The detection method, principle and safety protection of infrared receiver and external diode
The various parameters of the infrared light-emitting diode shall not exceed the limit value during the working process. Therefore, when replacing the model, pay attention to the model and parameters of the original tube, and cannot be replaced at will. In addition, the current limiting resistance of the infrared diode cannot be changed arbitrarily. Due to the wide range of infrared light wavelengths, infrared light-emitting diodes must be paired with infrared receiving diodes, otherwise it will affect the sensitivity of the remote control and even cause loss of control. Therefore, when replacing the model, you must pay attention to the wavelength parameters of the infrared light signal it radiates. The hardness of the infrared light-emitting diode packaging material is lower, and its high temperature resistance is worse. To avoid damage, the solder joints should be far away from the pins. The soldering temperature should not be too high and the soldering time should not be too long. It is best to clamp the root of the pin with metal tweezers to help heat dissipation. The shaping of the pin bending switch should be completed before welding, and neither the tube body nor the pins should be stressed during welding.
1. Infrared diode detection method and correct use:
The polarity of the infrared diode cannot be mistaken, usually the longer pin is the positive pole and the other pin is the negative pole. If it cannot be identified from the length of the pin (for example, the pin has been cut short), it can be determined by measuring its forward and reverse resistance. When the measured forward resistance is small, the pin connected to the black test lead is the positive pole.
By measuring the forward and reverse resistance of the infrared diode, it is also possible to infer the pros and cons of its performance to a large extent. Take the R×1k file of a 500-type multimeter as an example. If the measured forward resistance value is greater than 20kΩ, it is suspected of aging; if it is close to zero, it should be scrapped. If the reverse resistance is only a few thousand ohms, or even close to zero, the tube must be broken; the larger its reverse resistance, the smaller the leakage current and the better the quality. Measuring the working voltage and working current of the infrared light-emitting diode on the transmitter circuit can easily determine how well it works. When measuring the working voltage at both ends of the tube, it is usually zero under static conditions (that is, when no button is pressed), while under dynamic conditions (that is, when a button is pressed), it will jump to a smaller voltage value due to the coding of the remote control system The way, the structure of the drive circuit and the operating power supply voltage are different. The voltage value is usually between 0.07 and 0.4V, and the test leads should tremble slightly. When using a digital multimeter to measure, its measured value will generally be higher than the value measured by an analog multimeter, usually between 0.1 and 0.8V. If the watch hands tremble in static state but not in dynamic state, tremble in static state and in dynamic state, do not tremble in static state and in dynamic state, and there is no obvious difference between dynamic voltage and static voltage, it can be judged that the infrared light-emitting diode works abnormally. If the drive amplifier circuit is normal, the infrared light-emitting diode is mostly damaged.
2. Storage requirements of infrared diodes:
Infrared diodes should be kept clean and in good condition, especially the spherical emitting part of the front end must not have pollutants such as dirt, and must not be damaged by friction. Otherwise, the infrared light emitted from the die will be reflected and scattered. , It directly affects the transmission of infrared light, the lighter ones may reduce the sensitivity of the remote control and reduce the control distance, the more severe ones may cause malfunction or even the remote control fails.
3. The principle and application of infrared receiver:
The infrared receiving head adopts a small design and an inner shielding module package, which can be used for infrared decoding experiments, infrared remote control and so on. Cooperate with remote control to complete remote control decoding and infrared remote control experiment. It is widely used as a receiving element in infrared remote control systems. 1. Audiovisual equipment (such as VCD, DVD, DVB, TV, etc.) 2. Household equipment (such as air conditioners, electric fans, lights, etc.) 3. Infrared remote control (such as toys, etc.) )
The metal-encapsulated infrared receiver tube is suitable for various photoelectric conversion automatic control instruments and sensors. The signal light source of various photoelectric detectors. According to the driving mode, stable light can be obtained. Pulsed light, slow-changing light. Often used for control, alarm, etc. Hold point; Adopt the structure of reflection function, strong optical power, low driving voltage, easy to match with transistor circuit. Robust structure, shock resistance, high reliability. Metal glass package device, good wear resistance and temperature resistance.
The infrared receiver has only 3 external pins: Out, GND, Vcc, and it is very convenient to interface with the microcontroller.
①Pulse signal output connection, directly connected to the IO port of the microcontroller.
②GND connected to the ground wire of the system (0V)
③Vcc is connected to the positive pole of the power supply of the system (+5V)