Showing papers on "Relaxation oscillator published in 1969"

Radio frequency standard and voltage controlled oscillator

Abstract: A radio signal controlled oscillator is provided as a local frequency standard by synchronizing the oscillator using a phaselock servosystem comprising a long term integrating device as a voltage variable capacitor in the resonant circuit of the oscillator. The device consists of two columns of mercury separated by a substantial gap of electrolyte in a chamber made of dielectric material. Upon comparison of the oscillator signal with the radio signal, any error signal developed is applied across the electrolyte gap to the mercury column to transfer mercury from one to the other by the process of electrolysis. Conductive material wrapped around the chamber serves as a second plate of a capacitor for each of the columns one of which is used as part of the voltage variable capacitor. Means is provided for detecting the loss of the radio signal to interrupt any further change in the variable capacitor until the radio signal is restored.

A high power LSA relaxation oscillator

Abstract: A new high power LSA relaxation mode of operation offering wide electronic tuning of many times oversized GaAs diodes in high impedance waveguide post structures is presented: Experimental data and computer simulations explaining this mode of operation and characteristics of oscillations below and above the waveguide cutoff frequency are discussed.

Bias circuit oscillations in Gunn devices

Abstract: A theoretical and experimental study of low-frequency oscillations in the bias circuit of short (nominally 12 µ) Gunn devices is presented. Sinusoidal oscillations and relaxation oscillations including damped sinusoids and exponentially decaying pulses have been observed. The frequency, pulse width, and repetition rate are adjustable with bias voltage, bias circuit impedance, and the impedance of the microwave circuit. This behavior, as well as the conditions for stable bias, is explained in terms of an average terminal i-v characteristic for those devices which exhibit a terminal current drop. The oscillation amplitude is determined by the shape of this i-v curve. Pulses have been observed with subnanosecond rise times, peak voltages of 35 volts and adjustable pulse widths ranging from 3 to 200 ns for typical driver pulse widths of 100 to 500 ns. The sinusoidal frequencies were adjustable in the range of 300 to 550 MHz. The microwave output was in X-band and was self modulated by the bias circuit oscillations. The measured waveforms agree well with theory.

Oil burner spark ignition system

Abstract: AN OIL BURNER IGNITION SYSTEM PRODUCES A TONGUE-LIKE CONFIGURATION OF INDIVIDUAL SPARKS EXTENDING FROM A PAIR OF DISCHARGE ELECTRODES AND INTO THE SPRAY PATTERN OF OIL PARTICLES PRODUCED BY THE BURNER NOZZLE. THE SYSTEM INCLUDES A SPARK GENERATING RELAXATION OSCILLATOR CIRCUIT CAPABLE OF PRODUCING INDIVIDUAL SPARKS AT A FREQUENCY SUCH THAT SUBSEQUENT SPARKS ARE ABLE TO FOLLOW THE ELONGATING IONIZED AIR PATH ESTABLISHED BY PREVIOUS SPARKS. THE OSCILLATOR CIRCUIT INCLUDES A CAPACITOR CHARGED FROM AN AC POWER SOURCE AND REPTITIVELY DISCHARGED DURING ALTERNATE HALF CYCLES AT RAPID INTERVALS THROUGH THE PRIMARY WINDING OF A TRANSFORMER BY MEANS OF A CONTROLLED RECTIFIER GATED IN ACCORDANCE WITH THE CAPACITOR CHARGE LEVEL.

Lamp driver circuit

Abstract: An inverter or converter circuit is described for controlling the power to a suitable load such as a gas or vapor discharge lamp. The circuit includes a transformer having a secondary winding coupled to the load and a primary winding connected to a direct-current voltage source by a controlled rectifier such as a silicon-controlled rectifier. A variable-frequency trigger circuit, e.g., a relaxation oscillator, controls the switching rate of the controlled rectifier and the magnitude of the power delivered to the load. An inductive reactance independent of the transformer is connected in series with the primary winding. A capacitive reactance is connected in parallel with the inductive reactance and primary winding to form a resonant tank circuit for providing commutation of the switching device independently of the load impedance.

Astable multivibrator having a sweep frequency stabilized by a crystal oscillator

Abstract: A bistable complementary multivibrator is connected to an astable control multivibrator whose sweep frequency is stabilized by a crystal oscillator. The transistors of the complementary multivibrator are connected to the collector electrodes of the transistors of the control multivibrator and are connected in mutual feedback relation with elimination of interpolation of components.

