Programmable DC power supplies is also called DC stabilized power supply. Its service voltage is mostly alternating voltage, when the alternating current or output load resistance change, the direct output voltage of the voltage stabilizer can still keep stable.

It can be divide into two parts form the working style:

1. Controlled rectification style. It can adjust the output voltage though changing breakover time of the thyristor.

2. Chopped mode. Import the unstable direct voltage, in order to change the break-make ratio of the on-off circuit, then get the stable direct voltage after smoothing.

At present, the development of the programmable DC power supplies tend to be small size, high efficient, and digitization. More and more equipment adopt the singlechip to control the switch, greatly improve the efficient and stability.