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Author Topic: A Pendulum should really work  (Read 54392 times)

lumen

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Re: A Pendulum should really work
« Reply #30 on: April 08, 2011, 06:20:43 PM »
Vidar,
In a rotary design, the RPM could be increased to some resonate frequency for higher gain.

The testing I have done was on a high voltage element for a lighter and the measured compression was only about .001 inch. The disks can deflect further but they don't need much deflection for a large output. I believe this is a workable concept with the main disadvantage that they may fail over time.


Low-Q

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Re: A Pendulum should really work
« Reply #31 on: April 08, 2011, 07:57:38 PM »
Vidar,
In a rotary design, the RPM could be increased to some resonate frequency for higher gain.

The testing I have done was on a high voltage element for a lighter and the measured compression was only about .001 inch. The disks can deflect further but they don't need much deflection for a large output. I believe this is a workable concept with the main disadvantage that they may fail over time.
I think that if this works, my guess is that if something fails over time, it will already be covered by the "income" from such a design :)

A little rough, we can say that a modulus of elasticity of a quartz chrystal is about 70 GPa, so that compression of a 1 cm3 chrystal, will at 1 Newton force compress something like 1.4 nanometers. So there is not much compression to talk about.

Increasing the RPM will probably also increase efficiency as the electrostatic properties allows more current as the frequency increase.

Can't wait to try this out.

Vidar

Low-Q

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Re: A Pendulum should really work
« Reply #32 on: April 08, 2011, 09:00:15 PM »
A nice demonstration. It isn't much force required to ligt an LED. Ofcourse it doesn't require much energy to power an LED, but what if we apply tens of Newton, several hundered times pr. second? Should it at least be enough to run a small selfrunner?
http://www.youtube.com/watch?v=Xuw9frP1GNo&NR=1

DreamThinkBuild

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Re: A Pendulum should really work
« Reply #33 on: April 08, 2011, 09:39:00 PM »
Hi Low-Q,

I did a test with a piezo speaker through a 1/2 watt 10 ohm resistor.

The values back were between 10mv - 200mv. 200mv was obtained by dropping a 1/2" steel ball bearing on the piezo. This gives a range from low to high of 10uw - 4mw through 10ohms.

Low-Q

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Re: A Pendulum should really work
« Reply #34 on: April 08, 2011, 10:36:39 PM »
Hi Low-Q,

I did a test with a piezo speaker through a 1/2 watt 10 ohm resistor.

The values back were between 10mv - 200mv. 200mv was obtained by dropping a 1/2" steel ball bearing on the piezo. This gives a range from low to high of 10uw - 4mw through 10ohms.
That is 4mW in a very short time, but from what altitude did you drop the steel ball from?
The LED in the video above require approx 3V and a few mA. Let's say that piezo generate approx 15mW just by tapping it gently with the fingertip.

Thanks for the info DreamThinkBuild, but I now suddenly realize that the point is however not how many watt you get out, but how the energy are generated. With my preliminary knowledge about piezos, these devices does not provide a counterforce when loaded by a LED or resistor. Yes, they will resist deflection when loaded, but the mechanical interference seems not to disturb or counter the force which is applied to it in a significant way.
This means one can put some kinetic energy into the piezo generator, without actually spending energy to generate this energy, because the kinetic energy you put in seems to be equal to the kinetic energy that bounce back once the piezo has being hit.

Like dropping a steel ball on a polished solid steel plate. It will bounce for quite some time, but the loud high frequency sound it makes at each bounce appearently seems to be "excess" energy - which in a piezo will be electric energy rather than sound.

Vidar

DreamThinkBuild

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Re: A Pendulum should really work
« Reply #35 on: April 08, 2011, 11:07:35 PM »
Hi Vidar,

The height drop was around 2" to 3". The piezo was on a wood table so some of the force was dampened. The pulse width is short I didn't take the measurement on the time but it was less then 20msec. I noticed that if you take a small wheel and push it down with a lot of force while running over the piezo, it generates a longer pulse but with a much lower amplitude.

Dbowling

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Re: A Pendulum should really work
« Reply #36 on: April 09, 2011, 12:50:53 AM »
Just a thought.
I know Matt Jones has been mighty successful with his bouncer project, getting it to generate electricity. Take a look at it in combination with what you have been discussing here.
http://www.youtube.com/watch?v=LRkBamhlK8w
In particular, I am thinking about the point on the bouncer that travels up and down, and how that could be made to strike or compress the material you are discussing. Hope that this is worth considering and not a waste of your time.

Low-Q

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Re: A Pendulum should really work
« Reply #37 on: April 09, 2011, 09:38:36 AM »
Just a thought.
I know Matt Jones has been mighty successful with his bouncer project, getting it to generate electricity. Take a look at it in combination with what you have been discussing here.
http://www.youtube.com/watch?v=LRkBamhlK8w
In particular, I am thinking about the point on the bouncer that travels up and down, and how that could be made to strike or compress the material you are discussing. Hope that this is worth considering and not a waste of your time.
The inventor explains that the rotor speeds up when trying to stop the bouncing. The rotor will speed up when you try to stop the bouncing because when it bounce that much, the efficciency are very low due to the non circular movement of the rotating weight. The weight follows then an oval shape which means constantly acceleration and retardation of the weights during each revolution. Stopping the bounce will let the weight follow a circular path and rotate freely. He use this bouncing to generate energy, but this energy is a direct relationship with the energyloss he gets when the machine bounce - also with very low efficiency I would guess.