Null detector employing a product detector therein

Abstract: 1,202,073. Product; difference computing. AMERICAN OPTICAL CORP. 22 Nov., 1967 [1 Dec., 1966], No. 53273/67. Heading G4G. Alternating current analogue signals are combined to a third signal representing product or difference by applying one such signal (or a combination thereof) to a switch input generating a pulse control signal from the other thereof to control the switch operation between conducting and non conducting and filtering the switch output to produce the required signal. In Fig. 1, signals V A and -V B of identical frequency in antiphase (e.g. from the photo-cell outputs of a dual beam spectrophotometer) are applied to inputs 10, 12 from which they are algebraically added at junction 14 to produce error signal V s applied to a switching circuit (Fig. 3, not shown) comprising a transformer fed biased amplifier having a pulsed transistor alternately connecting and disconnecting the input to earth. Input V A is also amplified to constant amplitude V c which is applied to control the frequency of the output V o of a relaxation oscillator 20 according to its instantaneous voltage values, to drive a oneshot multivibrator 22, whose output is thus a sinusoidally frequency multiplied pulse train, to pulse the switch 16 (Fig. 2, not shown), whose output is integrated in low pass filter 24, to a direct voltage V F which is shown by mathematics to be combined of a constant voltage V R and a voltage proportional to the product V c , V s . Amplification by differential D.C. amplifier 26 receiving a voltage V R produces an output proportional to V c , V s and thus to (V A -V B ) since V C is constant. This signal may be applied to a null balance servosystem controlling V A and -V B for null error. Alternatively the output represents the product of (V A -V B ) V C where V C is proportional to V A . Where V A and V B are applied directly to the relaxation oscillator and the switch respectively, the output is proportional to the product V A , V B .

Wide pulse low prf pulse generator

Abstract: A pulse generator capable of producing wide low RPF pulses having fast rise and fall times is realized by circuits which alternately drive a bistable device. A multivibrator is periodically placed in a first stable state by a unijunction transistor relaxation oscillator having a slow period of oscillation. The multivibrator is returned to its second stable state by a unijunction transistor circuit that is activated by the first stable state voltage condition of the multivibrator. A time delay circuit associated with the unijunction transistor circuit delays actuation of the unijunction transistor and thus establishes the pulse width of the pulse generator.

Electronic converter for use in the voltage transformation and regulation of a uni-directional voltage

Abstract: An electronic converter for use in the voltage transformation and regulation of a unidirectional voltage having a controlled relaxation oscillator to which is coupled a power monostable circuit so as to be triggered thereby, an energy storage and voltage transformation transformer being coupled to the monostable circuit, the transformer having an output winding coupled to a load and a sensing winding tightly coupled to the output winding so as to sense the output voltage level. The sensing winding has coupled thereto a threshold detector which serves to transmit the excess energy stored in the transformer to a storage and filtering capacitor coupled to the detector via an amplifier which serves to switch the excess energy to the storage and filtering capacitor which is coupled to the relaxation oscillator so as to control its frequency and thereby maintain the output voltage at the required level.

Electroluminescent relaxation oscillator for dc operation

Abstract: An electroluminescent circuit for DC operation comprising a discrete electroluminescent element the capacitive reactance characteristic of which is utilized in a circuit containing a bidirectional threshold switching device having inherent turn-on time delay and inherent recovery time delay characteristics and, together with suitable circuit resistance form a bistable electroluminescent relaxation oscillator circuit which has stable ON and stable OFF conditions with a DC operating potential continuously applied thereto. When a start signal, which may be a pulse of predetermined time duration and amplitude, is applied to the electroluminescent circuit the circuit will begin to oscillate at a frequency determined by, among other things, the electrical values of the circuit components and the amplitude of the applied voltage and will continue to oscillate as a relaxation oscillator after termination of the start signal to energize the electroluminescent element of the circuit so that light will be emitted therefrom. When a stop signal of the proper time duration is applied to the electroluminescent relaxation oscillator circuit the circuit will stop oscillating and the electroluminescent element will no longer emit light.

Low pass astable multivibrator

Abstract: A free-running multivibrator circuit adapted to change oscillation frequency in response to the change in capacitance of at least one of a pair of capacitors which are not necessarily electrically isolated. The circuit comprises a free-running astable multivibrator of the common type which is controlled and synchronized by a set-reset bistable multivibrator. The outputs of the astable multivibrator provide the driving waveforms for the capacitors, but the waveforms are modified by the time constant of the capacitors which in turn control the bistable multivibrator that synchronizes the astable multivibrator. The low-pass astable multivibrator has application for measuring capacitance as in a microphone circuit having dual capacitor elements or any type of pressure sensor such as a rate-of-climb indicator for aircraft.

Voltage controlled oscillator consisting of a bistable multivibrator with feedback circuits

Abstract: A voltage controlled oscillator capable of producing a squarewave pulse repetition frequency, and characterized by a constantpercentage change in square-wave PRF at the output per volt change at the input. The VCO includes a limiter, integrator and Schmitt trigger connected seriatim.

