| 摘要 |
PURPOSE:To indicate the state of amplifying operation of A-class and B-class of a power amplifier so that visual observation can be made by driving different light emitting diodes at the A-class and B-class operations. CONSTITUTION:In case of class A amplification, when an AC signal S1 is produced at the emitter electrode of a power transistor Q1, since similar AC signal S2 is produced at a common connection B also, no output is caused at an operational amplifier IC1 and the output of an operational amplifier IC2 is lower than the potential at the anode side of a light emitting diode D2, allowing to conduct the diode D2. Further, in case of B-class amplification, the AC signal S1 is not changed toward negative side and the AC signal S2 is changed toward negative side, then the amplifiers IC1, IC2 output a positive voltage to conduct the light emitting diode D1. |
