How to measure infrared photodiode sensitivity

　　Set the multimeter to the R×1k position and measure the forward and reverse resistance values ​​of the infrared photodiode . Normally, the forward resistance value (the pin connected to the black test lead is the positive pole) is about 3~10 kΩ, and the reverse resistance value is more than 500 kΩ. If the measured forward and reverse resistance values ​​are both 0 or infinite, it means that the photosensitive diode has broken down or is damaged by an open circuit.

　　While measuring the reverse resistance value of the infrared photodiode, use the TV remote control to face the receiving window of the infrared photodiode under test (see Figure 4-75). For a normal infrared photodiode, when the button on the remote control is pressed, its reverse resistance value will decrease from more than 500 kΩ to between 50 and 100 kΩ. The more the resistance drops, the higher the sensitivity of the infrared photodiode .