Naked Science Forum

Non Life Sciences => Technology => Topic started by: Yahya on 27/05/2015 17:15:24

Title: Will this magnetic piezoelectric device work as a generator?
Post by: Yahya on 27/05/2015 17:15:24
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Title: Re: The magnetic piezoelectric generator
Post by: evan_au on 27/05/2015 22:34:14
Quote from: Yahya
it has output work more than its input work
What matters is the efficiency:
The principle of conservation of mass/energy suggests that no device can produce more energy than it consumes. This is a pretty high bar that demands more evidence than an explanation of a diagram.

Quote from: Yahya
12500 V  is huge
A device with an open-circuit voltage of 12500V delivers no power, so it has zero efficiency.

Piezo electric generators are effectively insulators, so they have a very high source impedance. They can deliver only very low currents, which translates into fairly low power levels (less than you put in).

Some of the input energy is converted to heat in the crystal, and some more is converted to fractures in the crystal structure. Even more is wasted as heat in the source and in the load.

Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: RD on 28/05/2015 12:29:34
yes the efficiency is more than 100% ...

Not possible , even Homer Simpson knows that ...

Quote
energy can be transformed from one form to another, but cannot be created or destroyed.
http://en.wikipedia.org/wiki/First_law_of_thermodynamics

Obtaining power from human-movement is very costly ...
http://news.cnet.com/8301-13512_3-9779334-23.html
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: RD on 28/05/2015 13:53:34
this device has nothing to do with human movement it is a generator can be moved by many means.

Your device, nor any other, cannot multiply energy from any source, human or otherwise.

Force can be multiplied by machines, but energy cannot. Energy cannot be created (or destroyed) ... http://en.wikipedia.org/wiki/First_law_of_thermodynamics

You'll find like-minded individuals in "Over-unity (https://www.google.com/search?q="Over+unity"+scam)" forums , but you're all* wasting your time.

[ * except the scammers there who sell suckers kits to build machines which allegedly defy the 1st law, they're raking in the cash ].
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: RD on 28/05/2015 16:42:18
this device works, thus violates the first law of thermodynamics, there have been attempts through history to create energy and this is a successful one.

You are mistaken. There never has been, and never will be, a device which can make energy.

Apparently people will be perpetually-interested in the concept of perpetual-motion machines, but such "over unity" energy-making machines are impossible ... http://en.wikipedia.org/wiki/Perpetual_motion#Impossibility
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: RD on 28/05/2015 21:50:11
..impossibility is not in science, every theory or law can be withdrawn

It's not like law enforced by humans which can be broken, it's a fundamental physical law (http://en.wikipedia.org/wiki/Physical_law) : a law of nature which cannot be broken.

  it is the law of thermodynamics and not the law of Moses

You have your priorities wrong way round : the laws of Moses can be broken , the fundamental laws of physics cannot.

... people thought in the past that nothing heavier than air can fly

Can only be true of people who had never seen a bee, a bird or a bat.

Can you give an example of a natural process which makes energy ? : that would be proof-of-concept that such a thing is possible. If the known-universe has not come up with an energy-creating-system in billions of years, what makes you believe you can make such a thing ? , ( other than the Dunning-Kruger effect (http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect) ).
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: RD on 29/05/2015 16:10:34
this device is simple , and its functionality can be traced very easy as I showed in the nine steps ...
Each step has conversion losses (http://en.wikipedia.org/wiki/Energy_conversion_efficiency#Example_of_energy_conversion_efficiency) : so a 100% efficiency from any device is not possible.  A hypothetical energy-generating device would have over 100% efficiency, ( a fantasy).

... every perpetual motion device has its flaws ...
True , as none of them has, or ever will, work as described ... http://en.wikipedia.org/wiki/Perpetual_motion
 
 So you're wasting your time trying to create one which does , ( you can't say we didn't warn you ).
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: alancalverd on 29/05/2015 18:36:57
As the device is so simple, why not make one and let us see the result?
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: Colin2B on 22/06/2015 22:59:04
how I will be able to measure the power of a small bulb?
You would do better to use a standard resistor and measure the current and voltage drop, a bulb is too imprecise resistance changes with temperature of filament.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: Colin2B on 24/06/2015 11:00:43

will a standard resistance and current measuring be enough ? will I need a voltmeter or just an ammeter ?  I think I can apply this law : power=I^2 *R
Yes, or measure voltage drop and use V2/R.
Your main problem will be if you dont have a constant voltage. You might need to measure with an oscilloscope to see the exact waveform, as a meter wont react correctly - even set to AC a meter will expect a sinewave.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 02/07/2015 18:12:40
If everything was made perfectly and perfectly rigid it would probably be quite efficient; but not over 100%.

