Inductors

Use inductors by themselves to control voltage, or with capacitors to amplify and dampen frequencies
By W. Aiman Mueller Inductors store energy in coil-generated magnetic fields. A capacitor performs a similar task in that it stores energy, but it stores electrostatic energy between two plates. Inductors and capacitors often combine to either amplify or dampen signal frequencies.
 

Inductors and capacitors have many uses, from reducing the hum of DC outputs, to preventing radio waves from interfering with sensitive electronic devices. Alone, a power inductor controls voltage levels, and the tiny chip inductor has a role on many electronics boards. Two inductors can also combine as elements of transformers, which step voltage or current up and down and also affect frequencies.

Besides the radius of the coil, the two factors that most affect inductor properties are the composition of the inductor core that the coil winds around and the shape of the inductor. Here are basic tips on these inductor properties:

1. The center of an air core inductor does not increase inductive properties. Neither do glass, plastic or wood cores.

2. Ferrous cores increase the inductance of an inductor coil.

3. A toroidal inductor looks like a donut and has greater inductance than a solenoid (cylindrical) inductor.

Determine the electrical specifications you need in inductors and buy the right parts

Inductors have many variables. You should mainly concern yourself with inductor current, as well as inductance range and tolerance. Maximum DC resistance is also a factor.
Try: Vishay does a good job of publishing their inductor properties. On their website, you can look up inductors by application, inductance range, mounting, shape and other basic variables. Wilco Corporation has an outstanding selection and clearly publishes part specifications to help you find the right inductor.

Find inductors that have the right physical characteristics to suit your applications

Radius and core material are primary options, but also look for surface (including PCB) or through-hole mount inductors. Also, some inductors have variable inductance.
Try: Coilcraft carries surface mount inductors to filter both radio frequency interference (RFI) and electromagnetic interference (EMI). Inductors, Inc. covers an array of inductor types, including a full line of each mount type and a number of core choices, including air and ferrous materials. They also carry chips.

Shop for inductors at sources that also have a wide selection of capacitors

If you are shopping for inductors, maybe you're shopping for capacitors as well, since the two often combine in an inductor circuit. You'll want to look for the best one-stop electronics sources.
Try: KOA Speer Electronics, Inc. carries electronic components, including resistors, inductors, capacitors and other products. Their stock includes a hybrid, three-terminal inductor/capacitor. Also, Marsh Electronics, Inc. carries capacitors and frequency filters, as well as many brands of basic coils, chokes, and inductors.

• Even the best inductor coils give off some heat due to resistance. Take this into account when mounting an inductor.