Power supply, also known as voltage regulator. With the development of electronic technology, especially after the application of computer technology to various industrial, scientific fields. Various electronic devices require a stable power supply, power supply can not meet the needs. So power supply appears to solve this a problem.

Commonly used AC power supply have:

1.Ferroresonance exchange AC regulator which consist of the saturable reactors and the corresponding capacitors, having constant voltage characteristics.

2.AC magnetic amplifier regulator which is to cascade the magnetic amplifier and auto transformer, then electronic circuit changes the impedance of the magnetic amplifier to stabilize the output voltage.

3.Sliding exchange AC regulator. By changing the position of the contact slide transformer output voltage stability.

4.AC induction regulator. By changing the transformer secondary, primary voltage phase difference, the output AC voltage stability.

5. SCR exchange AC regulator. Thyristor is used as power adjustment element. High stability, fast response and no noise. While it will cause interference for communications equipment and electronic devices.