Detection Angle:- Detection Range:- Model Number:SR501 Origin:Mainland China Certification:CE HC-SR501 (blue board/green board) Data download: http://pan.baidu.com/s/1mglwOMO HC-SR501 version is an automatic control module based on infrared technology. It adopts the original imported probe design, with high sensitivity, strong reliability, and ultra-low voltage working mode. It is widely used in various automatic inductive electrical equipment, especially automatic control products powered by dry batteries. Electrical parameters Product model:HC -- SR501 human body sensing module Operating voltage range:DC voltage 4.5-20V Quiescent current: Level output:High 3.3 V/low 0 V Trigger mode:L non repeatable trigger/H repeatable trigger (default repetitive trigger) Delay Time :0.5-200S (adjustable) can be made in the range of a few tenths of a second to tens of minutes Blocking time:2.5S (default) can be made in the range of a few tenths of a second to dozens of seconds Boundary dimensions of circuit board:32mm*24mm Sensing angle: working temperature :-15 -+70 degrees Inductive lens size:Diameter: 23mm (default) Pyroelectric infrared sensor is a kind of sensor that can detect the infrared ray emitted by people or animals and output electrical signals. As early as 1938, it was proposed to use the pyroelectric effect to detect infrared radiation, but it was not taken seriously. Until the 1960s, with the rapid development of laser and infrared technology, the research on the pyroelectric effect and the application of pyroelectric crystals were promoted. Pyroelectric crystals have been widely used in infrared spectrometers, infrared remote sensing and thermal radiation detectors. It can be used as an ideal detector for infrared lasers. Its goal is being widely used in various automatic control devices. In addition to being used in the corridor automatic switch and anti-theft alarm that we are familiar with, it has a promising application prospect in more fields. For example, air conditioners and water dispensers that automatically shut down when no one is in the room. A mechanism that automatically shuts down the TV set when it can judge that no one is watching or that the audience has gone to bed. Turn on the application on the monitor or automatic doorbell. Automatic recording of animal or human activities in combination with cameras or digital cameras. You can develop more new products based on your own ideas and other circuits. Or automatic control device. Basic knowledge of pyroelectric sensors Pyroelectric effect, similar to piezoelectric effect, refers to the phenomenon that the crystal surface is charged due to the change of temperature. Pyroelectric sensors are temperature sensitive sensors. It is composed of ceramic oxide or piezoelectric crystal element. The two surfaces of the element are made into electrodes. The temperature within the monitoring range of the sensor is Δ When T changes, the pyroelectric effect will generate charges on the two electrodes Δ Q. That is, a weak voltage is generated between the two electrodes Δ V. Because of its output impedance, there is a FET in the sensor for impedance transformation. Charge generated by pyroelectric effect Δ Q will disappear due to the combination of ions in the air, that is, when the ambient temperature is stable, Δ T=0, the sensor has no output. When the human body enters the detection area, due to the difference between the human body temperature and the ambient temperature Δ T. Yes Δ T output; If the human body does not move after entering the detection area, the temperature will not change and the sensor will not output. So this sensor detects the motion sensing of human or animal. It is proved by experiments that the detection distance of the sensor without optical lens (also known as Fresnel lens) is less than 2m, while with optical lens, the detection distance can be greater than 7m. Pay attention to the following points in use: 1, The DC working voltage meets the value required by us. Too high or too low DC working voltage will affect the performance of the module, and the power supply is required to pass a good voltage stabilization filter. For example, the computer USB power supply, the mobile phone charger power supply, and the older 9V laminated battery can not meet the working requirements of the module. It is recommended that customers use the power supply of the transformer and power through 220UF and 0.1UF capacitors after being stabilized by a three terminal voltage stabilization chip. 2, During debugging, the human body should be as far away from the sensing area as possible. Sometimes, although the human body is not directly in front of the module, the module can sense that there is always an output when the human body is too close to the module. Also, during debugging, the human body should not touch the circuit part, which will also affect the work of the module. A more scientific way is to connect the output terminal with an LED or a multimeter, cover the module with a newspaper, and leave the room, Wait 2 minutes to see if the module still has output? 3, The module can work normally when it is not connected to the load, but will work disorderly when it is connected to the load. One reason is that the power capacity is very small and the load consumes more power. The voltage fluctuation caused by the load operation causes the module to misoperate. The other reason is that the load will generate interference when it is powered on. For example, inductive loads such as relays or electromagnets will generate reverse electromotive force, and electromagnetic radiation will affect the module when the 315M transmitting board is working. The solution is as follows: A. Add inductive filtering to the power supply. B. The load and module use different voltages. For example, the load uses 24V working voltage, the module uses 12V working voltage, and the three terminal voltage regulator is used for isolation. C: Use a higher capacity power supply. 4, The human body sensing module can only work indoors and the working environment should avoid direct sunlight and strong light. If the working environment has strong RF interference, shielding measures can be taken. In case of strong air flow interference, close doors and windows or prevent convection. The sensing area shall be kept away from heating appliances and objects as well as sundries and clothes that are easy to be blown by the wind. 5, The human body sensing module is recommended to be installed in a sealed box, otherwise there may always be an output signal. 6, If the detection angle of the human body sensing module is required to be less than 90 degrees, it can be achieved by covering the lens with opaque adhesive tape or cutting and reducing the lens. 7, The human body sensing module uses a dual probe. The direction of motion of the human body's hands, feet and head is closely related to the sensing sensitivity, and the characteristics of the infrared module determine that the sensing distance cannot be controlled. 8, The probe (PIR) in the module can be installed and soldered on the other side of the circuit board. The probe can also be extended with double core shielded wire, and the length should be within 20cm.