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Topic: Ardunio relay module wiring (Read 4 times) previous topic - next topic


should I just invert the logic in the Arduino code

Yes every time providing the arduino can stand the load.


Mar 30, 2011, 09:30 pm Last Edit: Mar 30, 2011, 10:02 pm by stikeymo Reason: 1
Thanks very much for the help guys, much appreciated :)

So, just taken a look at the module - unless I'm mistaken, it sadly doesn't look like it's possible to do NO operation with it. If you take a look at the PCB traces:

And compare with the datasheet:


Pins 1 and 3 of the relay are hard-wired to the outermost contacts of the module, and the inner most contacts on the module are hard-wired to each other. Here's the view from the top for comparison:

As I understand it, switching the relay on swings the connection from pin 3 to pin 4 of the relay, opening it. It doesn't look like pin 4 is connected to anything to me...

Unless I'm talking nonsense - there's a strong possibility of that, mind.. ;)

If this is the case, I'll rewrite the logic of the Arduino code to send the output "low" when I want to switch the air freshener on - annoying to have power blips on start up, but it'll have to do for now..

EDIT: In fact, I was talking nonsense about 'power blips' - have the appropriate pin set to high in setup and it seems to be seamless! Lovely. :)

Terry King

Mar 30, 2011, 10:07 pm Last Edit: Mar 30, 2011, 10:13 pm by Terry King Reason: 1
I bet DFRobot didn't intend to do that....

This one gives you both options: http://arduino-direct.com/sunshop/index.php?l=product_detail&p=49

Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com


Yeah, it seems like an odd design choice to limit users like that. Thanks for that - I'll buy one of those next time!


Hi there,

I'm a total newbie in electronics, but I want to learn. I'm a software developer.

I bought the follow relay module http://cgi.ebay.ca/5V-4-Channel-Relay-Shield-Arduino-Electronic-DIY-/110648585724?pt=LH_DefaultDomain_0&hash=item19c32b6dfc#ht_1351wt_1139.

I thought that I knew how the basics of relay worked, i.e. put a small voltage and it close/open a switch. But nothing seems to work.

I have connected the VCC and the ground to the board and connected K1 to pin 13. Now let say for testing purpose I want to make a led blink from the relay, where do I plug the cables?


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