Jack: "sub board layer interference disk "perspective model" ? With the deepest respect - perhaps a liberal dose of "Occam's razor" might help (or perhaps the art of complication is also a necessary strategy to stop competitors stealing your idea)?Mechanical Magnet Manipulation Motor
Yup it seems as if it is magic but it isn't a trick!
What you are seeing is a sub board layer interference disk "perspective model". Part A
Maybe both to a degree............
Actually Don it is very simple and that is what is the most scary part of it..........Jack: "sub board layer interference disk "perspective model" ? With the deepest respect - perhaps a liberal dose of "Occam's razor" might help (or perhaps the art of complication is also a necessary strategy to stop competitors stealing your idea)?
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For other kinds of motors, see Motor (disambiguation). For a railroad engine, see Electric locomotive.
Various electric motors, compared to 9 V battery.
An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of mechanical energy into electrical energy and is done by an electric generator.
In normal motoring mode, most electric motors operate through the interaction between an electric motor's magnetic field and winding currents to generate force within the motor. In certain applications, such as in the transportation industry with traction motors, electric motors can operate in both motoring and generating or braking modes to also produce electrical energy from mechanical energy.
Found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives, electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as from the power grid, inverters or generators. Small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use. The largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, and so on.
Electric motors are used to produce linear or rotary force (torque), and should be distinguished from devices such as magnetic solenoids and loudspeakers that convert electricity into motion but do not generate usable mechanical powers, which are respectively referred to as actuators and transducers.
Cutaway view through stator of induction motor.
- 1 History
- 2 Motor construction
- 3 Motor supply and control
- 4 Major categories
- 5 Self-commutated motor
- 6 Externally commutated AC machine
- 7 Special magnetic motors
- 8 Comparison by major categories
- 9 Electromagnetism
- 10 Performance parameters
- 11 Standards
- 12 Non-magnetic motors
- 13 See also
- 14 Notes
- 15 References
- 16 Bibliography
- 17 Further reading
- 18 External links
[h=2]History[/h]Main article: History of the electric motor
Faraday's electromagnetic experiment, 1821[SUP][/SUP]
Perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s.[SUP][/SUP] The theoretical principle behind production of mechanical force by the interactions of an electric current and a magnetic field, Ampère's force law, was discovered later by André-Marie Ampère in 1820. The conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the English scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire.[SUP][/SUP] This motor is often demonstrated in physics experiments, brine substituting for toxic mercury. Though Barlow's wheel was an early refinement to this Faraday demonstration, these and similar homopolar motors were to remain unsuited to practical application until late in the century.
Jedlik's "electromagnetic self-rotor", 1827 (Museum of Applied Arts, Budapest). The historic motor still works perfectly today.[SUP][/SUP]
In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils. After Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices "electromagnetic self-rotors". Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three main components of practical DC motors: the stator, rotor and commutator. The device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced solely by the currents flowing through their windings.[SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP]
[h=3]Success with DC motors[/h]After many other more or less successful attempts with relatively weak rotating and reciprocating apparatus the Prussian Moritz von Jacobi created the first real rotating electric motor in May 1834 that actually developed a remarkable mechanical output power. His motor set a world record which was improved only four years later in September 1838 by Jacobi himself.[SUP][/SUP] His second motor was powerful enough to drive a boat with 14 people across a wide river. It was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance.
The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832.[SUP][/SUP] Following Sturgeon's work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools and a printing press.[SUP][/SUP] Due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues. No electricity distribution had been developed at the time. Like Sturgeon's motor, there was no practical commercial market for these motors.[SUP][/SUP]
In 1855, Jedlik built a device using similar principles to those used in his electromagnetic self-rotors that was capable of useful work.[SUP][/SUP][SUP][/SUP] He built a model electric vehicle that same year.[SUP][/SUP]
A major turning point in the development of DC machines took place in 1864, when Antonio Pacinotti described for the first time the ring armature with its symmetrically grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered practically non-fluctuating current.[SUP][/SUP][SUP][/SUP] The first commercially successful DC motors followed the invention by Zénobe Gramme who, in 1871, reinvented Pacinotti's design. In 1873, Gramme showed that his dynamo could be used as a motor, which he demonstrated to great effect at exhibitions in Vienna and Philadelphia by connecting two such DC motors at a distance of up to 2 km away from each other, one as a generator.[SUP][/SUP] (See also 1873 : l'expérience décisive [Decisive Workaround] .)
In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking motor that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided controls systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond VA, the electric elevator and control system in 1892, and the electric subway with independently powered centrally controlled cars, which were first installed in 1892 in Chicago by the South Side Elevated Railway where it became popularly known as the "L". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry, while almost simultaneously another great inventor was developing its primary competitor, which would become much more widespread. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of a relatively small air gap between rotor and stator. Efficient designs have a comparatively small air gap.[SUP][/SUP] [SUP][a][/SUP] The St. Louis motor, long used in classrooms to illustrate motor principles, is extremely inefficient for the same reason, as well as appearing nothing like a modern motor.[SUP][/SUP]
Application of electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead every machine could be equipped with its own electric motor, providing easy control at the point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors stand for more than half of the electric energy consumption in the US.[SUP][/SUP]
[h=3]Emergence of AC motors[/h]In 1824, the French physicist François Arago formulated the existence of rotating magnetic fields, termed Arago's rotations, which, by manually turning switches on and off, Walter Baily demonstrated in 1879 as in effect the first primitive induction motor.[SUP][/SUP][SUP][/SUP] [SUP][/SUP][SUP][/SUP] In the 1880s, many inventors were trying to develop workable AC motors[SUP][/SUP] because AC's advantages in long-distance high-voltage transmission were counterbalanced by the inability to operate motors on AC. The first alternating-current commutatorless induction motors were independently invented by Galileo Ferraris and Nikola Tesla, a working motor model having been demonstrated by the former in 1885 and by the latter in 1887. In 1888, the Royal Academy of Science of Turin published Ferraris's research detailing the foundations of motor operation while however concluding that "the apparatus based on that principle could not be of any commercial importance as motor."[SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP]
In 1888, Tesla presented his paper A New System for Alternating Current Motors and Transformers to the AIEE that described three patented two-phase four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor, another with a wound rotor forming a self-starting induction motor, and the third a true synchronous motor with separately excited DC supply to rotor winding.
One of the patents Tesla filed in 1887, however, also described a shorted-winding-rotor induction motor. George Westinghouse promptly bought Tesla's patents, employed Tesla to develop them, and assigned C. F. Scott to help Tesla; however, Tesla left for other pursuits in 1889.[SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP][SUP][/SUP] The constant speed AC induction motor was found not to be suitable for street cars,[SUP][/SUP] but Westinghouse engineers successfully adapted it to power a mining operation in Telluride, Colorado in 1891.[SUP][/SUP][SUP][/SUP][SUP][/SUP]
Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the three-phase cage-rotor induction motor in 1889 and the three-limb transformer in 1890. This type of motor is now used for the vast majority of commercial applications.[SUP][/SUP][SUP][/SUP] However, he claimed that Tesla's motor was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work.[SUP][/SUP] Although Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, these early Westinghouse motors were two-phase motors with wound rotors until B. G. Lamme developed a rotating bar winding rotor.[SUP][/SUP]
The General Electric Company began developing three-phase induction motors in 1891.[SUP][/SUP] By 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design, later called the squirrel-cage rotor.[SUP][/SUP] Induction motor improvements flowing from these inventions and innovations were such that a 100 horsepower (HP) induction motor currently has the same mounting dimensions as a 7.5 HP motor in 1897.[SUP][/SUP]
Electric motor rotor (left) and stator (right)
[h=3]Rotor[/h]Main article: Rotor (electric)
In an electric motor the moving part is the rotor which turns the shaft to deliver the mechanical power. The rotor usually has conductors laid into it which carry currents that interact with the magnetic field of the stator to generate the forces that turn the shaft. However, some rotors carry permanent magnets, and the stator holds the conductors.
[h=3]Stator[/h]Main article: Stator
The stator is the stationary part of the motor’s electromagnetic circuit and usually consists of either windings or permanent magnets. The stator core is made up of many thin metal sheets, called laminations. Laminations are used to reduce energy losses that would result if a solid core were used.
[h=3]Air gap[/h]The distance between the rotor and stator is called the air gap. The air gap has important effects, and is generally as small as possible, as a large gap has a strong negative effect on the performance of an electric motor. It is the main source of the low power factor at which motors operate.The air gap increases the magnetizing current needed. For this reason, the air gap should be minimal. Very small gaps may pose mechanical problems in addition to noise and losses.
[h=3]Windings[/h]Main article: Windings
Windings are wires that are laid in coils, usually wrapped around a laminated soft iron magnetic core so as to form magnetic poles when energized with current.
Electric machines come in two basic magnet field pole configurations: salient-pole machine and nonsalient-pole machine. In the salient-pole machine the pole's magnetic field is produced by a winding wound around the pole below the pole face. In the nonsalient-pole, or distributed field, or round-rotor, machine, the winding is distributed in pole face slots.[SUP][/SUP] A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole.
Some motors have conductors which consist of thicker metal, such as bars or sheets of metal, usually copper, although sometimes aluminum is used. These are usually powered by electromagnetic induction.
[h=3]Commutator[/h]Main article: Commutator (electric)
A toy's small DC motor with its commutator
A commutator is a mechanism used to switch the input of most DC machines and certain AC machines consisting of slip ring segments insulated from each other and from the electric motor's shaft. The motor's armature current is supplied through the stationary brushes in contact with the revolving commutator, which causes required current reversal and applies power to the machine in an optimal manner as the rotor rotates from pole to pole.[SUP][/SUP][SUP][/SUP] In absence of such current reversal, the motor would brake to a stop. In light of significant advances in the past few decades due to improved technologies in electronic controller, sensorless control, induction motor, and permanent magnet motor fields, electromechanically commutated motors are increasingly being displaced by externally commutated induction and permanent-magnet motors.
[h=2]Motor supply and control[/h][h=3]Motor supply[/h]A DC motor is usually supplied through slip ring commutator as described above. AC motors' commutation can be either slip ring commutator or externally commutated type, can be fixed-speed or variable-speed control type, and can be synchronous or asynchronous type. Universal motors can run on either AC or DC.
[h=3]Motor control[/h]Fixed-speed controlled AC motors are provided with direct-on-line or soft-start starters.
Variable speed controlled AC motors are provided with a range of different power inverter, variable-frequency drive or electronic commutator technologies.
The term electronic commutator is usually associated with self-commutated brushless DC motor and switched reluctance motor applications.
[h=2]Major categories[/h]Electric motors operate on three different physical principles: magnetic, electrostatic and piezoelectric. By far the most common is magnetic.
In magnetic motors, magnetic fields are formed in both the rotor and the stator. The product between these two fields gives rise to a force, and thus a torque on the motor shaft. One, or both, of these fields must be made to change with the rotation of the motor. This is done by switching the poles on and off at the right time, or varying the strength of the pole.
The main types are DC motors and AC motors, the former increasingly being displaced by the latter.[SUP][/SUP]
AC electric motors are either asynchronous or synchronous.
Once started, a synchronous motor requires synchronism with the moving magnetic field's synchronous speed for all normal torque conditions.
In synchronous machines, the magnetic field must be provided by means other than induction such as from separately excited windings or permanent magnets.
A fractional horsepower (FHP) motor either has a rating below about 1 horsepower (0.746 kW), or is manufactured with a standard frame size smaller than a standard 1 HP motor. Many household and industrial motors are in the fractional horsepower class.
Major Categories by Type of Motor Commutation
Self-Commutated Externally Commutated Mechanical-
[SUP]  [/SUP][SUP]  [/SUP][SUP]  [/SUP][SUP]  [/SUP][SUP]  [/SUP][SUP]  [/SUP]
[TH="align: left"]* Universal motor
series motor[SUP][/SUP] or
* Repulsion motor[/TH]
excited DC motor:
PM DC motor[/TH]
[TH="align: left"]With PM rotor:
* BLDC motor
[TH="align: left"]Three-phase motors:
* SCIM[SUP]3[/SUP][SUP],[/SUP] [SUP]8[/SUP]
* WRIM[SUP]4[/SUP][SUP],[/SUP] [SUP]7[/SUP][SUP],[/SUP] [SUP]8[/SUP]
[TH="align: left"]Three-phase motors:
* PMSM or
* SyRM-PM hybrid[/TH]
[TH="align: center"]Simple electronics[/TH]
or DC chopper[/TH]
[TH="align: center"]More elaborate
[TH="colspan: 2, align: center"]Most elaborate
electronics (VFD), when provided[/TH]
- Rotation is independent of the frequency of the AC voltage.
- Rotation is equal to synchronous speed (motor stator field speed).
- In SCIM fixed-speed operation rotation is equal to synchronous speed less slip speed.
- In non-slip energy recovery systems WRIM is usually used for motor starting but can be used to vary load speed.
- Variable-speed operation.
- Whereas induction and synchronous motor drives are typically with either six-step or sinusoidal waveform output, BLDC motor drives are usually with trapezoidal current waveform; the behavior of both sinusoidal and trapezoidal PM machines is however identical in terms of their fundamental aspects.[SUP][/SUP]
- In variable-speed operation WRIM is used in slip energy recovery and double-fed induction machine applications.
- A cage winding is a shorted-circuited squirrel-cage rotor, a wound winding is connected externally through slip rings.
- Mostly single-phase with some three-phase.
[h=2]Self-commutated motor[/h][h=3]Brushed DC motor[/h]Main article: DC motor
- BLAC - Brushless AC
- BLDC - Brushless DC
- BLDM - Brushless DC motor
- EC - Electronic commutator
- PM - Permanent magnet
- IPMSM - Interior permanent magnet synchronous motor
- PMSM - Permanent magnet synchronous motor
- SPMSM - Surface permanent magnet synchronous motor
- SCIM - Squirrel-cage induction motor
- SRM - Switched reluctance motor
- SyRM - Synchronous reluctance motor
- VFD - Variable-frequency drive
- WRIM - Wound-rotor induction motor
- WRSM - Wound-rotor synchronous motor
All self-commutated DC motors are by definition run on DC electric power. Most DC motors are small PM types. They contain a brushed internal mechanical commutation to reverse motor windings' current in synchronism with rotation.[SUP][/SUP]
[h=4]Electrically excited DC motor[/h]Main article: Brushed DC electric motor
Workings of a brushed electric motor with a two-pole rotor and PM stator. ("N" and "S" designate polarities on the inside faces of the magnets; the outside faces have opposite polarities.)
A commutated DC motor has a set of rotating windings wound on an armature mounted on a rotating shaft. The shaft also carries the commutator, a long-lasting rotary electrical switch that periodically reverses the flow of current in the rotor windings as the shaft rotates. Thus, every brushed DC motor has AC flowing through its rotating windings. Current flows through one or more pairs of brushes that bear on the commutator; the brushes connect an external source of electric power to the rotating armature.
The rotating armature consists of one or more coils of wire wound around a laminated, magnetically "soft" ferromagnetic core. Current from the brushes flows through the commutator and one winding of the armature, making it a temporary magnet (an electromagnet). The magnetic field produced by the armature interacts with a stationary magnetic field produced by either PMs or another winding (a field coil), as part of the motor frame. The force between the two magnetic fields tends to rotate the motor shaft. The commutator switches power to the coils as the rotor turns, keeping the magnetic poles of the rotor from ever fully aligning with the magnetic poles of the stator field, so that the rotor never stops (like a compass needle does), but rather keeps rotating as long as power is applied.
Many of the limitations of the classic commutator DC motor are due to the need for brushes to press against the commutator. This creates friction. Sparks are created by the brushes making and breaking circuits through the rotor coils as the brushes cross the insulating gaps between commutator sections. Depending on the commutator design, this may include the brushes shorting together adjacent sections – and hence coil ends – momentarily while crossing the gaps. Furthermore, the inductance of the rotor coils causes the voltage across each to rise when its circuit is opened, increasing the sparking of the brushes. This sparking limits the maximum speed of the machine, as too-rapid sparking will overheat, erode, or even melt the commutator. The current density per unit area of the brushes, in combination with their resistivity, limits the output of the motor. The making and breaking of electric contact also generates electrical noise; sparking generates RFI. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance (on larger motors) or replacement (on small motors). The commutator assembly on a large motor is a costly element, requiring precision assembly of many parts. On small motors, the commutator is usually permanently integrated into the rotor, so replacing it usually requires replacing the whole rotor.
While most commutators are cylindrical, some are flat discs consisting of several segments (typically, at least three) mounted on an insulator.
Large brushes are desired for a larger brush contact area to maximize motor output, but small brushes are desired for low mass to maximize the speed at which the motor can run without the brushes excessively bouncing and sparking. (Small brushes are also desirable for lower cost.) Stiffer brush springs can also be used to make brushes of a given mass work at a higher speed, but at the cost of greater friction losses (lower efficiency) and accelerated brush and commutator wear. Therefore, DC motor brush design entails a trade-off between output power, speed, and efficiency/wear.
DC machines are defined as follows:[SUP][/SUP]
- Armature circuit - A winding where the load current is carried, such that can be either stationary or rotating part of motor or generator.
- Field circuit - A set of windings that produces a magnetic field so that the electromagnetic induction can take place in electric machines.
- Commutation: A mechanical technique in which rectification can be achieved, or from which DC can be derived, in DC machines.
A: shunt B: series C: compound f = field coil
There are five types of brushed DC motor:-
[h=4]Permanent magnet DC motor[/h]Main article: Permanent-magnet electric motor
- DC shunt-wound motor
- DC series-wound motor
- DC compound motor (two configurations):
- Cumulative compound
- Differentially compounded
- PM DC motor (not shown)
- Separately excited (not shown).
A PM motor does not have a field winding on the stator frame, instead relying on PMs to provide the magnetic field against which the rotor field interacts to produce torque. Compensating windings in series with the armature may be used on large motors to improve commutation under load. Because this field is fixed, it cannot be adjusted for speed control. PM fields (stators) are convenient in miniature motors to eliminate the power consumption of the field winding. Most larger DC motors are of the "dynamo" type, which have stator windings. Historically, PMs could not be made to retain high flux if they were disassembled; field windings were more practical to obtain the needed amount of flux. However, large PMs are costly, as well as dangerous and difficult to assemble; this favors wound fields for large machines.
To minimize overall weight and size, miniature PM motors may use high energy magnets made with neodymium or other strategic elements; most such are neodymium-iron-boron alloy. With their higher flux density, electric machines with high-energy PMs are at least competitive with all optimally designed singly-fed synchronous and induction electric machines. Miniature motors resemble the structure in the illustration, except that they have at least three rotor poles (to ensure starting, regardless of rotor position) and their outer housing is a steel tube that magnetically links the exteriors of the curved field magnets.
[h=3]Electronic commutator (EC) motor[/h][h=4]Brushless DC motor[/h]Main article: Brushless DC electric motor
Some of the problems of the brushed DC motor are eliminated in the BLDC design. In this motor, the mechanical "rotating switch" or commutator is replaced by an external electronic switch synchronised to the rotor's position. BLDC motors are typically 85–90% efficient or more. Efficiency for a BLDC motor of up to 96.5% have been reported,[SUP][/SUP] whereas DC motors with brushgear are typically 75–80% efficient.
The BLDC motor's characteristic trapezoidal back-emf waveform is derived partly from the stator windings being evenly distributed, and partly from the placement of the rotor's PMs. Also known as electronically commutated DC or inside out DC motors, the stator windings of trapezoidal BLDC motors can be with single-phase, two-phase or three-phase and use Hall effect sensors mounted on their windings for rotor position sensing and low cost closed-loop control of the electronic commutator.
BLDC motors are commonly used where precise speed control is necessary, as in computer disk drives or in video cassette recorders, the spindles within CD, CD-ROM (etc.) drives, and mechanisms within office products such as fans, laser printers and photocopiers. They have several advantages over conventional motors:
Modern BLDC motors range in power from a fraction of a watt to many kilowatts. Larger BLDC motors up to about 100 kW rating are used in electric vehicles. They also find significant use in high-performance electric model aircraft.
- Compared to AC fans using shaded-pole motors, they are very efficient, running much cooler than the equivalent AC motors. This cool operation leads to much-improved life of the fan's bearings.
- Without a commutator to wear out, the life of a BLDC motor can be significantly longer compared to a DC motor using brushes and a commutator. Commutation also tends to cause a great deal of electrical and RF noise; without a commutator or brushes, a BLDC motor may be used in electrically sensitive devices like audio equipment or computers.
- The same Hall effect sensors that provide the commutation can also provide a convenient tachometer signal for closed-loop control (servo-controlled) applications. In fans, the tachometer signal can be used to derive a "fan OK" signal as well as provide running speed feedback.
- The motor can be easily synchronized to an internal or external clock, leading to precise speed control.
- BLDC motors have no chance of sparking, unlike brushed motors, making them better suited to environments with volatile chemicals and fuels. Also, sparking generates ozone which can accumulate in poorly ventilated buildings risking harm to occupants' health.
- BLDC motors are usually used in small equipment such as computers and are generally used in fans to get rid of unwanted heat.
- They are also acoustically very quiet motors which is an advantage if being used in equipment that is affected by vibrations.
[h=4]Switched reluctance motor[/h]
6/4 pole switched reluctance motor
Main article: Switched reluctance motor
The SRM has no brushes or PMs, and the rotor has no electric currents. Instead, torque comes from a slight misalignment of poles on the rotor with poles on the stator. The rotor aligns itself with the magnetic field of the stator, while the stator field windings are sequentially energized to rotate the stator field.
The magnetic flux created by the field windings follows the path of least magnetic reluctance, meaning the flux will flow through poles of the rotor that are closest to the energized poles of the stator, thereby magnetizing those poles of the rotor and creating torque. As the rotor turns, different windings will be energized, keeping the rotor turning.
SRMs are now being used in some appliances.[SUP][/SUP]
[h=3]Universal AC-DC motor[/h]Main article: Universal motor
Modern low-cost universal motor, from a vacuum cleaner. Field windings are dark copper-colored, toward the back, on both sides. The rotor's laminated core is gray metallic, with dark slots for winding the coils. The commutator (partly hidden) has become dark from use; it is toward the front. The large brown molded-plastic piece in the foreground supports the brush guides and brushes (both sides), as well as the front motor bearing.
A commutated electrically excited series or parallel wound motor is referred to as a universal motor because it can be designed to operate on AC or DC power. A universal motor can operate well on AC because the current in both the field and the armature coils (and hence the resultant magnetic fields) will alternate (reverse polarity) in synchronism, and hence the resulting mechanical force will occur in a constant direction of rotation.
Operating at normal power line frequencies, universal motors are often found in a range less than 1000 watts. Universal motors also formed the basis of the traditional railway traction motor in electric railways. In this application, the use of AC to power a motor originally designed to run on DC would lead to efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron and they are now rarely used.
An advantage of the universal motor is that AC supplies may be used on motors which have some characteristics more common in DC motors, specifically high starting torque and very compact design if high running speeds are used. The negative aspect is the maintenance and short life problems caused by the commutator. Such motors are used in devices such as food mixers and power tools which are used only intermittently, and often have high starting-torque demands. Multiple taps on the field coil provide (imprecise) stepped speed control. Household blenders that advertise many speeds frequently combine a field coil with several taps and a diode that can be inserted in series with the motor (causing the motor to run on half-wave rectified AC). Universal motors also lend themselves to electronic speed control and, as such, are an ideal choice for devices like domestic washing machines. The motor can be used to agitate the drum (both forwards and in reverse) by switching the field winding with respect to the armature.
Whereas SCIMs cannot turn a shaft faster than allowed by the power line frequency, universal motors can run at much higher speeds. This makes them useful for appliances such as blenders, vacuum cleaners, and hair dryers where high speed and light weight are desirable. They are also commonly used in portable power tools, such as drills, sanders, circular and jig saws, where the motor's characteristics work well. Many vacuum cleaner and weed trimmer motors exceed 10,000 rpm, while many similar miniature grinders exceed 30,000 rpm.
[h=2]Externally commutated AC machine[/h]Main article: AC motor
The design of AC induction and synchronous motors is optimized for operation on single-phase or polyphase sinusoidal or quasi-sinusoidal waveform power such as supplied for fixed-speed application from the AC power grid or for variable-speed application from VFD controllers. An AC motor has two parts: a stationary stator having coils supplied with AC to produce a rotating magnetic field, and a rotor attached to the output shaft that is given a torque by the rotating field.
[h=3]Induction motor[/h]Main article: Induction motor
Large 4,500 HP AC Induction Motor.
[h=4]Cage and wound rotor induction motor[/h]An induction motor is an asynchronous AC motor where power is transferred to the rotor by electromagnetic induction, much like transformer action. An induction motor resembles a rotating transformer, because the stator (stationary part) is essentially the primary side of the transformer and the rotor (rotating part) is the secondary side. Polyphase induction motors are widely used in industry.
Induction motors may be further divided into Squirrel Cage Induction Motors and Wound Rotor Induction Motors. SCIMs have a heavy winding made up of solid bars, usually aluminum or copper, joined by rings at the ends of the rotor. When one considers only the bars and rings as a whole, they are much like an animal's rotating exercise cage, hence the name.
Currents induced into this winding provide the rotor magnetic field. The shape of the rotor bars determines the speed-torque characteristics. At low speeds, the current induced in the squirrel cage is nearly at line frequency and tends to be in the outer parts of the rotor cage. As the motor accelerates, the slip frequency becomes lower, and more current is in the interior of the winding. By shaping the bars to change the resistance of the winding portions in the interior and outer parts of the cage, effectively a variable resistance is inserted in the rotor circuit. However, the majority of such motors have uniform bars.
In a WRIM, the rotor winding is made of many turns of insulated wire and is connected to slip rings on the motor shaft. An external resistor or other control devices can be connected in the rotor circuit. Resistors allow control of the motor speed, although significant power is dissipated in the external resistance. A converter can be fed from the rotor circuit and return the slip-frequency power that would otherwise be wasted back into the power system through an inverter or separate motor-generator.
The WRIM is used primarily to start a high inertia load or a load that requires a very high starting torque across the full speed range. By correctly selecting the resistors used in the secondary resistance or slip ring starter, the motor is able to produce maximum torque at a relatively low supply current from zero speed to full speed. This type of motor also offers controllable speed.
Motor speed can be changed because the torque curve of the motor is effectively modified by the amount of resistance connected to the rotor circuit. Increasing the value of resistance will move the speed of maximum torque down. If the resistance connected to the rotor is increased beyond the point where the maximum torque occurs at zero speed, the torque will be further reduced.
When used with a load that has a torque curve that increases with speed, the motor will operate at the speed where the torque developed by the motor is equal to the load torque. Reducing the load will cause the motor to speed up, and increasing the load will cause the motor to slow down until the load and motor torque are equal. Operated in this manner, the slip losses are dissipated in the secondary resistors and can be very significant. The speed regulation and net efficiency is also very poor.
[h=4]Torque motor[/h]Main article: Torque motor
A torque motor is a specialized form of electric motor which can operate indefinitely while stalled, that is, with the rotor blocked from turning, without incurring damage. In this mode of operation, the motor will apply a steady torque to the load (hence the name).
A common application of a torque motor would be the supply- and take-up reel motors in a tape drive. In this application, driven from a low voltage, the characteristics of these motors allow a relatively constant light tension to be applied to the tape whether or not the capstan is feeding tape past the tape heads. Driven from a higher voltage, (and so delivering a higher torque), the torque motors can also achieve fast-forward and rewind operation without requiring any additional mechanics such as gears or clutches. In the computer gaming world, torque motors are used in force feedback steering wheels.
Another common application is the control of the throttle of an internal combustion engine in conjunction with an electronic governor. In this usage, the motor works against a return spring to move the throttle in accordance with the output of the governor. The latter monitors engine speed by counting electrical pulses from the ignition system or from a magnetic pickup and, depending on the speed, makes small adjustments to the amount of current applied to the motor. If the engine starts to slow down relative to the desired speed, the current will be increased, the motor will develop more torque, pulling against the return spring and opening the throttle. Should the engine run too fast, the governor will reduce the current being applied to the motor, causing the return spring to pull back and close the throttle.
[h=3]Synchronous motor[/h]Main article: Synchronous motor
A synchronous electric motor is an AC motor distinguished by a rotor spinning with coils passing magnets at the same rate as the AC and resulting magnetic field which drives it. Another way of saying this is that it has zero slip under usual operating conditions. Contrast this with an induction motor, which must slip to produce torque. One type of synchronous motor is like an induction motor except the rotor is excited by a DC field. Slip rings and brushes are used to conduct current to the rotor. The rotor poles connect to each other and move at the same speed hence the name synchronous motor. Another type, for low load torque, has flats ground onto a conventional squirrel-cage rotor to create discrete poles. Yet another, such as made by Hammond for its pre-World War II clocks, and in the older Hammond organs, has no rotor windings and discrete poles. It is not self-starting. The clock requires manual starting by a small knob on the back, while the older Hammond organs had an auxiliary starting motor connected by a spring-loaded manually operated switch.
Finally, hysteresis synchronous motors typically are (essentially) two-phase motors with a phase-shifting capacitor for one phase. They start like induction motors, but when slip rate decreases sufficiently, the rotor (a smooth cylinder) becomes temporarily magnetized. Its distributed poles make it act like a PMSM. The rotor material, like that of a common nail, will stay magnetized, but can also be demagnetized with little difficulty. Once running, the rotor poles stay in place; they do not drift.
Low-power synchronous timing motors (such as those for traditional electric clocks) may have multi-pole PM external cup rotors, and use shading coils to provide starting torque. Telechron clock motors have shaded poles for starting torque, and a two-spoke ring rotor that performs like a discrete two-pole rotor.
[h=3]Doubly-fed electric machine[/h]Main article: Doubly-fed electric machine
Doubly fed electric motors have two independent multiphase winding sets, which contribute active (i.e., working) power to the energy conversion process, with at least one of the winding sets electronically controlled for variable speed operation. Two independent multiphase winding sets (i.e., dual armature) are the maximum provided in a single package without topology duplication. Doubly-fed electric motors are machines with an effective constant torque speed range that is twice synchronous speed for a given frequency of excitation. This is twice the constant torque speed range as singly-fed electric machines, which have only one active winding set.
A doubly-fed motor allows for a smaller electronic converter but the cost of the rotor winding and slip rings may offset the saving in the power electronics components. Difficulties with controlling speed near synchronous speed limit applications.[SUP][/SUP]
[h=2]Special magnetic motors[/h][h=3]Rotary[/h][h=4]Ironless or coreless rotor motor[/h]
A miniature coreless motor
Nothing in the principle of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate. If the soft magnetic material of the rotor is made in the form of a cylinder, then (except for the effect of hysteresis) torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the coreless or ironless DC motor, a specialized form of a PM DC motor.[SUP][/SUP] Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder, or a self-supporting structure comprising only the magnet wire and the bonding material. The rotor can fit inside the stator magnets; a magnetically soft stationary cylinder inside the rotor provides a return path for the stator magnetic flux. A second arrangement has the rotor winding basket surrounding the stator magnets. In that design, the rotor fits inside a magnetically soft cylinder that can serve as the housing for the motor, and likewise provides a return path for the flux.
Because the rotor is much lighter in weight (mass) than a conventional rotor formed from copper windings on steel laminations, the rotor can accelerate much more rapidly, often achieving a mechanical time constant under one ms. This is especially true if the windings use aluminum rather than the heavier copper. But because there is no metal mass in the rotor to act as a heat sink, even small coreless motors must often be cooled by forced air. Overheating might be an issue for coreless DC motor designs. Modern software, such as Motor-CAD, can help to increase the thermal efficiency of motors while still in the design stage.
Among these types are the disc-rotor types, described in more detail in the next section.
The vibrating alert of cellular phones is sometimes generated by tiny cylindrical PM field types, but there are also disc-shaped types which have a thin multipolar disc field magnet, and an intentionally unbalanced molded-plastic rotor structure with two bonded coreless coils. Metal brushes and a flat commutator switch power to the rotor coils.
Related limited-travel actuators have no core and a bonded coil placed between the poles of high-flux thin PMs. These are the fast head positioners for rigid-disk ("hard disk") drives. Although the contemporary design differs considerably from that of loudspeakers, it is still loosely (and incorrectly) referred to as a "voice coil" structure, because some earlier rigid-disk-drive heads moved in straight lines, and had a drive structure much like that of a loudspeaker.
[h=4]Pancake or axial rotor motor[/h]A rather unusual motor design, the printed armature or pancake motor has the windings shaped as a disc running between arrays of high-flux magnets. The magnets are arranged in a circle facing the rotor with space in between to form an axial air gap.[SUP][/SUP] This design is commonly known as the pancake motor because of its extremely flat profile, although the technology has had many brand names since its inception, such as ServoDisc.
The printed armature (originally formed on a printed circuit board) in a printed armature motor is made from punched copper sheets that are laminated together using advanced composites to form a thin rigid disc. The printed armature has a unique construction in the brushed motor world in that it does not have a separate ring commutator. The brushes run directly on the armature surface making the whole design very compact.
An alternative manufacturing method is to use wound copper wire laid flat with a central conventional commutator, in a flower and petal shape. The windings are typically stabilized by being impregnated with electrical epoxy potting systems. These are filled epoxies that have moderate mixed viscosity and a long gel time. They are highlighted by low shrinkage and low exotherm, and are typically UL 1446 recognized as a potting compound insulated with 180 °C, Class H rating.
The unique advantage of ironless DC motors is that there is no cogging (torque variations caused by changing attraction between the iron and the magnets). Parasitic eddy currents cannot form in the rotor as it is totally ironless, although iron rotors are laminated. This can greatly improve efficiency, but variable-speed controllers must use a higher switching rate (>40 kHz) or DC because of the decreased electromagnetic induction.
These motors were originally invented to drive the capstan(s) of magnetic tape drives in the burgeoning computer industry, where minimal time to reach operating speed and minimal stopping distance were critical. Pancake motors are still widely used in high-performance servo-controlled systems, robotic systems, industrial automation and medical devices. Due to the variety of constructions now available, the technology is used in applications from high temperature military to low cost pump and basic servos.
[h=4]Servo motor[/h]Main article: Servo motor
A servomotor is a motor, very often sold as a complete module, which is used within a position-control or speed-control feedback control system mainly control valves, such as motor-operated control valves. Servomotors are used in applications such as machine tools, pen plotters, and other process systems. Motors intended for use in a servomechanism must have well-documented characteristics for speed, torque, and power. The speed vs. torque curve is quite important and is high ratio for a servo motor. Dynamic response characteristics such as winding inductance and rotor inertia are also important; these factors limit the overall performance of the servomechanism loop. Large, powerful, but slow-responding servo loops may use conventional AC or DC motors and drive systems with position or speed feedback on the motor. As dynamic response requirements increase, more specialized motor designs such as coreless motors are used. AC motors' superior power density and acceleration characteristics compared to that of DC motors tends to favor PM synchronous, BLDC, induction, and SRM drive applications.[SUP][/SUP]
A servo system differs from some stepper motor applications in that the position feedback is continuous while the motor is running; a stepper system relies on the motor not to "miss steps" for short term accuracy, although a stepper system may include a "home" switch or other element to provide long-term stability of control.[SUP][/SUP] For instance, when a typical dot matrix computer printer starts up, its controller makes the print head stepper motor drive to its left-hand limit, where a position sensor defines home position and stops stepping. As long as power is on, a bidirectional counter in the printer's microprocessor keeps track of print-head position.
[h=4]Stepper motor[/h]Main article: Stepper motor
A stepper motor with a soft iron rotor, with active windings shown. In 'A' the active windings tend to hold the rotor in position. In 'B' a different set of windings are carrying a current, which generates torque and rotation.
Stepper motors are a type of motor frequently used when precise rotations are required. In a stepper motor an internal rotor containing PMs or a magnetically soft rotor with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the stepper motor may not rotate continuously; instead, it "steps"—starts and then quickly stops again—from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards, and it may change direction, stop, speed up or slow down arbitrarily at any time.
Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can proportionally control the power to the field windings, allowing the rotors to position between the cog points and thereby rotate extremely smoothly. This mode of operation is often called microstepping. Computer controlled stepper motors are one of the most versatile forms of positioning systems, particularly when part of a digital servo-controlled system.
Stepper motors can be rotated to a specific angle in discrete steps with ease, and hence stepper motors are used for read/write head positioning in computer floppy diskette drives. They were used for the same purpose in pre-gigabyte era computer disk drives, where the precision and speed they offered was adequate for the correct positioning of the read/write head of a hard disk drive. As drive density increased, the precision and speed limitations of stepper motors made them obsolete for hard drives—the precision limitation made them unusable, and the speed limitation made them uncompetitive—thus newer hard disk drives use voice coil-based head actuator systems. (The term "voice coil" in this connection is historic; it refers to the structure in a typical (cone type) loudspeaker. This structure was used for a while to position the heads. Modern drives have a pivoted coil mount; the coil swings back and forth, something like a blade of a rotating fan. Nevertheless, like a voice coil, modern actuator coil conductors (the magnet wire) move perpendicular to the magnetic lines of force.)
Stepper motors were and still are often used in computer printers, optical scanners, and digital photocopiers to move the optical scanning element, the print head carriage (of dot matrix and inkjet printers), and the platen or feed rollers. Likewise, many computer plotters (which since the early 1990s have been replaced with large-format inkjet and laser printers) used rotary stepper motors for pen and platen movement; the typical alternatives here were either linear stepper motors or servomotors with closed-loop analog control systems.
So-called quartz analog wristwatches contain the smallest commonplace stepping motors; they have one coil, draw very little power, and have a PM rotor. The same kind of motor drives battery-powered quartz clocks. Some of these watches, such as chronographs, contain more than one stepping motor.
Closely related in design to three-phase AC synchronous motors, stepper motors and SRMs are classified as variable reluctance motor type.[SUP][/SUP] Stepper motors were and still are often used in computer printers, optical scanners, and computer numerical control (CNC) machines such as routers, plasma cutters and CNC lathes.
[h=3]Linear motor[/h]Main article: Linear motor
A linear motor is essentially any electric motor that has been "unrolled" so that, instead of producing a torque (rotation), it produces a straight-line force along its length.
Linear motors are most commonly induction motors or stepper motors. Linear motors are commonly found in many roller-coasters where the rapid motion of the motorless railcar is controlled by the rail. They are also used in maglev trains, where the train "flies" over the ground. On a smaller scale, the 1978 era HP 7225A pen plotter used two linear stepper motors to move the pen along the X and Y axes.[SUP][/SUP]
Well I have built units that produced 600 FT pounds of starting TQ from zero.^^^^ Jack: I haven't seen this much motor design theory since I last opened my text books long, long time ago - way back last century when Wikipedia wasn't even a thought in Wales' and Sanger's minds. But of course, as you know, the major advantage of DC style motors is that they achieve maximum torque at zero RPM. Which brings me back to my previous question - regarding the quantity of output power from your invention. Even using rare earth magnets, and notwithstanding any innovation in the design of a brush-less commutator - without additional input energy from an external electrical current, how much power does your device output? Which is really another way of me asking- how much work does your device output as a stand alone unit?
1. How can I identify the poles of the magnets?
There are several simple methods that can be used to identify the (Scientific) North and South poles of neodymium magnets.
1) The easiest way is to use another magnet that is already marked. The North pole of the marked magnet will be attracted to the South pole of the unmarked magnet.
2) If you take an even number of magnets and pinch a string in the middle of the stack and dangle the magnets so they can freely rotate on the string, the North pole of the magnets will eventually settle pointing North. This actually contradicts the "opposites attract" rule of magnetism, but the naming convention of the poles is a carry over from the old days when the poles were called the "North-seeking" and "South-seeking" poles. These were shortened over time to the "North" and "South" poles that we know them as.
3) If you have a compass handy, the end of the needle that normally points North will be attracted to the South pole of the neodymium magnet.
4) Use one of our Pole Identifier Devices.
(Please note: In some magnetic therapy applications, the definitions of the poles are reversed from the scientific definition described above. Please be sure to confirm the proper definition of the poles prior to using magnets for medical purposes)
Also check out our article, Which Pole is North?
2. Is one pole stronger than the other?
No, both poles are equally strong.
3. Which is the strongest type of magnet?
Neodymium (more precisely Neodymium-Iron-Boron) magnets are the strongest permanent magnets in the world.
4. What does "Magnetized thru thickness" mean?
We use the description "Magnetized thru thickness" to identify the locations of the poles on our block magnets. The thickness is always the last dimension listed for block magnets. If you take one of our block magnets and place it on a flat surface with the thickness dimension as the vertical dimension, the poles will be on the top and bottom of the magnet as it sits. For example: Our BX082 blocks are 1" x 1/2" x 1/8" thick. If you place one of the blocks so it is on a flat surface with 1/8" as the vertical dimension, the poles will be on the top and bottom as the magnet sits. This means the poles are located in the middle of the 1" x 1/2" sides. Click here for Magnetization Directions Illustrated.
5. What materials do magnets attract?
Ferromagnetic materials are strongly attracted by a magnetic force. The elements iron (Fe), nickel (Ni), and cobalt (Co) are the most commonly available elements. Steel is ferromagnetic because it is an alloy of iron and other metals.
6. What materials can I use to block/shield magnetic fields?
Magnetic fields cannot be blocked, only redirected. The only materials that will redirect magnetic fields are materials that are ferromagnetic (attracted to magnets), such as iron, steel (which contains iron), cobalt, and nickel. The degree of redirection is proportional to the permeability of the material. The most efficient shielding material is the 80 Nickel family, followed by the 50 Nickel family.
7. Can you supply monopole magnets?
No, we don't, nor does anyone else, because they don't exist. All magnets must have at least two poles.
8. Can you supply a disc/cylinder/ring/sphere magnet with one pole on the outside and one on the inside?
Disc, cylinder, and sphere shapes definitely cannot be manufactured this way. Rings magnetized this way are referred to as "radially magnetized", but it is not currently possible to manufacture neodymium ring magnets this way. We are working on it, however.
9. Does stacking magnets together make them stronger?
Yes, two or more magnets stacked together will behave exactly like a single magnet of the combined size. For example, if you stacked two of our D82 disc magnets to form a 1/2" x 1/4" combined size, the two magnets would have the same strength and behave identically to our D84 discs, which are 1/2" diameter x 1/4" thick.
10. How is the strength of a magnet measured?
Gaussmeters are used to measure the magnetic field density at the surface of the magnet. This is referred to as the surface field and is measured in Gauss (or Tesla). Pull Force Testers are used to test the holding force of a magnet that is in contact with a flat steel plate. Pull forces are measured in pounds (or kilograms).
11. How is the pull force of each magnet determined?
All of the pull force values we specify have been tested in our laboratory. We test these magnets in two different configurations. Case 1 is the maximum pull force generated between a single magnet and a thick, ground, flat steel plate. Case 2 is the maximum pull force generated with a single magnet sandwiched between two thick, ground, flat steel plates. Case 3 is the maximum pull force generated on a magnet attracted to another magnet of the same type.
The values are an average value for five samples of each magnet. A digital force gauge records the tensile force on the magnet. The plates are pulled apart until the magnet disconnects from one of the plates. The peak value is recorded as the "pull force". If using steel that is thinner, coated, or has an uneven or rusty surface, the effective pull force may be different than recorded in our lab.
12. I am using another online magnet pull force calculator. Why is the pull force value from the calculator different from K&J Magnetics' pull force?
Most other online calculators are based on theoretical formulas, which are notoriously inaccurate, especially for very large or very small sizes. Our fanatical engineers have worked long and hard in the laboratory developing our online calculators that are VERY accurate based on thousands of test cases. Our pull force and magnetic field density calculators can be found here: K&J Magnet Calculator.
13. Will a magnet with a 20 lb pull force lift a 20 lb object?
Because pull force values are tested under laboratory conditions, you probably won't achieve the same holding force under real world conditions. The effective pull force is reduced by uneven contact with the metal surface, pulling in a direction that is not perpendicular to the steel, attaching to metal that is thinner than ideal, surface coatings, and other factors.
14. Can you supply BH Curves, or Demagnetization Curves for your magnets?
Yes, we've posted Demagnetization Curves for our most common Neodymium magnet grades right here.
15. What does a magnetic field look like?
The traditional way of visualizing magnetic fields is to place a magnet near a surface covered with iron filings. If you already have some of our magnets, this is a good experiment to conduct! In the meantime, we've created a series of images using Finite Element Analysis software, which can be viewed here.
16. How do magnets really work?
This is a very interesting question. It's actually a difficult question to answer well. As the late, great physicist Richard Feynman once said, "How much of an explanation is enough to satisfy you?" To watch him describe the difficulty in answering this question, check out Feynman: How do Magnets Work on YouTube.
