Four-level touch dimming circuit composed of HT7713

HT7713 is a four-stage dimming integrated circuit produced by Taiwan Hetai Company. The peripheral circuit of this chip is simple and the operation is stable and reliable. When a person touches the sensing electrode M1, a control signal is input to U1, and the trigger signal output by U1 (3) pin changes accordingly. The brightness of the bulb can change cyclically between low light, medium light, strong light, and off. D3 and D4 are used to protect the chip from damage due to excessive input voltage. This circuit does not need to strictly distinguish the phase line and neutral line of the power plug, which brings great convenience to use.