| 摘要 |
An output from an OCL type power output circuit is applied to a loudspeaker load through a switching means such as a relay. A first detector circuit and a second detector circuit detect a first operating status (e.g., output d.c. level) and a second operating status (e.g., output current level of an output transistor) of the OCL type power output circuit, respectively. The detection output signals of the first detector circuit and the second detector circuit are respectively applied to a first detecting transistor and a second detecting transistor. In the normal operation status of the OCL type power output circuit, the first detecting transistor and the second detecting transistor are respectively biased into "on" states by the first detector circuit and the second detector circuit so as to permit predetermined currents to flow. When the first and second detecting transistors are in their "on" states they control a driving transistor into an "on" state. Then, the switching means, such as a relay, is controlled into a closed state. In the abnormal operation status of the OCL type power output circuit, the first detector circuit or the second detector circuit controls the first detecting transistor or the second detecting transistor into an "off" state, so that the switching means, such as a relay, is controlled into an open state.
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