How to judge the quality of optocouplers? How to distinguish pins?

Opto isolators, or optical couplers, also known as optocouplers or isolators and their optoisolators, are also known as optocouplers. Optoelectronic coupling elements are a group of devices that transmit electrical signals using light as the medium. Its function is to maintain a good isolation effect between the input and output of electrical signals. When necessary, electrical signals can be transmitted according to the transmission method of the isolation layer. There are two common combinations: LED and photodiode, LED and phototransistor. To help you comprehensively understand, this article will summarize the relevant knowledge of optocouplers. If you are interested in the content to be covered in this article, please continue reading.

How to distinguish the quality of optocouplers?

1. Place the pointer multimeter in the resistor × 100 or R × 1KR position, zero point correction. Unless insulation between input and output terminals is detected, resistance gear R can be used × 10K, otherwise the resistance gear R cannot be used × (High current), R × 10K (using 9V or 15V stacked batteries), these two gears may puncture the detected optical coupling (usually the positive voltage of the optocoupler exceeds 1.3V and the reverse voltage exceeds 6V).

2、 The combination of light emitting diodes and photodiodes is optically coupled, with 3-4 as input terminals; 1-2 are output terminals. Connect a black electric pen with a multimeter to 3 pins; The red probe is connected to pin angle 4. Due to the larger forward dead band of LEDs compared to ordinary diodes, their forward resistance values range from over 1000 ohms to tens of thousands of ohms. The reverse resistance value is close to infinity, meaning that the pointer does not move on the left side (the germanium tube swing amplitude is also very small). Otherwise, the LED will be damaged. The output end is checked with a black electric pen connected to two pins of a multimeter; The red electric pen is connected to pin angle 1, and its positive and negative resistance values are the same.

When combining light-emitting diodes, optocouplers, and phototransistors, 1-2 is the input terminal; 4-5 are output terminals. Multimeter black pen pin 1; Connect the red probe to needle angle 2. The positive and negative resistance values are the same as above. When measuring the output terminals, it can be determined based on whether the six pin angles (base B) are used for electronic circuits, as they are floating or not. When they are not in use (their pins may hang), their positive and negative resistance values are close to infinity. During use, connect the black electric pen of the multimeter to pin angle 5 (collector C); Connect the red probe to pin 4 (transmitter E). Hold the needle angle 6 or 5 with your hand, or overlap with a resistance of approximately 1K, with the multimeter pointer shifting to the right. If there is no right offset, it also means that the phototransistor part of the optocoupler has been damaged.

If there are two types of multimeter, connect the input and output in the above way, and the pointer of the exported multimeter will shift to the right. If there is no right offset, it also indicates that the phototransistor part of the light coupling has been damaged.

4. Check the output insulation. The positive and negative resistance between the input and output of the optocoupler is between the 9th power of 10 ohms and the 11th power of 10 ohms, exceeding gigabohms. In other words, the input and output itself do not have electrical connections and withstand voltage exceeding 500V. Therefore, place a pointer multimeter in the resistance range r × 10K parallel zero correction. The red and black probes overlap onto the input and output terminals respectively. The pointer should be on the leftmost side, that is, Å Adjust the red and black pens, still the same. Otherwise, the input and output have been decomposed.

How to distinguish the pins of optocouplers? The model marked on the four legged optical coupling packaging shell is facing upwards. On the needle angle of the optocoupler, there is a needle angle with a small circular dot. The needle angle is 1 foot, and the counterclockwise number is 123, so it can be distinguished.

Simply put, the road pointer meter X10 does not measure. On one side of the one-way on-off is the sending diode, with the red pen indicating the negative stage of the sending diode and the black pen indicating the positive stage. It is the control end of the optocoupler and can be said to be the input end; After determining the two pins on one side, the remaining two pins are the pins of the receiver tube.

This article can only provide you with a preliminary understanding of optocouplers, and I hope it will be helpful to you. The main feature of optical couplers is one-way signal transmission, complete electrical isolation between the input and output ends, strong anti-interference, durability, and high transmission efficiency. Widely used in level conversion, signal isolation, interstage protection, switching circuits, long-distance data transmission, pulse amplification, solid-state relays (SSRs), in instrument equipment, communication equipment, and microcomputer interfaces.

If you have any purchasing needs for electronic components, please feel free to contact Chengyexing

Shenzhen electronic component IC chip supplier, one-stop BOM distribution company;

Can provide various electronic components (resistors, capacitors, inductors, switch connectors) for integrated circuit IC chips

If you cannot find the model you need, please contact us Chengyexing Company directly. The 50+purchasing team will be responsible for your needs and let us know the rest.

Service hotline: 134-3440-1267, 155-2178-1275