The sun sets earlier in the winter meaning I've started spending more time riding in the dark. When riding in the dark, its important to stay safe by being visible to cars. Visibility in turn correlates with how big / obnoxious your lights are. As a result, I decided to make the "safest" bike light possible using a 9" traffic light I picked up at a local surplus warehouse.
The whole thing is powered by a $20 UPS that I picked up at Fry's. To get it to blink, I opened it up and put a solid state relay in line with the output from the battery. This is then controlled by a small blinker circuit. This should last about 6 - 8 hours of continuous usage. Pretty good for one a couple hours work.
Technologies: Arduino, C, A/C Electronics, Basic Electronics