555 timer icLCD-LED Display

LED Indicator Light Schematic Circuit Diagram

The purpose of this project is to create an LED-based indication. LED indicator light is a low-cost electronic project that can be used to replace traditional indicators in bicycles and automobiles.

Circuit Components

The required components of the LED indicator light circuit include the following.

Circuit Connections

To create clock pulses, an astable 555 timer is employed. The timer’s trigger pin is connected to the threshold pin. By turning on and off the LEDs, a BCD counter IC 7490 is utilized to represent the pulse count. The LEDs are connected to the counter IC’s output.

Circuit Diagram and Its Operation

The 555 timers generate pulses that are supplied into the counter’s clock input. Based on the number of pulses received, the counter generates a strong signal at each of its output pins. The attached LED lights when any output pin receives a high signal. The light appears to shift towards the left as the countdown progresses.




The voltage at the inverting terminal is smaller than the voltage at the noninverting terminal when the battery voltage falls to 10 volts. The output of the OPAMP increases. LED2 begins to emit GREEN light, indicating that the battery requires charging.

Some LEDs emit infrared light, which is not visible to the naked eye. However, such LEDs are beneficial in remote controls and burglar alarm applications.



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