** Free energy with wires and magnets - can you come out
ahead?**

The basics of magnets and wires for free energy buffs.

*Prepared by Tom Napier.
Copyright © 1998, All rights reserved.*

* Over-unity motors and generators
-- the bottom line*

* ** Prepared by Tom Napier. Copyright
© 1999, All rights reserved.*

* ** *Some months ago I posted a detailed analysis of the
forces between magnets and

current carrying wires. (See "The basics
of magnets and wires for free energy

buffs.") For the benefit of those who
found its 3400 words a bit much to wade

through here is the "executive
summary." See my earlier article if you want more

information.

**Point 1.** Under ideal conditions the electrical power output
generated when you

move a conductor through a magnetic field is
exactly equal to the mechanical power

input needed to move the conductor.

**Point 2.** This applies to every microscopic piece of conductor, no
matter in which

direction it moves, at what speed it moves or how
strong the field is.

**
Point 3.** The sum of the output electrical power round any closed loop
is equal to

the sum of the input mechanical power, less any
resistive losses in the conductor and

frictional losses in the moving parts.

**Point 4**. Thus the output power from a electrical generator of any
type is always

less than the input power. No external
devices such as commutators, tuned circuits

or diodes can change this.

**Point 5.** Under ideal conditions the mechanical power output
generated when you

pass a current through a conductor in a magnetic
field is exactly equal to the

electrical power input applied.

**Point 6.** This applies to every microscopic piece of conductor, no
matter in which

direction it moves, at what speed it moves or how
strong the field is.

**
Point 7**. The sum of the output mechanical power round any closed loop
is equal to

the sum of the input electrical power, less any
resistive losses in the conductor and

frictional losses in the moving parts.

**
Point 8.** Thus the output power from a electric motor of any type is
always less

than the input power. No external devices
such as commutators, tuned circuits or

diodes can change this.

**Point 9.** When you test a motor or a generator it can be very
difficult to measure

both the mechanical and the electrical powers with
sufficient accuracy to compute the

real efficiency. The calculated efficiency
may be either higher or lower than the

real figure.

**
The bottom line:** You don't have an
over-unity system until you can demonstrate a

stand-alone device which drives itself and
simultaneously generates a non-zero output

power.

**Machines which use magnets**

Magnets are fascinating things, the way they push and pull and twist each other
with no apparent connection between them. It's tempting to suppose that
there must be some way of arranging them to extract energy from them. For
example, one of the earliest perpetual motion machines proposed to use a
lodestone, (a lump of naturally magnetic iron ore) to pull a ball up a slope
towards a hole through which it would drop to cycle back to the start.
This didn't work.

Neither do its modern derivatives, and for the same reason. Any work which a magnet does on an object has to be undone to get back to the starting position. (This is also why an unbalanced wheel won't work.) Moving something in a closed loop in either a magnetic or a gravitational field causes it neither to gain or lose net energy. Since this applies to all objects, it applies to every part of a machine, no matter how complicated it is. There's no way of combining many zeros to get a positive result.

This doesn't stop people proposing motors which are driven only by magnetic
fields. These motors have rotors which are pushed or pulled most of the
way around a circle by some arrangement of magnets. There's nothing
impossible about this, but the designers then expect the rotor to suddenly
ignore the magnetic field and to complete the cycle. This gets the rotor
back to its starting point after delivering a net output of energy. This
is impossible.

**Machines which use magnets and wires**

So forget magnets acting alone. Let's mix in some wires and electric
currents. Our whole civilization depends on devices which move wires in
magnetic fields to generate electrical power and other devices which pass an
electric current through a wire to generate motion; that is, on electrical
generators and electric motors.

People are always asking me whether their odd configuration of wires and
magnets will generate a power output from lesser input power. The answer
is no, but it is not always clear from elementary physics textbooks why this is
so. Textbooks are inclined to describe the forces involved without
explaining what the implications are.

