Abstract
A low-noise potentiostat, developed and built at NBS, is described. The instrument, which has built-in an ac current amplifier, is particularly suited for detecting small current fluctuations in the frequency range between 0.1 and 2000 Hz. The noise in the dc control voltage is of the order of 2.5 × 10(-8) V/√Hz, and the instability of the ac amplifier corresponds to a signal of 3 × 10(-11) A/√Hz. The performance characteristics of the instrument are fully described as well as its use in impedance measurements by means of a swept frequency signal. The instrument can also be used as a galvanostat.