Amplifier circuit

Abstract

Abstract PURPOSE:To prevent generation of pop noise by controlling an output transistor (TR) into an inoperating state at a prescribed time after application of power is detected so as to interrupt a current path to a load. CONSTITUTION:A circuit block 4 indicates a pop noise preventing circuit, and when a +Vcc power is applied, a charging current flows to a capacitor C2 and a resistor R4, a voltage drop is generated across the resistor R4, a bias voltage is applied to TRs QA, QB and both are brought into the on-state. No bias voltage is fed to a TRQ6 constituting a voltage-current converting circuit 5 in this case so that the TRQ6 is turned off. Thus, a power TRQ8 constituting a drive circuit 6 is turned off and no drive current flows to an output capacitor C3 and a headphone 11. Thus, no pop noise is generated at application of +Vcc power supply. The TRs QA, QB are inoperative at all after a time decided by a time constant comprising the capacitor C2 and the resistor R4 and normal amplifier operation is performed.

Inventors

• 👤 Kazuo Watanabe
• 👤 一雄 渡辺
• 👤 Tetsuo Sato
• 👤 哲雄 佐藤

Bibliographic Details