Power triode is used as output of power amplifier to control DC motor. The circuit structure and principle of linear drive are simple, with strong acceleration ability, and H-type bridge circuit composed of Darlington tube is adopted (as shown in Fig. 2.1). The Darlington tube is controlled by single chip microcomputer to work in the switch state with adjustable duty cycle, and the motor speed is precisely adjusted. This kind of circuit works in the saturated cut-off mode of the tube, and its efficiency is very high. The H-bridge circuit ensures the simple control of speed and direction. The switch speed of the electronic tube is very fast, and its stability is also very strong. It is a widely used PWM speed regulation technology. Now there are many such chips on the market, I chose L298N (as shown in Figure 2.2).