Abstract: In a servo system for manipulating a displaceble member in response to movement of a control through corresponding changes of position, which operates by comparing an electrical signal representative of the position of the control with an electrical signal representative of the position of the displaceable member to provide error signals which can drive the displaceable member in either of two opposite directions, a safety interlock circuit is provided which detects the presence of an error signal in either direction immediately after the application of operating voltage or immediately after the switching of the machinery into a different mode of operation and locks the displaceable member in position if an error signal initially appears until the error signal is cancelled by bringing the manual control into a position corresponding with that of the displaceable member. Unexpected sudden movements that may endanger personnel are thereby prevented.

Abstract: Motor driver/control apparatus employs a motor speed regulating amplifier configuration, e.g., two push-pull power amplifiers operable responsive to a motor speed-direction command input signal, and having the motor differentially connected between amplifier output ports. The amplifier(s) are supplied with an energizing potential of variable amplitude just sufficient for amplifier operation and to satisfy the then obtaining motor consumption. Accordingly, system power is effectively utilized; needless power drain avoided; and the amplifier cost and complexity is reduced since the amplifier need not dissipate inordinate source-supplied energy not required for motor actuation.In accordance with one further aspect of the present invention, a power supply switching regulator for a motor utilized in a radar application is operated at the radar pulse repetition rate. This produces a non-interferring zero frequency beat between the power supply and radar pulse rate in the radar receiver.

Abstract: A servo amplifier system includes first and second operational amplifiers, with the second amplifier having a low output impedance. A torque coil is connected directly from the output circuit of the first amplifier to the input circuit of the second amplifier free of any impedance elements which would tend to make the torque coil subject to frequency response variations. Various circuits are provided to feed back error signals from the output circuit of the second amplifier to the input circuit of the first amplifier. A test signal may be connected across torque coil to test the response of the accelerometer including the torque coil.

Abstract: A servo-system is provided for self-balancing systems using an ac servomotor capable of maintaining loop gain substantially constant irrespective of span adjustment and without capacitor coupling. It includes a direct-coupling dc amplifier for comparing input and comparison signals and amplifying the result, a servo amplifier having a differential direct-coupling amplifier with inverting and non-inverting input terminals, with feedback from its output to the inverting input terminal and a switch to the non-inverting input terminal operating at the same frequency as the ac power source for the servomotor, to maintain the loop gain constant irrespective of span adjustment, and means causing the ac servomotor to move a slide resistor to bring the compared signal into balance with the input signal.Provision is also made for receiving input signals from thermoelectric or resistance thermometers and balancing the system using these signals.

Abstract: The disclosed system includes a direct-current bridge circuit and a bridge-balancing reversible motor coupled to the bridge circuit, together with a differential high-gain amplifier which is responsive to even slight bridge unbalance to polarize the motor for rotation in the direction toward rebalance of the bridge circuit and also interrupts the motor operation when balance of the bridge is passed in either direction. Apparatus is included responsive to both positive and negative reversals in the polarity of unbalance of the bridge for deenergizing the motor when the null of the bridge is crossed in either direction.

Abstract: A process controller which has at least a derivative control mode includes a comparison amplifier wherein a measured variable signal is compared with a set-point signal to produce an error signal. An auxiliary control circuit including a signal level change detector is connected to detect changes in the set-point signal. During intervals of constant set-point signal, the primary control circuit operates normally. Upon the occurrence of a change in the set-point signal, the change is detected by the auxiliary control circuit and produces an auxiliary control signal which is applied to momentarily inhibit the operation of the derivative control function of the controller.

Abstract: A proportional motor control circuit for supplying bidirectional drive to a motor as a function of variations of a sensed parameter includes a temperature sensing amplifier which is responsive to an error signal indicative of deviations of the parameter from a set point to provide an output signal representing the direction and amount of the deviation, and a pair of operational amplifiers, each of which serves as a load for the other amplifier, which are responsive to the signal output of the temperature sensing amplifier to determine the polarity of the energizing potential applied to a D.C. motor over motor drive circuits. The motor control circuit is described with reference to an application in an environmental control system to effect positioning of dampers located in air ducts for supplying heated or cooled air to an area in response to changes in the air temperature in the area.

Abstract: A linear driving circuit includes a full bridge drive circuit across which a d.c. motor is connected. Each side of the bridge circuit is controlled by an associated complementary transistor loop, each of which is in turn controlled by an associated control operational amplifier. Each control operational amplifier is referred at one-half the voltage across the bridge circuit by a common voltage divider. The currents through each half of the bridge circuit are compared to provide current feedback.

