Im a beginner with arduino and I want to find out if there is an arduino module to power it with two sources. More specific I need to power arduino with an AC to DC adapter and with a 9V battery, so when a power outage happens the arduino will be powered by the 9V battery.
Also is there another way to do that (without a module) ? (par example with Mosfet or some electronic components).
Use a rechargeable battery. Put a charger on it. Use it for power.
Put a diode in series with the backup power source (assuming this will leave it with a lower output voltage than the other adapter). This is the standard solution for uncomplicated power supply OR-ing.
could use a power supply in the jack and connect a rechargeable battery to the Vin pin. so the diode on the Arduino board would prevent the battery from discharging into the power supply. You can also use power from the USB port in conjunction with the Vin pin or jack, the source selection is done automatically by the arduino. Just be careful not to connect a battery to the Vin pin and power via usb as this would cause reverse current in the controller. voltage.
You can also use power from the USB port in conjunction with the Vin pin or jack, the source selection is done automatically by the arduino.
Is it? How?
Not too sure about that, unless some magic happens in or around the regulator!
It does. Its right there on the schematic for the UNO.
Uno Schematic (https://www.arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf)