Simple motor speed regulator

Although the speed regulator introduced in this article is very simple, it can accurately adjust the speed of a motor whose operating current does not exceed 1A. As shown in the figure below, NE555 is used as an oscillator, and the pulse frequency of its output (pin 3) can be adjusted in the range of 5-12Hz. The adjustment range depends on the values ​​of R1 and C1. Transistors T1 and T2 form a power output stage to control the motor. AJ1 and P1 can control the 555's oscillation frequency. There are two modes to choose from: "speed adjustment" and "variable speed". "Speed ​​regulation" mode is to set P1 to a certain frequency and let the motor rotate at a certain speed. The "variable speed" mode uses automatic control means to continuously adjust P1 so that the motor changes speed at any time.