Types of transistors

The leads are labelled base (B), collector (C) and emitter (E).

There are two types of standard transistors, NPN and PNP, with different circuit symbols. The letters refer to the layers of semiconductor material used to make the transistor. Most transistors used today are NPN because this is the easiest type to make from silicon.

Heat sinks

Heat sink (теплоотвод)

Transistors produce heat because of current flowing through them. Power transistors need heat sinks because they pass large currents. The heat sink helps to remove heat to the air.

Integrated Circuits (Chips)

Integrated Circuits are usually called ICs or chips. They are complex circuits which have been etched onto tiny chips of semiconductor (silicon). The chip is packaged in a plastic holder with pins spaced on a 0.1" (2.54mm) grid. Very fine wires inside the package link the chip to the pins.

Pin numbers

The pins are numbered anti-clockwise around the IC (chip) starting near the notch or dot. The diagram shows the numbering for 8-pin and 14-pin ICs, but the principle is the same for all sizes.

Static precautions

Antistatic bags for ICs

Many ICs are static sensitive and can be damaged when you touch them because your body may have become charged with static electricity, from your clothes for example. You should earth your hands by touching a metal water pipe or window frame before handling the IC. For more sensitive (and expensive!) ICs there is special equipment: earthed wrist straps and earthed work surfaces.
Logic ICs (chips)

Logic ICs process digital signals and there are many devices, including logic gates, flip-flops, shift registers, counters and display drivers.

CMOS

CMOS is pronounced 'see-moss' and stands for Complementary Metal Oxide Semiconductor. This family of logic ICs are in 14-pin or 16-pin packages. They use CMOS circuitry which means they use very little power and can work with a wide range of power supply voltages (3 to 15V). It makes them ideal for battery powered circuits.

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