A New Peak-to-DC Comparator for Audio Frequencies

An adjustment-free peak-to-dc transfer technique is described for making precision comparisons between audio frequency ac voltages and a reference dc. Limitations and estimated systematic errors are discussed and justifications for an over-all ac-dc transfer worst case error of 50 ppm presented. Photographs of output oscilloscope patterns are shown for various conditions of ac-dc transfer agreement for several different ac sources. Experimental over-all comparison against a modification of the Smith-Clothier peak calibration technique is described with agreement on the order of 30 ppm.