PURPOSE: To correct the loss of a transformer when a load resistor is changed by connecting a low voltage end of the primary side of the transformer to a noninverting input terminal of a negative feedback amplifier and connecting the noninverting input terminal to ground via a resistor for detecting a load current.
CONSTITUTION: The negative feedback amplifier circuit 1 consists of an amplifier A, a transformer To, a signal source ei, an input resistor Rg, a feedback resistor Rf and a load resistor RL. Then one terminal of the primary winding of the transformer To is connected to a noninverting input terminal a2 of the amplifier A, and the noninverting input terminal a2 is connected to ground via a resistor Rn. Thus, the impedance of the feedback amplifier circuit 1 is increased as the load resistor RL at the secondary side increases, the voltage induced in the resistor Rn is decreased and no positive feedback is substantially caused, but when the load resistor RL is decreased, the impedance is decreased and an output voltage Eo is increased. Thus, the loss of the transformer To is corrected without being affected by the fluctuation of the load resistor RL to keep the stable operation.
AOYANAGI KAZUHIRO
TABATA MITSUHIRO