If you do want more details, this interesting video: How Special Relativity Makes Magnets Work has a great description about why an electromagnet is attracted to iron.
Their follow-on video, MAGNETS: How Do They Work? is even more relevant to permanent magnets. It addresses how permanent magnets with (seemingly) no current running through them can act magnetic. Ironically, even with that incredible level of detail, at some point they still end up saying, "(Why?) No one knows. We just know that's the way the universe works." Feynman was a pretty smart guy!
17. What are neodymium magnets? Are they the same as "rare earth"?
Neodymium magnets are a member of the rare earth magnet family. They are called "rare earth" because neodymium is a member of the "rare earth" elements on the periodic table. Neodymium magnets are the strongest of the rare earth magnets and are the strongest permanent magnets in the world.
18. What are neodymium magnets made from and how are they made?
Neodymium magnets are actually composed of neodymium, iron and boron (they are also referred to as NIB or NdFeB magnets). The powdered mixture is pressed under great pressure into molds. The material is then sintered (heated under a vacuum), cooled, and then ground or sliced into the desired shape. Coatings are then applied if required. Finally, the blank magnets are magnetized by exposing them to a very powerful magnetic field in excess of 30 KOe.
19. What does the "N rating", or grade, of the neodymium magnets mean?
The grade, or "N rating" of the magnet refers to the Maximum Energy Product of the material that the magnet is made from. It refers to the maximum strength that the material can be magnetized to. The grade of neodymium magnets is generally measured in units millions of Gauss Oersted (MGOe). A magnet of grade N42 has a Maximum Energy Product of 42 MGOe. Generally speaking, the higher the grade, the stronger the magnet.
20. Can I cut, drill, or machine neodymium magnets?
The Neodymium Iron Boron material is very hard and brittle, so machining is difficult at best. The hardness of the material is RC46 on the Rockwell "C" scale, which is harder than commercially available drills and tooling, so these tools will heat up and become damaged if used on NdFeB material. Diamond tooling, EDM (Electrostatic Discharge Machines), and abrasives are the preferred methods for shaping neodymium magnet material. Machining of neodymium magnets should only be done by experienced machinists familiar with the risk and safety issues involved. The heat generated during machining can demagnetize the magnet and could cause it to catch fire posing a safety risk. The dry powder produced while machining is also very flammable and great care must be taken to avoid combustion of this material.
21. Can I solder or weld to neodymium magnets?
You definitely cannot solder or weld to neodymium magnets. The heat will demagnetize the magnet and could cause it to catch fire posing a safety risk.
22. Do I have to worry about temperature with neodymium magnets?23. What is the gauss rating of your magnets?
Yes. Neodymium Iron Boron magnets are sensitive to heat. If a magnet heated above its maximum operating temperature (176°F (80°C) for standard N grades) the magnet will permanently lose a fraction of its magnetic strength. If they are heated above their Curie temperature (590°F (310°C) for standard N grades), they will lose all of their magnetic properties. Different grades of neodymium different maximum operating and Curie temperatures. See our Neodymium Magnet Specifications Page for more details. We do stock a range of high temperature magnets, which you can see here.
This depends on the context it is used. Most magnetic therapy people like to present the largest number possible, so they often use the Residual Flux Density (Br[SUB]max[/SUB]) of the material, which really doesn't specify much about the actual magnet. This value is essentially the magnetic field density inside the magnet material. Since you will never be inside the magnet, or using the field inside the magnet, this value doesn't really have any practical value. The surface field of a magnet is a much more accurate specification for a magnet. The surface field is exactly what it sounds like. It is the magnetic field density at the surface of the magnet as measured by a Gaussmeter. This value is tested and specified for each of our stock magnets. A comprehensive table of the surface field density for each of our stock magnets can be seen here: Magnet Summary Table.
24. Do neodymium magnets require a keeper?
No, neodymium magnets do not require a keeper for storage like Alnico magnets.
25. Will my neodymium magnets lose strength over time?
Very little. Neodymium magnets are the strongest and most permanent magnets known to man. If they are not overheated or physically damaged, neodymium magnets will lose less than 1% of their strength over 10 years - not enough for you to notice unless you have very sensitive measuring equipment. They won't even lose their strength if they are held in repelling or attracting positions with other magnets over long periods of time.
26. Will neodymium magnets lose strength if they are held in repelling or attracting positions for a long time?
In most applications, the answer is simply "no". If the magnets will be exposed to higher temperatures while in repelling applications, the answer is "possibly". The exact answer is a bit too complicated for a FAQ answer, and requires specifics about the application.
27. What are neodymium magnets used for?
Just about anything you can imagine! Please see our Uses Page for a list of some of the applications for these incredible magnets.
28. How is neodymium pronounced?
From a dictionary: [nē ō dim ē um]. Or, nee-oh-dim-ee-um.
The only real trick to pronouncing it correctly is to treat the 'y' as an 'i'. It is pronounced as if it were spelled "neodimium".
29. Are your Neodymium Rare Earth Magnets RoHS compliant?
Yes, our magnets are fully RoHS compliant, meeting the European Parliament Directive entitled "Restrictions on the use Of Hazardous Substances" (RoHS). This Directive prohibits the use of the following elements in electrical/electronic equipment sold after 7/1/2006: cadmium (Cd), lead (Pb), mercury (Hg), hexavalent chromium (Cr(VI)), polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs). Download an official RoHS Compliance Statement from K&J Magnetics here. Or, you can find individual PDF files for each specific magnet on the product detail pages, under the "Downloads" tab.
30. Can I make a magnet that I already have any stronger?
No, once a magnet is fully magnetized (saturated), it cannot be made any stronger.
31. I need a magnet the size of a penny/nickel/dime/quarter. What size do I need?
Here are the dimensions of these coins along with the closest matching magnet that we currently stock:
32. What is the difference between the maximum operating temperature and the Curie temperature of the magnets?
- US Penny = 0.75" dia. x 0.061" ==> DC1 (0.75" dia. x 0.063")
- US Nickel = 0.835" dia. x 0.077" ==> DE1 (0.88" dia. x 0.063")
- US Dime = 0.705" dia. x 0.053" ==> DA1 (0.63" dia. x 0.063"), DB1 (0.688" dia. x 0.063") or DC1 (0.75" dia. x 0.063")
- US Quarter = 0.955" dia. x 0.069" ==> DX01 (1.0" dia. x 0.063")
- US Half Dollar = 1.205" dia. x 0.085" ==> DX42 (1.25" dia. x 0.125")
The maximum operating temperature is the maximum temperature the magnet may be continuously subjected to with no significant loss of magnetic strength. This is 176ºF (80ºC) for standard grades of neodymium magnets. The Curie Temperature is the temperature at which the magnet will become completely demagnetized. This is 590ºF (310ºC) for standard grades of neodymium magnets. Higher temperature grades have higher maximum operating temperatures and higher Curie Temperatures. At temperatures between these two points, a magnet will permanently lose a portion of its magnetic strength. The loss will be greater the closer to the Curie Temperature it is heated.
For a more in-depth explanation, check out our article: Temperature and Neodymium Magnets.
33. How strong of a magnetic field is necessary to magnetize a neodymium magnet?
As a general rule of thumb, a peak field of between 2 and 2.5 times the intrinsic coercivity is required to fully saturate a magnet. For standard neodymium magnets, the field required is minimum of 24 KOe, but 30 KOe is usually the minimum used.
34. How do I separate large magnets?
Small and medium-sized magnets can usually be separated by hand by sliding the end magnet off of the stack. Medium-large magnets can often be separated by using the edge of a table or countertop. Place the magnets on a table top with one of the magnets hanging over the edge. Then, using your body weight, hold the magnet(s) on the table and push down on the magnet hanging over the edge. With a little work and practice, you should be able to slide the magnets apart. Just be careful that they don't snap back together once they become separated. For very large magnets (generally 2" and larger), we use a specially made magnet separating tool. You can see pictures of one of these tools as well as instructions on how to build your own on this page: Build your own magnet separating tool.
For a more in-depth explanation, check out our article: How to Separate Strong Magnets, which includes a number of short videos.
35. I have metal dust all over my magnets. How can I remove it?
Using adhesive tape to capture the metal dust is the best way to clean magnets.
36. Are there any regulations for shipping magnets?
According to the United States Department of Transportation and the Office of Hazardous Materials Safety, the limit for shipping magnets by air is a magnetic field strength of 0.00525 Gauss measured at 15 feet (4.5 meters) from any point on the outside of the package. There are no restrictions on the shipping of magnetized materials by ground. When in doubt, ship magnets by ground transportation.
For a more in-depth explanation, check out our article about Shipping Magnets.
37. Why are most neodymium magnets plated or coated?
Neodymium magnets are composed mainly of Neodymium, Iron, and Boron. If neodymium magnets are not plated, the iron in the material will oxidize very easily if exposed to moisture. Even normal humidity will rust the iron over time. To protect the iron from exposure to moisture, most neodymium magnets are plated or coated.
