I have been wondering about something about Piezoelectricity. If you squeeze the crystal does it release electricity as you squeeze or does the crystal have to go back in place before more electricity can be released? Basically if there is continuous pressure on the crystals will the crystals emit electricity? I don?t know if this is best way to explain it without being in person.
The crystal converts the pressure energy into charge separation.
For example you could have, when you sqeeze, a plus-minus separation on two faces.
Then, when you release, the crystal does the exact reverse (it 'sucks' inside the charges produced before, or if the charges have been shorted, it creates new 'inverted' minus-plus charges).
F_dyne
I agree.
It is a static action; increase or decrease presure and the voltage follows, ignoring losses and inconsistancies.
Attach a mirrors to several modulated piezos and make a laser show! ;D
Quote from: f_dyne on March 27, 2008, 02:17:04 PM
The crystal converts the pressure energy into charge separation.
That's true!
Quote from: f_dyne on March 27, 2008, 02:17:04 PM
(it 'sucks' inside the charges produced before, or if the charges have been shorted, it creates new 'inverted' minus-plus charges).
Well, that's not really correct.
The principle of the piezo is simple. If you press the chrystal, the different charged atoms in the crystal lattice get forced into a non-symmetric configuration, and therefore now the chrystal becomes an electret!
It does neither absorb nor output any electrons, for it is an insulator!!But if it becomes an electret it will generate an electric field! And if you now place a neutral conductor nearby (two plates) they will try to exchange electrons so long until the electric field of the two plates completey cancels the electric field of the "electret" (Piezo) (So you will see a current from one plate to the other). If the two fields cancel each other out, so that the total E-Field is 0 as seen by the two plates, no current will flow anymore. If you now release the force on the piezo, it will loose it's electret properties and become a conventional insulator. But the two plates which still have their E-Field, due to the charge imbalance made before, will now again try to get a 0-Field, and so current in the other direction will flow until the plates are again neutral. (BTW: The second part is nothing else than a conventional discharge of a capacitor with the chrystal as insulator)
just because something is an insulator doesn't mean electric can't flow through. A good insulator is an excellent resistor.
If you press it, you'll get electricity. If you hold it, it won't give you anything. However, if you are clever and make a rod that stick to it really tight, then extend the rod to the sky and attach a plate to the rod, the air will cause the rod to go back and forth creating cyclic stress. Now you have alternating current. These kind of current are high voltage low ampere current. Most of the time people ignore it because they don't know how to harness it.
Interesting idea there atomicX.
It got me to thinking about a different types of wind generation as you were posting.
What if the panel in the air were shaped as the picture attached (or even better yet as "wings", I'll explain later.) would the shutter movement opening slots in it's opposing sides that are alternately opened/closed depending on the shutter.
If it faces into the wind, the shuttering of alternate sides, it rocks back and forth which twists a plate between 2 quartz crystal slabs (I'm not even sure if they can be formed that way, or the cost) creating an alternating current from each plate that is diametrically opposed in charge?
Perhaps a better arrangement might be vertically mounted wing blades that provide alternate lift/drag into the oncoming wind and could be varied slightly to create an oscillating effect without too violent a stress reversal and low energy cost for that wing blade movement.
But what is the voltage/amperage potential per what size crystal with what amount of pressure?
Does it scale linearly with size of the crystal and compressed surface area?
Does force have to be applied over the entire face of the crystal structure to generate current, or can the alternate crystal end compression method proposed above work?
My experience w/ piezo electric is limited to cheap quick shop lighters, but they've always fascinated me and I've wondered since they (piezoelectric devices) can be manufactured so cheaply why that can't be scaled to different applications.
The trick in harnessing (or more correctly "harvesting") useful energy from a piezoelectric crystal is a 2 stage circuit
1. AC/DC converter to get the flow one way.
2. DC/DC converter to provide the proper power to charge a rechargable cell.
Penn State researchers were working on a circuit for this a few years back (i'll find the link later)
Oh...it was late, and so now is this picture.
