Date: Wed, 01 May 2002 09:25:06 -0600

Author: Jerry DiMarco

Subject: Re: Bicycle Generator 5K40.83


At 4/30/2002 09:03 PM, you wrote:
>1. It would be nice to start with one bulb, then switch in the second
>bulb, then the third, etc, so that the pedalling is easy and then gets
>progressively harder. However, with too small a load, the voltage
>spikes up and burns out the connected bulbs. I have to have a
>minimum of three or four bulbs in to keep the voltage around 12 V
>or else I lose bulbs. It depends on how hard the student pedals
>under light load. I would like to find a way to clamp the voltage to
>12V without complicating the circuit much. One idea is to add a
>discharged 12 V car battery but that complicates things conceptually.

The human power generator Sam found looks nice. I had seen these a
long time ago in the Whole Earth Catalog but didn't think they were still
available. You would still have the problem with voltage regulation at low
loads. But if you can still find old 12 V generators at junkyards, maybe
you can also find some old 12 V regulators. Other possibilities are a
zener regulator or a surge limiter circuit...

>2. Connecting more bulbs makes it very hard to pedal and makes
>the illumination very uneven. It is very hard to deliver power from
>the pedals continuously under heavy load. The exercise bike has
>a flywheel but no gearing, and the flywheel is not enough to even
>out the stroke.

It might not be necessary to have different gears. Maybe all you
need to do is change the size of the chainwheel or freewheel...