Inductors

Pre-set Ferrite-cored

This low-value inductor is used together with an equally small value of capacitance to form the tuned circuit in a VHF radio or TV receiver. The precise inductance value is made adjustable by means of a threaded ferrite core.

Torrodial Ferrite Core

Ferrite cores are used to increase the value of inductance that can be achieved with a given number of turns. This inductor uses a toroidal core which concentrates the magnetic flux into a closed loop and very little flux escapes into the space surrounding the inductor. Inductors of this type are used in power supply filters and in high-frequency switching applications.

RF Transformer

This screened radio frequency transformer comprises two coupled inductive windings and a parallel connected capacitor which brings the main winding to resonance at the desired frequency (often either 470kHz or 10.7MHz in radio receivers). A small range of frequency adjustment is provided by means of an adjustable ferrite core.

RF Choke

Since it is used as a filter which restricts the flow of high frequency current, this radio frequency inductor is sometimes referred to as a "choke". The value of inductance provided is 1.7mH but similar components are available with inductance values ranging from 100µH to 2.5mH.

Iron-cored Inductor (choke)

This iron-cored inductor is designed to form part of an L-C filter in a power supply. The inductor has an inductance of 5H and is rated at a d.c. current of 100mA. The core of the inductor is laminated steel and the complete assembly is held together by means of a U-shaped metal frame.

Iron-cored Power Transformer

So-called "iron-cored" transformers actually have laminated steel cores! This small power transformer is used to "step-down" the mains supply. Two series-connected primary windings are each rated at 120V whilst the two secondary windings each provide 12V at 0.5A maximum.

(Note that this transformer is designed for the United Kingdom domestic supply which is 220V a.c.)