I have a little problem with my circuit and I don't know keywords to types in Google so I'm here ! Sorry if my question is stupid.
I'm going to make a little plane controlled by Bluetooth. I have a Arduino Mini and 2 DC motors drive with PWM behind a 2n222 transistor. Surprise, the voltage is good (~3.7) but no current in the motor. If I put directly the motors on the Lipo, it makes a lot of noise. It isn't the case with the Arduino... And so my plane don't fly
That diagram appears to show the return current from the motor travelling across the Arduino between the two ground pins. Bad idea. Ground the motor-control transistor to the same terminal as the battery.
At low voltages, the loss inside a bipolar transistor is a significant fraction of your power. Use a MOSFET instead.
The flyback diode is in the wrong place. It should be across the motor terminals.
Also you may need a small snubber capacitor across the motor terminals.
A 1k base resistor isn't going to allow much current to flow in the collector circuit in saturation.
Replace it with 100 ohm (for 3.7V supply), and you can expect perhaps upto 0.6A of drive for you motor.
If you motor needs more than that you need a logic-level MOSFET.
By the way you haven't said what motors you are using, that is important to know.
