Showing papers on "RC circuit published in 1981"

Circuit for measuring capacitance

Abstract: A circuit and method for measuring the capacitance of a circuit element. A reference capacitor, a voltage source, and a switching circuit are arranged such that the circuit element and the reference capacitor are alternately charged and discharged from the voltage source at the same frequency, the charging of the circuit element being synchronized with either the charging or the discharging of the reference capacitor. Currents of the circuit element and the reference capacitor, for example the discharge currents, are supplied to a reservoir capacitor circuit and compared to provide a measure of the difference between the capacitances of the circuit element and the reference capacitor. The comparison is made by monitoring the feedback current necessary to maintain the charge of the reservoir capacitor circuit substantially constant.

GaAs Fet Ultrabroad-Band Amplifiers for Gbit/s Data Rate Systems

Abstract: A novel ultrabroad-band amplifier configuration suitable for GaAs FET's has been developed. The developed amplifier circuit operates as a capacitor-resistor ( C-R ) coupled mnpfifier circuit in the low-frequency range in which |S/sub 21/| for the GaAs FET's is constant. It also operates as a lossless impedance matching circuit in the microwave frequency range in which |S/sub 21/| for the GaAs FET has a slop of approximately -6 dB/octave. Using this configuration technique, 800-kHz 9.5-GHz band (13.5 octaves), 8.6-dB gain GaAs FET amplifier modules have been realized. The amplifier module has 40-ps step response rise time. It also has low input and output VSWR. By cascading two-amplifier modules, 19-dB gain over the 800-kHz to 8.5-GHz range and 50-ps step response rise time were obtained. NF is lower than 8 dB over the 50-MHz to 6-GHz range.

Universal reset circuit for digital circuitry

Abstract: The invention is a universal reset circuit for digital circuitry which monitors both clock pulses and DC voltage and provides a reset command when detecting a low DC voltage or missing clock pulse. The device uses two comparators and an RC circuit to form a pulse timing circuit which monitors clock pulses. Low DC voltage is monitored by a bridge circuit and a reference voltage. A third comparator receives signals from both the pulse timing circuit at the bridge circuit and produces a reset command. The reset command could re-initialize a microprocessor chip or the input controller of a main computer system.

A feedback control system for applying ac power to ballasted lamps

Abstract: Un systeme de commande a reaction d'eclairage pour appliquer un courant alternatif d'alimentation a au moins une lampe comprend un circuit de commutation a phase commandee a angle de conduction (20) connecte en serie avec la lampe (18) et une source d'alimentation a courant alternatif (12) pour envoyer du courant a la lampe (18), et un circuit de commutation de ligne (10) pour permettre l'application du courant alternatif a la lampe (18) par l'intermediaire du circuit de commutation de phase (20). A control system has reaction of lighting for applying an alternating current power supply has at least one lamp comprises a switching circuit stage CONTROLLED a conduction angle (20) connected in series with the lamp (18) and a source power alternating current (12) to send power to the lamp (18) and a line switching circuit (10) to enable the application of alternating current to the lamp (18) through the intermediary of the circuit shifting phase (20). Un capteur de lumiere (40) est prevu pour produire un signal de commande de lumiere indiquant la quantite de lumiere ambiante presente dans l'endroit en question. A light sensor (40) is expected to produce a light control signal indicating the amount of ambient light present in the area in question. Couple au circuit de detection de lumiere (40) un circuit de commande de conduction d'angle de phase produit et applique a une borne de commande du circuit de commutation de phase (20) un signal de commande de phase pour commander le temps de conduction d'angle de phase du circuit de commutation de phase (20) base sur la quantite de lumiere ambiante mesuree par le circuit de detection de lumiere (40) pour maintenir un niveau constant d'eclairage. Coupled to the light detection circuit (40) produces a phase angle conduction control circuit and applied to a control terminal of the phase switching circuit (20) a phase control signal for controlling the conduction time phase angle of the phase switching circuit (20) based on the amount of ambient light measured by the light of detection circuit (40) to maintain a constant level of lighting. Un circuit de filtre RC (44) integre dans le circuit de commande de conduction d'angle de phase augmente progressivement le temps de conduction de l'angle de phase commutant le circuit de zero, ou a partir d'une valeur minimum predeterminee, vers un temps de conduction d'angle de phase a etat constant base sur les conditions de la lumiere ambiante detectees par le circuit de detection de lumiere (40), apres validation du courant d'alimentation par le circuit de commutation de ligne (10). A filter RC circuit (44) integrated in the phase angle conduction control circuit gradually increases the conduction time of phase angle of zero the switching circuit, or from a minimum value predetermined to a time phase angle conduction a constant state based on ambient light conditions detected by the light of detection circuit (40), after validation of the supply current by the line switching circuit (10).