But that's what i was talking about above.....
You have good design concept ex. I'm really simple mind. What I would do is make a huge weight sitting on top of surface made of peizo quartz. The huge weight have intetmediate connection to diodes which allow current to go 1 way. We just sit there and collect dripple of current passing through the diodes array (like hypersonic mention). You can incooporate wind pushing details to enchance the current. But if you have the size of the great pyramid sitting on top of the quartz, I think there's enough electricity to fry some chicken dinner.
You have to understand that it's not the size or the force. It's the effective force, or pressure. If you have 10 kg sitting on a 100m^2 surface, there is almost zero pressure. If you put 10 kg on a pin like surface, you're now exerting enormouse pressure.
@ atomicX
Yup, that's (lots of pressure in a small area) sort of where I was going, but I didn't think enough into it @ the time.
The variable wing/vane concept would work much better for keeping the wind assembly facing into the oncoming wind and be up/down capable instead (from the same concept that gives us flight), as well as alternately being oriented for side to side motion.
EDIT
The up/down pressure potential is good as it uses the weight of the pole as a constant and if the "wings" were horizontal to provide "lift", you could oscillate between lift/drop for compression variance.
But that would be only 1 area of generation, and the fulcrum addition might make it possible to have 2.
If the pole or post the wind assembly is mounted to functions as a fulcrum for the compression material the "slab" of quartz becomes 4 separate quartz crystals mounted @ the 4 corners of the compression material so that leverage can exert much more compression force in proportion to the wind strength.
EDIT
See the attached pic.
But before I'd go farther into it, I'd like to get some answers to the questions I posed before as to whether the research and development into the idea would be fruitful.
I'll do some web crawling a little later today to see if I can find some hard numbers on piezo output.
couldn't find that penn state article, but here is a great primer on all things piezoelectric (with emphasis on ceramics, lots of useful numbers and formulae in the tutorial) http://www.americanpiezo.com/piezo_theory/index.html (http://www.americanpiezo.com/piezo_theory/index.html)
piezo crystals are not very strong, it's that very property that allows the compression in the first place. piezo ceramics and films are showing promise since they have higher output and greater mechanical strength.
Ok now I got a closer look at your system. I think you got it reverse. The crystal is suppose to be sandwich between the conductor. Let me see if I can come up a design.
got it
check my 10 min invention out lol
No you had it right the 1st time, I just omitted the box it would be put into (2nd conductor).
(That's what i get for 5 min. instructional graphics.)
I do like your wave device though, that is the only ocean wave generation idea that's made sense to me besides the damming of coves and harbors @ high tide to use the captured seawater as an propellant for generator wheels.
Could you also have crystals w/ conductors on the sides to reap the side to side impact of the roller weight?
Oh alright, then your device would work. We just need to improve on our impulse. The abrupt change in pressure is the key to victory. I would change my balls into balls with spikes. hehe And I think I could take out the diode since we don't need direct current to generate electricity. You should just forget about the peizo and turn your device into a pure wind generator. Make the rod hella high to amplify the swing. That's ton of free torque for use on the ground. Matter of fact, keep on doing the peizo, I'll steal your idea to make wind generator. hehe
Only if we get a hold of some big peizo crystals. Meanwhile, we'll just play around with design until our time come. lol
Let me see if I can amplify your device and turn it into a machine
How's this
I've combine the wind generator to peizo apparatus
I like the designs.
I'm not really sure I'm understanding the 1st concept w/ the wheel, but the next is pretty self explanatory.
The issue w/ the second might be if the piezo can generate more current than a standard generator.
I need to study a bit more as I'm not sure if a constant pressure will generate a current or if it would need to be a constantly varying one.
I've looked up the piezo capabilities of synthetic quartz (since it can be formed) and wondering if either of our ideas might make a more efficient harness of wind power for generation.
I STILL think the wave generator is the best design yet. ;)