The screw-case things include:

- any flexing in the mounts dissipates energy, things vibrate and take energy away. If they were perfectly lossless, this wouldn't be a problem... but:

- the piezo generator flexes slightly when it's generating; this behaves much like a flexure, but the energy goes into electrical energy, and you don't get this energy back again; it's gone into the electrical circuit and lost in resistance of the bulb or whatever you're driving. So the magnet has to actively get pushed down when repelled, and it has to actively get pulled back up when it's attracted, which takes energy. That slight difference causes drag associated with the generation, so you can't be 100% efficient.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: Colin2B on 03/07/2015 18:23:20

yes but this output electrical energy is more than the mechanical input energy.

I'll be waiting to see this. With some scepticism!
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: chiralSPO on 03/07/2015 21:34:34
conservation of energy

If your device actually produced energy, it would violate the first law of thermodynamics. If it produced no energy, but worked at 100% efficiency it would violate the second law of thermodynamics.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 03/07/2015 22:37:52
So the magnet has to actively get pushed down when repelled, and it has to actively get pulled back up when it's attracted, which takes energy.
the magnet is always at equilibrium , the repel force is always equal to attraction force, the distances will always be the same while magnet 3 moves from left to right and all magnets are identical .
Nope. Piezoelectric crystals flex slightly when they generate electricity. This fact is used for quartz crystal; they set up a mechanical vibration in a thin-cut piezo quartz crystal, by driving it electrically.

The flexure is critical to how it works, it's impossible for it to generate energy if it doesn't move slightly; but as soon as it moves, it upsets the symmetry and your system is no longer 100% mechanically perfect; and it will grind to a halt.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: alancalverd on 04/07/2015 14:35:30

does quantum mechanics depends on first law of thermodynamics ? what other physics realms depends on first law of thermodynamics?

There's no "dependence".

Quantum mechanics (QM) describes how very small systems (like atoms and molecules) work, and whilst it is theoretically possible to describe a big system (like a steam turbine) by quantum mechanics, it is impracticable an unnecessary to do so. All that matters is that whatever prediction we make by QM should degenerate to the observed behaviour of large systems as described by classical mechanics.

Large systems all appear to behave as though ruled by thermodynamics (TD). QM allows for local fluctuations that are not described by classical TD but when averaged over a large system and an observable time, QM again degenerates to TD.

Your proposed device is a large system.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 05/07/2015 00:13:32

Nope. Piezoelectric crystals flex slightly when they generate electricity. This fact is used for quartz crystal; they set up a mechanical vibration in a thin-cut piezo quartz crystal, by driving it electrically.

The flexure is critical to how it works, it's impossible for it to generate energy if it doesn't move slightly; but as soon as it moves, it upsets the symmetry and your system is no longer 100% mechanically perfect; and it will grind to a halt.
I think the change is 0.1 % of the volume of the crystal when it is pressed ,which may sound little distance to affect the magnets distance from each other and their equilibrium .
Yup, sounds about right. But that movement, small as it is, is completely central to how piezoelectric materials generate energy. And energy is force times distance, so we're not talking about the piezoelectric materials making much energy either.

Also, the thing you're missing is that piezoelectric materials are symmetric; a movement generates electricity, but also electricity causes movement; so when the circuit is using electricity, it's changing the shape of the piezoelectric materials. So the amount of asymmetry is proportional to how much power you're extracting.

And that's why it doesn't work.

There's no such thing as a free lunch.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: Bored chemist on 05/07/2015 10:41:45
I was just wondering , what part of physics would be violated if such device worked.
most of it. there's a whole bunch of things that rely on the conservation of energy.
Also since the conservation law follows mathematically from the symmetry of the universe with respect to time, the whole lot would probabaly need to be re-written because time is involved in most of physics.
https://en.wikipedia.org/wiki/Noether's_theorem#Example_1:_Conservation_of_energy

To cut a long story short; if your idea works you will redefine time.
Or, to put it another way, since we have observed how time actually works, you idea is mathematically proven to be impossible.

Perhaps you should have checked on that before you spent the money on the magnets.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 05/07/2015 13:48:16

 And energy is force times distance, so we're not talking about the piezoelectric materials making much energy either.
I can increase  the force as I want by increasing the strength of the magnets and that won't affect the equilibrium, also I can increase the number of devices to generate more power moving them with the same little force.
Nope, the retarding force caused by the distortion of the piezoelectric materials is proportional to the strength of the magnets.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 09/07/2015 23:41:05
Piezoelectric materials act like electrical pumps, as you mechanically squeeze them, they pump electrons around a circuit, (or they try to- if they're open circuit they won't move, unless they arc across.)

