DIY LED Lights

Years ago (2005) I noticed that a student posted an idea while hacking a fun LED application for bike wheels in a dorm. That was the concept. Her name was Ada Limor and roughly this is how it worked.

You place LED sticks on the spoke, hook up to a micro controller. And you need a set of sensors so the system can check itself. (For this baby you only need to know the rotational speed or angular momentum of the wheel.)

As the 2 subsequent spokes pass the chainstay the sensor (it is a set magnetic sensors utilising the so called 'Hall-effect') calculates the difference in time and gets the actual speed.

It feeds this info into the controller which then adjusts the flash frequency-to-color of LED units on the stick. And presto.

You pretty much have a LED wheel in its infancy. You can even program a set of images into the controller, and that is exactly what Limor did.
I was very impressed at the time.

Recently I found out she even sells her stuff as kits.
(Find her official in the resources.)

Exactly the same process is described by Ian Peterson with different hardware and firmware.

They both mention POV (persistence of vision) as part of the concept. But the exciting thing about what makes this all work is the inertia of the saccadic movement of your eye.

Just keep hacking at it exploiting all the possiblities of the eye's inertia. Great and mysterious things will follow, like messages hovering in the air.

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Request from Visitors

about ciruit to regulate brightness

Greg asked:
Hey, not sure if you can help, I bought this 3mm LED but I want a hack that varies brightness.

Leddies answer:
Hey Greg, -- ou can have your 3mm LED emit any amount of light you wish,
You simply need to current regulate it. All you need to do is vary the current juice that flows thru you LED. This requires dropping the rest of your supply voltage across some other circuit element. But their is a downside - a kind of a trade off. Less voltage means more power and if your source is a battery you could drain it much faster.