Power source voltage change discrimination circuit

Abstract: A power source voltage change discrimination circuit includes a voltage selection circuit for selectively supplying the greater one of main and auxiliary power source voltages, and a series circuit of a resistor and a capacitor coupled between the output terminal of the voltage selection circuit and ground. There is further provided a Schmitt circuit having hysteresis characteristics whose input terminal is coupled to a junction of the resistor and capacitor.

Electronic electric-energy meter

Abstract: An electronic electric-energy meter comprises a delay time setting circuit connected to one of a voltage transformer and a current transformer connected to power lines for providing a necessary delay time and a delay circuit for which a delay time is set by the delay time setting circuit, the delay circuit delaying a pulse width duty cycle signal corresponding to a voltage applied from the voltage transformer. The pulse width duty cycle signal is formed by a pulse width modulation circuit connected to the voltage transformer. In the delay circuit connected to the pulse width modulation circuit, the duty cycle signal is delayed by the delay time set by the delay time setting circuit. In a time division multiplying circuit connected to the delay circuit, the delayed signal is multiplied by a current signal from the current transformer, thereby forming a signal proportional to electric power. The electric power signal is integrated by an integration circuit connected to the time division multiplying circuit, whereby a signal proportional to electric energy is obtained. The electric energy signal is converted into a display signal in a processing circuit connected to the integration circuit. On the basis of the display signal, a display circuit connected to the processing circuit displays the electric energy measured.

Digital meter using calculator components

Abstract: The invention uses an RC circuit 12 to convert an analog quantity to be measured into a time interval proportional to the measured quantity by using a resistive element in the RC circuit responsive to the quantity being measured. The RC circuit starts and stops a time base generator 13 to produce pulses having a total number proportional to the time interval, and a gate system 14 applies the pulses to the key terminals of the circuitry 16 of a pocket calculator 10 for indicating the pulse count on a display 15, either directly or after being processed by functions available in the calculator circuitry. The RC circuit can also be used to start and stop a time base generator 33 built into a digital stopwatch for displaying a pulse count proportional to the quantity measured. The measured quantity can be a capacitance value, a resistance value, or energy impinging on a responsive transducer in the RC circuit.

Interconnection delays in MOSFET VLSI

Abstract: Although VLSI MOSFET devices have small inherent delays, the RC time constant of the interconnections limits the circuit maximum frequency of operation. A circuit-based solution to this problem, rather than a technology-based solution, is to use circuit configurations that maximize the charging/discharging currents delivered to the interconnections. This paper examines the different MOSFET circuit configurations based on the ability to charge/discharge the RCs of the interconnections and concludes that two circuit configurations are most suitable for VLSI: CMOS and a proposed current steering NMOS. In the latter configuration, the distributed RC network of the interconnection is included in a charging/discharging circuit path which is part of a difference stage. A multisource MOSFET structure is used in the design of the difference stage, in a common-drain/common-gate configuration to maximize the charging/discharging currents. Computer simulation using SPICE 2 and experimental measurements are used to confirm the predicted performance.

Level shifting circuit

Abstract: An output circuit and a biasing circuit for biasing an oscillation circuit comprise a current mirror circuit. The DC level of the output signal from the oscillation circuit is level shifted by controlling the current of the current mirror circuit comprising the biasing circuit and the output circuit. This control is performed by suitably determining the number of diodes and the resistances of the resistors making up the current mirror circuit. The biasing circuit of the oscillation circuit may thus be utilized as the level shifting circuit, the DC level of the output signal of the oscillation circuit may be set to a predetermined level, and fluctuations in the duty ratio of the oscillation output may be suppressed.

