Nuts and Volts - July/August 2018

Introduction

Resistors are the most common passive component on any printed circuit board (PCB), so it’s good that they cost just a little more than a penny each. Up in price an order of magnitude from resistors are capacitors, which are generally larger. Rare — except in radio frequency circuits — are inductors which are generally much larger than the capacitors, more expensive, and very hard to source.

Probably not a lot of folks have likely seen a memristor — the fourth passive component that completes the passive component family, as seen in Figure 1.

44 July/August 2018

Does Inductor Winding Have You Tied in Knots?

While resistors and capacitors are easily procured and stocked, most radio frequency circuits require inductors in a wide range of very specific values. In most cases, you need to create these yourself, by winding wire on ferrite rods or toroids of specific types and sizes. Is it possible to substitute another ferrite piece at hand and still get the right inductance value? How can a hobbyist measure inductance without buying an expensive instrument? This article describes the principle behind inductance and presents some tricks that I have used to make my own inductors.