Abstract: The effective sensor width of a path following vehicle guidance system is enlarged by having a first gain control amplifier for amplifying the sum of the path sensor signals, a second gain control amplifier for amplifying the difference of the path sensor signals and a third amplifier, in tandem with the second amplifier for amplifying the output of the second amplifier once the second amplifier's output has peaked out. All three amplifiers are gain-controlled by the same negative feedback signal. The outputs of the first and third amplifiers are synchronously detected to provide an error signal for an electromechanical steering servo for the vehicle.

Abstract: A time-proportioning control system is disclosed for controlling an on-off solenoid valve of an earth-working machine, the system having a sensor responsive to an external reference for producing an error signal, an amplifier switch for switching on and off the on-off solenoid valve in response to the error signal and a capacitive feedback circuit connected from the output to the input of the amplifier switch for controlling the on and off times of the solenoid valve dependent upon the magnitude of the error signal.

Abstract: This invention relates to the protection of power transistors in an H configuration power amplifier which drives a D.C. motor. When the amplifier is switched off, it may be possible for the base terminals of the transistors to be turned "on" which results in the transistors conducting. If two series transistors conduct, the resulting short circuit may damage or destroy the transistors. This invention provides an easy and economical apparatus for protecting the transistors in the power amplifier by grounding the base input terminals of the power transistors during all times when the transistors are switched "off.

Abstract: A servo amplifier for d-c servo motors which converts the error signal into pulses which are amplified in a saturating amplifier to drive the motor. Both the duty cycle and the repetition rate of the pulses vary with the error signal. At large error signals the duty cycle is 100 percent, i.e., "full on"; at small error signals the duty cycle is low and the pulses spaced far apart. As the system approaches balance the pulses become shorter and less frequent, and the motor slows. The circuit comprises a signal integrator which drives two comparators, one for positive signals and the other for negative. The integrator generates a ramp voltage in a direction opposite to the polarity of its input, and is reset automatically by reset pulses of controlled and variable length when a comparator set point is reached. The reset pulses are the pulses which are amplified to drive the servo motor. In this system, reducing the gain does not produce a widened dead band, but only increases the time required for rebalance.

Abstract: A device which detects the amount of displacement of a movable member moved by a feed device, and which outputs pulse signals corresponding to the amount of such displacement.

Abstract: A power controller having a plurality of power output modules which can be added or removed as desired to change the power output rating. The electrical output of the individual power modules are removably attached to an output combining structure. The electrical connections to the output combining structure also provide mechanical support for the power output modules. The servo controller is constructed so that as additional power modules are added, each provides a predetermined proportion of the output power. That is, each module will add in a linear fashion to the total output capability of the amplifier. Load sharing among the modules is provided. An etched copper resistor having a positive resistance versus temperature characteristic is provided to aid load sharing among the output semiconductors. A feedback signal is derived from the power output modules to protect the servo controller.

Abstract: Direct current error signals of either polarity are converted to a unipolar voltage and used to offset a triangular timing wave. The offset wave is applied to threshold amplifier so as to produce pulse width modulated signals. The pulse width modulated signals, together with a polarized direction signal and a clock signal from the triangular wave source, is applied to a servo amplifier containing first and second channels, each containing a flip flop for opening the associated channel in accordance with the polarity of the direction signal so as to pass direct or inverted pulse width modulating signals, respectively, through amplifier and filter circuits to the output terminal. Each of the amplifier circuits has a current sensing resistor, and a switching transistor arranged to switch the associated flip flop and thereby open that channel whenever the current through the sensing resistor exceeds a predetermined level.

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: A temperature transducer includes first and second resistor bridges connected across a voltage source and first and second differential amplifiers. A first input terminal of the amplifiers are connected together to a common junction of the first resistor bridge. The second input terminals are connected to the second resistor bridge, one directly and the other via a voltage divider so that the input voltages of the differential amplifiers are mutually shifted to obtain two different operating voltage thresholds.

Abstract: Means to control the speed of correction of a probe, and a slave such as a torch or welding head, for a welding guidance system, and the like, wherein the response of the probe controls or actuates a device, which is responsive to a predetermined electrical condition, characteristic or information, to continuously vary the magnitude of the output of the device in proportion to the change or deviation detected by the probe to actuate at least one motor to correct or change the position of the probe and the slave.

Abstract: A DC linear power amplifier is disclosed having a first amplifier referenced to +14VDC, for receiving a control signal. The first amplifier in turn controls a first power stage connected to a load through a first sensing resistor. The first resistor provides a differential voltage to a second amplifier forming a current control loop with the first amplifier. A third amplifier controls a second power stage connected to the load through a second sensing resistor, so that the first and second power stages each dissipate equal power. The resistors each provide differential signals to a comparator which provides a first output signal if the current through each resistor is the same. If the differential signals are different, resulting from the load shorting to ground, the comparator provides a second output signal which turns the entire power amplifier essentially off. The entire power amplifier returns to normal when the short is eliminated.

Abstract: An apparatus for positioning a carrier means along a line of print in either of two directions. The carrier means is positioned by a D.C. motor which is driven by a pair of current driver circuits, one of which controls the flow of drive current in a forward direction and the other of which controls the flow of current in the reverse direction. The motor is capable of driving the carrier means at a first predetermined high speed when it is determined that the desired destination carrier position is more than a predetermined number of carrier positions from the present carrier position and at a second predetermined low speed when the desired destination carrier position is less than or equal to a predetermined number of carrier positions from the present carrier position. An electronic tachometer means operates to maintain a relatively constant speed while operating in the predetermined high speed state and while operating in the predetermined low speed state.

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: A control circuit for servo-motors comprising a photoelectric element, a logarithmic conversion element, one or more operational amplifier, and a constant-current circuit so that various informaton in a wide range can be easily introduced into the circuit and that the influence of change of the power-source voltage and hunting phenomenon can be eliminated.

Abstract: A system for electrically actuating the pitch trim of an aircraft in both autopilot and manual modes includes a primary pitch servomotor coupled to a primary control surface and a pitch trim servomotor for actuating a trim control surface. In the autopilot mode, an electrical signal applied to the primary pitch servomotor by the autopilot is also applied to two channels of a trim controller providing complementary output signals applied to the pitch trim servomotor. Each channel of the trim controller includes a voltage translator for providing a single ended voltage applied to an integrator that generates an output varying with the time average of the electrical signal applied to the primary pitch servomotor. This time average signal as generated in each channel is chopped into an alternating current signal for driving an output stage. The chopping duty cycle of each channel is varied in accordance with the absolute value of a time average of the electrical signal applied to the primary pitch servomotor.

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.