Ignition system with overrun prevention

Abstract: An ignition system of the capacitor discharge type and capable of preventing overrunning of an internal combustion engine includes a control circuit to render a switching transistor connected to a gate-cathode circuit of a main thyristor conductive for a predetermined period of time to interrupt a backward or reverse phase voltage generated by a magneto and serving as an ignition signal for the main thyristor from being applied thereto. The control circuit includes an integrator circuit connected in parallel with a constant voltage source to develop a voltage increasing with time and includes a voltage divider of the constant voltage source to provide a reference voltage. A transistor circuit of the control circuit compares the output voltage of the integrator circuit and the output voltage of the voltage divider and the transistor circuit maintains a control signal to be applied to the transistor circuit until the output of the integrator circuit reaches the reference voltage of the divider. The period of time during which the control signal is applied to the switching circuit to maintain the switching circuit being conductive is precisely constant irrespective of a variation in rotational speed of the engine. When the rotational speed of the engine increases and exceeds a normal rotational speed region, the occurrence of the ignition signal or the backward voltage of the magneto becomes early to cause the leading portion of the ignition signal to overlap with the end portion of the predetermined period of time resulting in retardation of the ignition timing and preventing overrunning of the engine.

Buffer circuit including a current leak circuit for maintaining the charged voltages

Abstract: A semiconductor circuit used as a buffer circuit having an input stage circuit for receiving an input clock signal and an inverted input clock signal, a bootstrap circuit including a transistor for receiving the output of the input stage circuit and for maintaining the gate voltage of the transistor at a high level during the standby period, and an output circuit, including a transistor which is switched on and off by the output of the bootstrap circuit, for generating an output clock signal; the semiconductor circuit further comprising a current leak circuit for maintaining, during the standby period, the voltage of a point in the semiconductor circuit which is charged during the standby period at the value corresponding to the voltage of the power source, whereby the delay of the output clock signal, caused of the fluctuation by the voltage of the power supply during the standby period, is improved and then the high speed access time in the dynamic memory is carried out.

Quadrature detector using a double balanced differential circuit and a constant current circuit

Abstract: A quadrature detector comprising a double balanced differential circuit including a constant current circuit, and a phase shifter circuit. The constant current circuit comprises a plurality of transistors having their collectors connected together, their bases connected together and their emitters connected to a reference potential level through respective resistors. By the arrangement of the constant current circuit, a current density in the transistors is reduced, a noise generated by the constant current circuit is reduced and hence the S/N ratio of the quadrature detector is improved.

Discharging circuit for power source device with rectifier circuit

Abstract: A discharging circuit for a power source device with a rectifier circuit used in an power source for driving a motor in which when the alternating current power source is turned off and the load is electrically separated, the voltage of a time constant selection circuit (22, 23) falls rapidly, the voltage across a diode (25) rises, a Schmitt circuit (24) is activated, the circuit consisted of a transistor (27) and a resistor (26) is conducted, and a smoothing capacitor (28) is discharged, and hence the heat generation at the resistor is decreased and the concern over unsafety due to delayed discharge of the capacitor is eliminated.

Bandpass filter circuit

Abstract: A bandpass filter circuit includes first and second resistors connected in series between input and output terminals thereof, an amplifier having a gain of three and its output connected to the output terminal, and an RC circuit network connected between the connection point of the first and second resistors and the input of the amplifier and having bandpass characteristics. The RC circuit network comprises a series combination of a third resistor and a first capacitor connected between the connection point of the first and second resistors and the input of the amplifier, and a parallel combination of a fourth resistor and a second capacitor connected between the input of the amplifier and a common terminal of the filter circuit. The third and fourth resistors have an equal resistance value and the first and second capacitors have an equal capacitance value. As one of the first and second resistors use may be made of a variable resistor to change the quality factor, and the third and fourth resistors may be variable resistors ganged with each other to change the center frequency of the passband.

Recording/playing circuit

Abstract: A recording/playing circuit includes a noise reduction circuit, a switching circuit and a control circuit. The noise reduction circuit includes a pre-amplifier, a combining network, an inverter circuit and a side chain. The switching circuit has first, second and third input positions and an output terminal. The first input position is coupled to the output of the pre-amplifier, the second input position is coupled to the output of the inverter circuit, and the output terminal is coupled to the side chain. The third input position is connected to a muting circuit. The control circuit controls the switching circuit so that one of the electric signals applied to the first, second and third input positions of the switching circuit may be selectively transmitted to the output terminal of the switching circuit.

