Automatic power-on control circuit using SR5553 infrared sensor

As shown in the figure, the circuit includes a pyroelectric infrared sensor head, an infrared sensor control circuit, a thyristor control circuit, a music sound circuit and an AC step-down rectifier circuit. This control circuit can be used to control automatic fan startup, automatic doors, energy-saving lamps, security, automatic commentary, etc. The pyroelectric infrared sensor head includes the pyroelectric infrared sensor P2288 and Fresnel optical lens. The latter is used to concentrate the infrared energy radiated by the human body to increase the detection distance. Fresnel lenses have various specifications, the common ones are Q-6 type, Q1A type and Q-8 type. In order to maximize energy concentration, the lens surface is required to maintain a certain distance from the infrared sensor. Different lenses have different focusing distances. Reasonable configuration and installation of the two can greatly increase the detection distance. P2288 filters the infrared signal radiated by pedestrians, and after filtering, impedance matching and amplification of the field effect transistor (FET), it is output from the source S and added to the signal input terminal (OP1P) pin 3 of IC1.