-HN9 1 1 pyroelectric infrared control lighting.
Category: interface circuit
This example introduces HN9 1 1 lighting lamp with pyroelectric infrared control module, which can be used in toilets, storage rooms, stair corridors and other places, so that the lamp can be turned on when people come and turned off when people go, and it also has the function of automatic shielding during the day.
principle of operation
The schematic diagram of the lighting circuit using HN9 1 1 pyroelectric infrared control module is shown in Figure 6-9. The ICl in the circuit is HN9 1 1 pyroelectric infrared induction control module, which usually outputs high level. When infrared rays emitted by human body are detected, its output terminal pin 2 can output a negative pulse signal with a pulse width larger than 2s, which is directly applied to the trigger of 555 time-base integrated circuit IC3.
HN9 1 1 series modules adopt new technologies and processes, and combine high-sensitivity pyroelectric infrared sensors, amplifiers, signal processing and output circuits into modular circuits, which have all functions from signal reception to output control. Connecting transistor amplifier circuit or monostable circuit at its output end can drive relay, and connecting optocoupler circuit can drive bidirectional thyristor.
HN9 1 1 series modules * * have three types, namely, universal (HN9 1 1T), micro-power consumption (HN91L) and low temperature (HN91L).
HN9 1 1 series modules have good anti-interference performance, especially excellent anti-electromagnetic wave performance, and can work stably at the low temperature of 20℃(T type and L type) to 3000℃ (D type). HN9 1 1 series modules can work stably at low temperature, mainly due to their temperature compensation circuits. When the gain of the amplifier changes due to the change of ambient temperature, the circuit can compensate in time to keep the gain of the amplifier stable all the time. The output terminal of HN9 1 1 outputs a pulse signal with a pulse width larger than 2s, in which 1 pin outputs a positive pulse signal and the other two pins output a negative pulse signal.
In the circuit, IC3 is connected as a typical monostable flip-flop, the circuit is flipped and set, and pin 3 outputs a high level. V ling is quickly connected and relay K is attracted. When its normally open contact is closed, the power supply of the controlled lighting lamp can be turned on to make it electrify and emit light. At this time, the power supply charges C3 through R2, and it takes about 1. 1RzC3 at T 2. The transient ends, the circuit is reset, the pin 3 returns to low level, vI3 is turned off, K is released, and the controlled lighting lamp goes out. If someone keeps moving within the detection range of IC 1, the two pins of IC 1 will continuously output negative pulses, so the lighting will go out after the person leaves, and the lighting will go out after I. 1RzC3 is delayed. Adjusting the potentiometer RP 1 can adjust the detection sensitivity of IC 1 module.
1 1 1' RL, R3, R4 JR, etc. Forming an optical control circuit. During the day, the photoresistor RL is exposed to natural light, showing low resistance, and V'I' 1 is turned on, so the four pins of IC3 are clamped at a low level, and IC3 is forcibly reset, and the three pins remain at a low level all the time, so the lighting lamp will not light up. Only at night, when RL loses its natural light and presents high impedance state, V'I' 1 is turned off, thus releasing the forced reset of IC3, and the circuit can be triggered to work. Adjusting RP2 can change the light control sensitivity of the circuit. VIZ and R6 form a self-protection circuit, which can solve the interference of their own lights on the circuit at night. At night, someone walks into the detection range of IC 1, IC3 turns over, K pulls in, and the light it controls lights up. The high level output from pin 3 of 555 time-base integrated circuit is added to the base of V 12 through R6, so that V 1 is quickly turned on and V 1 is turned off.
The 4-pin level of 555 time-base integrated circuit will not drop, because RL is irradiated with its own light. If there is no self-protection circuit, RL must avoid its own light irradiation during installation, otherwise the circuit will not work normally. IC2 is a 7805 three-terminal regulated integrated circuit, which provides a stable working voltage of 5V for HN9 1 1 pyroelectric infrared sensor module.
Component selection:
ICl adopts HN9 1 1 pyroelectric infrared control module;
LM7805 three-terminal stabilized voltage integrated circuit is selected for IC2;
IC3 adopts NE555 time-base integrated circuit.
RL should choose MG45 photosensitive resistor, with bright resistance less than 5kn and dark resistance greater than IMn, such as MG44-03, MG45- 13.
Other components have no special requirements. It can be selected according to the model and parameters marked in the drawing.