Article révisé par les pairs
Résumé : A potentiostat with a dc amplifier fed with 110 V AC has been used to study the electrodeposition of metals by various direct methods (maximum 20 V, 400 mA). The electrolysis cell contained a cathode of 2·5 cm2, to obtain sufficient deposit for analysis and structure examination. The cathode potential was measured against a reference electrode by means of a Piontelli capillary whose distance to the electrode was adjustable, to study the influence of the distance between the capillary and the electrode on the stability of the potentiostat, with and without electrolyte circulation. Certain instabilities resulted from the amplification of side parasitic potentials, when the beginning of the electrochemical reaction at the controlled electrode had as consequence a lowering of feedback rate of the cell. By raising the feedback rate for the parasitic potentials by means of a small capacitance (100 pF) across the anode and the reference electrode, the capillary can be held against the cathode and even embedded in the deposit more than 0·1 mm thick, the cathode potential remaining stabilized within 2 mV. © 1965.