Abstract: A method and apparatus for testing a transformer. A controller generates a switching signal and supplies the switching signal to a solid state switch in circuit with a test load of known magnitude, switching the solid state switch to place the test load in circuit with the transformer. A signal through or across the transformer is then measured. Methods and apparatus for testing a transformer comprise the controller and solid state switch placing a series of test loads of different known magnitudes in circuit with the transformer from the lowest magnitude to the highest, from the highest to the lowest, or both. Additionally, a test load array comprises a plurality of power resistors, a heat sink for accommodating the plurality of power resistors, and a material providing electrical insulation of the power resistors from the heat sink and thermal conductivity between the power resistors and the heat sink.

Abstract: A method and apparatus for testing a transformer. A controller generates a switching signal and supplies the switching signal to a solid state switch in circuit with a test load of known magnitude, switching the solid state switch to place the test load in circuit with the transformer. A signal through or across the transformer is then measured. Methods and apparatus for testing a transformer comprise the controller and solid state switch placing a series of test loads of different known magnitudes in circuit with the transformer from the lowest magnitude to the highest, from the highest to the lowest, or both. Additionally, a test load array comprises a plurality of power resistors, a heat sink for accommodating the plurality of power resistors, and a material providing electrical insulation of the power resistors from the heat sink and thermal conductivity between the power resistors and the heat sink.

Abstract: A transformer includes at least two magnetically coupled cores with a common axis. The cores have cross sectional configurations transverse to the common axis which are not rectangular. An exciting voltage is to be applied across a first winding provided on one of the cores. A second winding provided on one of the cores includes first and second terminals across which a voltage is to be induced in response to the exciting voltage. A first device provides a relatively higher impedance between the first and second terminals of the second winding. The first device is coupled between the first and second terminals. Third, fourth and fifth windings have respective first and second terminals. The third and fourth windings are wound on one of the cores with a first polarity. The fifth winding is wound on one of the cores with a second polarity opposite to the first polarity.

Abstract: An apparatus for use in applying write signals for driving a write head to effect writing information to a memory device; the write signals including a first write signal and a second write signal; includes: (a) a directing circuit receiving the write signals, directing a current to establish a voltage across the write head in a first excursion toward a first polarity in response to the first write signal and directing the current to establish the voltage across the write head in a second excursion toward a second polarity substantially opposite the first polarity in response to the second write signal; (b) a first boost system coupled with the directing circuit and boosting the write voltage toward the first polarity during the first excursion; and (c) a second boost system coupled with the directing circuit and boosting the write voltage toward the second polarity during the second excursion.

Abstract: A transformer includes a first winding and a second winding coupled to the first winding through a magnetic circuit so that current through the first winding induces a voltage across the second winding. The first winding includes n separate shield portions, where n is an integer. Each of the n shield portions shields only a corresponding portion of the first winding. Each of the n shield portions is electrically coupled to the adjacent shield portion(s) substantially only through its coupling to the first winding, the first winding, and the other(s) of the adjacent shield portion's (s') coupling(s) to the first winding.

Abstract: A transformer includes at least two magnetically coupled cores with a common axis. The cores have cross sectional configurations transverse to the common axis which are not rectangular. An exciting voltage is to be applied across a first winding provided on one of the cores. A second winding provided on one of the cores includes first and second terminals across which a voltage is to be induced in response to the exciting voltage. A first device provides a relatively higher impedance between the first and second terminals of the second winding. The first device is coupled between the first and second terminals. Third, fourth and fifth windings have respective first and second terminals. The third and fourth windings are wound on one of the cores with a first polarity. The fifth winding is wound on one of the cores with a second polarity opposite to the first polarity.

Abstract: A transformer includes at least two magnetically coupled cores with a common axis. The cores have cross sectional configurations transverse to the common axis which are not rectangular. An exciting voltage is to be applied across a first winding provided on one of the cores. A second winding provided on one of the cores includes first and second terminals across which a voltage is to be induced in response to the exciting voltage. A first device provides a relatively higher impedance between the first and second terminals of the second winding. The first device is coupled between the first and second terminals. Third, fourth and fifth windings have respective first and second terminals. The third and fourth windings are wound on one of the cores with a first polarity. The fifth winding is wound on one of the cores with a second polarity opposite to the first polarity.

