A Method for Distinguishing Positive and Negative Poles of Light Emitting Diodes

Light Emitting Diode (LED) is a semiconductor device that works by combining electrons and sending photons under a positive voltage, resulting in a light effect. Due to the single conductivity of LEDs, it is crucial to correctly distinguish between positive and negative when using LEDs. This article will introduce several common methods to distinguish the positive and negative of LEDs.

1. Observe the appearance of the LED

The appearance of LEDs generally has two pins, one end with a long pin called Anode, and the other end with a short pin called Cathode. If you carefully observe the appearance of the LED, you can see a flat area on the negative side of the LED, indicating that this side is the negative side of the LED. In addition, some LED anodes will have a prominent mark that can also be used to distinguish positive and negative. If you are using an SMD LED, it often prints a small dot at the bottom of the negative side to describe the negative electrode.

2. Use a multimeter

If the positive and negative appearance of the LED cannot be determined, a multimeter can be used to detect it. Set the multimeter to resistance measurement mode and touch the two pins of the LED separately with the two probes. If the multimeter indicates low resistance, it also indicates that the probe connection refers to the positive level of the LED. If the multimeter indicates a high resistance, the probe connection refers to the negative stage of the LED. This is because LEDs can be cut off at a positive voltage, and current can flow in from the anode, ultimately returning to the negative electrode through the internal semiconductor devices of the LED. If you use a digital multimeter, you can set it to diode test mode, which can more conveniently detect the positive and negative LED.

3. Application battery

You can also use a battery to detect the positive and negative LED. Connect the two pins of the LED to the positive and negative terminals of the battery. If the LED lights up, it also means that the connection is correct. If the LED is not lit, change the connection method of the two pins. It should be noted that when using batteries to test LEDs, a suitable voltage should be selected. Generally speaking, it is best to use a 3V battery, as the rated current of LEDs is usually between 1.8V and 3.5V.

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