ELECTROMAGNETIC DEVICE

PURPOSE:To prevent a magnetic circuit from changing the characteristic thereof and extend the life of a device as a whole first by forming the magnetic circuit by filling and hardening a permeable resin in a coil-contained outer box, and then by preventing the overheating of the coil by removing the outer box. CONSTITUTION:After installing a coil 12 in an outer box 11, a fluid permeable resin 14 is hardened contiguously over the surface of the coil for filling. Such hardened permeable resin functions as a magnetic circuit. Because the hardened permeable resin is given an adequate elasticity, the contiguity thereof is not damaged by any vibrations, thermal expansion, and contraction. According to the constitution, the heat generated from the coil 12 is directly transferred to the magnetic circuit effectively, thereby preventing the overheating by radiation from the surface of the coil.