I have another question. Power for servo is coming from an external power source, while signal is coming from the venerable Arduino. I arranged the circuit so that both external power source and Arduino share a common ground. And everything worked just super-fine.
Than silliness got hold of me, and I wanted to see what will happen when I pull out the ground lead that is going into the Arduino’s ground pin. I thought that power will just shut down, but instead servo started spinning a full circles and several of them, at that. What is strange is that I thought that servo only can do a part of circle, and at this ‘silly’ condition it apparently can spin several full circles. How comes? Is this bad for servo?