Correct connection and precautions for light-emitting diodes

The working principle of light emitting diodes (LEDs) is based on the PN junction of semiconductor devices. When the PN junction is in a positive bias, electrons flow from the N region to the P region, and holes flow from the P region to the N region. When electrons and holes meet, a recombination occurs, releasing kinetic energy. These kinetic energies are emitted in the form of light, producing LED luminescence. This article will introduce the correct connection method and precautions for LEDs.

1. Correct connection method

The positive and negative values of LEDs can be determined by observing their appearance, using a multimeter, or using a battery. Generally speaking, one end of an LED has a long pin called anode, and the other end has a short pin called cathode. Connect the LED anode to the positive stage of the power supply and the negative electrode to the negative stage of the power supply, so that the LED can work normally.

It should be noted that if you use multiple LEDs, each LED should be independently connected to the power supply instead of being connected together. This is because LEDs have a single conductivity. If multiple LEDs are connected in series, current may not accurately flow through each LED, resulting in LED malfunction or damage.

2. Moderate resistance

When connecting LEDs, it is best to use appropriate resistors to limit the current to ensure that the LED is not damaged by overcurrent. The working current of LEDs is usually between 10ma and 30ma, which actually depends on the model and rated current of the LED. In order to calculate the required resistance value, it is necessary to identify the power supply current, LED rated voltage, and required current. The calculation method is as follows:

Resistance value=(power supply current - LED rated current/required current

For example, if a 3V battery is used for power supply, the rated voltage of the LED is 2V, and the required current is 20mA, then the required resistance value is (3V -2V)/0.02A=50 Ω. It should be noted that the power of the resistor should be large enough based on its current and power, and it is generally recommended to choose a resistor of 1/4 watt or more.

3. Precautions

When using LEDs, the following points should be noted:

(1) LEDs have a single conductivity, and must be distinguished between positive and negative when connected.

(2) The working current and rated current of the LED should comply with its specifications.

(3) LED requires the use of moderate resistance to limit current to prevent overcurrent damage to the LED.

(4) LED must be kept clean to prevent moisture or static interference.

(5) LED should pay attention to temperature, as excessive temperature can seriously affect its service life and performance.

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