The Electronics Weekly tech desk has been wanting to print a diagram of this rather lovely piece of mechanical design for a while now, but needed an excuse.

It is a Pedalite - a bicycle pedal with LEDs that makes its own electricity.

We got our excuse when its designers at Product Partners were short-listed for project team of the year at EW’s Elektra 05 awards.

The design uses a brushed DC motor as a generator. Why not a brushless machine, we asked company director Paul Neal?

“The team evaluated brushless motors. The high cost of these would have killed the project,” he said. “Long term testing of relatively inexpensive but high quality Igarashi DC brushed motors shows negligible brush wear due to very low commutator speeds, typically 350rpm and currents around 10mA.”

Brushed motors and gears both contribute to friction. How much?

“The mechanical resistance of each pedal equates to less than 1W, less than one per cent of the power expended by the average cyclist,” replied Neal. “Only serious cyclists with track bikes make reference to the resistance.”

www.productpartners.co.uk
www.pedalite.com 

See also: Electronics Weekly's roundup of content related to LED Technology