The board has a 3.3V regulator, but where does its power come from? Maybe someone else can figure it out.
Okay, that one seems to get power from the ICSP header with an onboard regulator, and looks to have a voltage divider for the Rx in line.Nice little combination of parts.
Ah so. In that case, we're back back to square-1. The XBee has it's own 3.3V regulator, but the powerto it comes from the 5V pin on the ICSP header. And that's the reason why the 5V regulator on theArduino board is overheating in the first place. Back to (12V - 5V) * .25A = 1.75W, which is much toomuch dissipation for smt devices, even DPAK, as noted many posts ago. So, three choices:1. run the XBee at low duty cycle, probably < 20%.2. use the series-R to drop the voltage in the pathway from the 12V battery.3. use a lower battery voltage, like 6 NiMH AA-cells.
I am trying to power an Arduino Uno with a 12v battery. The problem here is that the Uno uses 5v as its operating voltage and we need to use a power source that will last longer than an hour while sending wireless signals. A 9v battery will not last a full hour (as far as I know) so we are using a smaller version of a 12v car battery and need to convert the power to 5v and to last a long time. I've thought about using a voltage regulator, but 12v to 5v will seem to give a overheating problem. Also, the thought of using resistors as a voltage divider has brought up the fact that the battery may only last as long as a 5v.Does anyone have any suggestions or comments on how to power the Arduino for a long time on battery power at 5v with little or no cooling?[Hi how about your project ? do you use switching regulator to power up arduino using 12V battery ? please help me because i'm also gonna do a project named electric fence system]