Showing papers on "Comparator applications published in 1971"

Limiter circuit with enable function

Abstract: A limiter circuit employing two high-gain differential voltage comparators. A positive reference voltage is established at the noninverting input of one comparator and a reference voltage of ground is established at the inverting input of the other. Input signals are applied at the inverting input of the one comparator and at the noninverting input of the other. The output of the one comparator is connected to an input of a flip-flop composed of two cross-connected NAND gates. The output of the other comparator is connected through an inverter circuit and a triggering circuit to another input of the flip-flop. The output of the flip-flop and the output of the inverter circuit are connected to an output NAND gate. The flip-flop is set by the action of the one comparator when a positive-going input signal exceeds the threshold of the positive reference voltage, thus enabling the output NAND gate. Subsequent passing of the negative-going input signal through the zero voltage threshold causes the output NAND gate to switch producing a square-wave output. This negative-going signal also causes the triggering circuit to reset the flip-flop.

A fail-safe electronic comparator circuit

Abstract: This disclosure relates to a fail-safe comparator circuit having a free-running multivibrator powered by two separate d.c. supply voltages. A resonant circuit is coupled to the output of the multivibrator and tuned to the normal resonant frequency of oscillation of the multivibrator so that oscillations having the normally resonant frequency will be induced into the resonant circuit when and only when the two d.c. supply voltages are in agreement and no critical component or circuit failure is present.

Two-state zero-crossing detector

Abstract: A comparator having two output states and two input connections is used to develop an indication of the polarity of an alternating voltage. The comparator output is coupled with one of two inputs of the comparator. Two voltage controlled switches including opposite conductivity type transistors and oppositely poled diodes are connected such that the voltage being sensed is applied to the second input to the comparator when it changes polarity, thereby changing the state of the comparator output. Control of the switches in accordance with the comparator output and the sensed voltage provides a disconnect feature whereby the detector draws power from the sensed voltage only during switching intervals; no power is drawn after a change in polarity by the sensed voltage until it again reverses its polarity.

Output circuit for comparators

Abstract: There is disclosed an output circuit for a comparator which operates, because of its high gain, as a switching circuit. It is the major feature of the output circuit that it operates such that the drive current for its output stage and the amount of load current it can sink are independent of supply voltage variations. Thus the output circuit is relatively unaffected by changes in, for instance, the output of a portable power supply such as a battery. Whenever an analog input level from the comparator is below a given level, the drive current is coupled to drive an output transistor into saturation. When the comparator changes state this drive current is shunted to ground through a transistor of the comparator circuit. Thus the output transistor acts as either an opened or closed switch capable of sinking a predetermined amount of current.

Phased locked loop with voltage controlled oscillator

Abstract: Phase locked loop having a voltage controlled oscillator, a phase comparator and filtering means all of which are integrated into a single monolithic block The comparator is of The balanced bipolar analog multiplier type and is supplied a control voltage by a multivibrator of the voltage controlled oscillator The collector load of the multivibrator is provided by the diode drops of the comparator's transistors The multivibrator is driven by a differential current divider which in turn is provided current by a constant common current source

Voltage comparator controlled motor starting circuit

Abstract: A speed responsive motor starting circuit includes a pair of bilateral triode switches connected to the motor start system for controlling the current flow therethrough. A capacitor is connected to the control electrode of one of the triode switches for supplying enabling current thereto. Current supplied to the capacitor by an A. C. supply, the amount supplied being controlled by a comparator switch in accordance with the relative magnitudes of two voltages applied to the comparator switch. One such voltage is inversely proportional to the speed of the motor and is generated by a current-sensing transformer coupled in circuit with the motor run winding. The other such voltage is applied by the A. C. supply through a diode to the comparator switch. Various solid state devices may be utilized as the comparator switch.

Inertia welder speed control device

Abstract: An inertia welder speed switch assembly in which a signal is sensed by a magnetic pickup and is then passed through a squaring amplifier, differentiator, monostable multivibrator, filter integrator, and a plurality of comparator amplifiers. In each of the comparator amplifiers, the signal is compared to a reference voltage and a relay is operated by the signal as it reaches the value of the reference voltage.

Binary shaping circuit

Abstract: A level setting circuit changes the level of the input signals to a predetermined reference level when the input signals exceed the reference level. A comparator is connected to the level setting circuit and to the input for comparing the input signals with the signals having the reference level produced by the level setting circuit. The comparator produces an output corresponding to the difference in level between the input signals and the reference level. A binary circuit connected to the comparator produces a pulse when the output of the comparator exceeds a predetermined level.

