Arduino board voltage (12v too much?!) => It was too much!

Hi folks!

This my very first post and cry for help. I got an arduino starter kit containing cables, buttons, lcd screen and an adruino, of course.

I had a read and noticed that 7-12v is recommended and 6-20v is the limits.

When I started testing I read an article saying that e.g. to measure temperature, an external power supply is recommended (rather than using USB). I used a 9v block battery for that, it worked fine.

Then I attempted to measure am adjustable 0-90 Ohm resistor but i couldn't measure anything. Because this resistor is powered by 12v (in my car), I assumed 5v is not sufficient. I connected a block consisting of 10x1,2v batteries. The same block I saw included in another starter kit offered on eBay.

When I connected it without USB connected in paralell, after just a few seconds I recognized a smell that made me think "hey this is nooo good". The Arduino board is no longer connecting go my computer or running the program previously uploaded. All digital pins are now on 5v.

*** Broken *** :frowning:

Question is, how come??? It was 12v and even it it was a little above, 20v is the limit. What went wrong?

We need to know how you wired it up. It sounds like a wiring error.

5v should have been measurable on 90 ohms. Unless you had it a 0 ohms......

Once you let the smoke out it is difficult to replace it. And without the smoke being inside, it will not work!


I agree the wiring was probably wrong. Although it's true that Arduinos can run on 12V, that 12V has to be injected into the right place, so let's see the wiring diagram: perhaps you put 12V where it had no business being.

And /or, that might have been shorted to 0V if the resistor was on 0 and so it was the current doing the harm not necessarily voltage?