Good morning! (I am from Greece so I just woke up 
).
I want to build a remote controlled car with 3 wheels, 2 of them are controlled by DC Motors and the third one is free to move.
-The board I will use is Arduino UNO.
-The DC motors require 4-6VDC.
-The DC motors will be driven by DRV8835 Dual Motor Driver Carrier.
-What is the safest and most efficient way to power my Arduino and the 2 DC Motors ? Obiously I understand that it is not safe to power the motors directly from Arduino Vout pins.
-Also, if eventually two external power sources is used, must they have common GND ?
This is my available components:
- 1 x Battery pack of 9 volts (6 x 1.5AA batteries)
- 1 x Battery pack of 6 volts (4 x 1.5AA batteries)
- 1 x Arduino UNO
- 2 DC Motors 4-6VDC
- 1 x DRV8835 Dual Motor Driver Carrier
- Voltage Regulator L7805CV -> 5V ( I don't know if it's needed ).
- Bunch of capacitors and resistors.
- Breadboard & Jumper wires obviously
Thanks in advance!