# Understand the knowledge of the positive and negative poles of diodes in seconds, two methods to identify the positive and negative poles of light-emitting diodes

All light-emitting diodes are fixed regardless of the color of the positive and negative poles. For in-line light-emitting diodes, the long feet are the positive electrodes, and the short ones are the negative electrodes. You can also carefully observe the electrodes inside the tube. The smaller ones are the positive electrodes, and the larger ones that resemble a bowl are the negative electrodes. For SMD diodes, when viewed from the top, the colored line on one side is the negative electrode, and the other side is the positive electrode.

Method 1: Determine the positive and negative poles of the light-emitting diode

All light-emitting diodes are fixed regardless of the color of the positive and negative poles. For in-line light-emitting diodes, the long feet are the positive electrodes, and the short ones are the negative electrodes. You can also carefully observe the electrodes inside the tube. The smaller ones are the positive electrodes, and the larger ones that resemble a bowl are the negative electrodes. For SMD diodes, when viewed from the top, the colored line on one side is the negative electrode, and the other side is the positive electrode.

(Positive and negative poles of light-emitting diodes)

Method 2: Use a multimeter to determine the positive and negative poles of the light-emitting diode

Of course, we can also use a multimeter to judge the positive and negative poles of the LEDs. Operation method: multimeter R×1K block, red and black test leads are alternately connected to the two leads of the flashing diode. When one measurement is found, the gauge first swings a certain distance to the right, and then the gauge begins to vibrate slightly at this position (vibration). ), the swing range is about a small grid.

(Multimeter to test LEDs)

This phenomenon shows that the integrated circuit inside the self-flash LED starts to oscillate under the action of the 1.5V battery voltage inside the multimeter, and the output pulse current makes the pointer jitter, just because the voltage is too low to make the LED emit light. However, this phenomenon shows that the connection method of the red and black test leads of the multimeter is correct, that is, the black test lead of the multimeter is connected to the positive electrode of the self-flashing diode.

On the whole, there are two main ways to judge the positive and negative poles of light-emitting diodes. One is to observe the details of the light-emitting diodes, and the other is to judge the positive and negative poles of the light-emitting diodes through a multimeter. Thus we think that the understanding of light-emitting diodes is one step closer.

Finally, let’s take a look at the positive and negative symbols of the light-emitting diode

Author: Yoyokuo