A Simple Whimshurst Influence Machine
By Melville Fisk
The static machine described herein is
made of simple materials, is easy to
construct and the work does not
require the use of special tools. A similar
machine built by the writer produces a
violent and steady spark discharge about an
inch or more in length, without the use of
The plates are two twelve-inch phonograph
records of the disk type. Select two
which have one side blank. The tinfoil
sectors are cemented to the smooth side.
It is not necessary to varnish the plates.
The bosses that keep the plates parallel on
the shaft are small cotton spools, that have
a hole in them the size of the one in the
record. Fit the spools up with brass tube
bearing and fasten to the plates with glue.
A thin cloth or paper washer inserted between
the boss and plate will help the glueto
hold. Rubber tire cement will hold better
if at hand. The shaft on which the
plates revolve extends out 3/4 of an inch
on either side of the wooden standards;
it is held stationary by a cotter pin inserted
in a hole bored down thru the top of the
standard. Glue a cardboard washer 1 1/2
inches in diameter to the inside of one of
the plates. The base and standard are made
of wood in the manner illustrated.
Make the double driving pulley from a
large spool such as wire is sold on.
Fasten it to the shaft by drilling thru the
shank and shaft and inserting a cotter pin
or screw. Be sure and make the grooves
in the pulleys deep enough to hold the belts
securely. Rubber bands tied together make
very good driving belts. Tie them with
strong linen thread and leave a half inch
of slack between each band. As the plates
are to revolve in opposite directions, cross
The neutralizing rods are made from 1/8
inch copper wire bent to shape. They are
pivoted on the protruding ends of the shaft
by a short piece of tubing soldered to the
center. Press the tubing slightly together
at the open end to make it grip firmly. The
brushes are made from very fine copper
strands secured from wire such as is used
in receiver cords (gilt tinsel). Cut about
twelve strands two inches long; tie a knot
in the center, and fold over so that all ends
are together. The brushes are then slipt
into the small tubes soldered onto the ends
of the rods and are fastened by squeezing
the end of the tube together.
Make the collectors as per sketch, using
heavy copper wire. The points are long
phonograph needles, fastened to the arms
by drilling and then soldering. The needles
should be slanted slightly in the direction
in which the plate rotates. The supports
are brass tubing, soldered on.
The discharging arms are of brass rod of
a size that will fit in the collector supporting
tubes. Make a small dent in each tube
so that the rods do not slip all of the way
thru. Fit balls to the ends of the rods by
boring, then pegging and soldering.
The jars are used as supports only.
Varnish them inside and out and fit with
stoppers, bored to hold the collector tubes.
A simple stopper is made by cutting a large
wire spool in half and then winding paper
around the shank to make a fit with the
jar. Before using soak the stopper in
melted paraffin. Further insulation can be
obtained by placing pieces of a broken record
under the jars, glue the jars to the base.
In operation the neutralizing rods should
be at right angles to each other, the best
angle, however, can easily be found by trial.
The brushes should touch the plates lightly
- no pressure is necessary. The collector
points should be about 1/4 inch away from
plates. Be sure that they are all the same distance
away or else some will not contribute
to the collecting. The distance between
the plates should be about 1/8 to 1/4 inch.
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