Showing papers on "Comparator applications published in 1975"

Automatic threshold control means and the use thereof

Abstract: A threshold actuated information detection system comprising a noise level converter, and a non-inverting voltage totalizer, and a voltage comparator interconnected such that the comparator will not trigger any logic circuit if an amplified signal is lower than the threshold level, and the use thereof in acoustic emission and other informational discriminating systems

Rf power amplifier parallel redundant system

Abstract: An RF power amplifier parallel redundant circuit employs three amplifiers. Under normal operation when all three amplifiers are functioning, the output from a comparator holds a 0°, 60° two-bit phase shifter in the 60° position. When anyone of the amplifiers or any pair of amplifiers fail, the comparator output causes the two-bit phase shifter to switch to the 0° position. The system holds the power output constant at one-fourth the value of each individual amplifier for single or double failures. Only one simple switching position operation is required.

Conveyor overspeed-underspeed and/or slip detector

Abstract: A control system is provided for stopping the operation of a bulk material conveyor system in response to an indication that the speed of either drive or driven elements thereof are above or below acceptable amounts, that the output speed of a particular material handling component falls below an acceptable difference from the input speed to said component, or that the speed of an upstream material handling component falls outside an acceptable difference with respect to the speed of a downstream material handling component feeding material to said upstream component. Speed indication is provided by the electrical signal output from dc tachometer-generators associated with the drive or driven shafts of the component whose speed is being sensed. The signals are, in turn, transmitted to the input networks of speed comparators; there being one such comparator for each comparison to be made with each such speed comparator incorporating an integrated circuit operational amplifier and an emitter follower power amplifier connected as a comparator circuit with hysteresis. A reed relay also incorporated in the speed comparator, operates in response to a signal from said comparator circuit indicative of improper material handling component operation to effect stoppage of the conveyor system.

First timing circuit controlled by a second timing circuit for generating long timing intervals

Abstract: A timing circuit utilizing first and second hysteresis comparators. The first comparator senses the voltage across a capacitor in a first charging circuit. Whenever this voltage exceeds the high comparator reference level, the comparator output is at a first voltage level, permitting charging of the capacitor. When the capacitor voltage drops below the low comparator reference level, the comparator output switches to a second level, discharging the capacitor at a rate much faster than the charging rate. The second comparator interacts with a second capacitor in similar fashion; however, the second capacitor is permitted to charge only during the discharge periods of the first.

Speed limit passing indicator

Abstract: A speed limit system providing a passing of a given limit is disclosed. The speed-limit indicator comprises a frequency-voltage converter receiving at its input a signal which is produced by a sensor indicative of vehicle speed. A detection circuit comprising a frequency-voltage converter and a comparator followed by a gate circuit and signaling means are provided. The comparator utilizes the output of the voltage from the converter and a reference voltage which represents the speed limit. The gate circuit is interposed between the output of the comparator and the signaling means. A control signal is provided to the gate circuit, and in accordance with the state of that control signal, the gate circuit transmits or blocks the output signal of the comparator to the signaling means.

Means for controlling the phase or frequency output of an oscillator in a loop circuit

Abstract: A device for controlling, by means of a phase comparator which receives annput signal, the phase or frequency output of a voltage controlled oscillator connected with the phase comparator in a phase locked loop, this loop being also provided with a branch circuit including a high pass filter or appropriate characteristics.

Digital frequency shift-keyed transmitter

Abstract: The square-wave output of a comparator is coupled back to the input of an RC controlled integrator including an operational amplifier and an inverter circuit with an output signal maintained at a predetermined level. The RC network sets the pulse repetition rate of the square wave. The inverter and integrator outputs are connected to separate inputs of the comparator. A gating circuit couples a data source to the operational amplifier. In particular, the gating circuit couples an additional square-wave current to the integrator via a resistor. The square-wave current may be in phase and raise the pulse repetition rate of the resulting square wave or out of phase and lower the pulse repetition rate.

