Relays is simple electromechanical switch made up of an electromagnet and a set of mechanical contacts.

As the name indicates, electromagnet is based on the electrically controlled magnet, which controls the mechanical contacts.

The mechanical contact is like a switch with springs to hold them in default position.

The electromagnet when switched on, pulls the contact to other direction and so the relay acts as switch.

There are some disadvantages of using relay as switch e.g. creation of electromagnetic interference during switching, slow switching / response time due to mechanical movements.

To avoid such disadvantage, Solid State semiconductor based switching is preferred, but same time it adds up the cost.

Still relays are being used in variety of products till now because of their ability to switch loads operating on higher AC / DC voltages.

In fact, some of the first computers ever built used relays to implement Boolean gates.

The board is fully assembled and simple dual relay design. Each relay is controlled by individual transistor. Connect load (the electrical equipment which you want to control) to the Green connectors. Connection details are explained in the User Manual.

This board can be interfaced with any microcontroller board. Ensure to make common Ground connection between the microcontroller board and the relay board.

Connect regulated 5V or 6V DC as power input to the relay board. This power is used for transistor and also by the electromagnet inside relay.

Warning – Work with high voltage section only if you are qualified & understand the circuit. Danger of electrocution. With above connections, the PCB of Relay board is also connected to AC High voltage line. DO NOT TOUCH PCB while in use and /or Plugged to mains AC.

• One assembled & tested Relay board