| 摘要 |
PURPOSE:To output the monoral sound of stereophonic sound systems R and L to a speaker when a plug is not inserted into a jack by providing a selector switch for switching contacts as required when the plug is inserted into a stereo- jack. CONSTITUTION:When a plug is not inserted into a stereo-jack 13 with a selector, a selector switch part 13B opens a terminal (a) and terminals (b) and (c) is connected. L, R signals from a stereo-sound source generator 11 are synthesized in the terminals (a) and (b). The stereo-monoral signal of the L+R signal is supplied to a speaker 14 via the terminal (e) of a selector switch part 13A. When the plug is inserted into the jack, the contacts (a) and (b) are connected, the contact (c) is opened and the L, R signals power-amplified by an amplifier 12 are outputted. Accordingly, when the plug is not inserted into the jack, the monoral sound can be outputted from the speaker, power is amplified only when required and consumed power can be decreased. |
