# Topics

Design & Technology

Components:

There are many different types of electrical and electronic components, including resistors, capacitors and diodes. Each of these has a specific use in a circuit. 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 includeresistors, capacitors, diodes andtransistors.

Discrete components can also be used as components in circuits that include an integrated circuit. For example, a 555 astable integrated circuit requires two discrete resistors and a discrete capacitor to make it work.

# What is a resistor?

# Capacitors – A to Z of Electronics

# How a Capacitor Works – by Dr. Oliver Winn

# Integrated Circuit

# Analog and Digital [ explained in the easiest way ]

Many electronic circuits have to make decisions. They look at two or more inputs and use these to determine the outputs from the circuit. The process of doing this uses electronic logic, which is based on digital switches called gates.

# Electronic logic: digital and analogue signals

Logic gates allow an electronic system to make a decision based on a number on its inputs. They are digital electronic devices. Digital means that each input and output of the gates **must** be one of two states:

**high**, also known as 1 or ‘on’**low**, also known as 2 or ‘off’

Devices such as thermistors, microphones and light dependent resistors (LDRs) produce signals that are analogue. This means that they vary over a range. Analogue signals must be processed by an analogue-to-digital converter (ADC) before they can be processed by a logic gate.

A single digital signal can be either high or low: eg a light with one switch can be on or off. However if there is **more than one signal, there are more than two possible states**. For example, if two signals are present there are four possible combinations: high/high, high/low, low/high and low/low.

In a logic gate each combination can be made to produce a different outcome.