My initial blog  3rd Brake Flasher was about using an accelerometer and plug-n-play setup, with a  low cost popular GS-100A flasher.  I got a few requests about an option without an accelerometer, but with some delay feature, so it would not be so annoying in stop and go traffic. The challenging part of such a design is there isn’t constant power. Power is available only during brake application.  To solve this,  I have added a couple of big capacitors to my design and optimized it for very low power consumption, so the microprocessor can stay powered for an extra 10-15 seconds after every brake application.  The 3rd brake light will blink 4 times after initial brake application.  If intervals between brake applications are less than 10 seconds, it will simply pass through brake status.

This design option is available from my store.