Lighted wheelchair casters

[Liquid design]

Anyone know how the lighted wheelchair front casters work?

If you are not familiar with them they are in a hard, polyurethane I think, wheel approximately 4" diameter. They have lighted flashing LED's inside the wheel that light when the person moves and they last (continue to flash) throughout the life of the wheel. There are also no batteries to replace.

My friend had these on his wheelchair and I was supposed to get them when he changed wheels. He forgot and tossed them in the trash. I think these are interesting but without getting to disect them I am at a loss to the mechanics and electrical behind the idea.

 

[Resqueline]

I've never seen them but I'm sure they employ some magnets connected to the (stationary) axle and some coils in the (moving) wheel, being rectified and fed to the LED's.

 

[jackorocko]

If resqueline is right, then the design is no different then a "permanent magnet alternator" with the output connected to some led's (think wind generators). You can google a PMA to see how it works as well as the LED's. Plenty of information out there with tons of examples to help you see how it works.