I’ve heard that VIN pin on arduino UNO is used for external power source, but can i put a normal 9v battery on it? any warnings? Thanks
Here is a warning: A normal 9 V battery cannot supply the current to drive an UNO for very long.
But can i but the + side of the battery directly into VIN pin?
It makes much more sense to buy a 3.5 mm plug for the battery and plug it into the external dc power barrel jack. That's what it is designed for and what everyone else would do. Electrically , it is the same as what you asked but physically it is more secure than a wire stuck in the female header Vin pin. If you don't know where to get the plug just ask. Most people wouldn't even ask this question because they know what the barrel jack is for.
Yes, but read reply #1 again.
I guess a 9v battery is useful for confirming that another power source is causing you problems, and using the VIN pin is an appropriate measure.
So are you saying that there is a risk of burning the arduino board or something?
Ok guys, so supose i have 6 normal 1,5v battery connected to each other, there are no risks by putting them on the VIN pin and on GND pin??
I guess 6 1,5v batteries are going to last more than a 9v battery.
I mean, can i put 9V without burning anything?
Smug: I mean, can i put 9V without burning anything?
Yes. Max is 12V but I wouldn't use more than 9V.
Yes , six 1.5V AA batteries would be ok. I still don't see any reason why the barrel jack has not been mentioned . It connects to the V in pin and it is a more secure connection for a power source, be it wal wart or battery pack. The V in header pin is going to be a very flimsy connection for the power source.
Agreed. Optimum is 7 to 7.5 but that doesn't jive with available AA battery packs so 9V is the closest to that. Using more than 9V causes the regulator to heat up dissipating the extra voltage.
Smug: So are you saying that there is a risk of burning the arduino board or something?
No risk so long as you are sensible about the connection, and nothing wrong with using it either. Kind for kind, the grunt of a battery is more or less reflected by its volume, so 6xAAs trumps a 9v and 6xDs puts you on a (short) road to glory.