AOH :: NEWMAN11.TXT
Design Considerations for Rotating Magnet Newman Motors
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Subject: DESIGN CONSIDERATIONS FOR ROTATING MAGNET NEWMAN MOTORS
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Note: The views expressed herein may or may not represent the position of
Joseph Newman and, as informational material, are provided here from
submissions by other individuals interested in the technology
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DESIGN CONSIDERATIONS FOR ROTATING MAGNET NEWMAN MOTORS
(C)opyright 1991-1996 by -
Ralph M. Hartwell II
715 Jefferson Heights Avenue
Jefferson, Louisiana 70121-1110
* * * * * * * * * *
The motors demonstrated by inventor Joseph Newman to date have
been of two types. The rotating magnet armature version,
similar in appearance to a conventional DC electric motor, and
the reciprocating or "vertical" design, which resembles a giant
solenoid magnet. This discussion will concern itself with the
first type of motor, the rotary Newman machine.
* * * * * * * * * *
OVERVIEW -
The rotating magnet Newman motor is deceptivly simple,
apparently consisting of nothing more than a large coil of wire,
a rotating magnet armature, and a commutator. Unlike a
conventional DC electric motor, however, the Newman motor has no
iron or other ferromagnetic materials in the magnetic circuit.
In fact, the presence of any ferromagnetic materials except for
the magnetic armature severly degrades the performance of the
machine.
A Newman motor is assembled sort of "inside out" when compared
to a regular DC electric motor; that is, the coil is wound around
the magnet, and the magnet rotates, while the coil remains
stationary. A commutator is necessary to perform the dual
function of reversing the polarity of the voltage applied to the
coil as the magnet reverses position twice per revolution, and to
interrupt the current flow through the motor coil many times poer
revolution according to Newman's theory. The design of this
commutator is quite critical to the proper operation of the
motor, and is covered in a seperate paper written by this author.
* * * * * * * * * *
THE COIL - OPERATING VOLTAGES -
The coil is usually a simple solenoid design, with multiple
layers of wire wound on it. Depending on the applied voltage,
the wire gauge will vary from 8 gauge to about 32 gauge. Thge
lower voltages use the larger diameter wire, and the high voltage
machines will use the finer wire. Newman has used both extremes
on his various designs. Note that while Newman prefers the high
voltage designs (he feels the high voltage devices have less loss
because of the lower current in the windings) he has successfully
demonstrated a machine operating on 12 volts DC power input.
My suggestion is to use a voltage no higher than 300, due to
the problems with the very high back voltage generated by the
device. Output voltages of 50 times the input voltage are not
uncommon with the larger units. These great voltage spikes are
difficult to control, and tend to destroy test equipment connect-
ed to the Newman motor*. Also, high voltage machines require
many more turns of fine wire, with a rather rapid increase in
construction effort and cost.
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*Note: the voltage spiking problem has been solved with the latest
commutator designs. This permits the utilization of higher voltages without
the earlier back-emf problems.
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* * * * * * * * * *
THE MAGNET -
I have been asked many times about sources for magnets for
Mewman motors. My recommendation is to try surplus houses, such
as Fair Radio, Jerryco, or suppliers such as Edmund Scientific
Co. These folks usually have surplus magnets in various sizes
at reasonable prices - at least when compared to new magnets.
What is the best type of magnet*? Well, for the experimenter,
it's most probably whatever you can get at a good price. Newman
motors have been built with everything from Alnico (C) magnets to
the latest super-powered rare-earth magnets. A popular material
is ferrite composition, of the kind commonly used in
loudspeakers. These magnets are usually readily available in
surplus catalogues, and are not too unreasonably priced. They
also are usually made available in large quantities on the
surplus market, which is a good thing, since you will probably
need quite a few of them, depending on the size of the motor you
are building. [Note: neodymium magnets have been used]
If you use magnets such as ferrite loudspeaker magnets, they
are usually stacked end to end and covered with something such as
epoxy or fibreglas to prevent the assembly from flying apart due
to centrifugal force while in high-spoeed operation. If a
single stack is not as powerful as you would like, you can place
several stacks side-by-side to increase the magnetic field. The
magnets may also be placed inside a non-metallic tube to hold
them in place.
How large should the magnet be? I suggest that the weight of
the magnetic material in the rotor be made about 1/4 the weight
of the wire used in the coil of the motor. This is not an
absolute rule, just a first approximation for testing, but it has
worked well in previous designs.
* * * * * * * * * *
THE COIL -
What about the coil size? Remember that as the machine grows
bigger, everything interacts to cause the price of the parts
needed to increase! Design the coil so that it's axis is about
3/4 to 4/5 as long as the rotating magnet assembly. The coiul
should be close in dimensions to a so-called "square" coil
design; that is, a coil which is as wide across its diameter as
it is long. This design comes close to giving the greatest
inductance with the smallest mass of wire, and also keeps as much
of the wire as close to the magnet as possible.
