Unregulated AC/DC powerjack


I'm new in the Arduino world. I have these two power supplies, but I don't know if I can use them. The first one has a 500mA and 9V d.c. power output. The second one has a 300mA and also 9V d.c power output. Both of them are unregulated. The volt output of both of them was 17V when I measured them, but the are unregulated. The arduino that I am using is a Arduino Uno Rev 3.


It is not a good idea to use those power supplies. The on board regulator of the Uno is undersized, not well heatsinked, and tends to overheat if the input voltage goes above 12V, even if there is only a light load on the output pins (a couple of LEDs, for example).

You can buy a 5V buck regulator as a go between. Apply the regulator 5V to the "5V" pin to power the Arduino and a few light loads. Don't forget to connect the grounds.

Or, use a 5V phone charger. As above, apply the 5V to the "5V" pin.


Thank you for your fast reply. It really helped me! Do you know what kind of adaptor I could use for my arduino? Or where do I connect my phone charger to my Arduino?


If the phone charger has a USB outlet, cut an unused USB cable to access the 5V power and GND leads (usually red and black). Connect USB 5V to Arduino 5V and GND to GND.

Or use a 5volt cellphone charger with USB socket, and just plug the Arduino USB lead in there.


Thank you for your reaction. It helps a lot!