**Generating voltages in wires**

Let's start with generators. If you have a uniform magnetic field, say
between the poles of a horse-shoe magnet, and you move a straight wire through
the field so that the field, the length of the wire and the direction of motion
are all at right angles to each other then a voltage will appear between the
ends of the wire. In this simple case it is easy to calculate the
voltage, it is equal to BvL volts. L is the length of the wire in meters, B is
the strength of the field in webers/square-meter and v is the velocity of
motion in meters/second. To put this effect in perspective, 1
weber/square meter (10,000 Gauss) is a much stronger field than you can get
from a small permanent magnet. To generate a field this strong and a meter
across would require an electromagnet weighing several tons. Wiggling a
few inches of wire in the field of a small magnet will produce a few
millivolts. It makes no difference whether it is the conductor or the
field which is moving, only the relative motion counts.

Looking at this effect in isolation, we have a length of wire moving
continuously in a uniform field. No work is needed to keep the wire
moving since, once we have started it off, it is generating no electrical power
output. It took some energy to overcome the wire's inertia when we
started it moving and some more energy to establish the initial field between
the ends of the wire but we will overlook them. (When the wire stops
moving we can, in principle, recover that energy.)

**Completing the loop**

Suppose we want either to measure the voltage generated or to do something
useful with it. To attach a voltmeter or a load resistance we must
complete a loop which contains the bit of wire we are looking at. Suppose we
truly have a uniform field and that it is very large, at least in the direction
we are moving. Imagine, for example, that we are traveling north on rails
between the poles of a magnet which is several miles wide. Our test wire
extends from east to west and the field goes from down to up. We are
traveling fast enough to generate one volt between the ends of the wire.

To make it easy, we are sitting at the east end of the wire so we can hook up our voltmeter up to the east end without any trouble. How do we connect the voltmeter to the west end of the wire? With another wire, of course. But that wire is also going from east to west and is traveling at the same velocity as the first one. It also has a voltage of one volt induced in it. The west end of both wires have the same voltage on them; when we connect them together the net voltage around the circuit is zero and that is what our voltmeter will show. No matter what route the second wire takes from east to west it will have exactly the same voltage across it as the test wire. If we connect a load resistor to the loop of wire no current will flow and no output power will be generated.

What this shows is that in order to generate a voltage in a loop of wire one
of two conditions must hold. 1) the field in one part of the loop must be
different from the field in another part or, 2) the velocity of one part of the
loop must be different from the velocity of another part of the loop.

**Types of loops**

The first condition can be met, for example, by using a small magnet and a
large loop so that only a part of the loop is in the strong field.

Obviously this limits the length of time we can generate a voltage at any given
velocity.

One way to meet the second condition would be to slide the wire through the field on rails. Since the rails would not be moving they would not contribute to the voltage.

These illustrate a general principle which says that so long as the product
of a magnetic field and the area of a loop remains constant no

voltage is generated round the loop. Either the area of the loop or the
strength of the field must change to generate a voltage. You can vary the
strength of the field within the loop by moving the loop from a weak field to a
strong field, that was Case 1 above, or by changing the effective area of the
loop, as in Case 2 above.

Another way to vary the effective area of a loop is to rotate it in the field. This makes its effective area go from +A to -A and back to +A every complete turn. Or look at it this way, twice per turn one side of the loop will, briefly, be moving in the opposite direction to the other. It will generate a voltage which adds to the first side's voltage rather than subtracting. Half a turn later the loop will be generating a voltage in the opposite sense. Thus, if we hook up the two ends of the loop to slip rings we will see an output voltage which alternates as the loop turns. Not only can we measure the voltage but we can get a useful output. We have just invented the alternator.

If the two ends of the loop are connected to a split ring around the shaft
then a brush on each side of the ring will pick up pulses of voltage which all
have the same polarity. By adding loops, each at a slightly different
angle, and connecting each to a pair of segments on a commutator, at any moment
the brushes will connect only to the loop which is moving fastest in the
field. This gives an almost steady output voltage, resulting in a DC
generator.