Since the magnet rotates end-over-end inside the coil, the
length of the assembled magnetic rotor determines the inside
diameter of the coil. Let's take a few figures as an example.
The following is not necessarily a recommendation, but just
serves as an example...
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Note: in the newest designs, the magnetic rotor configuration is designed
differently.
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Suppose the magnet when assembled is 11 inches long. If we
allow 1/2 inch clearance between the ends of the magnet and the
inside of the coil form, that will make the coil form inside
diameter about 12 inches. Allowing 3/4 of that size, the coil
would be about 8 inches long.
Since this is a small motor, we might want to make the coil a
bit longer, perhaps a full 12 inches. This will allow us to
have a bit more copper wire in the magnetic field of the magnet.
The extra wire won't be as effective as the wire near the center
of the coil, but every bit helps.
* * * * * * * * * *
WINDING THE COIL -
The thickness of the wire wound on the coil ,depends on the
size of the motor, and the strength of the magnets. The bigger
the motor, naturally, the bigger the magnet, so the more wire is
required. I suggest making the wire thickness about 1.4 to 1/3
the inside diameter of the coil. In this example, this would
make the winding thickness about 3 to 4 inches. This makes the
outer diameter of the coil about 16 to 18 inches in diameter,
with a winding thickness on each side of the form.
You can calculate the amount of wire needed by computing the
area which will be occupied by the windings. To do this, take
the length of the coil, in this case, 12 inches, and multiply it
by the winding thickness, which is 4 inches in this example.
So, 12 X 4 = 48 Square inches.
The wire will not occupy the entire volume, since the wire is
round, and when wound on the form, will not fill the entire
volume. About 70% of the space will be filled by the wire. A
table of wire data, such as the one found in the Radio Amateur's
Handbook, will allow you to figure how many turns of wire will be
required.
Then, you can calculate the length of an "average" turn on the
coil by figuring the length around the coil when the coil form is
half full, which, in the case of our example here, will be about
16 inches. (12 inches for the inside of the form, plus 2 inches
of wire on each side of the form when it is half full). So,
3.1415926 X 16 = 50.26 inches per turn.
Let's suppose the wire we have chosen measures 0.05 inches in
diameter. If we were able to wind it evenly so that each turn
were side by side, we could get 1 inch / 0.05 inches per turn =
20 turns per inch. So, 20 TPI X 48 square inches = 960 turns on
the coil. Since we won't be able to get all those turns on the
coil so neatly, we can assume between 70-80% of them will fit.
Therefoire, 960 turns X .75 = 720 turns expected. Always buy a
bit more wire than you figure you'll need, just in case your
calculations are a bit off, or in case you really can wind the
wire really neatly!
Figure how much wire is needed - 720 turns needed; lets allow
an extra 15%, so 720 X 1.15 = 828 turns. 828 turns X 50.25
inchges per turn = 41615 inches, or 3468 feet of wire required.
The wire table will tell you how many feet of wire are in a pound
for the size wire you have chosen.
A suggestion at this point - It will probably be cheaper to
buy a 50 pound spool of wire then to buy only a couple of smaller
spools of wire if you need only 25 pounds or so.. check with
several wire suppliers before buying!!
* * * * * * * * * *
INSULATION CONSIDERATIONS -
Beware of winding a coil for a motor which will operate on
high voltage without using insulation between layers of wire in
the coil. It is entirely possible to have a flashover between
windings when the motor runs, due to the very high pulse produced
by the motor. This is the reason I suggest starting with
relatively low voltages. It also makes the commutator design
easier.*
Copyright 1991-1996, Ralph M. Hartwell, II
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*The latest commutator design enables higher voltages to be utilized.
Note: The above article was written several years ago. The principles
described above are generally applicable "across the breadth of the
technology." However, considerable improvements to the commutator design
have been made in the recent past. These improvements are intended to
actually reduce the intensity of the sparking by distributing the physical
connections over a wider area. The reader should bear in mind that there
are TWO totally different design systems (but many sub-configurations
within each basic design): there is one commutator design when the energy
machine is intended to function as a GENERATOR and a totally different
commutator design when the energy machine is intended to function as a
MOTOR. The latest design improvements to the commutator system apply to
the machine operating as a MOTOR. Subsequent torque can be utilized for
mechanical systems or can be used in conjunction with a conventional
generator.
Evan Soule'
josephnewman@earthlink.net
(504) 524-3063
P.O. Box 57684, New Orleans, LA 70157-7684
The latest Wiring/Construction Diagram is available to all purchasers of
Joseph Newman's book. It is not advisable that you contact Joseph Newman
directly unless you have read and mastered his book. Questions/insights
about machine designs, etc., may be addressed to the email list-service.
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