Abstract: A transformer includes taps by which electrical contact can be made to winding sections of the transformer at locations along its length between its end terminals. A first switch permits contact to be made selectively to a selected one of the taps. An amplifier has an inverting input terminal, a non-inverting input terminal and an output terminal. The output terminal of the amplifier is coupled to the first switch so that selectively making contact with one of the taps couples the selected tap to the output terminal of the amplifier.

Abstract: A method and apparatus for analog-to-digital (A/D) converting an input signal having a first polarity include providing an integrator including a capacitance coupled to an input port of an amplifier, coupling an A/D converter to an output port of the amplifier, changing the amount of charge stored in the capacitance by coupling the input signal and a reference source having a second and opposite polarity to the capacitance, and controlling an A/D conversion cycle of the A/D converter to simultaneously charge and discharge the capacitance with the input signal and the reference source prior to each A/D conversion cycle.

Abstract: An apparatus for monitoring changes in a magnetic field using a magneto-resistive device situated in the field includes a first and second input locus coupled with the magneto-resistive device. An amplifier means for amplifying electrical signals has input terminals and output terminals. A first input terminal is coupled with the first input locus with a first capacitor coupled in series between the first input locus and the first input terminal. A second input terminal is coupled with the second input locus with a second capacitor coupled in series between the second input locus and the second input terminal. The apparatus receives a bias current at the first input locus that cooperates with the magneto-resistive element to affect electrical potential at the first input locus. The amplifier device presents at least one output signal at the output terminals indicating changes in the magnetic field.

Abstract: An apparatus for use in applying write signals including a first and second write signal for a write head to write information to a memory device includes: (a) a current director for receiving the write signals and directing a write current to establish a write voltage across the write head in a first excursion in response to the first write signal and in a second excursion in response to the second write signal; the first and second excursions occurring about a common mode voltage; (b) a voltage drop unit coupled with a supply voltage and the current director at a connection locus for establishing the common mode voltage substantially equal with the supply voltage less a voltage drop; and (c) a switching unit coupled with the voltage drop unit and the connection locus and cooperating with the voltage drop unit to vary the voltage drop.

Abstract: An apparatus for use in applying write signals for driving a write head to effect writing information to a memory device; the write signals including a first write signal and a second write signal; includes: (a) a directing circuit receiving the write signals, directing a current to establish a voltage across the write head in a first excursion toward a first polarity in response to the first write signal and directing the current to establish the voltage across the write head in a second excursion toward a second polarity substantially opposite the first polarity in response to the second write signal; (b) a first boost system coupled with the directing circuit and boosting the write voltage toward the first polarity during the first excursion; and (c) a second boost system coupled with the directing circuit and boosting the write voltage toward the second polarity during the second excursion.

Abstract: A transformer (24) includes a first winding (28) and a second winding (30) coupled to the first winding (28) through a magnetic circuit so that current through the first winding (28) induces a voltage across the second winding (30). The first winding (28) includes n separate shield portions (32-1, 32-2, . . . 32-n), where n is an integer. Each of the n shield portions shields only a corresponding portion of the first winding (28). Each of the n shield portions is electrically coupled to the adjacent shield portion(s) (32-1, 32-2, . . . 32-n) substantially only through its coupling to the first winding (28), the first winding (28), and the other(s) of the adjacent shield portion's (s') coupling(s) to the first winding (28).

Abstract: A method and apparatus (20, 120) for analog-to-digital (A/D) converting an input signal having a first polarity include providing an integrator (22) including a capacitance (40) coupled to an input port of an amplifier (42), coupling an A/D converter (24) to an output port of the amplifier (42), changing the amount of charge stored in the capacitance (40) by coupling the input signal and a reference source (26, 28) having a second and opposite polarity to the capacitance (40), and controlling an A/D conversion cycle of the A/D converter (24) to simultaneously charge and discharge the capacitance (40) with the input signal and the reference source (26, 28) prior to each A/D conversion cycle.

