Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Plural ranges – scales or registration rates
Patent
1992-01-31
1993-10-05
Nguyen, Vinh
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Plural ranges, scales or registration rates
324 99D, G01R 1508
Patent
active
052508935
ABSTRACT:
A voltage measuring instrument which generally includes signal conditioning circuitry coupled to input probes for protection against overvoltages and processing of input voltage signals. A VAC/VDC control circuit will determine whether AC or DC voltages are present, and will positively indicate when no voltage is present in a test circuit. The metering circuit of the invention will thereby automatically determine the proper mode of operation for the type of voltage present in a test circuit so as to eliminate user selection of operating parameters and possible errors. Further, the metering circuit is adapted to generate a proper reference voltage for the measured voltage automatically, to again eliminate selection of a voltage range by the user. A power supervision circuit is adapted to automatically shut off the measuring instrument after a predetermined amount of time has elapsed, and will automatically shut off power in the event that available battery power drops below a given level. There may be additionally provided a true RMS measuring circuit and a continuity measuring circuit which may be automatically implemented. The voltmeter provides an instrument which is substantially insensitive to effects of distributive capacitance within a test circuit, and provides a safe, easy to operate and versatile measuring instrument.
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Fell Roger B.
Gambill Terry A.
Nguyen Vinh
Tegam, Inc.
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