Trying to power the 12V relay from an Arduino to make an automatic cocktail maker. Looking to power 12V water pumps off of the relay. However, the relay is not clicking, only getting the light.

The connections FROM the Arduino TO the relay is as follows:

Arduino Relay
pin 3 IN1

Also pictures of circuit are provided. The Arduino is powered by USB laptop.

Relay Arduino Test code

  • Have you set pin 3 to be an output? – Majenko Jun 20 at 9:05
  • What kind of relay or relay module are you using? – StarCat Jun 20 at 9:46
  • 5
    12V relay controlled by 5V arduino? You need a 5V relay or 12V supply for relay. – SBF Jun 20 at 10:18
  • True, if you already connected the relay to pin 3, just test if the pin is still working as it might have drawn too much current, you should use a 5v relay or a 12 volt power source with a transistor. – Coder9390 Jun 20 at 12:02
  • 1
    The digitalWrite() commands in your code use “quoted” values (such as “LOW” and “HIGH”) for the second operand. I dont’t think that will work correctly. Try to use the conventional LOW and HIGH. For example digitalWrite(relay, HiGH). – StarCat Jun 20 at 20:45

After search the internet, i believe the 12v relay need 12v to click.

You may check these :



  • The problem is, we have no idea which relay board is used. The first link you point to whoes a relay board that looks like the one in the question but then goes on to explain nothing about that boards’ particulars. It even shows a relay controlled by a transistor, without the optical isolators that are clearly on the board. However, I think these relay boards do need a +12V connection. – StarCat Jun 22 at 6:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.