Servo-system

A servo-system for self-balancing use using an ac servomotor with no capacitor coupling comprising:

• input circuit means including means to receive an input signal and means to receive a compared signal, said input circuit means including a direct-coupled dc amplifier capable of comparing and amplifying input and compared signals and further including feed-back signal adjustment means;
• a servo amplifier having a differential direct-coupling amplifier with an inverting input terminal and a noninverting input terminal, said two input terminals being supplied with the output of said input circuit means through individual resistors, and a switch connected between said noninverting input terminal and a common line, said switch being turned on and off in synchronism with an ac power supply;
• amplifier means comprising a pair of complementary transistor connected in series with their emitters in common and their bases driven by the output of said servo amplifier;
• a resistive dividing feedback circuit coupling the common connection of said transistor emitters directly to said inverting input terminal of said servo amplifier, said feedback circuit serving to make the potential at the inverting input terminal become equal to that at the non-inverting input terminal;
• an ac servo motor supplied by said ac power supply, said servomotor being driven by the output of said amplifier means;
• and
• means for causing said ac servo motor to control said feed-back signal adjustment means to bring the compared value into balance with said input signal.