Introduction: ARDUINO 3 Relays Shield (Part-1)

Hey peeps! Here comes my next instructable.

Presenting here 3 channel relay board shield for Arduino to control AC appliances at a time. A Relay is actually a switch which is electrically operated by an electromagnet Relays are useful for triggering AC appliances with a low signal which can be used in home automation systems. The Arduino 3 Relays Shield is a solution for driving high power loads that cannot be controlled by Arduino's digital IO's due to current and voltage limitations of the controller.


1) SPDT 12v Relay - 3

2) Optocoupler 817 - 3

3) LED - 4

4) BC547 Transistor - 3

5) 2 Pin Terminal Block - 4

6) Resistor 1k - 7

7) IN4007 Diode

8) Jumpers

9) 12v Adapter

10) Arduino UNO

11) Connecting Wires


In this 3 Relays circuit, an optocoupler is used to trigger the NP N transistor which further drives the relay . The Optocoupler will be triggered by an active low signal. In our project 12v relay is used. A 5v or 6v relay can also be used. LED's indicate the status of each relay.

Step 3: DESIGN

I have designed the 3 relays Arduino shield using Eagle CAD Tool which is convenient for me. Below is the board layout. I have also shared Gerber files which has to be sent to the manufacturer for fabricating board.

Step 4: PCB Fabrication

After generating Gerber from Eagle CAD tool I uploaded my design on LIONCIRCUITS where I can get instant DFM feedback after payment. Custom shape image rendering is also good. Highly recommended.

So guys, Stay tuned for the next part of this instructable.