Low voltage regulation circuit

Abstract: A low voltage regulation circuit especially suitable for supplying current to high frequency loads is provided. The circuit comprises two P channel MOSFETs having the same threshold voltage and two N channel MOSFETs having repsectively different threshold voltages. The difference between the threshold voltages of the two N channel MOSFETs is provided as a constant output from the circuit, and load current is supplied from the output terminal. Circuit construction is simplified such that a low voltage regulation circuit with a small pattern area on the integrated circuit is obtained.

Loudspeaker protection against sustained overload - rectifies and averages audio voltage to operate warning LED and relay (NL 18.2.81)

Abstract: The audio voltage across a loudspeaker (L) is monitored by a rectifier bridge (G1) and averaged by a RC circuit (R1,R2,R3,R4,R5,C1) with suitable charge and discharge time constants. A potentiometer (R4) presets the averaged voltage above which the speaker is to be protected from overload. When this voltage exceeds a Zener (ZD) voltage, a control transistor (T2) starts to conduct and light a warning LED (LD). Further increase turns on a transistor (T1) which operates a relay (Re1) whose contact (r) opens the speaker circuit. A second contact (a) switches in a resistor (R8) to bypass the control transistor (T2) and Zener (ZD), so that the speaker stays off until the voltage is reduced to a low level. A third transistor (T3) limits the current through the Zener and control transistor (T2). Diodes (D3,4) limit the current through the relay transistor. The circuit protects the speaker against damage by sustained overload but ignores harmless short overload peaks.

The Pole-Zero Locations of Some Trimmed Distributed RC Networks and the Application to Low Pass Active Filters

Abstract: The voltage transfer functions of abraded uniform distributed resistance-capacitance (RC) networks are discussed. A straight trim cut and an L-shaped trim cut either near the input port or near the output port of a uniform RC network are considered, and the pole-zero locations for these four cases are evaluated. It is shown that the trim cuts near the output port of an unloaded RC network have no effect on the pole positions of the transmission function. A straight cut near the input port is modeled by linearly tapered RC networks, and a loaded RC network is used to analyze the L cut near the input port. Measured results of trimmed thick film RC networks show good agreement with these models. From this analysis it is shown that the open circuit transfer function of a trimmed RC network with a straight cut near the input may be further approximated by two dominant poles and a delay term. This cut is shown to be the most useful in functionally adjusting the magnitude response of a distributed low pass active filter, and the dominant pole-pair locus of the trimmed distributed lumped active filter is plotted.

Delay circuit for inside lighting of vehicle - has switches responsive to door position and handle operation to connect RC circuit to supply

Abstract: The delay circuit has an RC circuit coupled to the base of a switching transistor that controls the relay that turns the lights on and off inside the vehicle. Each door switch is closed when its door is open. The RC circuit is influenced by the door-handle switches in addition to the door switches. The RC circuit (C2,R5,R6) is connected directly to one pole (+) of the vehicle's supply network (30) and via a switch (T2) to the other pole (-). The switch is connected to the door switch (TK) and to the door-handle switch (TG) such that it is closed when the door-handle switch is closed.

Sensitivities of impedance scaled SC filters

Abstract: A crucial effect of frequency dependent scaling of impedances on the frequency response is discussed. The essential point is illustrated by means of a simple RC lowpass simulation.

Relay operating circuit for high resistance power source - has relay operating RC circuit initiated by second RC circuit which switches transistor

Abstract: The equipment is for operating a relay from a high resistance energy source, for example in the mining industry where minimum battery is necessary. The energy source (1) charges a first RC circuit (5,6) through a current limiting resistor (2) which has a time constant tau 1. A second RC circuit (3,4) with a time constant tau 2, is also charged by the same high resistance source (1,2). Time constant tau 2 is 10 x tau 1. The relay (7) and switching transistor (8) together with base resistor (10) are in parallel with the capacitor (6) of the first RC circuit (5,6). When the operate switch (9) is closed, the first RC circuit charges but does not operate the relay (7) until the second RC circuit has charged to switch on the transistor (8). The fully charged capacitors (6) discharges to operate relay (7) through transistor (8). The energy source holds the relay operated.

