Having a rotor without knowing the direction is very much pointless. All antenna rotor will have a position indicator to tell the operator which direction his or her antenna is directed to.
The commercially available rotor such as YAESU G250, 450 and 600 e.t.c utilize a potentiometer to provide a feedback to drive a moving coil needle meter or maybe to a comparator circuitry to provide an indication of the direction.
Some may use encoders, but I choose the traditional and analogue way using potentiometer. I am using a 10 turn potentiometer and this give a more precise and also without the worry of snapping the potentiometer. Some may misunderstood by using a normal potentiometer. This is basically difficult and it cant turn 360 degree.
Anthony Good aka K3NG made a very good contribution the amateur radio world. He came out with Arduino based rotor controller and it is open source. You need to do a litle creativity on how you decide to make use of the controller.
In fact, it can be adapted to any rotor and it support Azimuth and Elevation too. PLUS! it can be use with Ham Radio Deluxe and PST Rotator software.
You can use the updated code and do some tweaking.
This is my version of the rotator controller.
The Finished Rotor (without weather cover)
For now, completed rotor is without weather cover and also without a connection box. I will install a junction box next to the motor with a connector inside it for the control cables. The a/c controller is just for size comparison. As mentioned earlier, my version of rotor is NOT mast/pole mounted.
Power supply for controller and motor.