Abstract: A transformer (90) includes taps (96a, 96b, 96c) by which electrical contact can be made to a winding (90) of the transformer (90) at locations along its length between its end terminals. A first section (90a) of the winding (90) has a first resistance R1 (R). A second section (90a+90b) of the winding (90) has a second resistance R2 (R+3R). One or both of the first (90a) and second (90a+90b) sections can be a multilayer section. The sections are configured so that one of the ratio R1:R2 (1:4) and the ratio R2:R1 (4:1) is substantially identical to the ratio 1:n (1:4) of the windings (90a, 90a+90b). A first switch (94) permits contact to be made selectively to a selected one of the taps (96a, 96b, 96c). An amplifier (98) has an inverting (−) input terminal, a non-inverting (+) input terminal and an output terminal. One (+) of the + and − input terminals is coupled to one of the terminals (end terminal of winding 90a) of the winding (90).

Abstract: A transformer includes at least two magnetically coupled cores with a common axis. The cores have cross sectional configurations transverse to the common axis which are not rectangular. An exciting voltage is to be applied across a first winding provided on one of the cores. A second winding provided on one of the cores includes first and second terminals across which a voltage is to be induced in response to the exciting voltage. A first device provides a relatively higher impedance between the first and second terminals of the second winding. The first device is coupled between the first and second terminals. Third, fourth and fifth windings have respective first and second terminals. The third and fourth windings are would on one of the cores with a first polarity. The fifth winding is would on one of the cores with a second polarity opposite to the first polarity.

Abstract: A transformer having a primary winding and a secondary winding across which load is coupled is compensated. A third winding is provided on the transformer. A first output terminal of an amplifier is coupled to a first terminal of the primary winding. A first terminal of the third winding is coupled to the second terminal of the primary winding. A second terminal of the third winding is coupled to an input terminal of the amplifier.

Abstract: A system for increasing the voltage handling capacity of an amplifier circuit coupled to a transformer output comprises a transformer secondary winding divided into n sub secondary windings, where n is an integer. A first terminal of a first of the sub secondary windings is coupled to a reference potential. n amplifiers, numbered sequentially 1.ltoreq.m.ltoreq.n as they appear in the amplification circuit with an output terminal of the nth amplifier comprising an output terminal of the amplification circuit, each have an input terminal and an output terminal. An input terminal of the first amplifier is coupled to a second terminal of the first sub secondary winding. An output terminal of each of the n amplifiers is coupled to a first terminal of the next adjacent higher numbered sub secondary winding, except for the nth amplifier, the output of which comprises the output of the amplifier circuit.

Abstract: A Programmable Demand Register (PDR.TM.) which has a multi-function externally programmable time based measuring system is disclosed. An optical communication port is provided for bidirectional communication of data, said meter being capable of recordation of energy consumption in several different modes, according to the decision of the meter programmer. Meter programming is accomplished by means of any one of three separate devices, namely a Programmer/Reader (P/R) which is a sophisticated computerized device fully adapted to reprogram the PDR.TM.

Abstract: A Power Transducer is disclosed, such as a watt-watthour Transducer, having a dual multiplier circuit receiving inputs from a power source to be monitored and a triangle wave generator. The circuit includes first and second transformers which separately receive voltage and current inputs representative of the power line to be monitored. The first transformer provides dual outputs of opposite polarity which are isolated and scaled replicas of the input voltage. The dual outputs are separately channeled through half-wave multiplier paths, to a comparator in each path, which comparators receive the input from the triangle wave generator to produce a pulse modulated output for control of a switch in each path, which switches also receive the current signal from the second transformer. The outputs from the switches have pulse heights proportional to the instantaneous value of the current and pulse widths proportional to the incoming voltage with the integral being equal to the product of the voltage and current.