Hardware Hacking Projects for Geeks

122

Part II: Advanced Hacks, Tools, and Techniques

How to Identify Transistors

Transistors are switches that control the flow of current in a circuit.

Depending on what type it is, either voltage or current can control these

switches. Transistors are made from materials that change their resistance

based on a control voltage or current. They are typically made from pure

silicon with trace amounts of other elements added in. Figure II-4 displays

different examples of transistor packages.

Most transistors have three connections: an input, an output, and a con-

trol. These connections are referred to differently depending on the type of

transistor.

How to Identify Integrated Circuit

and Component Packages

Throughout this book, I mention two types of packages for the components

you’ll use: surface mount (SMT) and through-hole (also called DIPs). The

following are brief descriptions for these two circuit-packaging technolo-

gies.

Surface-mount components

Surface-mount (SMT) components sit flat on top of a circuit board.

Connection pins are spaced more closely than in through-hole components,

and SMT parts are much smaller than through-hole parts. Several examples

of SMT parts are shown in Figure II-5. From left to right are a surface-

mount inductor, a 0603 surface-mount resistor, a surface-mount SOIC

logic gate, a 1206 surface-mount tantalum capacitor, and a surface-mount

SOT-23 transistor.

Figure II-4: Transistor packages

How to Identify Transistors

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