555 Timer based LED Project

Simple 555 timer based LED Project:

                    This is actually very simple circuit based on 555 timer IC. You can do it in a bread board within 15 minutes. We just name it as a warning light Project. If you understand the nature of the circuit and how to customize the operation, then you can name it as you wish (like blinking LED Project, Controlled Blinking of the LED etc.).

Circuit Description:
It is good to know about the operation of 555 timer IC and their pinouts.
Please click the following link to know about the 555 timer pinout details.

555 Timer IC Pinout Details: An Quick refresh

Schematic Diagram: 555 timer based led project
555_Timer_based_warning led1
If you understand the working principle of the 555 Timer IC, then you can realize that this circuit works in a very simple concept.  

Circuit Operation:

  • As shown in the schematic, the circuit is powered by 5V supply. You can use 4.5V Battery too.
  • The LED is connected to the 555 timer’s output pin. It is recommended to use red color LED as you can easily identify the ON/OFF condition of the LED.
  • When the circuit is powered, for every 4 seconds the LED will glow and becomes off.
  • The ON time and OFF time is controlled by three components namely R1, R3 and C1. Please read the Monostable Multivibrator Post to know about the formula.
  • By adjusting the two resistor values (R1, R3) we can adjust the charging/discharging of the capacitor.
  • By doing this, we can control the on/off process of the LED.( ie you can increase/decrease the time duration).
  • It is good to refresh about the LED at this moment for the purpose of troubleshooting the circuit.

Light Emitting Diode – LED: Basics

  • The Light Emitting Diode (LED) is a special type of P-N junction diode.
  • When passing the forward current through the P-N junction, it will emit the light.
  • A schematic symbol is shown in Figure.
    Diode_symbol
  • The lens of an LED is transparent and it focuses on the P-N junction. 
  • When the Light Emitting Diode is forward biased, electrons cross the PN junction and they combine with holes. 
  • It makes electrons moves from conduction band to the valence band. So the energy of free electrons are released.
  • Part of this energy goes as heat energy and the rest of the energy goes as light energy. To meet this requirement, LEDs are made by special materials like Gallium Arsenide (GaAs), Gallium Phosphide (GaP)
  • These materials have visible light energy emitting property . 
  • LEDs are ruggedly constructed. They can be made in various shapes and patterns.
  • General application of LED is in numeric displays (Indicating the numbers 0 – 9) used in calculators, digital meters and clocks.

Required Components:
For your convenience, we had given the list of components used in the above circuit.

Resistors – 3 Nos (1k, 10k, 680k)
capacitor – 1 no (10uF)
555 timer IC – 1No
To hold the 555 timer in the breadboard, you need the 8 pin socket.
Small amount of single strand wires.
This simple circuit building may be your start-up project. But you may  face some difficulties. All the best….

Read More 555 timer Mini Projects: 
Electronic Detector Projects based on 555 Timer
Single Pulse generator using 555 timer IC
Multi Pulse Generator circuit Design using 555 IC
Fixed & Variable Pulse Generator Circuit Design Project

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