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12VDC Relay not turning on

Ref. to Pololu Basic SPDT Relay Carrier with 12VDC Relay (Assembled) – The 12vDC relay.
Goal: Use this relay to turn on a 12vDC motor (0.8W) with Raspberry Pi (python script).
Problem/Question: The relay (red) LED turns on when executing the python script, but motor is not running. Not sure if the relay is activated or not.
Connection diagram: See below.

  1. The motor runs with direct 12v DC connection.
  2. Tried both 3.3v and 5v from Pi to the relay’s VDD pin, same behavior.
  3. After executing the python script, the red LED stays on. The continuity test fails between NO and COM.
  4. Checked the physical wiring/connections.

I bought 4 of those, I tested two, same behavior. I may be doing something fundamentally wrong.

Any help would be appreciated.

Hello, Ize.

It sounds like you are connecting 3.3V or 5V to the VDD pin on the relay board. The VDD voltage is what activates the relay, so if you are using the 12V version of our relay carrier, you would need to power that pin from 12V.

Alternatively, you could use the 5V version of the Basic SPDT relay carrier, and power it from 5V.


It’s totally my lack of understanding of the relay specifications. Thank you!

So, the “12V” for this relay is referring to the VDD voltage (the coil side, i.e. the relay operating voltage, not the contact/load side), the load side specification is listed at “Contact Ratings” section/table in the datasheet, correct?

It is working now after the wiring change as shown below:

Thanks again for your help.

Yes, it sounds like you have the correct understanding now, and I do not see anything obviously wrong with your updated diagram.