Showing papers on "RC circuit published in 1968"

Active RC filters—A state-space realization

Abstract: A standard configuration composed of RC and operational amplifiers is used for the realization of any second-order voltage transfer function. The approach blends well into the hybrid microelectronics field and promises absolute stability and very low sensitivity.

Stabilizing phase controlled ac induction motors

Abstract: An adjustable speed capacitor run or polyphase AC induction motor energized by phase controlled voltage is stabilized by an AC phase control circuit whose timing is referenced to the zero crossing of the capacitor voltage in an RC circuit and supplies gating signals to a thyristor in series with the motor, characterized by a degenerative feedback circuit comprising an impedance element connected to modify the capacitor voltage in such manner that the cessation of thyristor conduction modulates the timing of the next gating signal.

Resistance Multiplication in Integrated Circuits by Means of Switching

Abstract: A state-space analysis is given for RC networks containing an arbitrary number of periodically operated switches. The results are then applied to the design of RC integrated circuits in which large values of resistance are achieved by placing a switch in series with each resistor of small resistance. It is shown that the technique provides excellent desensitivity to environmental change. Finally an experiment verifying the usefulness of the method is described.

An elementary design procedure for digital filters

Abstract: The purpose of this paper is to parallel for digital filters the type of synthesis that might be found in a first course in circuit or control theory. The method described emphasizes the digital formulation as a separate entity rather than a carry-over from one domain to the other by means of conformal mappings. Implementation problems are considered, particularly that of the volume of computation required for operation of the filters.

Rectifier utilizing plural channels for eliminating ripple

Abstract: D R A W I N G AN OPERATIONAL RECITIFER OR CONVERTER INCLUDING A SERIES RC CIRCUIT TO CONDUCT AN AC SIGNAL TO A SUMMING JUNCTION AND A SECOND CIRCUIT PARALLEL TO THE SERIES RC CIRCUIT FOR DEVELOPING A DC COMPONENT AND AN INVERTED AC COMPONENT TO CANCEL THE AC CONDUCTED BY THE SERIES CIRCUIT. THE SECOND CIRCUIT INCLUDES AN OPERATIONAL AMPLIFIER HAVING TWO IDENTICAL DIODE-RESISTANCE FEEDBACK CIRCUITS. THE DC COMPONENT AND ONE HALF OF THE AC COMPONENT IS TAKEN FROM ONE FEEDBACK CIRCUIT THROUGH A RESISTOR, AND THE OTHER HALF OF THE AC COMPONENT IS COUPLED FROM THE OTHER FEEDBACK CIRCUIT THROUGH A CAPACITOR, TO THE OUTPUT TERMINAL. A SECOND EMBODIMENT SHOWS SUPPRESSION AND COMPENSATION CIRCUITS TO REFINE CIRCUIT OPERATION.

A starter circuit for a discharge lamp having preheated electrodes

Abstract: A starter circuit for a discharge lamp includes an inductor in series with the lamp across the AC input terminals and an SCR in shunt with the lamp and in series with the lamp electrodes. A resistor and capacitor are connected in series across the lamp. The impedance of the capacitor is 40 times to 150 times the lampoperating impedance and is approximately 95 percent of the impedance of the series RC circuit. A control circuit ignites the SCR between 30* and 135* after the zero crossing of the AC supply voltage.

Method and an arrangement of controlling a dc motor on constant speed

Abstract: A speed control circuit, electrically in parallel with a controllable semiconductor, which is electrically in series with a DC motor, said control circuit including an RC circuit in which the capacitor, upon cutoff of said semiconductor, discharges through the resistor of said RC circuit with a discharge current which is proportional to the motor current just before cutoff until the voltage across the semiconductor has reached its stationary DC voltage value. The discharge current is caused to flow through the resistor of the RC circuit thereby causing a voltage drop, which is detected and stored in a capacitor. The difference between the maximum actual stored resistor voltage and a command voltage is applied to the controllable semiconductor means to govern the speed of the motor.

Analog computer simulation of all-pass functions

Abstract: It is shown that an all-pass transfer function of any complexity can be simulated with a single operational amplifier embedded in a three-terminal RC network.

Active RC synthesis using a fractional gain amplifier

Abstract: A synthesis procedure, using a fractional gain amplifier and a three-terminal RC network, to realize many useful voltage transfer functions is proposed in this paper.