**What happens elsewhere in the loop?**

Let's go back to that original piece of wire. If it is not at right
angles to the field or if it is not moving at right angles to its length the
voltage generated will be less than in the right angle case. It will be
proportional to the sines of the angle between the motion and the field and the
sine of the angle between the wire and its direction of motion. If the
motion is along the field or the wire is moving lengthwise no voltage will be
generated.

By using this relationship we can, at least in theory, calculate the voltage
round any loop of wire moving at any velocity in any magnetic field by adding
up the contributions from each little piece of wire. Some quite ingenious
ideas fall flat when this is done. The inventors have looked only at the
interesting part of their machine and have ignored the fact

that all magnetic fields loop back on themselves somewhere. The voltage
generated in that part of the loop also has to be taken into account. It
often cancels out the voltage in the rest of the system.

**Where does energy come in?**

As I mentioned, moving a wire through a field requires no energy. That
rotor I mentioned will spin until friction stops it. (I know, I'm
ignoring eddy current losses here.) You can hang a voltmeter on the
output and measure the voltage without any significant effect. By giving
the loop of wire many turns you can generate as big an output voltage as you
please. Using a stronger field, a faster rotor speed or a longer rotor also
increases the output voltage. Unless some current flows no energy is needed
to keep things moving.

**What happens when current flows?**

Let's just stop there and look at another phenomenon which occurs when you play
with wires and magnets. This time let's hold that wire in the uniform
field in a fixed position and pass a current through it. What happens is
that the wire tries to move in a direction at right angles to both the field
and the current. The force needed to keep the wire still is given by ilB
where i is the current in amps, l is the length of the wire in meters and B is
the field strength in webers per square meter. The force is measured in
Newtons.

If we let the wire go it will start moving across the field. Its acceleration will be proportional to the current times the field strength. In Newtonian physics there is no limit to how fast it will go. (This principle has been proposed for firing payloads into space.) However, when the wire moves a voltage is generated across its ends. This is where we came in. The faster the wire moves the higher the voltage generated. This voltage acts in the opposite direction to the current we are feeding in, making it harder and harder to force that current through the wire. For a given current, low speed equals low back voltage and hence low electrical power input. A high speed generates a high back voltage and thus requires a high electrical input power. Now the mechanical energy out is simply equal to the force exerted times the speed. Low speed equals low output power and high speed equals high output power. Are you beginning to see a pattern? Low mechanical power out equals low electrical power in; high mechanical power out equals high electrical power in.

**Computing the input and output powers**

The power in watts which we are feeding into the wire is the product of the
current and the voltage. If the wire is moving at a constant velocity and
is lifting a weight at so many meters per second. Then the
mechanical power being generated is just the product of the velocity times the
force on the wire. The force is proportional to the current and the back
voltage is proportional to the velocity so the input power is proportional to
the output power. When you trouble to multiply out all the units it turns
out that the mechanical power out is exactly equal to the electrical power in.
(With the usual provisos about friction and resistive losses being negligible.)

**Turn things around**

Exactly the same thing applies the other way round when you apply mechanical
power to a wire. As the wire moves it generates a voltage proportional to
its velocity. If a current flows the electrical output power is
proportional to the product of the voltage and the current, that is, it is
proportional to the product of the current and the velocity. Now when a
current flows in the wire it generates a force on the wire. Surprise, surprise,
this force acts to oppose the motion of the wire. To keep it moving you
have to push it harder. The mechanical energy you must apply is
proportional to the velocity and the reverse force caused by the output current.
In this case the output electrical power is equal to the

input mechanical power.

In a way this is rather wonderful. It means that we can convert mechanical power into electrical power or electrical power into mechanical power with practically no losses. This is impractical with thermal power.

