Inductive data pick=up on eddy current principle - has HF AC coil placed in metal carrier sleeve end behind end plate

摘要

The end plate is a thin metal diaphragm consisting of a material having small magnetic permeability and high ohmic resistance. The frequency of the alternating current feeding the coil is between 104 and 105 Hertz. The thickness of the diaphragm is between 0.1 and 0.001 mm. The coil can be fitted in a shell-type core open on one side, whose open side is immediately behind the metal diaphragm. The end plate is made of a material which is magnetically permeable, resistant to temperature and resistant to chemical effects.