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
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.
NOTE: Since this document was prepared, many advancements, improvements, and/or variations have been made to the Newman Motor designs.
The rotating magnet Newman motor is deceptively 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 severely 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 per 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 separate paper written by this author.
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. The 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 connected 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.
I have been asked many
times about sources for magnets for Newman 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 (neos). 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 fiberglass to prevent the assembly from flying apart due to centrifugal force while in high-speed 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. That is not an absolute rule, just a first approximation for testing, but it has worked well in previous designs.
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 coil 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. That 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...
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.
is a small motor, we might want to make the coil a bit longer,
perhaps a full 12 inches. That 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.
The thickness of the wire wound on the coil depends upon 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, that would make the winding thickness about 3 to 4 inches. That 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 that, 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. Therefore, 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; let's allow an extra 15%, so 720 X 1.15 = 828 turns. 828 turns X 50.25 inches 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!
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. That is the reason I suggest starting with relatively low voltages. It also makes the commutator design easier.*
Copyright 1991-2003, R. M. Hartwell, II
*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. Those 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 witin the context of this discussion 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. In general,
there are many possible designs using the pioneering technology
innovated by Joseph Newman.