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Two Transistor LED Flasher Circuit for Beginners

Created on: 14 May 2013

An easy circuit for beginners in electronics that flashes an LED on and off. The circuit uses only two transistors as well as some passive components.

This video shows the circuit built on breadboard and powered from a 9V battery.

Can't see the video? View on YouTube →

Books that may interest you:

C Programming with Arduino Book Ultimate Arduino MEGA 2560 Hardware Manual Ultimage Arduino Uno Hardware Manual

LED Flasher Circuit Diagram

The circuit will operate using almost any small NPN transistors, e.g. KSP2222, PN2222, 2N2222, BC107, BC108, BC109, etc.

Two transistor LED flasher circuit diagram
Two Transistor LED Flasher Circuit Diagram for Beginners

The circuit can operate from a voltage of about 5V up to 12V, change the value R4 to about 1k if using a voltage higher than around 10V.