Circuit measuring RMS value of AC voltage - applies voltage to two thermocouples through comparator whose output delivers voltage digital value

摘要

The voltage is applied to the heating winding of a first thermocouple whose output is connected through a feed-back loop to the heating winding of a second thermocouple. The first thermocouple (TKl) is followed by a comparator (KO) whose output signals are applied to a digital device (DE) whose digital comparison results appear at an output. A digital analogue converter (DA) and other components are so arranged, that the comparator output signal polarity delivers the logarithmic r.m.s value of the AC voltage (Uw), starting from the first comparison result as the leading digit of a binary series.