| 摘要 |
PURPOSE:To prevent the oscillation of a power amplifying circuit when a connection cord is shifted and to give the ideal constant voltage driving to a load, by connecting a resistance between an output terminal and a detection terminal of the power amplifying circuit and setting the resistance value. CONSTITUTION:The voltage feedback is applied to an amplifying circuit 2 connected to an input terminal 1 via resistances R1 and R2, and an operational amplifying circuit 3 is provided as a feedback circuit. The output of the circuit 2 is connected to an output terminal 5 from an output terminal 4 via the going route of a load connection cord 7 and the coming-back route of a speaker 9 and the cord 7. At the same time, an inverted terminal of the circuit 3 is connected to the terminal 5 via a resistance Rd with the non-inverted terminal earthed. Then the output of the circuit 3 is connected to the inverted terminal of the circuit 2 via the resistance Rd. Furthermore a cord 8 is connected to the terminal 5, and a resistance Rg is connected between the terminal 5 and an output terminal 6 connected to the cord 8. Then the Rg value is set to prevent the oscillation when the cord 7 is shifted. This ensures the ideal driving of a load. |
