A Pendulum should really work

[lumen]

Vidar,

Interesting concept!
I have a stack of these piezoelectric disks I bought on eBay some time ago for a similar device. I have been distracted on other projects so it hasn't been built but it was going to be a rotary device with disks around it and each disk would have a full wave bridge soldered to it to convert to DC. The DC was going to charge a capacitor (did some tests on this already) and power a small motor to keep the magnet rotating. The disks deflect very little for a good output and should have almost no drag on the rotating magnet.

Your idea gave me some insight to some other ways to do this also. Thanks!

[Low-Q]

Vidar,

Interesting concept!
I have a stack of these piezoelectric disks I bought on eBay some time ago for a similar device. I have been distracted on other projects so it hasn't been built but it was going to be a rotary device with disks around it and each disk would have a full wave bridge soldered to it to convert to DC. The DC was going to charge a capacitor (did some tests on this already) and power a small motor to keep the magnet rotating. The disks deflect very little for a good output and should have almost no drag on the rotating magnet.

Your idea gave me some insight to some other ways to do this also. Thanks!

I also have an idea of a rotor with lots of narrow and long magnets, and a stator with the same amount of magnets fixed to a piezo each. In theory, the rotor will not require energy to rotate as long as the stator magnets doesn't deflect. However, ther will be cogging, but that is not energy loss by itself. But if the stator magnets deflect due to the compression in a piezo, accordingly to the energy output from a piezo, it will not be possible to make a sustaining motor.

So I have asked myself this:
If we apply 1N of force into a piezo, and the piezo compress 1um, the input energy is 1uJ. The question is then: Will the piezo provide at least the same energy, or will it provide more? Will the piezo provide energy according to the force times distance? Or will the piezo provide energy mainly due to the force applied rather than the force (1N) times distance (1um)?

The problem, as you sure have figured out, is the deflection, and how this will affect the efficiency. Because if the stator magnet doesn't have the same distance to the rotor magnet when the rotor magnet has passed, it will take more energy to enter the stator magnet, than it gives back after the rotor magnet has passed, we have energy loss.

Hmmmm....I wonder...

Vidar

[conradelektro]

It is obvious that the amperage coming out of a piezo element is very low (because it is an electrostatic effect). Whatever we do, we will not make the piezo effect more powerful in any significant way.

Therefore one has to come up with a "drive" that uses very low power (in the range of µA).

May be I am wrong, but I am aiming at a heavy imbalanced wheel or heavy pendulum which by itself (because its weight overwhelms air drag and friction in the axis bearings) comes almost back to its initial position. The heavy imbalanced wheel would almost complete a revolution and the heavy pendulum would almost complete the same amplitude at each swing. And because it is heavy it will bend the piezo element also at low speed.

And with the microamperes from the piezo elements one could hope to overcome the "almost" if the contraption is carefully built.

The imbalance in the pager motor (which is in itself a nice gadget) is not heavy enough to bend the piezo element when turned slowly. So, one needs Milliamperes to impart speed on the imbalanced wheel of the pager motor which only then gives the necessary "weight" to bend the piezo.

The question can be reduced to: is it possible to overcome the losses (air drag, friction in the bearing) in a heavy imbalanced wheel or a heavy pendulum with Micro-Watts? By "heavy" I am thinking about 1 kilo.

Greetings, Conrad

[Low-Q]

I have now ordered 50 pcs 43mm piezo's on ebay. It should do for trial and error. 35 dollars for all 50pcs. It's worth a try.

Regarding heavy imbalanced wheels. They suffer from the very same air drag and friction as any other wheels with same shape. However, if the weight is the main reason why there is applied more force to the piezo, this must be the only, and important, reason why a heavy imbalanced wheel will work better.

I choose a lighter, but probably at least as much efficient design using neodym magnets (Which at most repel and attract with several kg for each small magnet). The short pulses from the passing magnet represent a higher frequency, which in turn will increase the current from an electrostatic unit, and hopefully make it more efficient.

Well, I do not know the outcome yet, but therefor I want to test this out. I also have extracted a bunch of small long neos from brushless RC-motors lately. So I am prepared for some tests

Vidar

[Low-Q]

A nice link for those who want to do some research on piezo units:
http://www.americanpiezo.com/knowledge-center.html

Vidar