Abstract: An active, artificial inductor circuit is utilized as a two-terminal pair circuit used to provide an apparatus capable of measuring the AC electrical parameters of a device such as a resistor, a capacitor or an inductor at a desired frequency with less error in measurememt at lower frequencies.

Abstract: An improved type of vector impedance measuring instrument is disclosed. The vector impedance is a vector current relative to (or normalized to) a pertinent voltage. A transducer for converting the impedance to corresponding current and voltage includes a digital signal processing unit. The vector value of the current is derived from parameter values set in the digital signal processing unit. This configuration eliminates a conventional vector ratio detector, which conventionally followed the transducer, saves cost, reduces size, and achieves high performance. Also, algorithms implemented in the digital signal processing unit are easily modified for a variety of transfer functins phase compensation, and corrections.

Abstract: An apparatus is disclosed for providing the projections of signals supplied to two inputs on mutually perpendicular axises by applying a different combination of the signals respectively at said input terminals and quadrature phases of an AC wave to each of four phase detectors or by applying each combination in sequence to each phase detector. Means are provided for calculating impedances from the outputs of the phase detectors when the voltages applied to the inputs are respectively those appearing across an unknown impedance and a calibrated resistor that is in series with it, there being an AC voltage applied across the series circuit.

Abstract: This invention provides a polar device measuring apparatus which can bias a device under test in a proper polarity. The measuring apparatus is computer-controlled and automatically selects the polarity of the bias voltage based on the measured value of voltage across the device.

Abstract: A reed switch with high insulation for a very low current measurement system is provided. The reed switch is embodied by coating over its glass-made surface with fluoroplastics materials in order to reduce the leakage current on the surface.