Relay not working!


I know that this is a very basic question, but I am unable to find a solution to my problem anywhere. Please help me if you can..

I have an arduino UNO and a 2-relay module.

I have loaded the code from the BLINK example to the board. The LED is blinking.

Now, I attach a relay module to this setup. I connect the board as follows:

VCC of Relay to 5v of Arduino Gnd of Relay to Gnd of Arduino

IN 1 of relay to Pin 13 of Arduino

Now, everytime the LED blinks, the input LED in the RELAY board lights up (Actually every time the LED goes low, the input relay lights up as it is an active low relay) but the RELAY does not click and there is no connection between the Common and the NO pin.

I have tried with an external power as well, but the same result.

Thanks for your response in advance..


Need schematic and sketch please.

Sketch should be posted using code tags ( </> )

Check the relay driver requirements. If the relay needs more than 40 mA of current to drive the solenoid, it won't switch. If it needs more current, you will have to add a transistor circuit to beef up the current to the relay IN 1 connector. You could also use an opto-coupler as shown in the Arduino Projects Book, Project 15 on "Hacking Buttons".