Oscillator circuit whose frequency is voltage controllable which contains a comparator

Abstract: An oscillator utilizing a voltage comparator having hysteresis characteristics for producing a pulse train. The width of the pulses in the train is controlled by the charging rate of a capacitor coupled to one input of the comparator and the period of the pulse train is controlled by the discharge rate of this capacitor. The discharge rate and hence the oscillator frequency may be varied in response to a control voltage. Compensating elements ensure that the pulse width is highly stable with respect to temperature variations. The oscillator when in a feedback control circuit, produces oscillations at a frequency whose value is linearly related to the feedback control voltage.

Power pack with electronic switch - is controlled by comparator and may be periodically switched on and off

Abstract: The switch is between the supply voltage source and output, and in series with a storage choke forming with a diode and a load resistor a closed circuit; the comparator compares the output voltage with a reference voltage. A current measuring resistor is inserted into the circuit; the voltage drop across it is compared with a reference voltage by a comparator with hysteresis effect, which delivers a signal blocking the switch when the voltage drop across the resistor exceeds a specified values; the comparator output is connected to a first input of coincidence circuit delivering a control signal for the switch; its other input is connected to a circuit comparing the output voltage with a reference voltage.

IC engine fuel injection period duration control - has delay circuits and comparator for reference voltage and voltage from exhaust gas sensor (BR121076)

Abstract: The fuel injection regulator for an engine has a comparator (1) for a voltage representing the exhaust gas composition a reference voltage. An integrator receives the output from the comparator and produces a signal which controls the injection. A delay circuit (4) is responsive to the comparator output signal and establishes a monitoring period before operation. The delay circuit interrupts the integrator by an amplifier, and creates a predetermined mean output signal. A second delay circuit (6) receives a signal from the first delay circuit and increases the reference signal before decreasing it while the probe is energised.

Phase-locking loop with variable bandwidth filter

Abstract: A phase-locking network at the receiving end of a transmission channel carries an incoming wave of predetermined frequency matching the operating frequency of a local oscillator the incoming wave and the locally generated oscillations being fed to respective inputs of a phase comparator producing a control voltage delivered through a low-pass filter to the oscillator for reducing any existing phase difference. The signal path between the phase comparator and the oscillator includes one or more nonlinear impedance elements, either within the filter or in cascade therewith, which lowers the effective series resistance of the path in the presence of a high control voltage and thereby increases its bandwidth during an acquisition period as compared with steady-state operation.

Hybrid phase comparator applied to distance protection

Abstract: The paper describes the operation of a 1 bit processor which can be used to measure phase difference, and hence can be applied to distance protection. The processor averages over one cycle the sign coincidence between its two input signals and gives an analogue output proportional to their phase difference. Examples are given of its application to mho and quadrilateral impedance characteristics. Where appropriate its performance is compared with a block-average comparator.

Field shunting circuit

Abstract: A circuit for automatically shunting the field winding of a direct current motor and reapplying full field thereto. A low-level pull-in comparator compares a signal proportional to armature current to a low-level reference potential and causes the field to be shunted when the armature current signal falls below the low-level reference potential. A high-level drop-out comparator compares a signal proportional to armature current to a second independent high-level reference potential and causes the full field to be applied when the armature current signal is greater than the high-level reference potential. Prior to actuation, the pull-in comparator disables the drop-out comparator. Upon actuation, the pull-in comparator latches itself in actuated state and enables the drop-out comparator to be actuated. Upon actuation the drop-out comparator unlatches the pull-in comparator.

Automatic gain control of pulses

Abstract: The amplification of periodic or aperiodic pulses is varied by envelope detecting the received pulses and passing the resulting envelope waveform to a latching comparator which, when enabled, provides an output pulse whenever the input waveform has an amplitude which exceeds a predetermined value. An itegrator coupled to the output of the comparator is continuously operative to increase or decrease the gain of the amplifier according to the absence or presence respectively of the output comparator pulse. In this manner the amplitude of signals or pulses is automatically controlled despite circuit and transmission vagaries.

