Abstract: A system is provided for preventing overtemperature of the rotor bars of large squirrel-cage induction motors. A transmitter is mounted on the rotor and supplied with power from the rotor winding itself by a special current transformer. The transmitter is controlled by a temperature sensing element which causes it to transmit a signal in response to excessive temperature, and a slip frequency signal is also transmitted as a reliability check. A stationary receiver picks up the signal from the transmitter and includes circuitry for deenergizing the motor in response to the excessive temperature signal and for preventing energization of the motor if the slip frequency signal is not received.

Abstract: A stepping motor provided with an energizing circuit for simultaneously energizing two phase windings from current sources. For actively damping the rotor movements an active network has been provided which measures the difference between the voltages across the two phase windings and in accordance with a suitably selected function converts it into two currents which are in phase opposition to each other, and which are applied to the two phase windings.

Abstract: A brake apparatus is disclosed in which a rotary shaft coupled to a load to be rotated is rotatably supported by a plain bearing and a biasing device is located near the shaft to bias or move the shaft to the biasing device to applying braking force to the rotating load by the friction between the shaft and its bearing so as to stop the rotation of shaft and hence load.

Abstract: A system for controlling synchronous machines of the type comprising an ac winding, a dc excitation winding opposite to the ac winding across a gap, and a static switch connected to the ac winding is disclosed wherein a current variation is given to the dc excitation winding at commutation in the ac winding current.

Abstract: A memory circuit with protection circuit having particular application to MOS-IC memories is disclosed. The protection circuit prevents the memory from being damaged by an undesirable turn-on or turn-off sequence of main and substrate voltage supplies or by an abnormal substrate voltage.

Abstract: A force sensor comprising an array of three conductive points respectively insulated from one another; a movable conductive element normally resting in contact with the points and thus producing an electrical interconnection therebetween and displaceable out of contact with at least one of the points in response to the application of a predetermined force to the sensor; means for connecting the three points to logic circuitry for sensing the interruption of the electrical interconnection and determining in response thereto whether an alarm condition exists; a housing containing the three point array and the movable conductive elements and having an outer configuration which includes a spherical portion; means fixedly mountable onto an article and defining a socket surface complementary to the spherical portion; and clamp means for selectably attaching the housing to the mounting means and permitting ready adjustment of the orientation of the spherical portion with respect to the complementary socket portion w

Abstract: A control device which is suitable for use with electronic apparatus is used to scan a range of signal or data values, such as a frequency spectrum, and to cease scanning when a selected parameter is found. The scanning operation is driven by a d.c. ironless motor which, once it has been initially spun by hand, continues to rotate until the selected parameter is detected.

Abstract: A passive vehicle antitheft system utilizes a unique combination of condition responsive switching components to control the access to and use of a vehicle. Primary control over the vehicle is provided by a control relay including a first "protection" position in which the vehicle ignition system and starter are disabled and an alarm system is enabled and a second "use" position in which the ignition system and starter are enabled and the alarm system is disabled. The control relay is in turn controlled by three bistable switching components that are selectively enabled and disabled at various stages of use of the vehicle. The switching components, which in the preferred embodiment comprise a triac, a silicon controlled rectifier, and a second relay, automatically switch the control relay to its "protection" position as an authorized user leaves the vehicle and closes the last vehicle door.

Abstract: A drive control system for a stepping motor having an optical disk sensor on the rotor shaft. A binary counter counts output pulses from a clock running much faster than the maximum speed expected from the optical disk. Optically-generated pulses, synchronized with the counted pulses, transfer the count from the counter into a storage register and reset the counter. The count achieved by the counter is inversely proportional to the velocity of the rotor shaft. More pulses and a higher count means a lower shaft speed. Therefore, the contents of the register is a coded measure of shaft speed. A code converter is used to determine the power input to the stepping motor to maintain a desired shaft speed. Therefore, the higher the motor speed and the lower the counter output between successive optically generated pulses, the less power is delivered to the stepping motor coils.

Abstract: An electronic circuit is provided for controlling the energization of the windings of a stepper motor. The electronic circuit is responsive to a sequencing circuit which selects which one of the stepper windings is to be energized. The electronic circuit includes switching transistors which are electrically connected to the stepper windings. The switching transistors are responsive to a control circuit to allow a selected one of the stepper windings to be energized by a voltage source. The switching transistors interrupt the energization of the selected stepper winding when the control circuit senses a predetermined amount of current flowing through the selected stepper winding. The control circuit causes the switching transistors to maintain this interruption for a predetermined time period after which the control circuit allows the energization to continue. The control circuit includes a resettable delay monostable multivibrator which is reset upon receiving a sequencing signal from the sequencing circuit.

