Arduino Duemilanova heating up?

Hello, I’ve noticed that my Arduino gets very hot very quickly sometimes. I have a 9V battery in the VIN pin, a 5mw laser pointer connected to the 3V3 pin, and 2 servos connected to the 5V pin. I also have it plugged into my computer via the USB port, and a led connected through a 470 ohm resistor on one of the output pins.

Is it normal for it to be hot? The hot part seems to be the one right next to the wall-wart adapter, which has 3 pins but the middle one is disconnected. (It came like that. Is that also normal?)

Thanks in advance, I don’t want to ruin my board.

You are driving too much current load. The servos are probably the biggest loads. Search around this forum for powering servos and you will find that most recommend using an external +5vdc power module rated at one amp per servo for best results. Also check what that laser draws for current, as there is a small limit (50ma or less) of current avalible from the 3.3vdc voltage pin.


just a note. Despite what hackaday was saying yesterday. It is the duemilanove not duemilanova! :)

Do a little research on linear voltage regulators and basic electrical theory and then you'll know why it gets hot.


I've also hooked up a 5mW green laser pointer to my Arduino. It draws around 230mA of current when lit, which is way too much to draw from a single pin on the atmega. (You will destroy the MCU if you keep drawing that much power from it.)

I use an ordinary Dalington transistor which I can draw up to 500 mA of current through.