Inductors

An inductor comprising a coil wound on a ferrite core with composition 15 to 35 percent by weight Ni-Zn ferrite and the rest Mn-Zn ferrite. Preferably the ferrite composition is 25 percent Ni-Zn ferrite and 75 percent Mn-Zn ferrite. The core may comprise two components which include curved surfaces which are arranged to form gaps producing low permeability regions. The inductor may be encapsulated in cold setting resin composition of a foamed structure, unsaturated polyester resins or bisphenol A epoxy resins and a polyamide resin may be used. The resin may include one or more unreactive polymers as plasticiser.