Arduino digital pins not turning relay on...

Using Arduino Project Guidance
1

Hi there,
I have recently been making an automatic watering system using the arduino. I have realised last week that i need a relay module to be able to use the arduino as a switch for the 12v pump. Since then i've made one successfully. However there seems to be something wrong... to test the arduino with the pump and relay, i've simply used the blink example and changed the pins around. However, the pump doesn't turn on and off. I can hear the relay making veeeeeeery quiet switching noises but not turning on. To further test, i've pluged in the positive part of the relay module to the 5v pin on the arduino and the relay makes a loud switching noise and the pump turns on... Do the digital pins just not give out enough volts to turn on the relay??

Thanks in advance!

2

It's probably Amp.s, but, yes, that's the problem.
look into driving external loads through a FET and remember that a relay is an inductive load (Hint: feedback diode).

3

Remember also not to use the pins you may have already damaged.

4

123Splat:
It's probably Amp.s, but, yes, that's the problem.
look into driving external loads through a FET and remember that a relay is an inductive load (Hint: feedback diode).

Hi again, The relay circuit i have uses a BC108 Transistor to amplify the current... the same thing is still happening...

5

Always, always, always show us a schematic and a good image of your wiring.

Always, always, always show us your complete sketch using code tags.

Always, always, always show us links to your unique parts.

6

:roll_eyes:

7

larryd:
Always, always, always show us a schematic and a good image of your wiring.

Always, always, always show us your complete sketch using code tags.

Always, always, always show us links to your unique parts.

You forgot one (and that's immediately the summary of it all):

Always, always, always read the sticky (and follow the guidelines given in it, of course).