DIY
SCIENCE
Simple Van de Graaff Generator
Shoot electrical sparks with a soda can, rubber
band, and PVC pipe.
By Adam Wolf
WHEN I WAS YOUNGER, I SPENT HOURS
perusing Bill Beaty’s electrostatics web
pages. At the time, I didn’t achieve any real
successes trying to build his high-voltage
contraptions, and so my interest waned.
Years later, I saw someone online use a
soda can as a collector for their Van de Graaff
generator, and all my childhood memories of
futzing with styrofoam and foil came rushing
back. I made my first sparks that afternoon,
after a quick stop at our local surplus store.
Here’s the simple design I came up with
after consulting several tutorials. Using this
device, I’ve generated thick, bright sparks 3"
long, and faint sparks 6" long. Hold your finger
close to it in a darkened room and you’ll see
an eerie blue corona around your fingertip.
124 Make: makezine.com/28
How It Works
There are 2 types of Van de Graaff generators.
This one uses the triboelectric effect, in which
certain materials become charged by contact
with other materials — like when you rub a
balloon with your hair.
During operation, a motor and roller at the
bottom of the generator drive a rubber belt
around a glass roller at the top, which creates
a negative charge on the belt. A metal brush
transfers this charge to a soda can, which
is able to store a large amount of charge
because it is both hollow and a conductor.
The belt meanwhile becomes depleted of
free electrons and needs to be replenished,
and so a second brush at the bottom pulls
in charge from whatever it’s connected to.
Gregory Hayes
