Abstract: An overload protection circuit for an AC-DC transfer standard employing a thermoelement comprising a heater element and a temperature sensor. A first differentiator provides an output that is a function of the voltage across the heater element. A second differentiator produces an output that is a function of the output of the first differentiator. Further including a circuit creating an overload signal provided, which is responsive to the outputs of the first and second differentiators.

Abstract: A thermal transfer device for use in the measurement of alternating current comprising an evacuated enclosure containing a first electrical conductor heated by the alternating current being measured and a thermal sensor to provide an electrical signal representative of the temperature of the conductor, wherein the first electrical conductor is formed of a low temperature coefficient of resistivity material, and the thermal sensor is a second electrical conductor of a relatively high temperature coefficient of resistivity material thermally coupled with and encompassing most of the first electrical conductor.

Abstract: A voltmeter comprising a diode detector, a square root converter and a linear amplifier each connected to receive the diode detector output signal, a resistance network connected to receive the outputs of the square root converter and the linear amplifier, means for selectively switching the resistances of the resistance network to change the proportion at the resistance network output between the signal from the square root converter and the signal from the linear amplifier to inversely match the response curve of the diode detector, and means for displaying the amplitude value of the resistance network output signal.

Abstract: The present invention comprises a plastic case for housing electronic instruments and the like, having a top and bottom panel with two side panels connecting them. The edges of the top and bottom panels are mounted for telescoping movement in the side panels to enable adjustment of the case to the size of instrument housed.

Abstract: A digital display electronic meter apparatus is disclosed which is capable of displaying amplitude ratio measurements directly in decibels over its entire amplitude operating range.

Abstract: The present invention comprises a plastic case for housing electronic instruments and the like, having a top and bottom panel with two side panels connecting them. The edges of the top and bottom panels are mounted for telescoping movement in the side panels to enable adjustment of the case to the size of instrument housed.