38. What is the difference between the different platings and coatings?
Choosing different coatings does not affect the magnetic strength or performance of the magnet, except for our Plastic and Rubber Coated Magnets. The preferred coating is dictated by preference or intended application. More detailed specifications can be found on our Specs page.
39. Can I paint over the nickel plating?
- Nickel is the most common choice for plating neodymium magnets. It is actually a triple plating of nickel-copper-nickel. It has a shiny silver finish and has good resistance to corrosion in many applications. It is not waterproof.
- Black nickel has a shiny appearance in a charcoal or gunmetal color. A black dye is added to the final nickel plating process of the triple plating of nickel-copper-black nickel. NOTE: It does not appear completely black like epoxy coatings. It is also still shiny, much like plain nickel plated magnets.
- Zinc has a dull gray/bluish finish, that is more susceptible to corrosion than nickel. Zinc can leave a black residue on hands and other items.
- Epoxy is basically a plastic coating that is more corrosion resistant as long as the coating is intact. It is easily scratched. From our experience, it is the least durable of the available coatings.
- Gold plating is applied over the top of standard nickel plating. Gold plated magnets have the same characteristics as nickel plated ones, but with a gold finish.
Yes, you can use any paint formulated for use on metal surfaces. Spray-on paint seems to work best. Roughing the surface first can help improve paint adhesion to the smooth, nickel plated surface. Sandblasting or beadblasting works, as well as an etching primer.
40. What is the thickness of the nickel (Ni-Cu-Ni) plating?
The nickel plating is actually triple plating of nickel-copper-nickel. The layers are Ni: 5-6µm, Cu: 7-8µm, Ni: 5-6µm, for a total thickness of 17-20µm.
41. Do you stock any unplated magnets?
As mentioned above, the iron in the NdFeB material will oxidize if it is exposed to moisture. For this reason, we do not stock any unplated magnets. We can supply unplated magnets as custom order items.
42. What is the best adhesive to use with your magnets?
We and several customers have had great success adhering to the nickel-plating using Loctite 39205 (an acrylic adhesive) with Loctite 7380 activator. A Loctite representative also recommended Loctite 3032 (a 2-part acrylic adhesive) with Loctite primer 770. For more commonly found adhesives, we have also had great results using many kinds of epoxy, often sold as "5-minute" epoxy. "Liquid Nails" and "Gorilla Glue" can also work well, and are available in most hardware and home supply stores. It does help to scratch the surface of the plating lightly with sandpaper or other abrasive prior to applying the adhesive. For more information, read our in-depth article: Sticky Business: How to Glue Neodymium Magnets.
43. I noticed that the plastic- and rubber-coated magnets have a lower pull force than nickel-plated magnets of the same size. Does the plastic/rubber weaken the magnet?
These materials don't "weaken" the magnet, but the volume of magnet material is reduced to allow room for the coatings, which reduces the pull force. The layer of plastic or rubber also creates distance between the magnet and metal surface which also reduces the pull force.
44. How can I protect my magnets from damage due to impact?
We have found that wrapping magnets with a few layers of electrical tape protects them from most damage caused by collisions with other magnets and hard surfaces. Another great way to protect your magnets from damage and the elements is to coat them with rubberized coating. We have created a page with step-by-step instructions on how to do this. We also stock several sizes and shapes of plastic-coated and rubber-coated magnets.
45. I need a special size/shape of neodymium magnet. Can you supply custom magnets?
Yes, we can supply custom magnets. You can find details on our Custom Magnet Page.
46. What are the size limitations on manufacturing neodymium magnets?
The limits include:
2" max in magnetized direction
4" max diameter for discs and rings
4" max length and width for blocks
1/32" minimum on thickness on any magnet
1/16" minimum diameter on outer diameter
1/16" minimum diameter on any hole
47. I see you supply plastic- and rubber-coated neodymium magnets. Can I get XXX-size in plastic-coated (or rubber-coated)?
Maybe. Each size of plastic- and rubber-coated magnet requires its own special mold. These molds cost anywhere from $300-$2500, depending on the size and shape. If you are in need of a large quantity, creating a new mold may be worthwhile. If you only need a few, then doing your own rubber-coating may be a more cost-effective solution.
48. Are there health or safety concerns with neo magnets?
There are no known health concerns with exposure to permanent magnetic fields. In fact, many people believe that magnets can be used to speed up the healing process. There may be issues with people with pacemakers or other implanted medical devices handling or being around strong magnets. We are not medical professionals, so we cannot offer complete guidance on pacemaker safety. We've shared what we do know in our article about Pacemaker Safety. Please consult a physician for this information. There are several safety concerns when handling strong magnets. Please refer to our Safety Page for complete details.
49. What is a safe distance to keep magnets away from pacemakers?
We are not medical professionals, so we cannot offer complete guidance on pacemaker safety, or about any specific medical device. Please consult a physician and/or the manufacturer of your device for this information. We've shared what we do know in our article about Pacemaker Safety.
50. Will magnets harm my electronics?
Maybe...The strong magnetic fields of these magnets can damage certain magnetic media such as floppy disks, credit cards, magnetic I.D. cards, cassette tapes, video tapes or other such devices. They can also damage televisions, VCRs, computer monitors and other CRT displays. Never place neodymium magnets near any of these appliances. As for other electronics such as cell phones, iPods, flash drives, calculators and similar devices that do not contain magnetic storage media, probably not, but it is best to err on the safe side and try to avoid close contact between neo magnets and electronics.
51. How far away from electronics should I keep my magnets?
This depends on a lot of factors, but as a general rule of thumb, we recommend keeping the distance between magnets and electronics 4" + 1" for every 10 lbs of pull force.
52. Will using magnets on my refrigerator, stove, oven, or microwave harm the appliance?
No, magnets will not harm any of these appliances.
53. Will magnets erase my hard drive or harm my computer?
Not unless you really work at it. While you probably don't want to stick magnets directly to your computer case, having them nearby will not harm your computer. Magnets can damage floppy disks and magnetic tape storage media, so you must keep magnets away from these items. They should not, however, damage any data on your hard drive unless you place a very large and powerful magnet directly on top of the drive. Every hard drive already contains a powerful neodymium magnet, so one moving around outside the case will not affect the data.
We tried scrambling the contents of a running hard drive ourselves, and documented our failure to erase all the data in our article, Hard Drive Destruction
54. I am developing a product using magnets. Do I have to put a safety warning on it about pacemakers/electronics?
While we love answering technical questions about magnets, this one sounds more like a legal question. We're definitely not qualified to provide legal advice.
Again, we are not medical professionals, so we cannot provide firm details on pacemaker issues. As for safety and electronics, it really depends on the application of your product, the size of the magnet(s), how the magnet is used, and where the magnet is located within the product. We recommend providing any warnings that you think may be an issue.
55. Can I use neodymium magnets to trigger traffic lights with my motorcycle/moped/bicycle?
This one is a definite "maybe". We have received feedback that magnets as small as our D84 discs have successfully triggered traffic lights, but we have also received reports that magnets as large as our DX8C have failed to trip similar traffic light sensors. It seems that there are different types and different sensitivities of traffic light sensors, and magnets will trigger some, but not all of them. If you have any feedback or good information on this, we would appreciate an email with any details you may have.
56. Which magnets should I use for holding knives to my fridge?
For small knives, small magnets like our B444 cubes are sufficient. For butcher knives and other large knives, we recommend our BX084 blocks. Mid-sized knives can be held to a refrigerator using our B884 blocks.
Also check out our Magnetic Knife Holder article, which describes how to build a magnetic knife block!
57. Which magnets should I use for holding spice cans to my fridge?
The answer varies depending on the size of the can and the weight of the items being stored. Magnets as small as our D81 discs can be used to hold smaller cans, while magnets as large as our DC2 discs may be required to hold very large cans.
58. I am looking for the equivalent of a magician's M5/PK5 magnet. Which of your magnets is the equivalent?
The magician's M5 (aka PK5) magnet is the equivalent of our BY0Y08 block magnet.
59. I am making magnetic earrings. Which magnets should I use?
The best size varies, depending on the size of the decorations being held. Generally, the best options are discs like our D31-N52 or D41-N52. Other magnets of similar size can also be used.
60. I would like to erase hard drives/degauss tapes. Which magnet should I use?
Magnetic tapes can be erased with a strong magnet. Popular choices include: DX8C, DY0X0, or BY0Y08.
We used to think that a sufficiently large magnet would scramble the data on a hard drive. Some recent experiments we have conducted seem to disagree. See our blog article on the subject for more details. We don't recommend this method if you must be sure that the data is gone -- physical destruction of the drive is the safest choice.
61. Which magnets should I use for magnetic therapy?
A wide range of sizes can be used for magnetic therapy. Many people use magnets as small as our D41 discs for spot treatment, while others use magnets as large as our DY04 discs for large area treatment. It is best to select a size that "fits" the area being treated.
