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.

Abstract: 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.

Abstract: An access window enclosure which is mounted on the surface of a control equipment enclosure to protect indicators and controls located on the equipment enclosure surface. The access window enclosure is hinged and latched to allow easy access to the indicators and controls located beneath it. The front of the access window enclosure contains a transparent panel which keeps the indicators and controls in view when the access window enclosure is closed. The mounting frame of the access window enclosure uses a compliant gasket to seal against the transparent panel.