| 摘要 |
The pulse width modulated signal amplifier comprises a DC power supply for rectifying an AC input voltage to produce a pair of DC voltages of opposite polarity. A pulse width modulated signal amplifying circuit has switching devices driven in response to a pulse width modulated signal to produce a demodulated signal through a low pass filter. A detecting circuit is responsive to an abnormal level of the DC voltages to produce a detecting signal when a smoothing condenser of the DC power supply is overcharged by a current flowing through the low pass filter in one direction.
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