Re: MEDIA: oops, explanation!
Thu, 12 Aug 1999 19:21:51 -0700

my inner geek, <>, writes:
> I have a very simple task which a muscle actuator might improve:
> Spinning a superball around inside a lucite (acrylic) globe.
> Again, for those interested in a very simple yet rewarding project:
> HOME DEPOT - Lighting Department
> PART # P012WA (12" White)
> 5 1/4" Neckless
> Price: $17.90
> And TARGET (Toy Department)
> Wham-O Superball
> Price: $1.79

You can get those hand-held exercise balls that are somewhat similar. There is a large wheel inside whose axis is mounted in a groove on the interior of the ball. Once you get it spinning, by torqueing the ball you make the wheel's axis spin against one side of the groove so that the wheel's direction of orientation rotates. This then causes gyroscopic precession that keeps the wheel's axis pressed against that side. By rotating your wrist at just the right rate you feed energy into the spinning wheel and it gets going really, really fast, thousands of RPMs.

With practice you can hold your hand almost still, making tiny little circles, and be holding this screaming banshee of a wheel which is spinning frantically. It's pretty impressive. These things are actually kind of dangerous and you can get a nasty burn/scrape if you touch the exposed wheel when it is at maximum RPM.

> Imagine what you could do with hand-cranked power generation?
> Soybeans in, electricity out. Now that's a workforce!

As far as power output, the human body isn't that great. Go to the gym and try an exercise bike or an upper body ergometer. These things usually have a power rating in watts. It's tough to maintain any useful amount of power for long. Maybe if you could accumulate your power output from all day long, siphoning off a few milliwatts from each step, it might add up to something. I saw the other day that someone patented the idea of getting power from pressing keys on your laptop, to extend its battery life.