Electronics All-in-One For Dummies. Doug Lowe

temporarily (or permanently) holding wires and other things together.

       Jumper clips: These are short (typically 12 or 18 inches) wires that have alligator clips attached on either end, as shown in Figure 3-14. You’ll use them to make quick connections between components for testing purposes.

FIGURE 3-14: Jumper clips are great for making quick connections.

Stocking up on Basic Electronic Components

      Besides all the tools and supplies I’ve described so far in this chapter, you’ll also need to gather a collection of inexpensive electronic components to get you started with your circuits. You don’t have to buy everything all at once, but you’ll want to gather at least the basic parts before you go much farther in this book.

      Unfortunately, most communities don’t have a store where you can buy these components in person. (If you’re lucky enough to have a specialty electronics store in your community, purchase your parts from them to help these local businesses stay open!) If you don’t have a local supplier, you can buy the parts online from Amazon (www.amazon.com), Jameco (www.jameco.com), RadioShack (www.radioshack.com), or any other electronic parts distributor.

      Resistors

A resistor is a component that resists the flow of current. It’s one of the most basic components used in electronic circuits; in fact, you won’t find a single circuit anywhere in this book that doesn’t have at least one resistor. Figure 3-15 shows three resistors, next to a penny so you can get an idea of how small they are. You’ll learn all about resistors in Book 2, Chapter 2.

      FIGURE 3-15: Resistors are one of the most commonly used circuit components.

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

      All the circuits in this book can use resistors rated for one-half watt. You’ll need a wide variety of resistance values. I recommend you buy at least 10 each of the following 12 resistances:

470 Ω	4.7 kΩ	47 kΩ	470 kΩ
1 kΩ	10 kΩ	100 kΩ	1 MΩ
2.2 kΩ	22 kΩ	33 kΩ	220 kΩ

       You can save money by purchasing a package that contains a large assortment of resistors. For example, most suppliers sell a package that contains an assortment of 500 or so resistors — at least 10 of all values listed here, plus a few others, for about $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. You learn all about capacitors in Book 2, Chapter 3. Figure 3-16 shows some capacitors.

      FIGURE 3-16: Capacitors come in many shapes and sizes.

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, I suggest you 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

       As with resistors, you can purchase kits with a wide variety of assorted capacitor values. For about $15, you can get 500 or more capacitors in a range of useful values.

      Diodes

A diode is a device that lets current flow in only one direction. Figure 3-17 shows an assortment of various types of diodes.

      FIGURE 3-17: An assortment of diodes.

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.

      You learn all about diodes in Book 2, Chapter 5. For now, I suggest you get at least five of the basic diodes known as the 1N4001 (the middle one in Figure 3-17). You should be able to find these at any electronics parts distributor.

      Light-emitting diodes

A light-emitting diode (or LED) is a special type of diode that emits light when current passes through it. You learn about LEDs in Book 2, Chapter 5. Although there are many different types of LEDs available, I suggest you get started by purchasing at least five red diodes. Figure 3-18 shows a typical red LED.

FIGURE 3-18: Light-emitting diodes.

      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, and I cover it in detail in Book 2, Chapter 6. For now, you can just get a few simple 2N3904 NPN transistors, shown in Figure 3-19, to have on hand.

      FIGURE 3-19: A look at a 2N3904 NPN transistor.