Help me connect this PIR sensor with relay board to 12V LED controller?


I bought the PIR sensor board pictured below. The datasheet is also below.

The sensor is titled on ebay as "DC 12V 5A IR Pyroelectric Infrared PIR Motion Sensor Detector Module New" and has an output of 5A according to the item description.

I tried to understand what voltages to use and how to connect it. The 12V LED controller just has a positive and negative.


  1. What input voltage do I need to switch 12V LEDs
  2. Do I connect the yellow cable (output) to the LED positive?
  3. Do I create a common ground between the LEDs and the sensor?

Note: I tried this with a 12V 6A power supply and it was switching (click noise) but the 0.5m long 12V LED strip did not not light up.



Use your multimeter to find the NC and NO contacts of the relay, and which one is the centre contact (I’d guess that’s the yellow one, as it’s the centre of the connector as well).
If you connect your LED strip to the top and bottom contact it’ll never light up.

Try connecting YELLOW to 12V +, BLACK to LED + and LED - to 12V -, if it works backward, switch BLACK with RED.


Not sure I understand either comment properly. Sorry about that. Do you have some more details to add, such as what to connect power GND to? Both the black cable and the LED negative I think.

Well, the Ebay page says "Red to 12V +, Black to 12V - , Yellow - output, but doesn’t say if Yellow connects to + or - when activated. Do you have a DMM?

Power ground? Which power ground? From the Arduino?

The whole purpose of a relay is to have the two sides isolated.

Ebay link.

ok, when I said power ground I meant the power supply ground. I'm not using an Arduino here. If the PIR and LEDs are meant to be isolated from each other by the relay I guess they will not have a common ground and therefore they will have separate power supplies? I don't get it. The PIR board has a 5A output. I thought the current was to go through the PIR and straight to the LEDs.

I have done this before with the PIR below (common ground). Works a charm but it's too big for my purposes.

Any more thoughts on this? I plan to give it another go this weekend