Abstract: The output of an operational amplifier is connected to a bridge having as its diagonal two push-pull, complementary-symmetry, output stages, the servo motor being connected between the emitters junction of the one stage and the emitters junction of the other stage.

Abstract: Variable current generator arrangement for controlling the position of remote load components allowing replacement of a main control current generator by an auxiliary control current generator. The main control current generator is a current injector with high output impedance. The auxiliary control current generator is a voltage follower with low output impedance. For performing switchover, a switch means allows the voltage across the load component to be applied to an analog store means and the voltage in said store means to be applied to the voltage follower.

Abstract: A process control system including a control station responds to the departure of a process variable from a set point to provide a direct current signal in a two-wire transmission line in a direction dependent upon the direction of such departure and time-proportioned in accordance with the magnitude of the departure. A solid state power relay that accepts the d-c signal at a single pair of input terminals includes high-current rating triacs that are adapted selectively to be fired by triggering pulses generated in response to the d-c signals alternating current power from a source of alternating current to a heavy-duty motorized valve for operation of the latter in one direction or the other and at a speed in accordance with the signals.

Abstract: In the computer field tape handlers for magnetic tape are widely used. The magnetic tape is moved by a capstan driven by a high power low inertia motor since it is necessary to rapidly accelerate and decelerate the tape in both forward and reverse directions. A high power motor is provided with a command controlled direct current. The motor direction is determined by the selection of one of two pairs of solid state switches. Only one current control circuit is used. Transients are minimized by permitting only one pair of switches to be closed at any time and by switching when the controlled current is at a low value.

Abstract: An analog signal comparator receives a variable potential signal at each of two input ports. The signal at each input port is provided to a gate of one programmable unijunction transistor (PUT) and an anode of another PUT to form mirror-image symmetrical connections to the two PUT's. An output signal from either of the PUT's then indicates the lesser of the potentials at a corresponding one of the input terminals. The comparator is preferably intended for use in a closed-loop motor positioning system.

Abstract: There is disclosed a motor control circuit that is particularly useful for the control of a damper motor in a heating and ventilating system. The control circuit comprises a bridge circuit having a pair of operational amplifiers with cross connected input terminals. An input signal is provided by input signal circuit means to one of the cross-connecting conductors and a reference signal is provided to the other of the conductors by a reference signal circuit means. The operational amplifiers are provided with feedback circuit means between their output and noninverting terminals to drive the amplifiers into an unstable condition where they function as on and off switches. Dead band means in the form of a load dropping resistor is provided between the input signal circuit and the noninverting terminal of one of the amplifiers.

Abstract: A multi-range, self-balancing instrument using a Zener diode circuit and a phase compensating circuit is disclosed. The Zener diode circuit is capable of generating a white noise, which is effectively applied to the self-balancing system whereby the dead zone is maintained constant irrespective of the range. The phase compensating circuit, comprising a non-inverting input amplifier, is capable of compensating for the phase lag of the self-balancing instrument by adjusting the amplification factor of the amplifier without affecting the stability of the servo amplifier system.

Abstract: A double pump device for mixing with variable ratios and concentrations two or more liquids, comprising in combination: a first peristaltic pump, and a second peristaltic pump, each of said pumps acting on a plurality of collapsible tubes, said pumps being operated by two electric motors, interdependant and preferably identical to each other, driven by an electronic circuit comprising as main elements a differential amplifier and circuitry means for adjusting the input voltage of the differential amplifier and for amplifying the output signals from the differential amplifier before their application to the two driving motors.

Abstract: An electronic switching system for the control of a load, such as a motor serving to adjust the diaphragm of a motion-picture camera, comprises a normally inactive comparison circuit including a transistor bridge with a pair of NPN transistors in one pair of adjoining arms and a pair of PNP transistors in the other pair. Two complementary transistors in each half of the bridge, lying between diagonally opposite corners, are provided with a common biasing circuit shunted across that bridge diagonal, the load being connected across the other bridge diagonal. Each biasing circuit includes a resistive voltage divider with taps joined to the bases of the associated bridge transistors and a group of cascaded ancillary transistors connected across a section of the voltage divider containing one of these taps. The first ancillary transistor of each cascaded group has its base connected to an associated input terminal receiving a switching signal and a reference voltage, respectively.