High speed analog to digital converter recirculating analog input for high speed output

Abstract: In an analog to digital converter an analog voltage is sampled. To provide a digital output indicative of one sample, the analog voltage sample is recirculated. During each successive circulation, a successively less significant bit of the digital output is determined by comparing a DC level dependent upon the analog input level to a reference level in a single level comparator. A power divider in the single level comparator couples direct current inputs to the comparator and to a combiner. The combiner has an output connected to a feedback loop including a hard limited modulated channel, the output of which is amplified and coupled to the input of the power divider. The comparator thus provides successive digital bits upon the completion of each recirculation.

Phase locked loop

Abstract: A signal frequency, controlled by the output of a phase comparator, is obtained from a constant or reference signal frequency source by means of a frequency divider, the division ratio of which is voltage-controlled and variable, the control signal being obtained from the output of the phase comparator, in digital, or analog form. When in analog form, a monostable multivibrator is interposed so that a voltage-controlled divider having a division ratio of an average, predetermined factor can be used. The signal, the frequency of which is to be identified, is applied as one input to the phase comparator for comparison with the output signal from the frequency divider, the comparison providing the aforementioned division control signal.

Comparator/bistable circuit

Abstract: In a comparator/bistable circuit, wherein the bistable circuit is tripped in response to a predetermined relationship between first and second inputs supplied to a comparator circuit, one of the inputs to the comparator circuit is supplied as an input to an adjustable reset circuit which develops the bistable reset level as a percentage function of one of the comparator input signals. This contrasts with the conventional technique of developing the bistable reset level as a feedback function of the output of the bistable circuit.

Supervisory circuit for single phase synchronous motor - using two comparators and one limiter circuit

Abstract: A resistor is provided in the phase lead to the motor and one side connected to one input of a first comparator, whilst the other side is connected to the limiter circuit. The second limiter input is connected to the neutral lead, and the limiter output is connected to the second input of the comparator. The comparator output is evaluated in an integrating circuit, and a further comparator, or level detector, used to operate an alarm circuit. The apparatus operates by measuring the phase angle between applied voltage and line current. The norm is determined by the power factor of the synchronously running normally loaded motor. Deviations are measured by the integrator receiving a variable pulse length signal from the output of the first comparator.

MF and HF rectifier and clamping cct - has comparator with one input at reference voltage and second input at D.C. -free oscillations

Abstract: The circuit incorporates a comparator whose one input is at reference voltage, while its other input receives D.C.-free oscillations, e.g. via a capacitor. To the oscillation input of the comparator a high-e.g. battery voltage of the circuit is additionally connected via a series combination of a low pass and a diode. The low pass factor is chosen to be higher than that of the comparator. The diode polarity provides for decoupling of the oscillation generator relative to the low pass. The output from the feedback circuit provides the limited output signal, whose limit threshold is set by the reference voltage at the comparator input. If the limited output signal is fed into a low pass filter, a rectified equivalent of the initial input signal may be obtained.

Voltage comparator with adjustable tolerance range - has differential amplifier with rectifier bridge at inputs

Abstract: Voltages to be compared are applied to the bridge one diagonal, while the other diagonal ends are connected to the amplifier inputs, and through a resistor each to a bias voltage source; input resistors are inserted between the comparator inputs and the ends of the above first diagonal; the tolerance range for the voltages to be compared is determined by the resistance ratio of the input resistors and resistors in the bias circuit. A certain signal is sent out from the output of the difference amplifier only when the difference between the compared potentials passes a predetermined, chosen value.

Fast tunnel diode comparator with controlled hysteresis

Abstract: A modified form of an earlier high-speed tunnel diode-transistor comparator is described. This comparator is expected to operate at frequencies greater than 800 MHz with a well-controlled hysteresis and temperature insensitive threshold levels.