Sorry... I don't want to seem inconvenient, but I had one more idea... ::)
I call it the the "piezoelectric-magnetic hammer", and it looks like this:
How it works (or should work):
If that electro-magnet over there is not getting electric current, but it suddenly receives a quick pulse of electricity (just a few miliseconds) in such a way that it causes magnetic REPULSION with the permanent magnet below it, the permanent magnet will be pushed down. So the hammer in the other extremity will go up, and then, gravity will pull the hammer, and it hits the piezoelectric material.
So, everything depends on how much electricity the piezoelectric material can generate, and how strong is the permanent magnet (the stronger it is, stronger will be the repulsion towards the same pole of the the electro-magnet, even if the electro-magnet is not so strong).
Can we dream that the piezoelectric crystal has capacity to generate enough electricity to activate the electro-magnet with a magnetic field sufficient to cause a strong repulsion towards the permanent magnet?
Wow...
In an extreme situation you can imagine that, at each impact, the piezoelectric crystal can charge TWO capacitors. So, after seconds, only ONE capacitor is discharged to generate the pulse in the electro-magnet! Then we have a new impact, and TWO more capacitors are charged... This is insane!
Is it just delirium?
Allright, I'm starting to think that it's not just delirium...
Look what this guy did with only 3 volts and 480uF:
http://www.youtube.com/watch?v=6nowIn-QdbE
Magnetic repulsion between neodymium magnets and eletromagnets is huge!
And I also found this:
http://home.howstuffworks.com/question383.htm
"How does the lighter in a BBQ grill work?"
See what they say:
"For example, in a BBQ lighter, the popping noise you hear is a little spring-loaded hammer hitting a crystal and generating thousands of volts across the faces of the crystal."
I got it right? Thousands of volts? We only need 3 volts!
Even if we have very few milliamps, but with thousands of volts we can compensate for that...
OK, now this is good:
http://www.electronics-manufacturers.com/products/piezo-generator-245.html
"Ceramic multilayer generators are built up with a number of thin ceramic layers sandwiched between internal electrodes, resulting in a low output voltage but high current compared to conventional single layer piezoelectric generators."
We can use these with higher current and lower voltage!
And to improve the design of our device, we can put another piezo generator above the hammer, so when the hammer goes up it will impact a piezo generator, and when the hammer falls (pulled by gravity) it will impact a second piezo generator. Two piezo generators impacted in a cycle.
High efficiency piezoelectric generators using resonance:
http://www.freshpatents.com/-dt20090611ptan20090146534.php
http://www.ieeexplore.ieee.org/iel5/6171/16493/00762301.pdf?arnumber=762301
Could we activate that electromagnet for 50 milliseconds with the output power of the piezos?
Maybe my hammer can have wires wrapped in it, forming a coil. And we can place a static ring magnet at its side while it's moving up and down, something like the opposite of this video:
http://www.youtube.com/watch?v=xUxGqG8u-ME
Obviously, the effect has to be the same, don't matter what is moving, the ring magnet or the coil.
So, now we can have electricity generation in three points: the upper piezo, the lower piezo, and in the moving coil.
See:
http://www.youtube.com/watch?v=R9QrpwCp9pU
Can someone explain what is happening in this video? It's a little bit confusing, and the description is enigmatic: "piezo, electromagnet feedback".
Multilayer piezoelectric energy scavenger for large current generation:
http://www.springerlink.com/content/9v23732061q6847t/
"The piezoelectric material has been usually considered as a high voltage and low current source. When charging current into the thin film battery or supercapacitor, a larger current is needed to shorten the charging time. In order to increase the current in the piezoelectric energy harvesting, multilayer ceramics were fabricated. N-layer multilayer ceramics decreased the voltage but increased the current N times. The impedance of the multilayer ceramics are matched to 1 kΩ which is similar to the impedance of general electrical devices."
Someone knows how many volts and amps we need to pulse in a small coil to make it in a electromagnet capable of attract a small neodymium magnet 5 centimeters away?
Mini Piezo Generators Make more than 0.5 milliwatt with Random Ambient Vibrations:
http://www.sciencedaily.com/releases/2010/03/100323105952.htm
http://www.physorg.com/news188569711.html
0.5 milliwatt just with random ambient vibrations? How much power this piezo can generate being hit by a hammer???
I think one could just take some soft Iron powder and mix it with Piezoelectric powder, say, 50/50 ratio, then form some toroid out of it so that winding can be applied, the electromagnetic winding would cause the toroid to deform enough to cause the piezoelectric powder to discharge a spark of high voltage.
pretty simple.