This is my first electronics mini project based on IC 555 timer. 555 timer can be used to blink a LED with desired frequency when used as astable mode.

Led blinking using 555 timer

LED blinking

Part List:

led flashing circuit parts list

LED Flashing parts list

  1. 1X – IC 555 Timer
  2. 1X – LED
  3. 2X – 1k Resistor
  4. 1X – 470k Resistor
  5. 1X – 1u Electrolytic Capacitor
  6. 1x – Battery 9v


Led blinking Schematic

Led blinking Schematic


555 timer when used as astable multivibrator produce Square wave signal at output. So when output is high LED is in ‘On’ state and when Output is low LED is in ‘Off’ stage. Frequency at which square wave is generating decides the speed of flashing LED. This can be set by using resistor R1 and R2 and by value of capacitor.


Resistor R1 and R2 decides the frequency of the LED blinking. Hence duty cycle is controlled by R1 and R2. Capacitor C1 charges through R1 and R2 and discharges at R2 only. With high value of capacitor charging and discharging time will increase and hence LED will flash slowly. You can connect different capacitor and see the effect.



  • You can Connect one more LED at out, Pin no. 3 so that two LED blink at a time.
  • Use Variable Resistor (POT) instead resistor R2 to control duty cycle of LED blinking.