How to test ic chip pc817?

pc817 is a type of optocoupler. The optocoupler (opTIcalcoupler, abbreviated as OC in English) is also known as opto-isolator or optocoupler, abbreviated as optocoupler. It is a device that transmits electrical signals through light.

 

The working principle of pc817:

PC817 is a device that encapsulates infrared light emitting devices, infrared light receiving devices and signal processing circuits in the same socket. When the input electrical signal is applied to the input light emitting device LED, the LED emits light, the light receiving device receives the light signal and converts it into an electrical signal, and then directly outputs the electrical signal, or amplifies and processes the electrical signal to a standard digital level output. The conversion and transmission of "electricity-optical-electricity" are realized. Light is the transmission medium, so the input end and the output end are electrically insulated, which is also called electrical isolation.

 

The detection method of photocoupler PC817:

1. Use a multimeter to block electricity (Rx1 to RX1k gears are acceptable). Check whether the light-emitting diode inside pin 2 of the input port is good (judgment method is the same as that of ordinary diodes), and determine its positive and negative poles.

2. Use Rx1k to block the output terminal 3) 4) The positive and negative resistance between the emitter and collector of the phototransistor inside the pin should be ∞. Otherwise, it is damaged.

3. Take an electrolytic capacitor with a capacitance of 1000~3300pF (the larger the capacitance, the better the effect). Charge it with Rx1k gear. After charging, set the multimeter to Rx1k, and black pen pin 4, red pen pin 3, and then use the charged capacitor to discharge the 1.2 pin (positive pin port, negative pin 2)). At the moment of discharging, if the watch hands move to the right quickly, and then quickly and slowly return to the leftmost end ∞ (this phenomenon is determined by the discharge characteristics of the capacitor), it indicates that the photoelectric coupling characteristics between the input and the output are good. Otherwise, the performance of the photocoupler is poor.