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-----Original Message-----
From: John Bowditch 
Sent: Thursday, June 01, 2006 9:57 AM
To: [log in to unmask]
Cc: John Bowditch
Subject: RE: Energy Exhibit Ideas?

I agree with this assessment. I've built several such exhibits and these
have always been hand-wheel powered. Most of these have used a fairly
expensive alternator made by Gerator Corp. This is a PM three-phase unit
that works extremely well for this purpose. I built two for the Henry
Ford Museum that are built into a so-called "Tower of Power" with trains
of 40 watt bulbs strung up the sides. If the person is strong enough he
or she can light 19 such bulbs (they come on sequentially) to produce
just a bit over 1 HP (sorry you metric folks!) The two exhibits face
each other so there are lively competitions to see who can produce the
most power. You'd be surprised how many folks can light them all. 

I've used a variety of gear trains. These used a combination of roller
chain and spur gears to keep the whole power transmission train exposed
(I still have the patterns for the castings that supported the pillow
blocks if anyone wants to use this system. I also built two unit for use
here and I changed the design somewhat be inserting a helical gearbox in
line with the same alternator. This was a faster, cheaper solution but
of course doesn't show as much. One could no doubt use gear belts but
v-belts should be avoided at all costs as the energy wasted in friction
masks the whole effect.

This generator  was coupled to a rectifier after being stepped down to
about 12 volts in the versions used here. The visitor can select various
devices to power such as incandescent lamps, a small fan or a back-up
alarm from a truck combined with a bubble-gum light from an emergency
vehicle. 

All these exhibits have lasted years with virtually no maintenance so I
would recommend this approach. 

What to go smaller and cheaper? McMaster-Carr sells a range of small PM
gear motors that work great for miniature exhibits to show circuit
theories, etc. These only cost about 60 bucks and for an additional 35
dollars you can buy a small hand wheel that set-screws right onto the
shaft. 

The main problem with all these units is they rarely if ever show the
interior of the generator and so the basic principles are "black-boxed"
out of the picture. I therefore have been slowly developing an idea to
build a sort of historical update of magnetos built in the 1860s which
featured horseshoe magnets, open coils and the like. With modern
magnetic materials and electrical engineering such machines should be
able to be far more efficient then the originals. I'd combine this
design with a multi-polar design to reduce operating speed, making it
possible to directly couple the drive hand wheel to the generator itself
with no intervening gearing(Only using a ratchet to prevent back-feed of
torque). I think this design would go a long way to de-mystifying the
inner workings of generators.

-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of jeff courtman
Sent: Wednesday, May 31, 2006 5:57 PM
To: [log in to unmask]
Subject: Re: Energy Exhibit Ideas?

ISEN-ASTC-L is a service of the Association of Science-Technology
Centers
Incorporated, a worldwide network of science museums and related
institutions.
************************************************************************
*****

I hate to be so pedestrian, but the pedal-for-energy exhibits are always
popular, and fairly easy to do.  I think the most successful one we
did/had,
was actually a table top exhibit:  we made the bicycle train where you
could
crank it (rather than having to get up on a seat - always difficult
because
of the height variance).  The biggest hit as far as what we powered was
a
tv....

Hey, why not get them to donate a hybrid car for the museum's use and
put
their name on it?

If I've learned anything in the last 20 years, its ask: the worst than
can
do is say no...... 


Jeff Courtman
Exhibits & Special Projects Coordinator
251.208.6851
Exploreum Science Center
www.exploreum.net

-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Shane Pickett
Sent: Wednesday, May 31, 2006 3:01 PM
To: [log in to unmask]
Subject: Energy Exhibit Ideas?

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