| 摘要 |
The positive half-cycle for an ac input signal is applied to a wave rectifier ( 20, 22 ), a filter ( 41 ) and a voltage regulator ( 30, 31 ) for generating a dc output signal. The ac input signal is also applied to a transistor ( 50 ) in either the common emitter or common source configuration which shifts the ac input signal by 180 degrees. This signal is then applied to another rectifier ( 21, 23 ) for converting the shifted ac input signal into a pulsating dc output signal. Then shifted dc output signal is applied to a second capacitor filter to reduce the signal variations. The final stage for the second output stage is also a voltage regulator ( 32, 33 ) (i.e., two series zener diodes). The transformerless power supply produces either a dual positive or dual negative dc voltage supply. In addition, the voltage supply circuits may include a relay voltage, which may be controlled by a control circuit.
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