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Detection method of infrared receiver and external diode

 Detection method, principle and safety protection of infrared receiver and external diode

The parameters of the infrared light-emitting diode shall not exceed the limit value in the process of operation. Therefore, the model and parameters of the original tube shall be paid attention to when selecting the replacement type, and can not be replaced at will. In addition, the current limiting resistance of the infrared diode cannot be changed arbitrarily. Because of the wide range of infrared wavelength, the infrared light-emitting diode must be paired with the infrared receiving diode, otherwise it will affect the sensitivity of remote control and even cause out of control. Therefore, it is necessary to pay attention to the wavelength parameters of the infrared light signal radiated by the infrared light-emitting diode packaging materials. The hardness of the infrared light-emitting diode packaging materials is low, and its high-temperature resistance is worse. To avoid damage, the solder joint should be away from the root of the pin in the daytime, the welding temperature should not be too high, and the welding time should not be too long. It is better to clamp the root of the pin with metal tweezers to help heat dissipation. The pin bending switch shall be finalized before welding, during which neither the pipe body nor the pin shall be stressed.

1、 Detection method and correct use of infrared diode:

The polarity of the infrared diode cannot be mistaken. Usually the longer pin is positive and the other pin is negative. If the pin length cannot be identified (for example, the pin has been cut short), it can be determined by measuring its positive and negative resistance. When the positive resistance is small, the pin of the black lead is positive

By measuring the forward and reverse resistance of the infrared diode, the performance of the diode can be inferred to a great extent. Take the R × 1K gear of the 500 multimeter as an example, if the measured positive resistance value is greater than 20K Ω, there is a suspicion of aging; if it is close to zero, it should be scrapped. If the reverse resistance is only thousands of ohm, or even close to zero, the tube will be broken; the larger the reverse resistance is, the smaller the leakage current is, the better the quality is. By measuring the working voltage and current of the infrared light-emitting diode on the transmitter circuit, it is easy to determine how well it works. When measuring the working voltage at both ends of the tube, it is usually zero under static state (i.e. when there is no key pressed), while it will jump to a smaller voltage value under dynamic state (i.e. when a key is pressed). Due to the different coding mode of the remote control system, the structure of the driving circuit and the working power supply voltage, the voltage value is usually between 0.07-0.4v, and the probe should tremble slightly. When the digital multimeter is used for measurement, the measured value will generally be higher than that of the pointer multimeter, usually between 0.1 and 0.8V. If the meter needle shakes in static state and does not shake in dynamic state, shakes in static state and dynamic state, does not shake in static state and dynamic state, and there is no obvious difference between dynamic voltage and static voltage, it can be judged that the operation of the infrared light-emitting diode is abnormal. If the driving amplifier circuit is normal, the infrared light-emitting diode is mostly damaged.

2、 Storage requirements of infrared diode:

The infrared diode shall be kept clean and in good condition, especially the spherical emitting part at the front end shall be free of dirt and other pollutants, and shall not be damaged by friction. Otherwise, the infrared light emitted from the tube core will produce reflection and scattering phenomenon, which will directly affect the transmission of infrared light. The light one may reduce the sensitivity of remote control, reduce the control distance, and the heavy one may produce Failure, even remote control failure.

3、 Principle and application of infrared receiver:

The infrared receiver is a small-scale design, internal shielding module packaging, can do infrared decoding experiments, infrared remote control and so on. Cooperate with remote controller to complete remote decoding and infrared remote control experiment. It is widely used as receiving element in infrared remote control system. 1. Audio visual equipment (such as VCD, DVD, DVB, TV, etc.) 2. Household equipment (such as air conditioner, electric fan, electric lamp, etc.) 3. Infrared remote control (such as toys, etc.)

Metal package infrared receiving tube is suitable for all kinds of photoelectric conversion automatic control instruments, sensors and signal light sources of all kinds of photoelectric detectors. According to the driving mode, stable light, pulse light and slow change light can be obtained. It is commonly used in control, alarm and other aspects. Holding point; the structure of reflection function is adopted, with strong optical power and low driving voltage, It is easy to match with transistor circuit. The structure is firm and shockproof. The reliability is high

The infrared receiver has only three pins: out, GND and VCC, which are very convenient to interface with MCU.

① The output of pulse signal is connected directly to the IO port of single chip microcomputer.

② GND ground wire (0V)

③ VCC is connected to the power supply positive pole of the system (+ 5V)