Figure 1 Synchro Schematics
The receiver, or synchro motor, is electrically similar to the synchro generator. The synchro
receiver uses the voltage generated by each of the synchro generator windings to position the
receiver rotor. Since the transmitter and receiver are electrically similar, the angular position of
the receiver rotor corresponds to that of the synchro transmitter rotor. The receiver differs
mechanically from the transmitter in that it incorporates a damping device to prevent hunting.
Hunting refers to the overshoot and undershoot that occur as the receiving device tries to match
the sending device. Without the damping device, the receiver would go past the desired point
slightly, then return past the desired point slightly in the other direction. This would continue,
by smaller amounts each time, until the receiver came to rest at the desired position. The damper
prevents hunting by feeding some of the signal back, thus slowing down the approach to the
Differential synchros are used with transmitter and receiver synchros to insert a second signal.
The angular positions of the transmitter and the differential synchros are compared, and the
difference or sum is transmitted to the receiver. This setup can be used to provide a feedback
signal to slow the response time of the receiver, thus providing a smooth receiver motion.