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Two Transistor LED Flasher Circuit

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.

Amazon.com

Amazon.co.uk

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

Can't see the video? View on YouTube →

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

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.