Instrument for measuring conductance or capacitance of an electrical load during operation

Abstract: Instrumentation for measuring electrical characteristics of a load during application of stored electrical energy to the load. The current to the load is accurately monitored over a wide dynamic range. An instrument including a current source for charging a capacitance, a switch for discharging the capacitance through a diode into the load, and an RC circuit for developing an output signal which is the derivative of the voltage across the diode, with this output signal being directly proportional to the conductance of the load at any time during the discharge of the capacitance. A similar instrument for measurement of capacitance of a load. The instruments are suitable for the measurement of conductance and capacitance of an electric emulsion treater during operation of the treater.

Synthesis of rational transfer function approximations using a tapped distributed RC line with feedback

Abstract: This paper describes a simple procedure for synthesizing an active distributed RC network which, by using dominant poles and zeros, realizes a very accurate approximation of an arbitrary stable rational transfer function. The network uses a single uniformly distributed RC line with taps spaced along its length. A linear combination of tap voltages is added to the input signal to form the driving voltage for the RC line; the output signal is also a linear combination of the tap voltages. The network offers a number of significant advantages. Since it realizes a nearly rational transfer function, the approximation problem can be conveniently solved using readily available results on rational function approximation. Also, the network uses only one uniform RC line, the transfer function can be changed simply by changing resistor values, and the frequency can be scaled by minor connection changes. Thus one standard network with minor modification is useful for a wide variety of applications. This paper develops the design procedure and derives the various sensitivity functions of importance. Two example designs are carried out: an approximation to a second-order low-pass transfer function and an approximation to a second-order band-pass transfer function with a Q of 100. The sensitivities for the examples are very reasonable and the measurements made on laboratory models indicate excellent agreement with theoretical predictions.

Distributed parameter RC network analysis

Abstract: Met.hods of analyzing uniform and tapered distribute parameter RC networks are reviewed and correlated in this dissertation. ~ultilayer networks and simple three layer networks are considered. Analogies :Petween two-wire transmission line theory and multilayer distributed network theory are developed, i.e., standing wave and traveling wave concepts. An accurate computer-aided steady state analysis procedure is presented which has a solution accuracy that , . can be determined prior to actual analysis computations. The impulsive response of the uniform RC network is investigated with the goal of measuring the network's parameters. Procedures to determine the parameters R and C of a uniform RC microcircuit from transient measurements are included. ii

Apparatus for analyzing complex signal waveforms

Abstract: 1,180,288. Speech recognition. STANDARD TELEPHONES & CABLES Ltd, 23 June, 1967, No. 29100/67. Heading G4R. Apparatus for analysing complex signal waveforms containing characteristic zero crossing distributions classifies zero crossings according to the time period in which they occur relative to preceding zero crossings and determines which category dominates. Pulses produced at zero-crossings of a speech waveform to be recognized are applied to circuits 1, 2, 3 which produce an output pulse whenever the interval between successive input pulses exceeds t 1 , t 2 , t 3 respectively, circuits 1, 2, 3 being essentially mono-stable RC circuits. The outputs of circuits 1, 2, 3 together with the original zero-crossing pulses are fed to gating circuits 4, 5 which produce output pulses in true and inverse form for zero-crossing intervals in the ranges t 1 -t 2 and t 2 -t 3 respectively. In circuit 6, an RC integrator is charged by t 1 -t 2 true pulses and discharged by inverse t 2 -t 3 pulses, the capacitor voltage being thresholded to give an output. Circuit 7 is similar, with the roles of t 1 -t 2 and t 2 -t 3 pulses reversed. Circuits 8, 9 produce output pulses when the output of 6 is greater than or less than the output of 7 respectively, provided a threshold is exceeded. Circuit 10 contains an RC integrator which is charged during pulses from 8 and discharged during their absence, the capacitor voltage being thresholded to give an output. Circuit 11 performs the same function for circuit 9.