Like a pump, this means that they act as a mechanical damper reducing and opposing the motion of the magnets that are pushing on the magnets mounted on them; it takes work to pump those electrons, just like it takes work to pump up a bicycle tyre.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 11/07/2015 22:07:58
No, of course it's not right.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 12/07/2015 16:58:28
The repulsive pole of the moving magnet, as it moves onto the piezo; the piezo will go down under the force it applies, but as it goes past, it will not lift back up again until the opposite magnetic pole approaches; so the force going towards it is higher than the force going away- it's a net retarding force.

As the other pole approaches, the attractive force initially will be less, then the magnet will be pulled up, and then as it leaves it will have to apply more force to get away again, because the magnet is then closer.

The net effect is that the moving rotor needs a net force to be present in both parts of the cycle to generate energy.

Conservation of energy is not an optional thing in physics!
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: Colin2B on 13/07/2015 11:41:58
......also the efficiency of this device is more than the efficiency of the rotating electrical generator.
So, do we assume from that comment that you have built and tested the device and taken measurements?
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 13/07/2015 20:59:44
Instead of building it in a straight line, why not build it in a circle and make a rotary piezoelectric generator?

It turns out that linear generators are less efficient because you get end effects.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: alancalverd on 14/07/2015 16:04:40
Conservation of energy.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: Bored chemist on 02/08/2015 10:27:58
I think I took the wrong way for this thread by claiming that this is an energy from nothing device , I learned that it is not important for a device to be an energy from nothing device to be useful, so will this magnetic piezoelectric device work as a generator?

Badly.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 26/08/2015 21:00:01
I think I took the wrong way for this thread by claiming that this is an energy from nothing device , I learned that it is not important for a device to be an energy from nothing device to be useful, so will this magnetic piezoelectric device work as a generator?

Badly.
Actually, no it's probably a practical device, particularly if you make it circular.

It's just a piezo generator; people build them into shoes and all kinds of things. The opposite thing- piezo motors are also practical.

It's just not a magical thing that can generate free energy/overunity etc.

Instead of building it in a straight line, why not build it in a circle and make a rotary piezoelectric generator?

It turns out that linear generators are less efficient because you get end effects.
rotary generator is difficult using magnets ; it will be more complicated , beside I do not need for the moving part to move at high speed moreover if it moves at high speed it will loose magnetic effect, i.e magnets will not work , so the moving part will move in harmonic motion with little speed and sufficient efficiency.

You'd better tell the national grid that, those lights you're sitting under; they're powered from rotary generators.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 28/08/2015 11:57:55
The flaw is that you think that piezo materials don't flex very much, so you think that means that they don't flex significantly.

You've conflated the two.

If you assume that they don't flex significantly, while still generating energy, then you would believe that they violate conservation of energy.

In fact, although they don't flex very much, the force needed to flex them that small amount is really quite high, and when you multiply the force by the distance to calculate the energy you discover they are fairly efficient, and energy conservation is not violated.

To put this in perspective, the change in shape of a piezo material is usually 0.1%, which is very small, and to make practical devices manufacturers usually bond the material to a metal plate. When the metal plate flexes/is flexed; this implies an enormous force. It's very similar to bimetallic strips; thermal expansion and contraction involves similar extreme forces that are large fractions of the breaking stress of the material, and piezo forces are comparable.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 28/08/2015 15:43:03
Piezotransducers usually work best at a resonant frequency, usually a few kilohertz. It's unlikely that a linear generator will be fast enough for that. A rotary one is likely to work better.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 03/09/2015 17:58:23
No. Piezoelectric materials only produce current when they move; you can get voltage- until it leaks away from compressing or stretching these materials, but not continuous current.

When it's moving, you can run it through some diodes to produce a near DC current, particularly if you wire it 3 phase, but you will still have some ripple.
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 03/09/2015 23:04:24
Current flows only while the pressure is increasing or decreasing. If you just put a steady force on it, no current.

Otherwise you could just put a brick on it, and drive a bulb off it forever! THAT DOESN'T WORK!!! ;)
Title: Re: Will this magnetic piezoelectric device work as a generator?
Post by: wolfekeeper on 04/09/2015 13:54:47
Why don't you try it? Piezo transducers are cheap and will also work as generators. I recently bought 5 at 37 pence each from RS components. You can get magnets for similar prices.

You'll also need: wood, superglue, a saw, and a multimeter

I recommend attaching the magnet to the center of the transducers and mounting them at their edges. However you attach the magnet- make sure the transducer can still flex.