An apparatus for converting a complex AC voltage wave to an equivalent DC value which is a measure of its true RMS value and which may then be read on an accurate indicating device such as a digital voltmeter, incorporating thermal converters and operational amplifiers in a temperature-compensated configuration The apparatus maintains a portion of an unknown AC voltage wave, which is thermally converted into a DC voltage, substantially equal to a DC reference voltage A portion of a DC output voltage is also maintained substantially equal to the DC reference voltage Since the proportioning means for the complex AC voltage wave and the DC output voltage is the same, the true RMS value of the complex AC voltage wave is equal to the DC output voltage

True rms to dc converters

RECIRCULATING RMS AC CONVERSION METHOD AND APPARATUS Abstract of the Disclosure A signal whose RMS value is to be accurately determined is first converted into DC form by a relatively inaccurate RMS converter, such as a thermal RMS converter. The result is a first converter signal (Y1), which is stored for recirculation in a suitable storage device, such as a sample and hold circuit. The first converter signal is also doubled (2Y1) and stored. Thereafter the first converter signal stored in the storage device is recirculated to the converter to create a second converter signal (Y2). Then, the second converter signal is subtracted from the doubled first converter signal (2Y1 - Y2) to produce a highly accurate RMS output signal.

Recirculating RMS AC conversion method and apparatus

The glass stem (4) is hollow and opens into the bowl (3). The function of the stem is volume measurement. A set quantity of fluid to be tasted in the stem, takes up an integer fraction of the bottle volume initially holding it.

Joseph Duckworth James

Papers

System providing a d. c. voltage equal to the r.m.s. value of an unknown a. c. voltage

Anlage,durch die eine Gleichspannung dem Effektivwert einer unbekannten Wechselspannung selbsttaetig gleichgemacht wird