| 摘要 |
PURPOSE:To prevent destruction of a headphone by giving a limit to a headphone output with a Zener diode. CONSTITUTION:A Zener diode is provided to a circuit in which part of an output of an audio amplifier is used as an output of a headphone to apply limit to a headphone output as a protection circuit. Moreover, two switches 1,2 are provided to the audio amplifier and the one switch 1 is used for power supply application of a built-in headphone amplifier (also in common for application of heater power in the case of employing a vacuum tube type audio amplifier), and the other switch 2 is used for application of power to the entire amplifier. Thus, the speaker is sounded while a headphone plug is left plugged in and the power consumption is saved. |
