Tegam, Inc.

Terry A Gambill

Roger B Fell

Roger A Stancliff

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.

Digital voltmeter

A method and apparatus for testing handheld soldering irons having a three wire soldering tip by touching the soldering iron tip to a single point sensor to measure tip temperature, tip voltage to ground the tip resistance to ground. A thermocouple sensor for use with a soldering iron testing apparatus is described.

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N. Perry, OH, United States of America

Terry A Gambill