Unfortunately, since the equality of power in and power out applies to each
little piece of wire, no matter how it is moving and in whatever magnetic
field, you can never come out ahead. Any device, no matter how ingenious,
which generates an output current also generates a force opposing its
motion. Any device which generates motion from a current also

generates a back voltage which opposes the input current.

**A practical case**

The alternator I described will spin happily with almost no input power until
you connect something to its output terminals. Then a current will flow
which is given by the output voltage divided by the total resistance of the
wire loop plus the resistance the load you apply. If the loop resistance
is not zero the output voltage will drop. The useful output power is this
lower voltage times the current so it pays to use low resistance wire.

By allowing a current to pass you are applying a mechanical load to the
alternator. It thus requires more input power to keep it turning.
The more output power you take the more difficult it becomes to turn the rotor.
I have a DC motor with a built-in reduction gearbox. It is easy to turn
its output shaft by hand when its leads are open circuit but almost impossible
to turn it if they are shorted together. Power out, at best, equals power
in.

**What about the homopolar generator?**

Sometimes it can be quite hard to see just where the current loop is. Faraday
discovered that if you turn a conducting disk in a magnetic field you can
measure a voltage between the shaft of the disk and its rim. This device,
the homopolar generator and its equivalent, the homopolar motorhave been
baffling people ever since.

Consider a disk which is rotating in a uniform magnetic field. The field passes through the disk at right angles to its surface. Any radius of that disk is moving through the field. The parts of the radius near the shaft are moving slowly and the parts near the rim are moving quickly but they are all moving in the same direction so the voltages generates by each little bit of the radius all add up. The result is a voltage all round the rim of the disk which is higher than the voltage at the center.

If you mount a sliding contact at any point on the rim you can measure this voltage. It won't be a large voltage since only a single conductor is moving through the field and parts of it are not moving at the full speed. Suppose you had a copper disk 20 cm (8") in diameter, turning at 10,000 revolutions per minute, and that you could put it in a uniform 0.1 weber field. (This would be a very dangerous thing to try!) The rim will be moving at 105 m/s so the mean velocity of a radius is half that. The length of the radius is 0.1 meters and the field is 0.1 webers so the voltage will be 0.52 Volts, about a third of what you'd get from an alkaline cell!

If your disk had a low resistance, and if the brush contact and the external circuit also had a low resistance, then quite a substantial current would flow from the shaft to the rim. Because the voltage is generated on all radii of the disk you could put brushes all round the rim and reduce the effective generator resistance. Unfortunately the frictional forces on the edge of the rim chew up a lot of input power. As in any other generator, the motion of the disk is resisted by the force which the magnetic field exerts on the output current. Thus homopolar generators are only useful if you need a high current at a low voltage and don't care how much energy it takes to turn the disk.

As a footnote, I mentioned using a uniform magnetic field. You might
think that having a field just between the shaft and the point on the rim where
the brush is placed would be more efficient. Unfortunately, when the
field is not uniform over the whole disk local currents are generated in the
disk, heating it up and wasting input power. This
"eddy-current" effect is the basis of the magnetic brake.
Electricity meters are one common application and some car speedometers also
depend on this effect.

**The homopolar motor**

If you pump a huge current into the disk the magnetic field will generate
enough force on it to make it rotate despite the brush friction. (Early experimenters
made contact to the rim of the disk by making it pass through pools of
mercury. Since mercury vapor is rather poisonous this is not done any
more.) Unfortunately, generating large direct currents at low voltages is a
notoriously inefficient process. AC can be transformed down to get a low
voltage but the rectifying device needed to convert the output to DC tends to
drop about half a volt, making the efficiency less than 50% before you start
moving anything. About the only device which can generate large currents
at low voltages at all efficiently is, you guessed it, a homopolar generator.

