There are many types of regulated power supplies. Series-type stabilized power supplies are composed of power transformers, rectifier elements, filter capacitors, adjustment elements (adjustment tubes or three-ray regulators, etc.), reference voltage, sampling network, comparison expansion, and overload or short circuit protection and other combinations. Because the series-type stabilized power supply is a linear stabilized circuit, and the regulator tube is stable. Its disadvantages are high power consumption, low efficiency and small scale of fluctuations in the grid. Generally, the series regulated power supply allows the grid fluctuation scale to be 220&±22V. In order to reduce power consumption and improve efficiency, a switch-type regulated power supply is introduced.

Switching regulated power supplies are generally called switching power supplies. It has the following characteristics:

1. The switching power supply directly performs rectification and filtering adjustment on the grid voltage, and then the voltage is stabilized by the switching regulator. So no transformer is needed.

2. Switching power supplies generally use power semiconductor devices as switches, and adjust the output voltage by manipulating the duty cycle of the switch. Take the power transistor (GTR) as an example. When the switching tube is saturated and turned on, the voltage drop across the collector and emitter is close to zero. When the switching tube is turned off, its collector current is zero, so the power consumption is small and the efficiency is high. The efficiency can be as high as 70%-95%. And the power consumption is small, the radiator is also reduced accordingly.

3. The switching frequency is tens of kilohertz, and the capacitance value of the filter capacitor and inductor used is small. Therefore, the switching power supply has the characteristics of light weight and small size.

4. Because of the low power consumption and low temperature rise inside the machine, the stability and reliability of the whole machine are improved.

Power supplies are divided into switching power supplies and regulated power supplies. These two power supplies are different, but there are similarities.

Switching power supply is a regulated power supply popularized in modern times. It has the characteristics of high efficiency, wide voltage scale, and stable output voltage. It is now widely used. For example, ATX power supplies for computers, laptop power adapters, printer power supplies, mobile phone chargers, and so on. Regulated power supply is when the load power changes, the output voltage still maintains a fixed voltage value. Switching power supplies are also regulated power supplies, but regulated power supplies cannot be directly called switching power supplies.