LED Indicator Light:in 5 Wonderful Applications

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In the 10 years before the advent of LED indicator light in the 1960s to the 1980s, LEDs had only red, yellow, and green colors, with very low luminous efficiency (only about 1 lm/W), low brightness, and high prices. , People just use it as an indicator light for electronic products.

From the perspective of LED development and application history, this period is the indicator application stage of LEDs.

Although LED has developed to the stage of the full-color application and general lighting, the application of LED indicator light has not disappeared, and it is more extensive, and people can see it almost anytime and anywhere.

1、 AC power indicator light

The AC power indicator circuit is shown in Figure 1. As long as the circuit is connected to a 220V/50Hz AC power supply line, the LED will be lit to indicate that the power is on. The resistance value of the current limiting resistor R is 220V/IF.

 indicator light circuit
Figure 1 AC power indicator light circuit

2、AC switch indicator light

The circuit that uses LED as an incandescent lamp switch indicator is shown in Figure 2.
When the switch is disconnected and the bulb goes out, the current flows through R, LED and bulb EL to form a loop, and the LED is on, which is convenient for people to find the switch in the dark.
At this time, the current in the loop is very small, and the bulb will not light up. When the switch is turned on, the bulb is lit, and the LED is off.

led switch indicator circuit
Figure 2 Self-incandescent switch indicator circuit

3、 AC power socket indicator light

Figure 3 shows a circuit that uses two-color (common cathode) LEDs as indicators for AC power sockets.
The power supply of the socket is controlled by switch S.
When the red LED is on, the socket has no electricity; when the green LED is on, the socket has electricity.

socket indicator circuit
Figure 3 AC power socket indicator circuit

4、Fuse holder indicator light

Figure 4 shows the circuit where LEDs are used as indicators for fuse holders in factory equipment distribution boxes.
When the fuse is intact, the LED will not light up;
When the fuse is blown, the LED will be lit to indicate the user which fuse has been blown for replacement.
This is very convenient for porcelain core fuse which cannot be observed with the naked eye.

 Fuse socket indicator circuit
Figure 4 Fuse socket indicator circuit

5、DC power indicator light

The circuit that uses LED as direct current power indicator light is shown as in Fig. 5.
Among them, Figure 5 (a) shows the indicator circuit of the battery-powered circuit;
Figure 5(b) shows the indicating circuit of the DC stabilized power supply.
In Figure 5(a), R=(E-VF)/IF.

 power indicator
DC power indicator circuit


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FILN company introduction

Filn is an innovative industrial and trading company integrating R&D, production and sales. The company was founded in 1998 and has 21 years of history. Now the company has three factories and one trading company.

FILN produces indicator lights, button switches, boat switches, guitar switches, touch control system switches, waterproof micro switches and other products.

FILN is the world’s most complete indicator lamp category of a manufacturing company, but also China’s only one has a small indicator lamp UL certificate mainland manufacturers.

In 2017, he started to design and develop guitar switch products, and in 2018, he completed the design of the new guitar switch with lights. He also participated in the electronics show in Thailand and the electronics show in Brazil.

In 2018, I obtained the indicator light UL certification in the United States and CCC quality certification in China. At the same time, I participated in exhibitions in Singapore, the United States and Germany.

In 2019, a research and development center was set up in Shenzhen to develop touch control system switches, and the switch laboratory was established after obtaining the UL certificate for buttons and the UL certificate for ship type. At the same time, the company participated in the electronic exhibition in Brazil and the electronic exhibition in Hong Kong.

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