Mar 172015

Flashing LED bike lights circuit

When we go down the street at night, it is common to find some cyclist that are visible only when they are very close.  This is very dangerous situation and could cause many accidents. To avoid this problem, we could use a circuit that lights leds in a striking manner.

If you’re a cycling fan and you like biking, night and day, this Flashing LED bike lights circuit is very useful, as it will cause you to be easily visible.

Flashing Led Bike Lights Circuit

I saw circuit designs that use two integrated circuits 555 and 12 red LEDs, but I managed to change the design in order to use only an IC 555. With this new, simplified design, lighting times of the 2 groups of leds (see diagram) are not equal, but are very close. I think that’s not a problem.

How the Flashing LED bike lights circuit works?

We will use a 555 timer configured as an astable multivibrator. The output of this multivibrator has a square wave shape..

This circuit has two groups of 6 LEDs.

  • The top group will light when the output of 555 is low (approximately 0.75 volts)
  • The bottom group will light when the output of 555 is high (approximately 8.4 volts).

This alternating light movement is very striking and easy to see at night.

LEDs can be placed in several ways. They can be placed as shown on the diagram, or you can make your own design to suit the cyclist wishes. This circuit is designed to be used with a 9 volt battery, in order to be portable.

Note: You can also use a combination of white an red LEDs, in order to increase your visibility.

List of circuit components for the Flashing LED bike lights

  • 1 555 timer IC (IC1)
  • 12 LED: D1 to D12: common red o white LEDs
  • 1 10K resistor (R1)
  • 1 100K resistor (R2)
  • 12 1K resistors (R3 to R14)
  • 1 10 uF Electrolytic Capacitor (C1)
  • 1 9 volt battery
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