Geophone with damping coil

摘要

A conventional electromagnetic geophone includes a coil assembly that is spring-suspended in an air gap between concentric pole pieces of a magnet. The coil assembly is wound on the outer wall of a bobbin. The bobbin is typically made from or includes a metallic material to provide a mass for mechanical damping and a conductor for electrical eddy-current damping of the spring-suspended coil assembly. The improvement of this invention lies in mounting on the bobbin, a vernier mechanical damping mass made of a coil of insulated wire. The coil is open-ended and the mechanical damping force is adjustable in accordance with the number of turns in the coil.