Light pulse then on

[nzgrub]

Newbie to electronics, but love to learn.
12vdc circuit. I want when power is applied to circuit the output will be a light that pulses 5 times in about 3 seconds (adjustable would be nice) then stays on until power switched off.
I have available a 555 timer and a 4017 Decade Counter. Which I think should be suitable.
If someone could help with a circuit diagram that would be much appreciated.
Thank you.

 

[ZipZapOuch]

Technically, it's supposed to be a "modulated light" and alternate up to 4-times before staying until the brake is released. Modulated meant 25 to 50% of power in the low brightness state and 100% brightness in the high brightness state. A judge had ruled that a modulated light was not a flashing light (which is specifically listed as an illegal modification in most states. In any case, most aftermarket taillight flashers actually flash and most cops don't care unless it flashes continuously.

 

[danadak]

This would give 5 steps of brightness, 1 step / pulse, 20% brightness increase each successive pulse :

 

[danadak]

Result of design, PWM duty cycle increased 20% each pulse train (eg. LED brightness), and then
as OP stated stays on full brightness -

You cant see the PWM duty cycle in this screen shot since its buried in the pulse(s) burst
timewise during each burst/flash.

If you want a video of sequence brightness ramping up let me know.

Whole event started/triggered when power is applied to circuit.


Regards, Dana.