Taken my preliminary knowledge into account: If he had applied a piezoelectric device, which was fixed to the rig, and also fixed to the table, so no bouncing occoured, he would get the best efficiency and maximum output of the piezo without loosing energy due to bouncing. Only the difference in force applied to the piezo would be the energy source. And a stand still, but yet varying force, does not require energy - because energy are force times distance. If distance are zero, there is no energy input, but still energy output from the piezo due to the difference in applied force.

So, if anyone wants to build a bouncing machine, consider the low efficiency the bouncing applies to the machine. Make it "rock solid", then I believe one can make the most efficient machine.

Vidar

Low-Q

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Re: A Pendulum should really work
« Reply #38 on: April 09, 2011, 09:51:02 AM »
Hi Vidar,

The height drop was around 2" to 3". The piezo was on a wood table so some of the force was dampened. The pulse width is short I didn't take the measurement on the time but it was less then 20msec. I noticed that if you take a small wheel and push it down with a lot of force while running over the piezo, it generates a longer pulse but with a much lower amplitude.
I did read this post once more, and realized you got a very good idea! Imagine a ball bearing-like rotor with spring loaded balls or small wheels which is pushed outward to the outer ring. Inside this outer ring we apply an array of piezos, and thet those piezos be the surface for the balls to roll on. If the surface are very smooth, the rolls would roll freely even if they applies great force to the piezos. Then the energy we get out from the piezos can run a small brushless motor which rotate the rotor... What do you think?

Vidar

Dbowling

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Re: A Pendulum should really work
« Reply #39 on: April 09, 2011, 07:47:39 PM »
I think if you talked to Matt about the bouncer, you would be very surprised by the energy it produces. I have met with him in person, and have been following his progress for a while. He is not the only one going down this path. I don't believe he would claim overunity, but he gets quite a bit from the coil collapse and the unusual rotation doesn't use as much energy as a standard rotating wheel, from what I understand. I could be wrong. With the addition of the voltage produced by piezos, it might be very interesting. I am going to mention it to him as well.

Low-Q

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Re: A Pendulum should really work
« Reply #40 on: April 09, 2011, 08:39:50 PM »
I think if you talked to Matt about the bouncer, you would be very surprised by the energy it produces. I have met with him in person, and have been following his progress for a while. He is not the only one going down this path. I don't believe he would claim overunity, but he gets quite a bit from the coil collapse and the unusual rotation doesn't use as much energy as a standard rotating wheel, from what I understand. I could be wrong. With the addition of the voltage produced by piezos, it might be very interesting. I am going to mention it to him as well.
I would think that a "standard" rotary generator found in most power plants are still the most efficient, most maintenance free, with respect to the energy input requirements - wind, waterfall, waves, steam etc.
But making energy by applying force alone seems to be more interesting since there is allmost no deformation in a chrystal when force are applied - as mentioned 1N force on a 1cm^3 quartz chrystal compress it by approx 1.4nm. Imagine a piezotransducer with 0.2mm thickness and 1cm^2, and apply 1000N of force, the compression is not more than 0.28um (Which is 1000N x 0.28um = 0.28mJ), but the energy output is capable of more than 0.28mJ. So I think it is a good idea to mention the piezoelectric devices to your friend. Let him leave the bouncing machine, and go for a more "silent" generator :)

DreamThinkBuild

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Re: A Pendulum should really work
« Reply #41 on: April 14, 2011, 04:09:12 AM »
Hi Vidar,

I missed this, I don't seem to always get notification that a topic has been replied to.

Quote
Then the energy we get out from the piezos can run a small brush-less motor which rotate the rotor

It might be possible with a more powerful piezo element. That would be a good idea hook the piezo up to it's own pulse coil to push itself from a fixed magnet to the next piezo element. A piezo pulse motor.

I'm getting low voltage when rolling, it could be also the piezo speaker I'm using is low quality also. I hooked it to a LED and wasn't able to light it by hitting on the piezo with a small tack hammer.  :)

conradelektro

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Re: A Pendulum should really work
« Reply #42 on: April 14, 2011, 12:25:51 PM »
It might be possible with a more powerful piezo element.

I am in the middle of building a hybrid of a pendulum and an imbalanced wheel (it is a pendulum when you do not drive it over 360°), and I did some tests and some reading about piezo elements:

---  There are no "powerful piezo elements", we are always getting only µWatts. ---

What I try is to stack many piezo elements and to use their combined output (see the circuit with the many diodes further up in this thread).

But I found that stacking has its limits, because the "mechanical pulse" that made the top element in the stack create some electricity becomes weaker when travelling down the stack. (The piezo elements themselves dampen the hit on the top one.)

May be three elements in a stack is still a useful setup, therefore I want to use many "three element stacks". I am not sure yet, whether stacking is really helping, may be many single-piezo-elements is the better strategy? The trick is to distribute a "hit" over many piezo elements.

First of all I want to come up with a drive for the pendulum/wheel that needs only Microwatts, which might not be possible. I hope that "gravity assists" and that the drive only has to overcome friction in the single bearing and air drag.

The people who built "Bedini Pendulums" needed many Milliwatts (about a thousand times more than I intend to use).

So, first a very low power drive and then many three-piezo-element-stacks or many single-piezo-elements.

Greetings, Conrad

P.S.: At least I get a very low power pendulum out of it (a device to calm your nerves or to drive you crazy, whatever your mental disposition).

onthecuttingedge2010

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Re: A Pendulum should really work
« Reply #43 on: April 14, 2011, 10:16:47 PM »
what you want is a large surface area Piezoelectric flat transducer, not stacked. just volume. if you could make your own you could make some pretty big ones with good surface volume. surface area is very important here.

onthecuttingedge2010

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Re: A Pendulum should really work
« Reply #44 on: April 14, 2011, 10:57:22 PM »
can you imagine a Piezoelectric Transducer the size of a big Gong?