Lance Allen wrote:

> >
> > Piezo-electric ???
> > I wonder how those childrens' shoes with blinking LEDs
> > work.  The LEDs blink when the sole contact ground.
> >
>
> A Piezo Kynar disc flexes, generates a voltage that turns
> a fet on and current is drained from an on board (on
> shoe?) battery that drives the led.
> Alas.. there is insufficient power to drive a led from the
> piezo disc direct.

I once ripped one of those shoes apart. All that was inside was a clear
plastic block with a round watch battery, a couple LEDs, and a ball
bearing in a channel molded inside the block. When the child took a
step, the bearing slid forward, then back where it made contact with two
wires, lighting the LED, then was pushed forward with a little spring. I
assume this was so the LED could never be constantly lit thereby
draining the battery.

Josh Koffman
joshy@mb.sympatico.ca