Electronics Circuit – LED Blink using Astable Multivibrator


      This is simple two LED blink example using astable multi-vibrator circuit. This circuit generate two different not stabled state outputs pulses. We can connect the LED in the two output pulse point and our LED blink easily. This following all instructions given because to help who is beginner in electronics. if you have knowledge skip what you know already.


Video Demonstration

First thanks to Mr: Datta Benur for creating the real time application using this circuit. Subscribe YouTube Channel.


Pr-Request to lean

You want to learn how this works logically read the following first, if know already ignore and continue next


Required Components : (approximate cost : $0.93)


LED Blink using Astable Multivibrator
Items Image Value Required Quantity Data Sheet Approx Price Buy Link Notes
LED-L1,L2,L3 1.5v, 20mA LEDs 3 $0.06 You can use SMD also
Transistor-Q1,Q2 BC548 (NPN Transistor) 2 BC548 $0.14 Aliexpress You can use SMD also
Capacitor-C1,C2. 47uf 16v electrolytic capacitor 2 47uf, 16v $0.03 Aliexpress
47Ω, 0.25w 5% (Yellow, Violet, Black, Gold) 2 47Ω, $0.04 Aliexpress Used Carbon film Resistor. You can use SMD also.
47KΩ, 0.25w, 5% (Yellow, Violet, Yellow, Gold) 2 47KΩ $0.04 Aliexpress Used Carbon film Resistor. You can use SMD also.
Dot Board Approx 5cm x 4cm 1 Nil $0.12 Aliexpress
En-closer DIY 6cm x 5cm 1 Nil

You can make your own using sheets or Buy in Online

Battery 9V, 350mA 1 Battery $0.50 Aliexpress Used 350mA, 9v Source you can use any other power source 5-12v, min-200mA.
Battery Holder 1 Nil


$ 0.06 Aliexpress


Note : This above price is mentioned at 2018-05-26 (approximate only). It may be vary when you will buy again.  Project cost App : US-$1. Indian – 35rs.


Required Tools

  • Hardware
    • Soldering Station
    • Wire Cutter or sipper
  • Software Simulation (optional)
    • Proteus simulator



Circuit Diagram

Note : Resistor R1-10-Ohm used because used Two LED’s (D1,D2), You can use 47Ohm resistor for one LED , Other side used R4-47-Ohm.


Simulation Output

Note : Used Proteus Simulation Tool – Version Professional Proteus 8. Proteus Project file download.



Circuit Working Explanation

  • When the power ON time C1 and C2 charge same time. That time LED1, LED2 and LED 3 is OFF condition.
  • When C1 or C2 charged full any of the capacitor its discharge the charged power.
  • That time cross coupled transistor get active and its like a switch, and connect the ground line to LED cathode side the corresponding LED ON.
  • Once discharged completely, that capacitor goes to charge. the parallel capacitor discharge. then time another LED will be ON.
  • This process continuously doing so LED will be blink.
  • You can change the blink time  by change the capacitor c1, c2 values.



Real time application

  • Timer Module
  • Police Light
  • Emergency vehicle Light







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