Pyroelectric infrared induction automatic light circuit (1)

It is a pyroelectric infrared induction automatic light that can be used in stairways, walkways, guard rooms and other occasions. It can
make the lights turn on when people come and turn off when people leave. It can also be blocked during the day without turning on the lights.
    PIR is a pyroelectric infrared sensor. It can detect 7-14ym far-infrared rays emitted by a moving human body,
and convert it into a weak electrical signal, which is sent to the operational amplifier I.M324 for amplification and other processing. Photoresistor
RI. It forms a light control circuit with the operational amplifier A3 in 1.M324. On H day, RL shows low
resistance when exposed to light, so that the ⑨ pin of LM324 is low level, the ⑧ pin is the quotient level, and VD1 is cut off, so the ⑦ pin of A4 Constantly
at high level, VT1 is turned on, the thyristor wrH is turned off, and the light E does not light up. If it is at night, the resistance of RL increases
. The level of pin ⑨ is rising, and there is human activity in front of the PIR, so pin ⑧ is low level, VD1 is turned on,
and Ct. After VD1 is discharged, pin ⑦ outputs low level, VT1 is cut off, and VTH can pass R. . The trigger current is turned
on and the lamp E lights up. After the person leaves, the @ pin of A2 has no signal output, the ⑨ pin returns to low level, the ⑧ pin outputs
high level, VD1 is cut off, and at this time the power supply passes through RP and R; to C. ． Charging, so the ⑦ pin can still maintain low level
and the light will still light up. When (1tt charge is fully charged, pin ⑦ returns to high level, VT1 is turned on, and VTFf loses
the trigger current. When the alternating current crosses zero, it turns off and the light E goes out. PIR can use pyroelectric infrared sensors
    such as P228 type. , in order to improve its detection sensitivity, it is best to install a Fresnel lens. The coke oxygen of the lens should be located in the sensing window of the sensor. RP is the adjustment potentiometer for the circuit delay time , and an ordinary fixed resistor can also be used.