**Defeating your own object**

One hopeful inventor thought that you could generate an output voltage without
generating a reverse force by attaching the magnets generating the field to the
rotating disk. Unfortunately, this doesn't work. Only relative
motion of the field and the current carrying disk generates a voltage.
What misled this inventor was that he did measure a voltage when he connected a
meter between the shaft and the rim of the disk. He hadn't realized that
the ring magnets were generating two fields, one in the disk between the
magnets and another toroidal field in the space around the disk. The disk
wasn't generating a voltage but the wire leading to the meter was being cut by
this rotating field and was generating a small voltage. Connecting a
current meter would have shown an output current. However, this current would
have reacted on the rotating field to slow the disk down. As I said before,
you have to consider what is happening

everywhere in the system, not just focus on one part of it and ignore the rest.

The effect was the same as if the disk and magnets were stationary and a contact had been spun round the edge of the disk. The wire going to the contact would have been moving in a magnetic field and all the usual rules would apply.

**Conclusion**

No arrangement of wires and magnetic fields and moving parts is going to
generate more electrical power than the input mechanical power or generate more
mechanical power than the input electrical power. If you want to
experiment, by all means have fun, but please don't think you are going to
bring about an energy revolution. Above all, spend only your own money,
not other people's unless you want to spend the rest of your life dodging irate
investors.

Additional
notes by Eric:

A perpetual motion of new "inventors" thinks they are making fresh
attempts at this "engineering holy grail". I've had scores of
people tell me that they are hoping to fine tune some collection of wires and
magnets that can finally come out ahead. Justifications are given along
the lines, "*if I try hard enough"* "i*t must be
possible because it is needed*", "*xyz book reports someone did
it and then forgot how*", or "*my new theory of physics explains
why it can work*". My prize money for proof of free
energy will be awarded if anyone can show me the real thing working - and I
have no interest in someone's new theory until they win the prize. I feel
the existing formulas comprising relationships between energy, motion, current,
magnet flux lines, fields, etc. do a fine job of explaining evidence.

**What about systems involving batteries?**

Putting an occasional back surge of voltage in a battery can help get a
temporary increase of performance. Also, most batteries after being discharged
and disconnected can revive a little on their own. FE claims involving
batteries never are operated indefinitely which would show if they are just
running down the batteries. Most demonstrations I know of (like the farces Joe Newman puts on)
involve pathetic means of comparing input and output energy levels.
Motors/generators with big sparks are only wasting excess energy and likely
creating illegal noise on radio frequency bands.

Links:

Free
Energy FAQ page

Joe Newman's nutty claims.

History of free energy claims

Eric's discussion of real forms
of free energy

great
discussion of entropy

Eric's history of Perpetual
Motion and Free Energy Machines

Joe Newman's Free
Energy Claims - are they valid?

Free Energy FAQ page

Eric's Page examining Dennis
Lee's amazing claims of Better World Technology

**Tom Bearden’s MEG device **A rational
review of meg claims and Randi’s info and my info

.** free energy scams T**back to Eric's main Dennis Lee page ** **what about Joe Newman? **Also,
****Amin****, ****Mills ****(who may be
legit?) Tilley, Perendev, Bearden Lutec
and ****Tewari** **Xogen** and **GWE Adams **

Get on the Free Energy Email list –

PhACT-FAQ on Heat
Based Free Energy Prepared by Tom Napier

ERIC'S OPEN PRIZE OFFER
FOR PROOF

**Things
you won't learn at a free energy seminar.**

Prepared by Tom Napier. Copyright © 1999, All rights reserved.

You would expect that anyone promoting a machine to generate
free

energy would be an expert on the subject of energy and its measurement.

After all, if you can't measure energy input and output accurately how can

you tell that the output exceeds the input? Of course there is a simple

answer to that. Connect the output of the machine to its input and

demonstrate that it runs continuously while generating significant excess

power. Failing this test, which no free energy machine has yet been seen

to pass, you must rely on measurements of input and output power. You

must also know how to compare them.

