Pyroelectric infrared light automatic control circuit

The infrared light controller uses a pyroelectric infrared sensor as a human body contact sensing device, so that the light controller can realize
the function of "lights on when someone comes and lights off when someone leaves". It is especially suitable for hotels, institutions, residential corridors and homes. use.
    The circuit of gt exterior light controller is shown in Figure 6-58. It is mainly composed of pyroelectric infrared sensor, infrared processing integrated circuit S 01, control circuit
and power supply. The integrated circuit Icl includes amplifiers, comparators, state controllers, delays, etc. R2, RP1 and R3 connected outside 1C1
are adjustment devices designed to automatically turn off lights during the day. R3 is a photoresistor, and its resistance changes with light.
The resistance of R during the day is between a few hundred ohms and several thousand E, and it will increase to more than 1Mfl at night. By adjusting the resistance of RP1, pin ② of IC1 can output a high level when night falls
and a low level after dawn. Wind in the circuit--R. It is set to determine the gain of the internal amplifier of 1CI.
In addition, Rn and Ci external to IC1 are delay networks, and the delay is 2min.
    When the pyroelectric infrared sensor detects the infrared signal of the human body, it will output a weak electrical signal to the ⑩ pin of ICl. After
being amplified by the two-stage amplifier inside 1C1, it is compared with the set reference voltage through the voltage comparator, and then The output high level is output by the ② pin of IC1 after delay processing
, driving VT1 to make the relay K work, and its normally open contact K connects to the lamp power supply and lights the lamp. When people leave, the
light will go out automatically after 2 minutes. This circuit also has the function of continuous triggering. When the lamp is on and lit, if a second trigger occurs, the delay will restart
to keep the lamp on. If someone stays at the scene and does not leave, the light will continue to light up without going out.