Abstract: A thin film path of medium resistivity provided by a strip of tantalum by which a design parameter of an electronic component is determined is modified by making contact with the path by an electrode having an electrolyte at its tip in passing an anodizing current into the path through the electrode that is much smaller in value than the normal current flowing through the path under design conditions of operation. In consequence, the current injected to produce chemical change in the resistance has a negligible effect on the characteristics of operation of the component and the component can have operating conditions applied to it during the trimming process can be carried while the component is under operating conditions and the parameter to be adjusted is being measured, so that the measurements of the parameter can control the current injected through the electrode so as to shut it off when the desired value of the measured parameter is reached.