Well, if there is one thing which free energy promoters seem to
have in

common it is a massive ignorance, real or feigned, about what energy is

and how to measure it. Luckily for them, their audiences seem to share

this failing and thus cannot readily distinguish between the plausible and

the possible. To remedy this lack, this note attempts to summarize the

basics of energy in two thousand words or so.

**What is energy?**

"Energy" is a general concept which scientists and
engineers use to

make their sums come out right. Energy comes in many different forms,

light, heat, mechanical motion and electricity are all forms of energy but

these can all be measured in the same units. When you change one form of

energy into another you always end up with exactly as much as you started

with, if you have accounted correctly for all the inputs and outputs.

This is such a basic idea that it is given a name, the Conservation of

Energy. It is the most fundamental of the scientific laws. By the
way,

it is a generalization from observation, not something which spoil-sport

scientists just made up because they liked it.

In practice, when you convert energy from one form to another
some of

it is invariably converted into an undesired form such as frictional heat.

This subtracts from the useful output energy. Thus the useful output of a

conversion device always contains a bit less energy than its input. This

is expressed in the form of an efficiency, (Useful output)/(Necessary

input). Since useful energy is always lost the efficiency is always less

than one.

We are used to the idea that scientists and engineers are
making

constant improvements in things and efficiencies are always rising. Is

there a limit to efficiency? After all, the idea behind one type of free

energy machine is that one can make the efficiency greater than one, hence

the name "over-unity" applied to such devices.

An over-unity machine would require an input of energy in some
form to

make it run but it would generate more energy, in the same or a different

form, than it consumes. As mentioned above, the simple way to prove that

a device is "over-unity" is to run it from its own output. No
matter how

many calculations you may be shown to "prove" that a machine is over-

unity, if it can't pass that test then it isn't.

**Mechanical energy**

Let's define a few terms without getting too technical.
Force should

be a familiar concept. A push from a spring is a force and so is the

weight of an object. However, until the thing to which the force is

applied actually moves, no work is done. You may think you are working

hard when you hold a weight up in the air but you aren't really. You

could be replaced by a shelf which does no work at all. When you lifted

the weight off the floor you did do work. You exerted a force for a

distance and that is the definition of "work," Force times
Distance. In

this case the work, or energy, would be measured in foot.pounds.

Because you lifted it, the weight has acquired energy which it
didn't

have when it was on the floor. You could get this energy back again by

letting the weight fall, for example by connecting a string to the weight

and letting it drive an electric generator. (Of course you could just let

the weight fall. Then its energy will go into making a hole in the

floor.)

No amount of push represents energy unless the thing being
pushed

moves. One demonstration you might see is a car engine bending a torque

wrench. Torque is just a force which tends to make something turn.
It is

measured by multiplying the force by the distance from the pivot. Funnily

enough this also gives foot.pounds but this doesn't mean that torque

equals energy unless the thing the torque is applied to moves. If the

shaft made a complete turn then the torque would have been exerted through

2 pi radians. The work done would have been equal to 2 pi times the

torque.

**Power**

Power is simply the rate of doing work, that is, it is work
done per

second. A one horsepower motor outputs 550 foot.pounds per second.
That

is, it could lift a 550 pound weight at one foot per second or a 50 pound

weight at 11 feet per second.

One way of measuring the 1 HP output would be to apply a brake
to slow

the motor down. This is wasteful, all the motor output is converted to

heat, but it allows you to measure the motor's output at any speed you

want. The torque exerted on the brake can be multiplied by 2 pi times the

rotation rate to calculate the output power. For example, suppose the

motor was rated at 1 HP at 3000 rpm. If you braked it to run at 3000 rpm

then in each minute it should generate an output of 550 times 60

foot.pounds. At 3000 rpm this is 11 foot.pounds per turn, corresponding

to a torque of 11 divided by 2 pi or about 1.75 foot.pounds. If you

measured the force on the brake at one foot from the motor shaft it should

be 1.75 pounds if the motor is performing as planned.

