Basic knowledge and detection methods of crystal diodes 6

3. Detection of infrared light-emitting diodes

Due to the infrared light-emitting diode, it emits infrared light of 1-3 μ m, which cannot be seen by the human eye. Usually, the emission power of a single infrared LED is only a few mW, and the angular distribution of the emission intensity of different types of infrared LEDs is also different. The forward voltage drop of infrared LEDs is generally 1.3-2.5V. It is precisely because the infrared light emitted by them is invisible to the human eye that the detection method for visible light LEDs can only determine whether their PN junction positive and negative electrical characteristics are normal, but cannot determine whether their light emission is normal. For this, diode it is best to prepare a photosensitive device (such as 2CR, 2DR type silicon photovoltaic cell) as the receiver. Use a multimeter to measure the voltage changes at both ends of the battery. To determine whether the infrared LED emits infrared light when subjected to an appropriate forward current. The measurement circuit is shown in Figure 11.diode