The circuit diagram above is a simple LED flasher circuit enabling to light emitting diodes to flash alternately using 555 timer ic. 

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If you only want 1 flashing LED you can substitute LED1 with a 1N4001 diode.

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R1, R2 and C1 set the time of the flash rate. With the components shown in the diagram each LED will be on for around 0.7 seconds.

 

The circuit can be built onto strip board very easily and will work on a supply voltage of 5-12V DC.