Seismic system for real-time reporting

Abstract: A seismic system for real-time directional reporting for providing radio signals indicating the direction and location of traffic along a path wherein two geophones positioned adjacent said path and spaced from each other are each connected to separate channels each of which includes amplifier means coupled to an integrator capacitor which in turn is coupled to a trigger circuit whereby the signals developed by the geophone are converted to a sharp trigger pulse. The output of each channel is coupled through a diode to a one-shot multivibrator whose output is coupled to a transistor switch in series with the emitter circuit of a transistor audio frequency oscillator and power supply whereby when a trigger pulse from either channel is applied to the one-shot multivibrator the audio frequency oscillator is activated for the period of the one-shot multivibrator. The trigger pulses of the channels are also connected to the inputs of a flip-flop which is set by one channel and reset by the other. The output of the flip-flop is coupled to a transistor switch in series with an astable multivibrator and the power supply whereby said astable multivibrator may be activated when the transistor switch is enabled by the flip-flop.

Astable transistor multivibrator frequency divider

Abstract: A frequency divider is formed by an astable transistorized multivibrator of symmetrical construction comprising two parts. Rectangular input signals are applied symmetrically and in opposite phase to each part, and fed to the emitters of the transistors through a respective input capacitor. The multivibrator is a relaxation oscillator consisting of two NPN transistors coupled through two capacitors, so that the input of one transistor is actuated through the respective capacitor, by the output of the other transistor. The input signals may be supplied by an identical multivibrator.

Adjustable frequency bipolar square wave generating circuit

Abstract: An inverter circuit for providing low-frequency pulses to a load device, such as the ringer winding of a telephone set, the circuit having a high-frequency oscillator, a capacitor charging circuit energized by the output of the high-frequency oscillator for providing positive going pulses across the output of the inverter circuit each time the high-frequency oscillator is rendered operative for a predetermined period of time, a pulse circuit for providing the load device with negative going pulses each time it is operative; and a low-frequency multivibrator for alternately, at a low-frequency rendering the high-frequency oscillator and the pulse circuit operative for predetermined periods of time, whereby said output of the inverter circuit is energized by alternately positive and negative going pulses, the frequency of oscillation of the multivibrator being variable. A multivibrator whose frequency of oscillation is variable over a wide range by a resistance type control.

Temperature-compensated unijunction transistor relaxation oscillator with switched reference voltage

Abstract: Temperature-compensated pulse-generating apparatus employs a complementary unijunction transistor as a threshold detector in a bridge-type comparator circuit for generating output pulses. A unijunction relaxation oscillator operatively controls an electronic switch which, in turn, controls the operation of the complementary unijunction transistor in a switching mode to effectively multiply the peak point current available to the complementary unijunction transistor. The cycle of the output pulses is determined by the delay of an RC timing circuit provided in the comparator circuit, the time constant of the timing circuit being controlled by selectively connecting therein of a timing resistance. The optional provision of the output pulses to shift registers provides easily programmed very long time delays wherein the total time thereof is controlled through a switch for selectively changing the value of the timing resistance.

Relaxation oscillator gated by transistor switch

Abstract: A unijunction transistor, a switch such as the emitter-tocollector path of a bipolar transistor, connected with the emitter-to-base path of the unijunction transistor, and a charged capacitor connected across the series circuit. When the switch is closed, the capacitor instantaneously discharges through the emitter-to-base diode of the unijunction transistor. Thus, the leading edge of this discharge wave is substantially coincident in time with the closing of the switch, that is, with the turn-on pulse employed to drive the bipolar transistor into conduction.

High frequency coaxial line circuit for an avalanche diode noise generator

Abstract: The coaxial line circuit for an avalanche diode noise generator is disclosed. The coaxial line circuit includes a short at one end thereof with the avalanche diode connected in series with the inner conductor at the shorted end of the coaxial line. The short preferably includes a block of thermally conductive material closing off the end of the coaxial line with one terminal of the diode being connected to the block for heat sinking the diode. In addition, the shorting block includes a portion concentric to and axially coextensive with the end portion of the outer conductor of the transmission line to form a relatively high capacitance between the outer conductor and the shorting block. This capacitance stores the energy for the relaxation oscillator mode of the avalanche diode which is preferably operated as a noise generator. In another embodiment, a wave-reflective member is placed within the coaxial line a distance from the shortcircuited end thereof to produce a subharmonic cavity for increasing the power density of the noise spectrum output at higher harmonics of the cavity. In another embodiment, a varactor diode is placed in the coaxial transmission line at a point of maximum electric field of the output mode for tuning the output frequency of the noise.

Scr firing circuit

Abstract: An SCR firing circuit is provided for each SCR in a multiphase power circuit supplying a DC motor. Each firing circuit includes an output transistor, controlled in the on-off mode by a multivibrator circuit, for providing continuous gate drive to its associated SCR when the multivibrator switching circuit turns it on. A charging circuit includes a capacitor and a transistor connected so that a control signal applied to the transistor determines the rate of capacitor charge. When a predetermined voltage is applied across the capacitor, a unijunction transistor fires and applies a trigger signal to the multivibrator switching circuit for applying a continuous gate drive to the SCR. A signal from the input AC line which supplies the power circuit is utilized to reset the multivibrator switching circuit and remove the gate drive at the proper time.