| 摘要 |
The positive half-cycle for an AC input signal is applied to wave rectifier (20, 22), a filter 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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