Determine the positive and negative poles of packaged LED diodes

During the welding process of LED energy-saving lamps, we often encounter the problem of how to identify the positive and negative poles of the light-emitting diode . This is particularly important, as it determines whether the lamp is on or not!

The first observation method. Observe the shape of the two lead wires in the tube from the side. The smaller one is the positive electrode. As shown below

Secondly, you can also see the positive and negative poles of the light-emitting diode by looking at the length of the pins. The longer the pin is, the positive pole, and the shorter the pin is.

The second multimeter detection method. When using a multimeter to detect light-emitting diodes, you must use the "R×l0k" range. As we have already mentioned before, the tube voltage drop of the light-emitting diode is 2V. When the multimeter is in the "R×lk" and lower ranges, the battery in the meter is only 1.5V. It is lower than the tube voltage drop. Regardless of whether it is connected in the forward or reverse direction, the light-emitting diode cannot be turned on, and it cannot be detected. In the "R×1k" position, a 9V (or 15V) high-voltage battery is connected to the meter, which is higher than the tube voltage drop, so it can be used to detect light-emitting diodes. During the test, connect the two test leads to the two leads of the light-emitting diode respectively. If the meter needle deflects more than half, and there is a bright light spot in the light-emitting diode, it means that the light-emitting diode is connected in the forward direction. At this time, the black test lead (connected to the positive pole of the battery in the meter) is connected to the positive pole; the red test lead (connected to the negative pole of the battery in the meter) is connected to the negative pole. Then swap the two test leads and connect them to the light-emitting diode. This is reverse connection, and the meter needle should not move. If the meter needle deflects to the end or does not move regardless of forward or reverse connection, the light-emitting diode is damaged.

Determine the positive and negative poles of the straw hat LED

The positive and negative poles of the straw hat LED are relatively easy to distinguish, so let's use the simplest method.

From the picture, we can easily see that there are two block-shaped pins inside the LED, which we call the LED bracket. The negative bracket is relatively large because the negative bracket carries the LED chip, and the positive bracket is relatively small!

So the conclusion we came to is: "Visually, inside the LED, the pin connected to the large bracket is the negative pole, and the pin connected to the small bracket is the positive pole"

Another simpler method is that if your LED is relatively new and the pins are still intact, you can directly look at the length of the pins to tell which one is longer.

In fact, there are many ways to detect the positive and negative poles of LEDs. The best way is to use a multimeter.

Determine the positive and negative poles of 5050 SMD LEDs

5050 SMD LED is a commonly used SMD LED in the LED energy-saving lamp lighting industry. However, many users do not know how to solder the 5050 SMD LED. The reason is that they do not know how to distinguish the positive and negative poles of the 5050 SMD LED. Today we will tell you how to distinguish the positive and negative poles of the 5050 SMD LED. We use pictures to introduce it to you intuitively. I hope it will be useful to you!

The entire 5050 SMD LED is square. One of the four right angles has a small notch, which is the place with the red circle in the middle. The other right angles do not have small notches. The end with the small notch is the negative pole, and the other end is the positive pole!