By | October 28, 2015
“”Relay is a Magnetic switch it can turn ON and Off your Load automatically “”
NO(normally open) & NC( normally closed)

Components Required:
Arduino UNO
4 or 5 Channel Relay Module
2x LEDs
330-ohm resistors x 2
Jumper Wires (male to male & female to male)

Project Description :
* The Red will glow when you applied power to relay module though VCC pin
* The green light goes on and the relay will switch from NC( normally closed) to NO(normally open)
* whenever a power is removed the relay will switch back to it,s  NC position from NO
* Yellow LED will be on and the green Led will be off  if there is no power applied to the CH1 pin 
* The green Led off due to breaking in the circuit the contacts switched 
* When power applied to the CH1 pin the yellow LED turns off and green LED turns on.
* When power applied to the CH3 pin then onboard LED will illuminate.
* At source code i used to operate one Relays through CH1 and yes you can modify the source code to operate more relays.
Schematic :
Table of contents : 

Source Code :

3 Replies to “How to operate 4 Channel Relay Module using arduino uno”

  1. Abid Jamal

    we have a clear duty to help a students and provide good articles to them ……You can check it out the original source link is there


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