Electrostatic Motor
This photo shows the finished motor sitting on
top of my Cockcroft-Walton voltage multiplier, ready to run. The
three, one quart, high density polyethylene bottles are sitting on a piece
of 3/4" thick ultra high molecular weight polyethylene board. The
two end bottles are wrapped with aluminum foil duct tape and bolted to
the board with short lengths of 1/4-20 threaded 18-8 stainless steel rod
and nuts. The rod on the left bottle extends through the board and
contacts the output terminal of the CW. The middle bottle has three
2" X 6" strips of foil tape and is supported on a needle bearing ground
from a length of 1/4" drill rod. The rod sits in a 1/4" hole drilled
1/2" deep into the board and passes through a 1/4" hole in the bottom of
the bottle. The point of the rod rests in a dimple made in a piece
of 1/32" Teflon sheet which is held in the mouth of the bottle by the screw
cap. Taped to each end bottle is a 1" wide strip of aluminum roof
flashing, with the far end bent at 90º and cut to make a pair of sharp
points. The right hand bottle sits on a short length of flashing
which is used for the ground connection.
This is a no flash (hence long shutter time) photo of the motor in
operation. The three aluminum foil sectors on the center bottle are
blurred into a gray band by rapid rotation. Several arcs are visible
between the left hand brush and the center bottle. More can be seen
between the center bottle and the right hand bottle. This is not
ideal for motor operation, but makes a nice picture. At lower voltages
(~40,000 volts) there is no arcing and the center bottle spins even faster.
A digital multimeter spliced into the ground connection showed a current
draw of 40 mA under these conditions.
This sketch should help clarify some of the construction details I
gave above.
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