User Manual

34
Lesson 4 Relay Module
Introduction
Relay is a device which is used to provide connection between two or more points or devices
in response to the input signal applied. It is suitable for driving high power electric equipment,
such as light bulbs, electric fans and air conditioning. You can use a relay to control high
voltage with low voltage by connecting it to Raspberry Pi.
Components
- 1 * Raspberry Pi
- 1 * Breadboard
- 4 * Jumper wires (Male to Male, 2 red and 2 black)
- 1 * Network cable (or USB wireless network adapter)
- 1 * Relay module
- 1 * Dual-color LED module
- 2 * 3-Pin anti-reverse cable
Experimental Principle
Relay – There are 5 parts in every relay:
1. Electromagnet – It consists of an iron core wounded by coil of wires. When electricity is
passed through, it becomes magnetic. Therefore, it is called electromagnet.
2. Armature – The movable magnetic strip is known as armature. When current flows through
them, the coil is it energized thus producing a magnetic field which is used to make or break
the normally open (N/O) or normally close (N/C) points. And the armature can be moved
with direct current (DC) as well as alternating current (AC).
3. Spring – When no currents flow through the coil on the electromagnet, the spring pulls the
armature away so the circuit cannot be completed.
4. Set of electrical contacts – There are two contact points:
． Normally open - connected when the relay is activated, and disconnected when it is
inactive.
． Normally close – not connected when the relay is activated, and connected when it is
inactive.
5. Molded frame – Relays are covered with plastic for protection.