Fail-safe circuit for multiple channel vacuum modulated adaptive braking system

Abstract: A FAIL-SAFE CIRCUIT WHICH IS SUITABLY USED IN AN ADAPTIVE BRAKING SYSTEM. NORMALLY, IN KNOWN ADAPTIVE BRAKING SYSTEMS A CONTROL SIGNAL IS APPLIED TO A BRAKE PRESSURE MODULATOR WHICH IS THEREBY CAUSED TO OPTIMIZE THE BRAKING CHARACTERISTICS OF A WHEELED VEHICLE DURING THE TIME THE VEHICLE IS BEING BRAKED. IN THE PRESENT INVENTION A NORMALLY CLOSED MODULATOR LIMIT SWITCH IS PROVIDED WHICH OPENS WHENEVER THE MODULATOR ATTEMPTS TO CONTROL THE VEHICLE BRAKING CHARACTERISTICS. A NORMALLY OPEN BRAKE SWITCH IS CONNECTED ACROSS THE MODULATOR SWITCH THUS SHUNTING THIS LATTER SWITCH WHENEVER THE BRAKE PEDAL IS DEPRESSED. A LATCHING CIRCUIT WHICH IS LATCHED WHEN THE VEHICLE STARTER IS ENERGIZED AND WHICH SUPPLIES POWER TO THE MODULATORS WHENEVER LATCHED, IS SERIALLY CONNECTED TO THE SHUNTED COMBINATION OF BRAKE SWITCH AND MODULATOR LIMIT SWITCH. ADDITIONALLY THE CONTROL SIGNAL IS SAMPLED AT THE LOW VOLTAGE END OF THE LATCHING CIRCUIT BY AN RC CIRCUIT. IF THE DURATION OF THE ERROR SIGNAL IS EXCESSIVE THE VOLTAGE AT THE LOW VOLTAGE END OF THE LATCHING CIRCUIT, THAT IS, THE VOLTAGE ACROSS THE RC CIRCUIT, WILL BUILD TO A LEVEL TO UNLATCH THE LATCHING CIRCUIT. WHEN THE LATCHING CIRCUIT IS UNLATCHED, WHETHER BY THE OPENING OF THE LIMIT SWITCH WHILE THE BRAKE SWITCH IS OPEN OR BY VOLTAGE ACROSS THE RC CIRCUIT, POWER IS REMOVED FROM THE MODULATOR WHICH WILL THUS RETURN TO A NORMAL POSITION AND RESTORE NORMAL VEHICLE BRAKING.

Active RC filters with differential integrators

Abstract: A method is described for synthetising active RC filters by using the subtraction property of differential operational amplifiers. The differential operational amplifiers used have infinite gain. The advantages of the filters are simple adjustments, low sensitivities and fewer amplifiers compared with analogue-computer circuits.

Relay time control circuit

Abstract: A relay time control circuit that varies the inherent response and dropout times of the relay and maintains the actual response and dropout times to a defined range. An electronic switch is controlled by an RC time control circuit to initiate relay actuation when predetermined voltage conditions exist within the RC circuit. The electronic switch is decoupled from the time control circuit, and therefore temperature sensitivity of the electronic switch is not affected by the latter.

Write noise in magnetic-film memories due to current diffusion in the ground plate

Abstract: In magnetic-film memories which have the bit current returning through a ground plate, the write noise, i.e., the sense-line voltage caused by the bit-current pulse, contains a slowly decaying component. Theoretical and experimental results show that the time derivative of this component, which should be as small as possible for best rejection by the sense system, can be reduced by 1) appropriately stratifying the ground plate, 2) keeping the ground plate at a low temperature, or 3) terminating the bit-sense line with a suitable RC network. The experiments were carried out using a scale model of the bit-sense line, with the physical dimensions, the time scale, and the resistivity of the conductors all being increased by the same factor. Electrical properties of such a scale model are identical to those of the simulated system.

Servocontrol circuit for electrical discharge machining apparatus

Abstract: 1,254,211. Automatic control of electric discharge machinery apparatus. ELOX Inc. Jan.3, 1969 [Jan.22, 1968], No.456/69. Heading G3R. Electrical discharge machinery apparatus of the type wherein a transistor 16 is controlled to pass power pulses from a source 10 to a dielectric coolant-filled gap between an electrode 12 and a workpiece 14, is provided with the control circuit shown for automatically maintaining the gap spacing at a predetermined value. The electrode movement is controlled by a coil 44 which forms part of a hydraulic motor and servo valve system (not shown) and which is included in a differential amplifier comprising transistors 46, 48 to show bases are respectively applied signals representative of actual and desired gap spacing. The former signal is derived from a sensing circuit which comprises members 34, 36, 38, 40, 42 and which is connected between a multi-vibrator drive 22, 24 for the transistor 16 and members 12, 14. During normal operation an RC circuit 64, 66 is connected in series with the coil 44 and transistor 46 is turned on by the signals from the drive 22, 24, which also operates the transistor 16 at a predetermined frequency and mark/space ratio. Thus current passes through the coil 44 in a direction corresponding to downward movement of the electrode 12 and the gap spacing is held at a value determined by the setting of a reference potentiometer 30. Should the gap be "shorted", transistor 48 conducts to reverse the current flow through the coil 44, the consequent discharge of capacitors 60, 66 producing a rapid electrode movement upwards and the subsequent charging of these capacitors producing a rapid downward movement, these features ensuring rapid short circuit clearance and restoration to normal gap spacing. A second RC circuit 68, 70, 72 of different time constant from the first is used during a high frequency finishing operation to slow down the servosystem. The illustrated arrangement of members 44, 54, 56, 58, 60 is suitable for operation at relatively high frequencies and may be modified. Fig.1a (not shown) for low frequency operation. The sensing circuit 34--42 may be connected to point B instead of point A, the transistor 16 may be replaced by an equivalent three electrode electronic switch (e.g. a vacuum tube) and the coil-hydraulic motor combination may be replaced by the direct control of an electric motor.

