To get started building electronic circuits, you'll need to gather a collection of inexpensive electronic components like resistors and capacitors, diodes and transistors. You don't have to buy everything all at once, but you'll want to gather at least the basic parts before you get started. You can buy many of these components at any RadioShack or other specialty electronics store.

## Resistors

A resistor is a component that resists the flow of current. It's one of the most basic components used in electronic circuits. If you put resistors next to a penny, you get an idea of how small they are.

Resistors come in a variety of resistance values (how much they resist current, measured in units called ohms and designated by the symbol Ωand power ratings (how much power they can handle without burning up, measured in watts).

Most circuits can use resistors rated for one-half watt. You'll need a wide variety of resistance values. Buy at least 10 each of the following 12 resistances:

 470 Ù 4.7 kÙ 47 kÙ 470 kÙ 1 kÙ 10 kÙ 100 kÙ 1 MÙ 2.2 kÙ 22 kÙ 33 kÙ 220 kÙ

You can save money by purchasing a package that contains a large assortment of resistors. For example, RadioShack sells a package that contains an assortment of 500 resistors — at least 10 of all values listed here, plus a few others, for under \$15.

## Capacitors

Next to resistors, capacitors are probably the second most commonly used component in electronic circuits. A capacitor is a device that can temporarily store an electric charge.

Capacitors come in several different varieties, the two most common being ceramic disk and electrolytic. The amount of capacitance of a given capacitor is usually measured in microfarads, abbreviated μF . As a starting assortment of capacitors, get at least five each of the following capacitors:

• Ceramic disk: 0.01 μF and 0.1 μF .

• Electrolytic: 1 μF , 10 μF , 100 μF , 220 μF , and 470 μF .

## Diodes

A diode is a device that lets current flow in only one direction. A diode has two terminals, called the anode and the cathode. Current will flow through the diode only when positive voltage is applied to the anode and negative voltage to the cathode. If these voltages are reversed, current will not flow.

Get at least five of the basic diodes known as the 1N4001. You should be able to find these at any RadioShack.

## Light-Emitting Diodes

A light-emitting diode (or LED) is a special type of diode that emits light when current passes through it. Although there are many different types of LEDs available, get started by purchasing five red LEDs.

## Transistors

A transistor is a three-terminal device in which a voltage applied to one of the terminals (called the base) can control current that flows across the other two terminals (called the collector and the emitter). The transistor is one of the most important devices in electronics. You can just get a few simple 2N3904 NPN transistors to have on hand.

## Integrated Circuits

An integrated circuit is a special component that contains an entire electronic circuit, complete with transistors, diodes, and other elements, all photographically etched onto a tiny piece of silicon. Integrated circuits are the building blocks of modern electronic devices such as computers and cellphones.

To get started, you'll want to pick up a few each of at least two different types of integrated circuits: a 555 timer and an LM741 op-amp.