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Building a bike light. 12v power source, 12v pre-built led fixture. Need SIMPLE way to make it flash. Answered

I am building a cool bike light (which when finished, will be my first instructable).  I have a 12v power source and a pre-made 12v LED trailer tail light  that I am using for the light element.  What I need is something simple and cheap that I can build or buy to go in between the power and the lights to make it all flash.  Thanks in advance for whatever help that you can provide.


5 Replies

peterlonz (author)2010-03-31

That's a problem I have also been researching.
It does seem that the use of a timer IC555 is likely the best choice but finding a circuit that will flash multiple LED's (of perhaps significant total power) is not so easy, Many use boost circuits which is no use to you.
BTW adjustability means you want to alter the flash rate & the flash time.
Forget the car indicator flasher & forget the mercury switch, not suitable solutions.
Also remember many flasher circuits will be designed for something different than a 12VDC source so you have to consider this also.
I think you might best try to contact the posters of circuits you can find & ask politely if they can modify their circuits to suit this need.
Not so simple after all really, sorry I could not be more immediately constructive.
Peter O

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Jayefuu (author)2010-01-03

You need a 555 timer IC in astable mode. This web page has a good explanation of how they work.

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frollard (author)Jayefuu2010-01-04

Seconded!  It seems complex when you look at the schematic, but its really quite simple to calculate what parts to use for the flash rate you want - you can even make it adjustable with a potentiometer!

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RavingMadStudios (author)2010-01-04

Wire in a mercury switch mounted to the housing with a wobbly spring, like the one out of a ballpoint pen. The bouncing of the switch as the bike moves will make the light flash.

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stephenniall (author)2010-01-03

you could take the circuit out of an old indicator from a car they run on 12 volts .

Or You could use a 555 timer

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