Power with 9V Battery

Hey everyone,
i want to build a simple circuit on a circuit board with a LED and one or two resistors and therefore i need a voltage source. Since I only have got a 12VDC - 9Vblockbattery adapter, i wanted to use my arduino uno to transfer the current to my circuit board. But I dont know which pins i should use and im afraid of doing it wrong and destroying sth (im a total beginner and do not have much experience with arduino).

I already tried connecting the GND pin of POWER with the -strip on the circuit board and the 5V pin of power with the +strip and it actually worked. I still do not quite understand what the 5V pin does, thus i dont dare to use this longer than a few seconds without the confirmation that im doing nothing wrong of someone with more expertise than me.

What is the value of that resistor?
I don't see any issues except that people tend to use a data pin to control an led so they can change it from within the program.
Check out this tutorial:
Tutorial 16: Blink an LED Without using the delay() Function | Programming Electronics Academy

You can use either your 9V battery or you USB cable to safely power your Arduino. Don't use both at the same time and as you add more things you will need more power than the 9V is capable of.

Hi, @silverdragon2003
Welcome to the forum.

What do you mean by a "12VDC - 9Vblockbattery adapter"?

Do you mean a device that has 12Vdc input and outputs 9Vdc?

If it is the device in your picture, that looks like a 9V battery.
For your project, with just some LEDs, the 9V battery should be okay, BUT it will not last long as it is not designed for this sort of application.

You can connect the 9V to the UNO, either through the black DC jack on the board, centre is positive.
9V positive to the UNO Vin pin and 9V negative to the UNO gnd pin.

Do you have a DMM?

Thanks.. Tom... :smiley: :+1: :coffee: :australia:

What you have is fine. That is what the "5v" pin is for: 5 volts to supply external circuits.

Only up to the maximum of the regulator.
Also might be good to point out the pin outputs usually recommended at no more than 20mA.