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

I have been using the standard Wabash Instruments Van de Graaff for years and 
find them to be very reliable.   This is the 400,000 volt model that you find 
in all the science supply catalogs, but you can also purchase them from the 
manufacturer at:

Wabash Instruments
300 Olive Street
Wabash IN 46992
(260)563-8406   Fax: (260)563-8400

As long as you maintain it properly, it will almost work under water, which 
is important if you are unloading gear in the rain.   Wabash will also sell you 
replacement parts, so if the dome gets damaged, you can buy a new dome 
instead of an entire machine.   

They are also very reliable.   As long as you keep them clean, dry and 
undamaged, they run forever.   Have a replacement belt available, as that will wear 
out, but they are cheap.   They have a shelf life of about 6 months, so don't 
buy too many.

Whichever model you get, don't buy all of the demo gadgets to go with it 
(discharge spheres, plumes, etc.).   You can make much better demos yourself, and 
the entire set will cost you less than $20.

If you have other questions, you are welcome to contact me off list anytime.

Robert Krampf
Robert Krampf's Science Education Company
www.krampf.com
Sign up for my FREE Experiment of the Week e-mail list by sending an e-mail 
to: 
[log in to unmask]

***********************************************************************
More information about the Informal Science Education Network and the
Association of Science-Technology Centers may be found at http://www.astc.org.
To remove your e-mail address from the ISEN-ASTC-L list, send the
message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
[log in to unmask]