62. I would like to use magnets for water treatment. Which magnets should I use?
Magnets on the main water line should be of dimensions 1.5 - 2.5 times the outside diameter of the pipe coming in. Larger magnets will provide a stronger and more consistent magnetic field between them. For this application, we often recommend our BY0Y08 blocks. They will work well on any water line up to 1.5" in diameter. Water conditioning works best if you use two magnets, one on each side of the pipe in attracting arrangement. The two magnets in this arrangement create the strongest possible magnetic field between them. It works very well if you have two "shims" which are the same thickness as the diameter of the water pipe. If you tape the shims to either side of the pipe, they will provide a flat surface for the magnets to rest on. The large magnets should hold each other in place across the pipe and shims. The magnets can then be held in place with tape to prevent them from slipping off due to vibration.
Interested in learning more about how magnetic water treatment might work? Check out our Magnetic Water Treatment article, where we discover some surprising facts about this controversial subject!
63. Which magnets should I use for holding pictures and papers to my refrigerator?
For refrigerator magnets, there are many options. We carry a neat line of magnetic thumbtacks as well as dozens of other shapes and sizes that work well. A few suggestions are our D42, D34, B333, S4 (also available in black color or gold), and ST4 stars. Many other magnets of similar sizes will also work very well for fridge magnets.
Also check out our Refrigerator Magnets section, which includes a number of great suggested magnets.
64. Which magnets should I use for holding pins/badges through clothing instead of using pins?
For holding average-sized pins and badges, we recommend our D62 disc magnets, as they provide the appropriate amount of pull strength through a wide range of fabric thicknesses. If you will be holding large or heavy pins or badges, or will be holding through exceptionally thick material, then our D72 or D82 discs may be necessary to provide enough holding force.
Also check out our Sewing Magnets that are made specifically for use as magnetic closures. They are intended to be sewn inside the fabric, remaining hidden from view.
They come in 3 different sizes and are sold in matched pairs. Also note that some have a thin plastic cover that protects them from moisture, which is an excellent solution for anything that goes through the washing machine.
See our Sewing Magnet Article for an example of how to use them. There, we describe how we replaced the Velcro fasteners on a pair of cargo shorts.
65. I heard you can repair dents in brass instruments using magnets. How can I do this?
Dent removal is accomplished by inserting a steel ball into the instrument as close to, but smaller than, the diameter of the section of tubing being repaired. The steel ball can be moved through the tube using a magnet on the outside. Working the steel ball over the damaged area will gradually smooth out the dent. A magnet like our DX0X0 will pull out most small- and medium-sized dents, while a larger magnet like our DX8C may be necessary for larger and more stubborn dents. We do carry a line of steel balls that can be used for this application.
66. I need magnets for a binder/brochure closure. Which magnets work for this?
We have many printers and other customers that use our magnets in brochures and binders to hold them closed. The most common sizes used for brochures and binders are our D401, D41, D501, D51, D601, D61, D701, D71, D801, D81 disc magnets, and our B4401, B441, B6301, B631, B661, B821, B841, B8801, and B881 block magnets, but larger sizes can also be used for larger applications.
See our Adhesive Backed Magnets article for a great example of how to do this.
67. I am trying to order online, but every time I add something to my shopping cart, I get a message that my cart is empty. What do I need to do?
Most of the time, this is caused by cookies being disabled on your computer. Our shopping cart must be allowed to write a small cookie to your computer to "remember" what you place in your shopping cart. To find out how to enable cookies for various browsers, please refer to this web page: Google: How to Enable Cookies. If you continue to have difficulty ordering online, you can order by phone by calling us at 215-766-8055 during normal business hours.
68. I don't want to put my credit card info online. Is there some other way I can pay?
We take every measure possible to ensure that your online transaction with us is secure. You can read more about this on our Security Page. If you would still prefer not to order online, there are many other ways to place an order with us. Please see our Ordering/Shipping Page for more details.
69. Can I get the quantity discount pricing for an odd quantity of magnets (i.e. quantity of 87)?
Yes. If you are ordering an odd quantity of a particular magnet, you can get the quantity pricing by simply adding a single magnet to your shopping cart. Then, while viewing the shopping cart, change the quantity from "1" to your desired quantity and click "Update Totals". The shopping cart will recalculate the price and total and will give you the quantity discounted price.
70. Can I open an account with K&J Magnetics?
We accept Purchase Orders from businesses with approved credit. For additional information, please email us at email@example.com.
71. Can you just put my magnets in a small envelope to save postage?
No. All magnets must be shipped in a box in order to comply with United States Department of Transportation, USPS, UPS, and FedEx regulations for the shipment of magnetic materials.
72. Where can I get a discount code?
You can receive discounts by joining our Mailing List. Our periodic newsletter (sent once every month or two) contains news, new products and Mailing List-only coupons and specials!
73. Where are you located?
Our main offices and warehouse is currently located in Pipersville, PA, about 30 miles north of Philadelphia. We currently do not have a retail store, nor do we accept walk-in customers or pick-ups at this time.
74. Do you have a local distributor near me?
We do not have any local distributors of our magnets. All sales are through our website www.kjmagnetics.com.
75. Do you have an affiliate program?
Yes, we do. If you have a website and would like to earn commissions for sales generated by your link to our store, please email us for details.
76. Do you have a printed catalog?
No we do not have a printed catalog available. Find information about all of our magnets online, here at our website.
77. Are neodymium magnets affected by recent changes in US Conflict Minerals Law, as made in section 1502 of the Dodd-Frank Wall Street Reform and Consumer Protection Act?
This law requires reporting of the use of columbite-tantalite (tantalum, used in capacitors), cassiterite (used to make tin), wolframite (tungsten) and gold that comes from mines located in the eastern part of the Democratic Reublic of Congo. Since neodymium magnets don't usually contain these elements, they shouldn't be covered by this law. Learn more about what elements are used in the manufacture of neodymium magnets in our article: How Neodymium Magnets are Made.
Einstein's biggest blunder turned out to explain one of the greatest scientific revelations of the 20th century
Kevin Reilly and Jessica Orwig
May 22, 2017, 11:30 AM
Brian Greene, Columbia University physicist and co-founder of the World Science Festival, explains how today's physicists and mathematicians use an Einsteinian formula to explain the universe that Einstein himself originally thought was false.
You can learn more fascinating science at this year's 10th annual World Science Festival in NYC taking place from May 30-June 4. Following is a transcript of the video.
The amazing thing is that blunder in Einstein’s mind is something that we now believe describes the actual universe.
Einstein became Einstein really because of his discovery of the general theory of relativity in 1915. The core of it are the Einstein field equations. And that’s a set of equations that relate the curvature of spacetime to the amount of matter and energy moving through a region of spacetime.
Interesting when Einstein applied theses equations to the entire universe, he found a result that he wasn’t happy with. He found that the universe could not be static and unchanging. It had to be either stretching or contracting.
And he said, “no.” The universe is clearly static and eternal. So what did he do? He went back to the equations.Put in one more term. On the left hand side he put in lambda. Lambda is what’s called the cosmological constant. He called it the cosmological member. And what it does is it can kind of give an outward push that can stabilize the inward pull of gravity, resulting in a static universe.And then Einstein was happy. Right?
But then in 1929 we learn that the universe is expanding and Einstein says,
Ugh, I wish I would not have put that term in.
Because my equations predicted that the universe is expanding and I would have gotten there 12 years before the observations. Today the amazing thing is that blunder in Einstein’s mind is something that we now believe describes the actual universe.
Because when we found that the accelerated expansion is happening, we want something that can push everything apart. What can do that?Einstein’s cosmological constant pushes things apart. We employ a different value.A different number than Einstein would have thought. But the idea is exactly what Einstein came up with.
Even Einstein’s bad ideas wind up being pretty darn good.
Look I know many have said stuff like this before......... but this is something I have been dreaming about since childhood.
I can't get around the whole sleep thing....... it is where I go over something bothering me in a virtual and to me I guess to a point is meditation to a degree....... so I have to say sure Don.
I do have tons of stuff on my mind & all the time, between a speech impediment and reading writing comprehension issue, it is always been an uphill battle for me.
Today a major solution was accomplished for resonance reduction related and speed control.
Yes I have I believe a pretty good IP lawyer for this in mind, the dilemma with this type of device is it uses natural forces that the USPTO just likes to say no way Jose....
This on the other hand is not perpetual.
The big Joke today when I tried to share this internally today with the attendant was ( More power to you ) ( May the force be with you ) ha ha ha real funny I said.
I am simplifying the axis points and reducing static field strength to gain a more refined control by KISS.
The thing that is going to blow everyone's mind, is that is it is totally mechanical..........It blows mine right now because according to my brother and Artie & most people I engage on this say it is impossible.
The big Joke today when I tried to share this internally today with the attendant was ( More power to you ) ( May the force be with you ) ha ha ha real funny I said.
I am on the record saying that current scientific beliefs today say that there is no such thing as free energy. If it works, then you have found a way to tap a previously-unknown force. I am also on the record pointing out that the accepted scientific belief back when Galileo was alive was that the sun and stars revolved around the Earth, and he was ridiculed, nearly excommunicated, and lived the rest of his life living under house arrest for merely saying that the universe didn't revolve around Rome. You're in good company, and hopefully one day there will be a shuttle craft named after you as well.....The thing that is going to blow everyone's mind, is that is it is totally mechanical..........It blows mine right now because according to my brother and Artie & most people I engage on this say it is impossible.