Auxiliary power circuit of power unit

Abstract: PURPOSE:To reduce a loss of electric power and prime cost by providing a series- connected capacitor and rectifying circuit for an AC power input and by using the rectification output of the rectifying circuit as the auxiliary power source of a power unit. CONSTITUTION:The AC voltage of AC input power source 1 is divided by capacitor C9 and the input impedance of rectifying circuit 8 and applied to circuit 8. Circuit 8 rectifies the input voltage into a direct current, which is supplied to control circuit 5. With the output of circuit 5, power converting circuit 3 is controlled to regulate and stabilize the output, which is applied to load 4. A desired DC voltage can be developed by circuit 8 by properly selecting the reactance of C9 and applied to circuit 5, so that the low-priced auxiliary power circuit with a small power loss can be obtained.

Large signal instability in active-R and a class of compensated active-RC filters

Abstract: Analysis of the large signal instability in compensated active-RC and active-R filters with high pole-Q and pole-frequency is presented. The instability is produced by an oscillator loop formed by two operational amplifiers (OA's). The condition for and the frequency of oscillations are derived.

Software for nonlinear analysis of op-amp RC circuits under large sinusoidal excitations

Abstract: A procedure for the computer-aided steady-state analysis of op-amp RC circuits under large signal sinusoidal excitation is presented. It is shown that the execution time is reduced considerably compared to other methods.

Deterioration detecting circuit for smoothing circuit

Abstract: PURPOSE:To enable direct detection of deterioration in a smoothing circuit by monitoring a ripple voltage thereof. CONSTITUTION:A.C. ripple component alone is taken into a rectification circuit 3 through a capacitor 2 from a capacitor 1 to be detected and the voltage following the rectification is compared with the output of a threshold voltage generation circuit 5 by means of a comparator circuit 4. When the voltage following the rectification exceeds the threshold, the LED of a display/alarm circuit 6 is turned on.

Ultrasound examination apparatus comprising a mosaic of transducers of an electrostrictive material

Abstract: An ultrasound examination apparatus comprises a processing circuit for echo signals from a mosaic of ultrasonic transducers which are made of an electrostrictive material with a non-remanent polarization. These signals are applied to processing channels which comprise coupling means (10i) for coupling the electrodes of the transducers to a circuit (20) for generating a polarization voltage ramp whose waveform is the inverse of that of the attenuation curve of the ultrasonic signals in the structures examined. These coupling means, for example, an RC circuit (11i, 12i) or a transformer (13i) enable the polarization voltage to be applied to the electrodes while inhibiting the transmission to the part of the processing channels which is situated behind the coupling means.

Schmitt trigger with signal-dependent hysteresis - has operational amplifier with non-inverting input grounded via RC circuit

Abstract: The Schmitt trigger circuit is arranged so that its hysteresis is dependent on the amplitude of the input voltage and consists of a differential amplifier or operational amplifier whose inverting input is the signal input. A resistor (R1) connects the amplifier output back to the non-inverting input. The non-inverting input is connected via a second and a third resistor (R2, R3)in series to ground. The third resistor (R3) is shunted by a capacitor (C). The first resistor is much greater than the second resistor, and the third resistor is much greater than the second resistor. The advantage lies in input-dependent hysteresis. The trigger is also less likely to oscillate.

Application of multiplying digital-to-analogue convertor to digital control of active filter characteristics

Abstract: The paper examines the use of the multiplying digital-to-analogue convertor (DAC) in op-amp inverting summers and integrators. The digitally controlled analogue filtering circuits are obtained when analogue computer-type RC filters are implemented with digitally controlled summers and integrators. An example of a fully programmable state variable bandpass filter is outlined.

Overload control for mechanical power presses

Abstract: An overload control for a mechanical press wherein excess hydraulic pressure generated by the mechanical overload of the press is applied to a transducer which develops an electrical signal which in turn is applied to a circuit which is responsive to the magnitude of the electrical signal and to the time increment during which the magnitude of the electrical signal is developed and applied to the circuit. The circuit includes a timing and reference portion comprising a voltage divider network and an RC network, and the circuit also includes a differential amplifier responsive to a difference in magnitude between the transducer signal and a signal from the timing and reference portion. As a result, when the instantaneous signal from the transducer increases suddenly due to an actual overload on the press, the circuit responds and operates a relay to cause stoppage of the press. On the other hand, the circuit does not respond to a relatively slower change in the transducer signal resulting from a slow change in pressure during non-overload conditions.