Connect the GND of the battery to the GND of arduino – common GND. If you are using a 5V relay instead of 12V relay, you only have to connect the arduino GND. I am using a 12V relay. So the coil ...

Driving a brushless DC (gimbal) motor can be a pain in the transistors. [Ignas] has written up a nice article not only explaining how to do just this with an Arduino, but also explaining a little ...

[Frank Herrmann] had an interesting idea to turn a geared DC motor into a servo motor assembly, but with a stepper motor-like interface. By stacking some small PCBs behind the motor body, it was po… ...