| 摘要 |
The input dc voltage is used to operate an astable multivibrator, the output of which is supplied to an emitter-follower that is coupled to an amplifier through a current-limiting resistor, so that a transistor across the input of the amplifier can controllably reduce the amplification of the amplifier. The amplifier output is supplied to the primary winding of a transformer which has a secondary winding that feeds a rectifier to supply the output dc voltage. The output dc voltage is coupled back to the control transistor through a Zener diode and a resistor in series, so that when the output voltage exceeds the Zener diode voltage, the control transistor will reduce the amplification of the amplifier, reducing the amplitude of the rectified ac voltage and hence regulating the output voltage.
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