The basic working principle of the circuit is that the frequency of human body charging is the same as that of commercial power. When the human body touches the touchpad, it becomes the standard MOS level after being limited, amplified and shaped in the input buffer stage. When the touch duration is more than 32 milliseconds and less than 332 milliseconds, the control circuit of the control logic part is in the switch working state. When the touch duration is more than 332 milliseconds, the control circuit of the control logic part is in dimming working state, and the phase angle of the output trigger pulse changes continuously and periodically from 4 1 to 159, which is divided into three processes according to human perception: fast, slow and pause. When the touch is over, the brightness memory will remember the phase angle. If the touch application time is more than 32 milliseconds and less than 332 milliseconds, the phase angle will still be remembered by this part when the circuit is closed, so as to ensure that the originally selected phase angle and the original brightness of the light source will be maintained when the circuit is connected next time. Phase-locked loop ensures the synchronization of trigger pulse and commercial power, and the working clock of the circuit is also generated by it. At the same time, the circuit also has the functions of remote control (that is, remote trigger) and gradual sleep (that is, from light to dark and finally closed), and its duration is set by external circuits.