LED glow sick - A hack to make it flash

Hi I have bought a LED glow sitck. The type used in cars for "effect" lighting. I am using it  on the back of my recumbent bike. However I think it would create a bit more safety for me if it flashed. It currently runs off a small 12 volt battery. I have looked through instructables to find out if there is anything already written up. However my knowledge is  very limited, so I am uncertain if I could use some of the circuits described. I can solder okay and that is about it.

So my burning question is how do I make a circuit that will flip the 12 volt power supply to the LED's on and off. Alternatively are there circuits already on instructables and I just have to build and run 12 volts through it ( and it won't destroy the light stick). I dealy I would like it to flash on and off fairly rapidly. Any assistance would be appreciated.

Goodhart7 years ago
Jayefuu's answer gives you all the info you need. 

If you need more visual,  here is an IBLE that has a basic form of the 555 circuit design in it. 
Jayefuu7 years ago
Flashing lights make it harder to judge distance. You'd be better seen if you kept it on and didn't flash it. But.... if you still want to do it....

The circuit below is for an astable made using the 555 timer IC. An astable pulses on and off. The frequency is set by the following formula.

f = 1.44 / ((R1+R2)*C)

This won't produce an even on/off ratio (mark to space ratio), if you want that to be the case, you can use the equations here.

A 555 timer like this one would be suitable, it can handle a supply of up to 16V and is cheap.

Jayefuu Jayefuu7 years ago
Woops, forgot to upload the image.

You may also need a transistor to supply the required current.
Jayefuu Jayefuu7 years ago
Eufff. Image uploading failed. Here, have a link: