I know there have been a few threads on this board in regards to using a relay but I've been scratching my head and trying to get this circuit working for a while and I've given up....
What I'm working with:
- 12v1A pump
- 12v1A SPDT relay (side 1 has the image of the coil on the diagram)
Here's an image:
- A NPN switching transistor
It's very simple, turning digital pin 2 on will turn the pump on.
So I need help making sure my connections are right and I don't fry my board...
I'll do my best to express how I think the circuit should be, any corrections would be appreciated!
Arduino Pin 2 --> 1k resistor --> transistor base
Arduino ground --> transistor emitter
Transistor collector --> relay (side 1)
Arduino ground --> relay (side 1)
12v DC power supply + --> relay (side 2)
Pump power + --> relay (side 2)
12v DC power supply ground --> Pump ground
I guess I'm not sure where to connect the "common" 5th pin on the relay.
Obviously it's incorrect and I don't think I'm understanding the relay correctly. I understand a small current across the coils will close the connection on the other side to create a separate circuit for the 12V DC power supply going to the pump but it's just not working out as planned.
Is it possible to trigger the relay directly from the Arduino without the transistor?
Thanks for any replies! It's very much appreciated. This is for an Arduino demo I'm doing next week so I'm hoping to have this circuit figured out by the weekend and running....