The rectifier and smoothing circuit of the switching regulator have two types: capacitor input type and choke coil input type, which need to be flexibly used according to the circuit mode of the switching regulator.

The step-down chopper switching regulator uses a choke coil input, while the step-up chopper and reverse polarity chopper switching regulators use a capacitor input.

Supply ON demand (adjust the ON and OFF ratio of the transistor), you can get any value of DC, stable output voltage.

A switching regulator that does not pass through a power transformer but inputs AC directly to the power supply is usually called a linear adjustable power supply or off-line converter.

Linear adjustable type switching regulator structure, a. Self-excited b. Separately excited.

Self-excited type, continuous oscillation generated by switching transistor and output transformer. The composition of the circuit is simple and only suitable for devices with low power output.

Separately excited, there is an oscillator in the control circuit, the circuit structure is complex but the characteristics are good, suitable for high-power equipment. [1]

The linear adjustable switching regulator contains an output transformer, and the input and output must be isolated to avoid induced voltage.

Usually the switching frequency of the switching transistor is set outside the human hearing frequency, more than 20KHz.