Boarduino DC plug polarity

[natpump856]

Hi there,

This might be an inexperienced question, but what is the polarity of the DC jack on the boarduino?

While I'm asking questions, I'll ask another: I have a project with a hefty 24V battery to power 24v relays and loads. I was wondering if I can power the arduino from the 24V battery somehow, or if I'm better off with a separate 9v battery for the arduino. (And if I do that, I would presumably connect the negative terminals of the 24v and 9v batteries. Or would that be a bad idea?)

[adafruit_support_bill]

From the specs:

•Standard 2.1mm DC jack (just like the original) with 5V regulator to run on 7V-17V power

So 24 volts is a bad idea.

Whan you say 24v relays, are you talking about the coils or the load? You will need to connect the grounds of your Arduino and watever you are using to drive the coils. The load side can be isolated.

[natpump856]

I'm talking about both the coils and the loads. I'm using a transistor to switch the relays with 24v coils and the loads they are switching are also 24v.

However, my first question still stands: what is the polarity of the DC power jack? Outside positive? Inside positive?

[Len17]

Inside positive. And there's a protection diode in case you connect it backwards.

[natpump856]

Thanks!