Normal electric motors become very inefficient if you brake
them so

that they run much slower than the makers intended. When running at their

normal speed, motors are from 75% to 90% efficient. If you hear of a

device which doubles the output of an electric motor this doesn't mean

that it has gone from 80% to 160%. It is much more likely to have gone

from 10% to 20%.

Mechanical energy is commonly measured in the foot.pounds used
above

and mechanical power in foot.pounds per second or, with the 550 conversion

factor, in horsepower. (This is all much simpler in the metric system.)

Since many over-unity systems use electric power either as an input or an

output we need to be able to measure electrical power and to compare it to

mechanical power.

**Electrical power**

Since we usually encounter electricity in the form of a current
which

supplies continuous power it is much more common to refer to electrical

power than to electrical energy. Thus we talk of watts or kilowatts, the

units of power. In mechanics our basic energy unit, the foot.pound, was

divided by time to get the rate of power usage. In electricity we

multiply power by time to get total energy. Thus the electric company

bills you for your energy usage in kilowatt.hours.

Two things need to be considered next. How to convert
from electrical

measurements to mechanical measurements and how to measure electrical

power. Let's take the easy one first. If you compare the units in
which

electrical and mechanical power are measured you find that one horsepower

is 0.7457 kilowatts. One outcome of this is that if you had an over-unity

electric motor it would drive that brake I mentioned at a 1 HP output

level using less than 0.7457 kilowatts of input. If the motor is 85%

efficient, a typical figure, it will actually take 0.7457/0.85 or 0.877

kilowatts to drive it.

**Measuring electrical power**

Measuring electrical power is very easy in principle and very
difficult

in practice. If the current and voltage going to a device never change

than the power input is simply current times voltage. Both can be easily

measured with an accuracy of a percent or so. Unfortunately, while supply

voltages, as from a battery, can be almost constant, currents vary rapidly

with time, particularly when you are driving a motor. Most current meters

measure the mean value of the current. This will only tell you the mean

power if the voltage is absolutely steady.

If the voltage changes when the current changes, which it
almost

certainly does, then measuring the mean current gives quite the wrong

value for the power. What you have to do is to use a wattmeter.
This

multiplies the instantaneous voltage by the instantaneous current to get

the power and then averages the power to arrive at the mean value.

However, even accurate wattmeters can give spurious results if the current

contains very fast spikes. The current into electric motors often does.

Things get much more complicated when the power source is
alternating

current (AC). Then, even if the mean current and voltage are absolutely

constant the power can be changing.

There are two ways of measuring AC voltages and currents.
Cheap meters

assume that the AC voltage is always a pure sine wave. They turn it into

half cycles all in the same direction and measure the mean value. Then

they apply a correction factor to convert this into a true voltage. Since

the AC voltage is rarely a pure sine wave and AC current almost never is,

cheap meters are unreliable even when measuring voltage, much less power.

They only give reliable results if the load you are connected to is a pure

resistor such as an electric heater.

The alternative is to use an RMS meter. (Root Mean
Square, it's a

description of the averaging method they use.) This will give a correct

voltage or current reading unless there are spikes in the current.

There are two standard ways of measuring current. One is
to pass the

current through a small resistor and to measure the voltage. This is

potentially accurate but is prone to error in practice since the voltage

measured is usually in the millivolt range. It is easy to pick up

interference or to include more resistance in the circuit than you mean

to. The alternative is the "clip-on" ammeter. This can
also pick up

interference and may not be better than 5% accurate anyway. Not all clip-

on meters can measure DC.

**The power factor problem**

Even accurate RMS voltage and current meters cannot measure
power input

or output. This is because of the so-called Power Factor (PF) of the

source or the load. The PF is the ratio between the real power and the

product of the current and voltage. It is the cosine of the phase angle

between the AC voltage and the AC current. Luckily the true power is

never greater than the product of the RMS current and voltage so current

and voltage measurements give an upper limit to the input power of a

device. They should not be used to measure the output power.

