12 volts trigger - GPIO pin output .150 volts when output signal is off

Good afternoon all!

I’m currently building a 12v circuit with a relay to turn on my amp using the 12v port when I start playing music through volumio. I checked both the logic and the eletric signals. The logic is fine, as I checked it using gpio readall command (when I stop or pause music for more than 10 seconds, it turns off the signal on GPIO #17). But as it turns out, it keeps a voltage of .150 volts between the ground signal and the GPIO #17 pin. This .150 voltage apparently is enough for my relay to understand that the signal is still “on”, and the amp keeps on all the time.

Has anyone been through it or have a hint of what to do in this case?

Thanks in advance.

Best Regards

Have a look here:

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You need to use resistors.

EDIT: Ups @Wheaten was faster :upside_down_face:

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Thank you, you guys are the best!!