1. Look at the logo
Some LED light-emitting diodes, such as 0805 and 0603 packages, will have a "T" or inverted triangle symbol at the bottom. One side of the "T" is positive and the other side is negative; the "side" of the triangle symbol is close to the positive and the "corner" "The one that is close is the negative pole.
2. Look at the pins
LED light-emitting diodes generally have longer anode pins and shorter cathode pins.
, Take care of the body shape
Observe the shape of the two lead wires inside the tube from the side, the smaller one is the positive electrode, and the larger one is the negative electrode.
4. Pass the multimeter test
Set the multimeter to "ohm x1" and when the diode is emitting light, the red test lead is connected to the positive end of the SMDLED, and the black test lead is connected to the negative end of the SMDLED.
Because the LED turn-on threshold is about 1.5-1.8V. It is possible that the voltage provided by the digital multimeter cannot start it. So still look at the mark. SMD LED lamp beads, the green dot is the negative electrode, and the opposite is the positive electrode.
5. Look at the missing corner
5050 SMD light-emitting diodes are often used in the LED energy-saving lamp lighting industry. This LED light-emitting diode is square. One of the four right angles has a small corner, and the end with the small corner is the negative electrode. One end is the positive electrode.
