Variable resistor with circular track used as trimmer - has smooth section on base plate with glass coating and coil shaped wiper

摘要

A variable resistor has a circular resistance track and a ceramic base plate with a collector plate at the centre of the resistance track. There is a spindle at right angles to the track supporting a wiper which is pressed onto the track. The spindle is mounted in a housing with a stop for the wiper. The resistance housing is clipped onto brackets on the remote side of the base plate. There is a section on the base-plate (31) with a smooth surface structure consisting of an insulating material, such as glass. The wiper support (23) of the contact coil (27) can be rotated over this smooth surface between the resistance track (35) and the collector plate (33).