Tail Light Modulator

Discussion in 'The Projects Forum' started by brad81987, May 6, 2009.

  1. brad81987

    Thread Starter New Member

    May 6, 2009
    I'm adding an LED tail light to my motorcycle. I'd like to emulate the effect of a standard dual filament bulb. I currently plan on using a relay and 555 based PWM circuit. The LED will get constant 12V. Ground will be returned through the relay. Normally it will go through the normally closed contact and through the 50% PWM circuit to emulate the "running light." When the brake light is activated, the relay will energize and take the LED strait to ground for max brightness.

    Id like to add a circuit to flash the light a couple of times fast (maybe 5 times, 1 second periods) to alert any dozy drivers, then remain 100% on. (Tail light modulators like such are legal on motorcycles in WI).

    I've attached my currently envisioned circuit and where I foresee needing the flasher circuit.

    I haven't been able to find anything on a circut to pulse 5 times and then stay on, so that is where I need assistance. If there is a way to combine everything into one circuit and eliminate the relay, im open to that too.

  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    R6 sets the pulse rate and R1 sets how long the pulsing lasts. Ive used the circuit on two vehicles.