| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide the radio equipment by which output of a noise sound is prevented, even when no mute function is in operation immediately after application of power. SOLUTION: On the premises of the radio equipment provided with a power amplifier 1 for sound signal amplification and a speaker 4 providing an output of the amplifier externally, a switching controller 3 that is turned off for a prescribed period after the application of power is provided in series between the amplifier 1 and the speaker 4. The switching controller 3 is provided with an FET 7, a control section 8 that controls conduction/nonconduction of the FET 7, and a latch section 9 that latches the on state when the FET 7 is conductive. The latch means 9 is provided with a capacitor C1 for DC component cut-off between the FET 7 and the speaker 4, and a voltage between the capacitor C1 and the speaker 4 is fed to a gate of the FET 7. Then the gate voltage is lower by a DC component voltage portion from the voltage applied to its source, so that the gate voltage is always kept low and the FET 7 maintains the conductive state.</p> |
