Internet Guide to Electronics

When a beginner to electronics first looks at a circuit board full of components he/she is often overwhelmed by the diversity of do-dads. In these next few  sections we will help you to identify some of the simple components and their schematical symbol. Then you should be able to call them resistors and transistors instead of "Whatchamacallits". In later sections we will go into the workings of each component.  Just try to familiarize yourself with the basics for now.

Electronic component are classed into either being Passive devices or Active devices.

A Passive Device is one that contributes no power gain (amplification) to a circuit or system. It has not control action and does not require any input other than a signal to perform its function. In other words, "A components with no brains!" Examples are Resistors, Capacitors and Inductors

Active Devices are components that are capable of controlling voltages or currents and can create a switching action in the circuit. In other words, "Devices with smarts!" Examples are Diodes, Transistors and Integrated circuits.

This is the most common component in electronics. It is used mainly to control current and voltage within the circuit. You can identify a simple resistor by its simple cigar shape with a wire lead coming out of each end. It uses a system of color coded bands to identify the value of the component (measured in Ohms) *A surface mount resistor is in fact mere millimeters in size but performs the same function as its bigger brother, the simple resistor. A potentiometer is a variable resistor. It lets you vary the resistance with a dial or sliding control in order to alter current or voltage on the fly. This is opposed to the "fixed" simple resistors.

Capacitors, or "caps", vary in size and shape - from a small surface mount model up to a huge electric motor cap the size of a paint can. Whatever the size or shape, the purpose is the same - It storage electrical energy in the form of electrostatic charge. We will get into the mechanics and further properties of this later. The size of a capacitor generally determines how much charge it can store. A small surface mount or ceramic cap will only hold a minuscule charge. A cylindrical electrolytic cap will store a much larger charge. Some of the large electrolytic caps can store enough charge to kill a person. Another type, called Tantalum Capacitors, store a larger charge in a smaller package.

You may remember from science class that adding electrical current to a coil of wire produces a magnetic field around itself. This is how the inductor works. It is charged with a magnetic field and when that field collapses it produces current in the opposite direction. Inductors are used in Alternating Current circuits to oppose changes in the existing current. The mechanics of this will be described later. Most inductors can be identified by the "coil" appearance. Others actually look like a resistor but are usually green in color.
A. Air Core, B. Iron Core, C. Powered Metal Core.