Metal and Oxide Film Potentiometers

Recent developments in resistors and potentiometers of the noble metal and metal oxide film types are described. Photographic methods of producing "meandered" resistance paths in the two types have been developed, as well as means of rhodium reinforcing the track portions to improve the wear characteristics, and in the case of oxide films, to reduce the contact resistance against the wiper. The relation between resistance, temperature coefficient, and film thickness has been determined for oxide films on glass comprising tin oxide as the major constituent, and from these, the conditions to result in low temperature coefficients over a relatively wide resistance range are deduced. The characteristics in respect of wear, noise, temperature coefficient, and electrical load for either type of element are briefly discussed.