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Author Topic: Will this magnetic piezoelectric device work as a generator?  (Read 15934 times)

Offline wolfekeeper

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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.
« Last Edit: 26/08/2015 21:02:25 by wolfekeeper »
 

Offline wolfekeeper

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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.
 

Offline wolfekeeper

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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.
 

Offline wolfekeeper

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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.
 

Offline wolfekeeper

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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!!! ;)
 

Offline wolfekeeper

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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.
« Last Edit: 04/09/2015 14:54:16 by wolfekeeper »
 

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