The PF of a device can range from one down to zero.
Resistors have a

PF of one but pure capacitors and inductors have a PF of zero. Most real

devices are designed to have PFs close to one but the real power input or

output of a device can be close to zero even when input large currents are

flowing.

To take a dangerous example, if you connected a big capacitor
to a 110

V outlet a huge current would flow through it but your electricity meter,

which measures watts quite accurately, wouldn't register any power drain.

Unfortunately the current flowing through the wires leading to your house

would make them heat up so the power company would be supplying power

which no one would be billed for. They don't like doing this which is why

they are likely to disconnect you if you try this experiment.

Electric motors are quite inductive and show a similar
effect. This is

why large electric motors are fitted with capacitors. These stop them

taking more current than their power rating would indicate.

Thus to measure the output power of a device you must use a
meter which

takes the power factor into account or which uses the same instantaneous

multiplication process mentioned above for DC power measurements.

**The last resort**

Luckily there is a way of measuring electrical output power
which

cannot be fooled. If you drive a resistive load the rate of heat output

is an accurate measurement of the electrical input power. Some RMS meters

actually measure the heat generated by the input power. A good way of

measuring the output of an over-unity device is to connect it to an

electric kettle containing a known amount of water. If the room

temperature is known, and the kettle is well wrapped in insulation, the

time it takes to bring the water to the boil will indicate the true power

output. Just don't bank on any inventor letting you run this test!

**Conclusion**

I hope this note goes some way to showing that there is scope
for error

even in apparently simple input and output measurements. If any device

were really "over-unity" it would be easy to connect its output to
its

input. There's a good reason why that demonstration is never shown, it's

too hard to fake.

The following are usefull power measurement ideas from David:

From: dhowe17@hotmail.com

Paul MacDonald <paulmacdonald1@xxxxxxxx.xxx> wrote:

>A better way is to measure the voltage drop across a resistor.
Man, if you

>took a repair course, you would have been soundly scolded. A clever
term for

>this is "fault finding by smoke" another term that almost applies
is

>"crowbarring" (where you put some tin foil over a blown fuse).

Agreed. A shunt resister is the way to go in these cases. Use a
low-resistance,

precision resistor and measure the voltage drop across it with a millivolt

meter. In DC circuitry you can get really accurate results if you're
careful

with your calibration.

It's a whole different ball game with AC circuitry. Phase differences
between

the voltage across the device and current through the device make power

measurement tricky, to say the least. This is why RLC circuitry shows up

so often in free energy devices. The experimenter usually uses standard

AC voltmeters and ammeters which are fooled by non-sinusoidal waveforms.
Many

of the off-the-shelf meters are even fooled by non-unit power factor (cosine

of the voltage-current phase difference). Measure the electrical input
power

into the device with one of these off-the-shelf meters and you get a very low

number. Compare it to the output power (shaft, chemical, etc.) and you
have

what looks like free energy. Add a DC offset to the AC signals and
virtually

any off-the-shelf meter is screwed. (Dennis Lee makes great use of this

error in his traveling road show.)

When you get right down to it, the best way to measure power into or out of

a device using RLC circuitry is to use a shunt resistor on one of the leads

and to measure the voltage drops across the resistor and across the device.

A high-speed data acquisition system with simultaneous sampling of the two

voltages is a must. And the acquisition rate must be at least twice the

frequency of the highest harmonic you hope to resolve. Low-pass filtering

will help eliminate aliasing of frequencies above the Nyquist.

The shunt resistor voltage record is then translated into a current record.

Then for each instant in time, the corresponding voltage and current values

are multiplied to calculate an instantaneous power value. This
"power

waveform" is then integrated with respect to time.

National Instruments makes a data acquisition card for the PC that will
sample

four channels simultaneously at 12 bits and 5 MHz/channel, for a mere $3000.

They've got some less expensive ones, but they don't sample simultaneously.