Fluke Corporation

John M Lund

Benjamin Eng, Jr

Monte R Washburn

Steven D Swift

Jonathan J Parle

A multimeter having measurement terminals and configured to receive measurement signals applied to the measurement terminals and a measurement value and also configured to receive communication signals applied to the measurement terminals and extract encoded information from the communication signals. The multimeter can be included in a multimeter communication system having a device coupled to the measurement terminals of the multimeter. The device is configured to generate communication signals having encoded information and provide the communication signals to the measurement terminals of the multimeter.

Multimeter having communications via measurement terminals and communication system for same

An apparatus and method of measuring capacitances are provided in which charge packets of known value are delivered to a capacitor of unknown value until a final voltage is determined, and the capacitance is calculated based on the known total charge and measured voltage.

Capacitance measurement

A calibrated isothermal assembly for a thermocouple thermometer is provided to obviate a calibration step after manufacture of the instrument. A compact isothermal block is fabricated on a specialized printed circuit board which includes a thick metal plate to establish sufficient thermal mass and good heat conductivity. A temperature sensor is mounted at the thermocouple reference junction on the printed circuit board to track the reference junction temperature. The calibrated isothermal assembly also includes a current source for the temperature sensor, and a memory device containing stored calibration data specific to the temperature sensor.

Calibrated isothermal assembly for a thermocouple thermometer

A circuit for measuring alternating current (a.c.) and direct current (d.c.) in a conductor without breaking the conductor is provided. A modulated current source is coupled in parallel with a segment of the conductor to inject a test current. A synchronous demodulator is also coupled in parallel across the segment to separate the test voltage drop induced by the test current from the voltage drop due to the current in the conductor. The test voltage drop and the voltage drop are measured by a voltmeter and the resistance of the segment and the current flowing through the segment can then be calculated.

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Marysville, WA, United States of America

John M Lund