duration of the ''''on'''' portion of the cycle can be controlled by a variable resistor, and the circuits are also provided with a mechanical switch for selection between different oscillator frequencies.

Ignition system utilizing a saturable-core square wave oscillator circuit

Abstract: An improved saturable-core transistor oscillator circuit for feeding a negative resistance characteristic load. It includes a Jensen-type oscillator that has an added saturation winding to control starting and time duration of the oscillation. There is a high turns ratio output transformer connected to the load and a saturable-core transformer in the oscillator. And, the electromagnetic characteristics of the output transformer are set to resonate with the output at no load in order to provide high starting voltage, while the electromagnetic characteristics of the saturable-core transformer are set to provide an increase in the oscillator frequency as the load increases in order to reduce the output voltage so as to compensate for the negative resistance effect of the load.

Capacitive discharge ignition system utilizing a feedback controlled oscillator

Abstract: An ignition circuit includes a capacitor, an inductor, an oscillator, and a semiconductor switch interconnected in a manner directing the voltage of the inductance of an ignition coil opposing cessation of current therein onto the capacitor. The capacitor charge is then directed onto the inductor, which activates the oscillator by a feedback loop responsive to the current flowing in the inductor. The oscillator conducts to present a current flowpath through the inductor to a battery, until the current reaches a predetermined level, after which the oscillator is turned off. The flyback voltage in the inductor is thereafter applied to recharge the capacitor for the next cycle.

Vibrato signal generating apparatus for an electronic musical instrument

Abstract: A vibrato signal generating apparatus for an electronic musical instrument characterized in that an AND gate circuit is interposed in a circuit connected between a high frequency oscillator and an octave frequency divider, and an astable multivibrator modulated by a vibrato oscillator is provided and is so arranged that the AND gate circuit is controlled by the output signal of the astable multivibrator.

Saturable-core square wave oscillator circuit

Abstract: An improved saturable-core transistor oscillator circuit for feeding a negative resistance characteristic load. It includes a Jensen type oscillator that has an added saturation winding to control starting and time duration of the oscillation. There is a high turns ratio output transformer connected to the load and a saturable-core transformer in the oscillator. And, the electromagnetic characteristics of the output transformer are set to resonate with the output at no load in order to provide high starting voltage, while the electromagnetic characteristics of the saturable-core transformer are set to provide an increase in the oscillator frequency as the load increases in order to reduce the output voltage so as to compensate for the negative resistance effect of the load.

Transistor oscillator with diode in feedback circuit providing amplitude stabilization

Abstract: A voltage-dependent capacitor tuned oscillator employs a diode as a coupling element between an amplifying device and a resonant circuit to provide a feedback signal to the amplifying device required to sustain oscillations. The diode further provides charging current for a capacitor in the resonant circuit when a first polarity portion of the oscillations increase above a predetermined level. The charge on the capacitor decreases the feedback level, thus stabilizing the level of oscillations in the resonant circuit for each frequency to which the oscillator is tuned.

Low-distortion constant-amplitude oscillator

Abstract: An oscillator circuit is proposed, which has a low distortion, a good amplitude stability, a very low self-modulation and which is of simple design. For instantaneous variations use is made of an amplifier circuit which operates in the linear region and which has a gain factor which is smaller than is required for undamping, and a source of auxiliary oscillations, which provides the excitation of the oscillator circuit. The constant excitation is preferably derived from the oscillator output voltage.

Brushless variable speed drive for a. c. synchronous motor

Abstract: A motor speed control circuit is provided for varying the speed of a motor in response to a change in an ambient parameter. An A.C. hysteresis motor is driven from a D. C. supply by a multivibrator. The multivibrator is driven in synchronism with a unijunction relaxation oscillator which oscillates at a variable frequency determined by changes in said ambient parameter. A resistive sensor means is provided in circuit with the relaxation oscillator for detecting changes in the ambient parameter. The resistance of the sensor varies logarithmically with changes in the ambient parameter. The unijunction oscillator means is provided with means to compensate for the logarithmic change in the sensor, to thereby provide an oscillator frequency which varies linearly with said ambient parameter. Since the speed of the motor is controlled by the frequency of the oscillator, the motor speed is also a linear function of the change in the ambient parameter.

Solid-State Proportional Temperature Controller

Abstract: A new proportional temperature control circuit that uses a unique thermistor oscillator as the temperature sensing element is discussed. A series connected positive temperature coefficient (PTC) thermistor and negative temperature coefficient (NTC) thermistor form an electrothermal relaxation oscillator. The environmental temperatures which the thermistors experience determine the amplitude and frequency of the oscillator. Coupling the oscillator with a thyristor and using the temperature dependence of the oscillator, proportional temperature control can be achieved.

Tuneable UJT oscillator circuit

Abstract: A relaxation oscillator with an offset control. A timing circuit including a charge storage device in the relaxation oscillator is energized from a normally constant voltage source and one or more variable voltage sources. The first source also establishes a reference signal in a discharge circuit in the relaxation oscillator. Changes in the voltage from the variable voltage source do not affect the reference signal, but do affect a timing signal from the charge storage device. As the discharge circuit discharges the charge storage device each time the timing signal exceeds the reference voltage, changing the voltage from the variable voltage source does alter oscillator frequency.

A consideration of wide-band blocking oscillation excited by high frequency

Abstract: The voltage controlled wide-band blocking oscillator is obtained by the modified Colpitts-type transistor high-frequency oscillator adding a capacitor and an inductor. The principle of action is mentioned on the basis of the experimental results.

Square wave transistor relaxation oscillator

Abstract: A control system, particularly for a diesel engine, has a square wave oscillator, the output from which is fed to the primary winding of a transformer having a secondary winding, the coupling between the windings being varied to vary the output of the secondary winding. This signal can provide an input to a control circuit for determining the fuel supply to the engine, or can be used for other purposes.