Synchro motor type instrument

A synchro motor instrument comprising:

• a synchro transmitter including a stator having a first three-phase AC winding and a rotor having a single phase AC winding;
• a synchro receiver including a stator having a second three-phase AC winding and a rotor having two magnetic poles, said rotor fabricated of a high permeability material;
• said rotor of said synchro receiver further including a needle and an automatic return means attached thereto, said needle having a predetermined OFF position;
• said first and second three-phase AC windings connected together, wherein when said transmitter rotor is displaced by a specific rotational angle, AC currents flow between said first and second three-phase AC windings to thereby cause a torque to be exerted on said synchro receiver rotor, whereby said receiver rotor and said needle attached thereto rotate an angle equal to said specific rotational angle, providing that said rotor of said synchro transmitter is provided with a single phase AC excitation signal;
• and wherein said automatic return means causes said receiver rotor and said needle attached thereto to rotate to said predetermined OFF position of said needle in the absence of the providing of said single phase AC excitation signal to said synchro transmitter rotor.