Electric circuit for pulse control of d.c. motors, especially for electrically driven vehicles

Abstract: 1,218,231. Control of D.C. motors. NAUTCHNO - ISSLEDOVATELSKI I PROEKTNO - KONSTRUKTORSKI INSTITUT PO ELEKTROTECHNITCHESKA PROMISHLENOST. 9 Feb., 1968, No. 6664/68. Heading H2J. [Also in Divisions G2-G3] A control circuit for a D.C. motor energized from a unidirectional supply through a controllable semi-conductor switch comprises a summing and level sensing device which triggers the switch and which receives three signals respectively representative of the instantaneous motor current, the mean value of the motor voltage over an initial range thereof, and the desired speed setting, the latter signal being a maximum at the zero setting and decreasing as the setting is changed. The figure shows only the control-circuit which comprises a flip-flop circuit 7 controlling the switch, a summing device 6 for receiving the signals, a D.C. amplifier 3 receiving the current signal I from a resistance in the motor supply circuit, an RC circuit 2 for receiving the motor voltage U and a reference element 1 controlled by an adjustable member such as an accelerator pedal and delivering a signal which is a maximum at the initial, zero speed setting of the element and is zero at the maximum setting. The signal from circuit 2 is passed to a summing device 4 fed with a negative voltage for subtraction from the signal. The resultant signal is fed to a clamping circuit 5 which limits the signal fed to the device 6 to a value dependent on the signal from the element 1, on the gain of the amplifier 3 and on the value of the abovementioned negative voltage. As a result the motor voltage and current signals provide speed stabilization at low motor speeds, but at higher speeds and for a particular setting of the element 1 the voltage signal is limited to provide constant current operation of the motor until the natural speedtorque characteristic is reached. A typical cycle of operation of the control circuit is discussed with reference to the speed-torque characteristic and the various settings of the element 1, Fig. 2 (not shown). The arrangement also keeps the ripple amplitude of the motor current substantially constant.

Temperature control system using a nonreentrant temperature-sensitive bridge transducer

Abstract: A wheatstone bridge element including temperature-sensitive resistors is placed in or adjacent to a fluid which is to be temperature controlled and is energized at its input nodes. A diode and light source or a diode and an amplifier for driving a light source are connected across the output nodes of the bridge. A high-current triac is triggered by the charging of an RC circuit in which a resistive element is photocontrolled by the light source. Power control by the triac is used to control heating the fluid.

Phase-controlled pulse generator

Abstract: A phase controlled thyristor system having a shunt RC circuit including a laminate structure pressure sensitive, negative resistance device.

Off delay solid-state time delay apparatus

Abstract: An off delay circuit utilizes an output controlled rectifier together with diodes and transistors and an RC network to provide time delay. The controlled rectifier is maintained in conduction by a controllable half cycle trigger current and a half cycle phase shifted load current.

A tunnel diode model for NET-1

Abstract: Tunnel diodes can be simulated it the NET-1 digital computer program for circuit analysis by use of a combination of positive and negative resistors, three diodes, and a voltage source. Good approximations of dc and ac characteristics can be obtained as demonstrated with an example of a high-speed switching circuit.

Light sensitive signal generator

Abstract: A circuit for producing an electrical signal proportional to light intensity having two amplifiers interconnected in a multivibrator configuration. The timing circuit of one amplifier is a standard RC circuit and in the second a photodiode. In one configuration, the amplifiers including associated transistors, resistors and capacitors along with a light sensitive diode are fabricated as an integrated circuit on a monolithic substrate. Because the device responds to light in the visible range which is absorbed close to the incident surface of silicon, the diffused diode must be as thin as possible to obtain the desired high light current. A process for fabricating the light sensitive diode and associated circuitry includes the step of a dilute deposition of phosphorous oxytrichloride for the transistor emitter. Special processing techniques are employed to minimize thermal shock and dislocations.