It's a LED light originally conceived as an accesory for cyclists, but it could be used for any purpose. The frequency at which it blinks depends on the resistors and capacitors used. It can be calculated using this calculator for 555 Astable Circuits.
In the end we settled with the following values that set the frequency to 1.215 Hz or roughly 823ms.
R1= 100 ohm
R2= 100 kohm
R3 and R4= 220 ohm
C1= 2.2 µF
C2= 10 nF
1 Wazzabi LED Light PCB (PDF available)
6 Red LEDs
1 555 Timer Integrated Circuit
1 On/off switch
1 9v Battery
1 9v Battery connector
2 short cables (5cm each)
This part is up to your imagination. We used a transparent paper clip case that fit perfectly but a hand lotion jar could work too.
Velcro tape (20 cm)
Nail or metalic piece for heating and perforating plastic
During this instructable you'll see a 4,7 kohm resistor instead of the 100 kohm we finally settled with. This was a change we did at the last moment and we couldn't reshoot the photos. Just take the 4.7 kohm resistor as if it was a 100 kohm one.
Step 1: Printing the PCB
Step 2: Soldering the Components
We suggest you mark where every component goes with a sharpie marker on the rear side of the PCB. Once you have the components in place, solder them to the PCB.
We soldered them in the following order:
4. 555 Timer IC
7. Battery connector
We suggest you always leave the Integrated Circuits for the end, since they're sensible to heat, you reduce the chances of burning them.
Step 3: Preparing the Case
This is the most creative part of the process. Here we'll have to find an object to repurpose into a case for our light.
As you can see in the picture, our first option was to use a round plastic container, then we found a paper clip transparent box that ended up being a perfect fit.
First make sure your circuit fits the box you chose. Then, mark the place where you'll have to cut for the lights to come out.
Then, you'll need to make a hole for the switch. It's up to you where you put it :)
After it's all set and the circuit is working, glue a piece of velcro tape to your case. It will be used for strapping the light to your bike.
Step 4: Strap It to Your Bike!
Now strap it to your bike! Here's a video of the light blinking:
Here's a video.