Electronics hobbyists often wish to copy a circuit for which suitable coils or fixed inductors are not readily available. However, you can wind just about any type of inductor if you only know how. Or you can take inductors from old equipment and modify or adjust them. All you have to do is determine is how many turns you need.Low-value inductors are primarily used in RF circuits. A general distinction must be made between inductors with magnetisable cores (made from ferrite or iron) and ‘air-core’ inductors, which are wound on insulating forms or entirely without any sort of coil form.