Bobbin Wound Transformer Theory
Bobbin wound electronic transformer refers to a type (or method) of construction. Toroidal coils are wound directly onto a toroidal core. The core may be coated or boxed to insulate it form the coil windings. In contrast, bobbin wound electronic transformer coils are wound independently of the core. The coil must hold its shape (or form) until the coil is assembled onto the transformer core. One common method of doing this is to wind the coil onto a bobbin (also referred to as a spool), hence the term bobbin wound transformer. The bobbin is a pre-formed reasonably rigid part. The bobbin material is usually (but not always) an insulating material, hence it can provide electrical isolation between the coil and the adjoining core material provided suitable creepage distance is used. Multi-section bobbins are available to provide increased electrical isolation between coil windings.
Bobbin wound transformers are used in a variety of applications, hence bobbins are made from a variety of materials: plastics, phenolic, glass, TeflonTM and others. Most bobbins are molded. Some are fabricated. Bobbin designs for bobbin wound transformers often provide terminals, pins, and/or surface mount pads to ease wire termination and to facilitate printed circuit board mounting.
Bobbin wound transformers (and inductors) are available in a variety of shapes. Bobbin wound transformer shapes include pot cores (round), RM (square pot cores), RS (round slab pot cores) and DS (double slab pot cores), EP, PQ, E, EI, EEM, EFD, U, UI, EC, ETD, ER, EER, and some others including custom shapes. Bobbin wound transformers in these shapes are available in several different sizes.
Bobbin wound transformers (and inductors) can also use a variety of core materials: laminated or taped wound silicon steel alloys, nickel-iron alloys, cobalt alloys; powdered irons and nickels; ferrite; air core; core materials processed for square loop or round loop properties; and others.
Gowanda designs and manufactures bobbin wound transformers (and inductors) in a wide variety of materials and sizes with pin-thru, surface mount, and/or flying lead terminations. Additional options include tube wound transformers (and inductors) and air core coils. Our upper limits are 40 pounds of weight and 2 kilowatts of power. Our capabilities include foil windings, litz wire windings and perfect layering. For toroids, the list includes sector winding, progressive winding, bank winding and progressive bank winding. Gowanda has a variety of winding machines, including programmable automated machines and a taping machine for toroids. Gowanda has vacuum chambers for vacuum impregnation and can also encapsulate. To ensure quality, Gowanda utilizes programmable automated testing machines. Most of our production is 100% tested on these machines.