Picture of BBB (Bothersome Blinker for Bikes)
In my city, as I guess in many other, you'll always have to do your best to stay alive when you ride your bike, this is particularly true by night. This is the reason which brought me to design this circuit.
I anticipate worried drivers (I should be the first to complain) saying that my bike light hadn't become a stroboscopic floodlight which makes you blind, only catch your attention a little more than before, it will be more as looking at an old very used neon light.

Step 1: The frequency

Picture of the frequency
This blinker circuit runs at about 50 Hz, this means that it's very near to the frequency at which our eyes work. So you'll see an "almost" fixed light, the difference with a fixed light is that it's a little bothersome to see, and it keeps your attention at once. Indeed old TVs and PC monitors worked a few hertz more than this frequency, and after some hours in front of those, your eyes were tired. To work long periods in front of your monitor it's better this is 60 Hz or more (more or equal to 85 Hz with old crt monitors, LCD are less stressful).
This circuit is intended to work with any LED light with a power source of about 4.5-6V. If you have different voltage you have to review the design adding a voltage regulator (or booster) for the chip.
I like the clean design!
chetancc2 years ago
Hi Andrea, can you please upload video of the same?
andrea biffi (author)  chetancc2 years ago
I will upload a better photo where you'll see a longer trace, maybe with variable blinker. A video is not much effective. About the lights they're two USB spotlight, and so they work at 5.5 V. Each one has 3 leds, they're very cheap and I adapted them to be mounted on my bicycle.
chetancc2 years ago
Andrea, I like this very much. I liked these LEDs in picture too. Which one are you using? Can you tell me specification of these LEDs
omnibot2 years ago
You don't actually need the transistor though since the ne555 is rated to switch up to 200ma on pin 3, well beyond those three LEDs. Unless mistaken one bright white LED is usually 20ma.
andrea biffi (author)  omnibot2 years ago
hi omnibot, yes you're right, but I think my 6 leds (three for each light) are not 5 mm ones but something more similar to cree leds, I'll check it, but they could need more power. And also I kept the possibility to use this circuit and batteries for a different light.
doetsmart2 years ago
Great, Waiting for next tips
Media Infonetku
WriterChick2 years ago
Brilliant, not only the application but in the knowledge you brought to design.
andrea biffi (author)  WriterChick2 years ago
thanks! the circuit is simple but often there is much to learn in simple things ;-)