When sound recording reached the point where the sound was recorded on a synchronized but separate piece of media (such as 35mm film, audio tape, or other media) a method of keeping the recording media and camera film "in sync" was needed. The solution was to use a special form of motor which has multiple "windings" in it, and which can be connected to another identical motor in such a way that turning one motor a certain distance will turn the other motor exactly the same distance. The motors did not have to be close together, and, with appropriate circuitry, did not have to be of the same size or power. These motors were called selsyn (self synchronous) motors. A system was created where a single sound recording room could be connected to any of the stages on a studio lot (you can still see the connection points on some of the oldest stages). The sound mixer (sound man) on stage connected the control panel to the recording room and the camera. There was a selsyn motor on the camera and it was linked to a matching selsyn motor on the sound recording equipment at another point on the studio lot.