Flashing Brake Light for Motorcycles Circuit

This flashing brake light circuit can be used for motorcycles. When brake-light switch S1 is closed, power is applied to U1 and U2. Two inverters of U2, a 4049 hex inverting buffer, are connected in a low frequency oscillator that feeds clock pulses into U1, a 4017 decade counter/divider. Outputs 0, 2, 4, 6 and 8 of U1 are coupled to the gate of Q1 through a 1N914 diode.

Schematic of the Flashing Brake Light Circuit

As the 4017 counts, it turns the brake light on and off four times and then leaves it on until the brake switch is released. The on/off rate can be set by potentiometer R2.
For best results, the on/off rate should be set so that it is rapid.


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  • dekster

    hi, i made one of this circuit. i replaced the 1n914 to red LEDs instead. it made LEDs to flash sequentially (im happy). could adjust the sequence fast to slow and vv (success!) . however, after 4sets of flash, it didnt turn to steady lights, did i miss anything ? ?…. i checked my connections several times. would appreciate if anyone give comment what went wrong with my circuit…. also how to turn LED flashes to strobe effect…

  • Alex

    R u sure this thing works ? I Have made a small modification but It shoudl have work.
    I Have check the circuit 10 times and evrything is in place as the drawings .
    The only mod I made was the IRF511 wich i couldnt find… I Used instead a BUZ20 for it.

    Can someone confirm this thing works, and better yet if it would work with one single led or more… All That it does is keep my led glowing when BOTH 12 v+ wires are coupled ! And IT doesnt flashes at all !

  • Tim

    Is the 10uF capacitor connected between pin 3 of U2-a and pin 4 of U2-b a polarized cap?

    The cap between pin 16 of U1 and pin 1 of U2-a is marked “104” correct?

    I’m a newbie with this stuff 🙂
    Thanks for the help!

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