Ferrite ring core with internal air gap - provides high inductance at low loads, and significant inductance at high loads

摘要

The small chokes, for example as employed in suppressor circuits, is formed to provide a high inductance at low load but a still useful inductance at high loads. The required core conditions can be achieved by making a sintered ferrite ring which has an air gap formed into it during the manufacturing process. The gap is enclosed by a thin ring of ferrite material and takes the form of a flattened bubble across the section of the core. A ring core of this type gives very high permeability at very low currents. A lower but, useful permeability is present when only the core sections round the air gap are saturated, and a low permeability is present when the whole core is saturated.