Abstract: A portable cutter for cutting materials such as conduit tubing made of metal or other semi-rigid material including a motor, a power source for the motor, a saw blade, gripping mechanism for gripping an object to be cut, mechanism for automatically connecting the power source to the motor for a cutting operation, and mechanism for automatically activating the gripping mechanism.

Abstract: An electrical test device for testing the function of a receptacle ground fault circuit interrupter. The tester plugs into a receptacle and includes a current source, timer, testing circuit, and display. The current source introduces a substantially constant fault current between the hot and ground leads of the receptacle. Once this occurs, the timer begins counting time and generates a time count signal. The test circuit receives the time count signal and determines whether the interrupter enters a tripped state within a designated time. The testing circuit responsively generates a trip indicator signal reflecting whether or not the ground fault interrupter circuit tripped within the designated trip time. The display means receives the trip indicator signal and responsively indicates whether the interrupter functioned properly by tripping the designated trip time.

Abstract: An electrical test device for use by an electrician in testing circuits. The device includes a voltage sensor, display, and steady current source. The voltage sensor monitors the type of voltage (AC or DC) between the two conductors, and provides a signal to the display which responsively displays the type of voltage and the voltage level. The power supply has a steady current source that is in series with a tactile transducer, so that the test device may measure a broad range of voltages while only a limited amount of current flows through the voltage sensor. Consequently, lower cost components may be used in the voltage sensor. In another embodiment, the tester also includes a substantially independent continuity tester. The continuity tester includes its own power supply and alarm to indicate the continuity of a conductor and, thus, may operate even if the voltage sensor and display become inoperable.

Abstract: An electrical test device for use by an electrician in testing circuits. The device includes a voltage sensor, display, and steady current source. The voltage sensor monitors the type of voltage (AC or DC) between the two conductors, and provides a signal to the display which responsively displays the type of voltage and the voltage level. The power supply has a steady current source that is in series with a tactile transducer, so that the test device may measure a broad range of voltages while only a limited amount of current flows through the voltage sensor. Consequently, lower cost components may be used in the voltage sensor. In another embodiment, the tester also includes a substantially independent continuity tester. The continuity tester includes its own power supply and alarm to indicate the continuity of a conductor and, thus, may operate even if the voltage sensor and display become inoperable.

Abstract: An electrical test device for use by an electrician in testing circuits. The device includes a voltage sensor, display, voltage transducer and steady current source. The voltage sensor measures the voltage between two conductors and provides a signal to the display, which responsively displays the voltage. The steady current source is in series with the voltage transducer, so that the voltage sensor may respond to a broad range of voltages while only a limited amount of current flows through the voltage transducer. Consequently, lower cost components may be used in the voltage transducer.

Abstract: This invention permits one to trace more than one electrical conductor, each of the electrical conductors being associated with both a circuit breaker and an electrical outlet. The invention consists of a receiver and multiple transmitters. Further, in a single transmitter form of the invention, the invention permits the transmitter to continually transmit its signature signal without power dissipation concerns, just like the ability to continually transmit in the multiple transmitter form of the invention. Lastly, the device is able to trace conductors regardless of the load electrically connected to the conductor.

Abstract: An apparatus for determining the length of wires includes connector assemblies, a current source circuit, a voltage gain circuit, analog-to-digital converter, a read-only memory, a microprocessor and a display unit. The connector assemblies are connected across the ends of the wire whose length is to be determined. The current source circuit is used to selectively supply different values of currents to the wire whose length is to be determined. The voltage gain circuit is responsive to the different values of currents for selectively generating a plurality of different voltage levels for each of the different values of currents so as to provide an analog voltage signal having a predetermined range. The analog-to-digital converter is responsive to the analog voltage signal for converting the same to a first digital signal corresponding to a resistance of the wire.

Abstract: A driven rotary shaft system has a rotor including a core with a generally cylindrical surface, made from a stack of circular laminates of magnetic material which are clamped together in alignment. Permanent magnets are mounted in aligned windows formed in each laminate near diametrically opposed pole pieces for providing at least a pair of magnetic fields in positions which interact with magnetic fields of an adjacent stator. The permanent magnets and the windows have an arcuate cross section generally corresponding to the contours of the generally cylindrical surface. At least a pair of opposed air gaps are formed on diametrically opposed sides of the core, and between said pole pieces. These air gaps have internal concave contours which follow, correspond, and conform to the contours of flux lines produced by said permanent magnets. In one embodiment, the air gaps are completely within the perimeter of the circular laminates.

Abstract: A rotor has permanent magnets mounted on a core having a pair of opposing air gaps formed therein. Preferably, the permanent magnets are a material sold under the mark "NEOMAX", with an extremely high flux density, as compared to previously available permenant magnets. The contour of the air gap follows the contour of the naturally occurring flux lines which result from the mounting of the permanent magnets. The resulting rotor has a more efficient magnetic structure, with better overall characteristics than were available heretofore. The rotor may be used with any driven shaft system such as: motors, generators, dynamometers, and combinations thereof.

Abstract: A variable speed induction motor control system includes a variable voltage DC bridge coupled to a frequency controlled power inverter which in turn drives an induction motor. A motor power factor detecting circuit determines the relative voltage/current phase angle for the motor and derives a corresponding power factor error signal. The DC bridge and inverter respond to the power factor error signal to maintain the input power conditions of the motor at a near optimum efficiency. The power factor detecting circuit uses an exclusive OR gate to provide a pulse having a duration corresponding to the motor power factor which enables a counter during the pulse interval. After each pulse, the count which is indicative of the motor power factor, is applied to a holding circuit and converted to an analog error voltage.