| 摘要 |
PURPOSE:To reduce hum sound appearing through a circuit preventing shock sound at application of power supply by charging a capacitor of a ripple filter at application of power supply by a constant current independently of power supply voltage fluctuation. CONSTITUTION:When a power supply is applied, a voltage decided by diodes D3, D4 is applied to the base of a transistor (TR)Q22, and the voltage of the diodes D3, D4 becomes a substantially constant voltage independently of the ripple component of the power supply voltage. Thus, the TRQ22 charges a capacitor C2 with a constant current together with a constant current source. Thus, no ripple component appears substantially at the capacitor C2 and no ripple component is outputted to an output terminal (e). Further, this constant current circuit is interrupted by a switch W at steady-state.
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