Abstract: A conventional stepping motor has an optical disk connected to its rotor. Optically generated pulses from the disk are used to generate a signal indicating the speed of the rotor. A code converter converts the speed signals into a binary-encoded power-required signal for feedback to control the power delivered to the coils of the stepping motor so as to maintain a constant stepping speed. The encoded power-required signal is delivered to a binary comparator which delivers an output pulse of one binary sense or the other. A clock driving a counter generates a binary count having the same number of binary levels as the encoded power-required signal fed to the comparator. The output of the counter is also fed to the comparator. The comparator delivers an output of one binary sense when the clock count is less than the binary-encoded power-required signal and an output of the other binary sense when the counter output is greater than the power-required signal.

Abstract: A circuit and circuit elements are disclosed to operate a lamp independently from either a two-position wall-mounted switch or a two-position lamp-mounted switch.

Abstract: A propulsion system for traction vehicles utilizing separately excited electric traction motors in which a level of reverse motor torque is produced when speed control is released to effect a dynamic drag on the vehicle. The system simulates in an electric vehicle the dynamic drag effect characteristic of an internal combustion engine driven vehicle when the accelerator is released. The effect is attained by providing a motor armature regenerative current path through a load resistor and by maintaining motor field current at a selected minimum level when the speed control is released. A function generator adapted to regulate motor field current as a function of motor armature current provides a minimum field current signal when armature current is less than a selected value to thereby maintain field current and motor torque when the speed control is released.

Abstract: A dynamoelectric machine in the form of an induction motor is provided which is capable of two speed operation with a minimum number of motor leads and a minimum number of motor windings. The motor includes a stator assembly and a rotor assembly, the stator assembly being adapted to receive the motor windings in a conventional manner. The motor windings are constructed from a plurality of coil sets, groups of which define physical poles for the motor. The windings include a first main winding, a second main winding and an auxiliary winding. The first main winding and the auxiliary winding have an equal number of physical motor poles. The second main winding has twice the number of physical motor poles as the first main winding. The first main winding and the auxiliary winding are energized to permit motor operation at a first speed.

Abstract: A dynamoelectric machine in the form of an induction motor provides two speed operation with a minimum number of motor leads and a minimum number of motor windings. The motor includes a stator assembly having a core of magnetic material. The core has a plurality of slots formed in it. The motor windings are carried in the slots. The motor windings include a main winding, a first auxiliary winding and a second auxiliary winding. The main inding and one of the auxiliary windings have an equal number of electrical and physical poles. The second auxiliary winding has twice the number of physical poles as the main winding. First speed operation is attained by electrically energizing the main winding with the first auxiliary winding. Second speed operation is attained by interconnecting the main winding so that it produces two consequent physical poles resulting in four electrical poles and energizing the second auxiliary winding for operation with the reconnected main winding.

Abstract: An electronic circuit is disclosed that provides a delay of operation until a piece of equipment reaches operating temperature. The circuit automatically adjusts the delay time to provide only the time necessary for warmup should there be a short outage of line power causing only partial cooling of the equipment. By proportioning the warmup delay time to the time of power loss, the equipment outage can be minimized. The proportionality between the warmup delay time and the time of power loss can be either linear or non-linear depending on the specific application.

Abstract: The speed of an elevator is controlled and adjusted by utilizing a differential voltage obtained from a variable voltage indicating actual speed and a control voltage reflecting an ideal curve of speed variation. The resulting voltage or reference curve has a series of straight sections corresponding to distance lengths decoded from a distance counter for the distance travelled from the giving of a slowing order at a fixed distance from the stopping point. Each control section has it origin realigned with the reference curve.

Abstract: A precision drive system for a chart recorder adapted to record time histories of one or more sensed parameters on a single chart including one power source, one or more sensing means adapted for electrical connection to said power source, a drive motor having a rotatable output shaft and adapted for electrical connection to the power source, a pulse generator operative in response to the power source to provide a pulse at selectable regular time intervals, a motor and sensor starting means operative in response to a pulse from the pulse generator for starting the motor and the sensing means at the regular time intervals, and a self interrupting means for the motor and the sensing means to turn the motor and the sensing means off after a reading has been recorded on said chart recorder, to provide a chart recorder which can operate in a remote location for long periods of time and give a precise time record independent of the power source voltage, with a low power consumption.

Abstract: An induction motor is operated by a power supply of variable voltage and variable frequency. The voltage and frequency of the variable-voltage variable-frequency power supply is changed by a control circuit to accelerate or decelerate the induction motor. For slowly controlling the speed of the induction motor, the ratio of the output voltage to the output frequency of the variable-voltage variable-frequency power supply is maintained substantially constant. The control circuit includes a voltage correcting means which, in response to a command for sudden acceleration or deceleration of the speed of the motor, corrects the output voltage of the power supply in accordance with the acceleration or deceleration rate and the prevailing magnitude of the output frequency of the variable-voltage variable-frequency power supply.

Abstract: A motor arranged directly to drive a gramophone turntable which comprises a number of permanent magnet rotor pole pairs arranged on the circumference of a circle centered at the motor shaft, a number of air cored stator windings there being less stator windings than rotor pole pairs, and a commutator arrangement for controlling current through the windings whereby they react with the rotor poles to produce rotation of the turntable the current being controlled so that torque ripple is obviated.