Components

Electronic components can be divided into two groups: discrete electronic components and integrated circuits (ICs).

Discrete electronic components

Discrete (meaning separate) electronic components can be selected individually and put together to make a circuit. Examples of discrete components include resistorsresistor: An electrical component that restricts the flow of electrical current. Fixed-value resistors do not change their resistance, but with variable resistors it is possible to vary the resistance., capacitors [capacitor: Circuit component which stores and discharges electrical current. They are made from two parallel metal plates separated by an insulator (called a dielectric). ], diodes and transistorstransistor: Components which do not conduct electricity unless they are turned on by a (different) electrical current. This means they can be used as switches, amplifiers and in other ways..

Discrete components can also be used as components in circuits that include an integrated circuit. For example, a 555 astable [astable: An astable circuit gives a pulsed digital output. For example, it could be used to make an LED flash. ] integrated circuit requires two discrete resistors and a discrete capacitor to make it work.

Integrated circuits

These are miniature circuits etched onto a piece of silicon, often called a chip. These chips are fitted inside a protective plastic package and are manufactured in large quantities.

The circuits inside the package are arranged in different configurations depending upon the type of chip and its function. The most common type of configuration is called the dual-in-line or DIL package, which has two rows of connecting 'legs', one on each side.

You don't need to understand how the circuit inside a silicon chip works. It's best to think of ICs simply in terms of their function: eg as timers, counters, logic gateslogic gate: Digital electronic devices that allow an electronic system to make a decision based on a number of inputs. or operational amplifiersoperational amplifier: A device which takes a relatively weak signal as an input and produces a much stronger signal as an output. (op-amps).

Normally they are one of the process blocks in an electronic system, as in the image here:

When using ICs you need to know:

• which pins have to be connected
• the function of each pin
• how the IC is connected to the power supply

A circuit diagram that includes one or more ICs should show the pin numbers and how the pins are connected to the rest of the circuit.