Foil potentiometer

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A foil potentiometer is a special type of potentiometer , i.e. a mechanically adjustable voltage divider .

A foil potentiometer consists of several foil layers which are isolated from each other by a spacer. A resistor layer is applied to one of the foils, usually the lower one, using a screen printing process , for example . There is a highly conductive coating on the overlying film, the collector film.

There are different versions for setting and tapping the middle connection ("slider"): The upper sheet can be brought into contact with the lower sheet by pressure, by means of a tap or an upper ferrous foil and a permanent magnet underneath conventional potentiometer the respective local voltage can be tapped.

The difference to conventional potentiometers is that no sliding contact is required to make contact with the resistance track , so that hardly any wear occurs.

Due to their thin film structure of less than 1 mm in height and the hermetically sealed adhesive on the outer edges, they have established themselves in many areas in which conventional potentiometers cannot be used. As a setpoint adjuster, they offer good sealing against dirt in operating units. As an actual value transmitter, the low overall height enables a high degree of flexibility in construction.

Foil potentiometers have been established in the German market for many years and, due to their small footprint, are particularly popular in those places where the flat design and tightness are of great importance.

When it comes to tightness, however, it should be noted that strong changes in ambient pressure can inflate or compress the film package, which in the worst case can lead to an unintentional release. Therefore, absolute tightness is not always the optimum. Some manufacturers offer the option of venting through which moisture and gas exchange can then take place. In this version, however, the automatic return of the film when the actuation location changes due to the internal air pressure is omitted (resilient effect of the enclosed air cushion with a slight overpressure, which pushes the film back again).