Remote control receiver using a phase locked loop

Abstract: A remote control receiver selectively responsive to a plurality of different frequency command signals to control corresponding different command functions. The receiver uses a phase locked loop including a controlled oscillator having a variable frequency output which is compared in a phase comparator with the received command signal. The detected phase difference generates an error voltage which shifts the oscillator from its quiescent frequency to the incoming frequency and phase locks the controlled oscillator to the command signal. The error voltage also activates only one of several DC voltage comparators, with a different comparator corresponding to each command function. Each comparator includes a means of establishing a reference voltage and means for activating a driver stage for the corresponding remote function when the error voltage generated by the phase comparator to lock the receiver to a particular command frequency and equals the corresponding reference voltage.

Cos/mos phase comparator for monolithic integration

Abstract: A phase comparator integrated circuit apparatus for comparing a pair of AC signals and providing a substantially pure DC output. The phase converter utilizes the time difference between pulses from two different input signals to provide a DC voltage which is free from AC ripple.

Phase-controlled oscillator for producing a stabilized phase output

Abstract: A phase-controlled oscillator has a loop comprising phase-detecting means, a loop filter connected to the phase-detecting means and a voltage-controlled oscillator connected to the phase-detecting means and the loop filter. The phase-detecting means compares an input signal with the output signal of the voltage-controlled oscillator. The phase-detecting means comprises a first phase detector coupling input means to the voltage-controlled oscillator. A second phase detector has a comparison phase which differs from that of the first phase detector by π/2 radians. The second phase detector is coupled to the input means. A voltage comparator coupled to the second phase detector discriminates the polarity of the output of the second phase detector. An inverter coupled to the first phase detector, to the voltage comparator and to the input means inverts the phase of the output of the first phase detector in accordance with the output of the voltage comparator and shifts the phase of the output of the phase-controlled oscillator by π radians in accordance with the output of the voltage comparator.

Arrangement for preventing the locking of wheels of motor vehicles

Abstract: A D.C. voltage of amplitude inversely proportional to vehicle speed is directly applied to the second inputs of a first and second comparator stage. The D.C. voltage is also applied to a logarithmic circuit and then differentiated. The output of the differentiator is applied to the first input of the second comparator stage and further, through an inverter, to the first input of the first comparator stage. The outputs of the comparator stages control, through a switching amplifier, the operation of an electrically operated pressure decreasing brake valve.

Exposure control system and method for photoplotters

Abstract: A velocity independent exposure control system and method for photoplotters which uses exposure feedback to control the ON-OFF cycle of a light source. A photodetector produces a voltage that is proportional to the amount of light impinging upon a photosensitive plotting surface. The photodetector output is integrated by a resettable integrator and the output of the integrator is used as one input to a voltage comparator. The other input to the comparator is a preselected, variable voltage which represents the desired exposure. When the integrated photodetector output voltage equals the reference voltage, the comparator produces an equality signal. A light source control circuit that is responsive to the comparator equality signal then turns the light source off.

Arrangement for maintaining a constant direct current voltage

Abstract: An arrangement for maintaining a constant voltage at a variable load includes an adjustable direct current voltage source having a positive and a negative pole. A voltage regulator is provided which has comparator inputs and a triac which is connected to the voltage source for adjusting the voltage source in response to changing values of voltages applied to the comparator inputs. Four similar conductors are provided which are equal and adjustable in length and which together form a bridge circuit for maintaining the load voltage constant independently of the conductor lengths. To accomplish this, the first conductor is connected between the positive pole of the voltage source to one terminal of the load, the second conductor is connected between the negative pole of the voltage source and to other terminal of the load, the third conductor is connected between the one terminal of the load and the one comparator input of the voltage regulator, and the fourth conductor is connected between the other terminal of the load and the other comparator input of the voltage regulator. A voltage equalizer is interposed between the third conductor and the one comparator input to equalize the voltages applied to the differential inputs of an operational amplifier whose output controls the triac. A full wave rectified voltage derived from the main alternating current power source is supplied to one of the differential inputs of the operational amplifier and a sawtoothed reference voltage is applied to the other differential input, these two fluctuating voltages being superimposed on the direct current voltages supplied by the third and fourth conductors.

Fail-safe comparator

Abstract: This disclosure relates to a fail-safe comparator circuit having an input transformer, the primary of which is fed by an a.c. signal voltage. The secondary winding of the first transformer is serially connected to the primary winding of a saturable type of output transformer. A current-limiting resistor forms a series circuit with the secondary winding of the input transformer and the primary winding of the output transformer. A separate d.c. input voltage is applied to each end of the series circuit so that a.c. output signals are induced into the secondary winding of the output transformer when and only when the d.c. input voltages are in agreement and no critical circuit or component failure is present.

Voltage changing rate detecting circuit

Abstract: A voltage changing rate detecting circuit includes an integrator and a comparator, in which an input signal voltage is applied to one of the input terminals of the comparator while an output voltage of the integrator is applied to the other input terminal thereof, and the output voltage of the comparator is negatively fed back to said integrator, to thereby detect the voltage changing rate of the input signal voltage.