How the Circuit Works
That looks too good to be true, however the following diagram will simply prove that it's really possible to create a legal LED flasher circuit using just one general purpose transistor as the main component.I came across this phenomena some eight years ago, accidentally, while trying to make a smallest possible motorcycle side indicator flasher, and was really amazed.
However, then I did have not any idea that it was happening due to the negative resistance characteristics of the transistor.
The circuit actually exploits the negative resistance factor in transistors to produce the blinking effect.
I'll be soon writing a comprehensive article on this and we'll see there how the concept can be modified in many different ways.
Parts List for the proposed single transistor LED flasher circuit
R1 = 2K7,
R2 = 100 Ohms,
T1 = BC 547,
C1 = 100 uF to 470 uF
LED = Any Type, any color