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Author Topic: Acoustic magnetic generator.  (Read 132471 times)

itsu

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Re: Acoustic magnetic generator.
« Reply #180 on: March 16, 2014, 12:15:13 PM »

Hi Synchro1,

no, no bridge rectifier, its the old speaker bracket.

Regards Itsu

MileHigh

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Re: Acoustic magnetic generator.
« Reply #181 on: March 16, 2014, 01:44:53 PM »
Itsu:

There is no need for you to cut the iron bar, it won't make any difference with respect to the amount of magnetic flux that flows through the magnetic circuit.

I think that your build is great.  From my perspective I don't see how beaming sound down the two rods will affect the amount of flux that flows through the circuit.  It's really a mystery to me.

It may be a bit preliminary to pass judgement, but we can see how your pickup coil barely generates any EMF.  It's possible that the EMF that is being picked up has very little or nothing to do with any possible flux modulation from the acoustic waves.

MileHigh

itsu

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Re: Acoustic magnetic generator.
« Reply #182 on: March 16, 2014, 06:10:18 PM »


I momentarely upped the input power into the piezo to what is possible with my present setup (Fg + PA)
I used my x100 HV probe on CH1 to measure the voltage which was around 820V pp.

But even then no extraordinary EMF was picked up by the pick up coil.
This screenshot was taken at 11.790KHz where normally no audio was heard (by me), but there was again
this spurious 4-6KHz audible signal.
But as can be seen, it did not produce any high signal in the pickup coil (blue trace).

So brute force is probably not the way to go.

What puzzles me is the negative mean power of -600mW * 2 (for the current probe terminator) = -1.2W
Ch4 (current) is inverted, as it depends how i clip up the probe, but you can see that at this low frequency
the current is leading the voltage which i think is correct (capacitive/low side of the LC).


Regards Itsu

synchro1

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Re: Acoustic magnetic generator.
« Reply #183 on: March 16, 2014, 06:44:33 PM »
@Itsu,


I think the ferrite rods are super saturated at this point, and that it would help to begin to reduce the number of magnets.


It would also help to rectify the output to DC to illuminate the LED.

verpies

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Re: Acoustic magnetic generator.
« Reply #184 on: March 16, 2014, 11:39:56 PM »
From my perspective I don't see how beaming sound down the two rods will affect the amount of flux that flows through the circuit.  It's really a mystery to me.
When the sound affects the permeability of the ferrite (and it really does) its reluctance changes locally.
Your intuition probably tells you that the net flux does not change, because any decrease of reluctance in one segment of the core is offset by exactly the same increase in another segment of the core, leading to a zero net reluctance change.
And you would be correct, but only for series magnetic circuits and flux changes over integer acoustic wavelengths.

Parallel magnetic circuits circuits and non-integer acoustic wavelengths can and do produce significant reluctance and flux changes (see here).  If you muse over it, you'll immediately come up with multitude of magneto-acoustc configurations that will maximize reluctance&flux changes.
IMO if nodes of longitudinal acoustic standing waves in the ferrite are not determined accurately (e.g. by real time visualization) then it is very hard to properly tune and design a parallel magnetic circuit that will maximize these flux variations.

P.S.
I am not insisting that these reluctance changes are free or overly efficient, just because they are caused by acoustic compressions and rarefaction of the ferrite core.  The purpose of these experiments is to determine just that.  ..so let's leave the quantitative O/I discussion for later, when we have more data.

verpies

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Re: Acoustic magnetic generator.
« Reply #185 on: March 17, 2014, 12:12:53 AM »
In response to a private message I'm posting the diagram below that illustrates what I mean by a "magnetic circuit".
I'm posting it here because attachments are not allowed in private messages.

This diagram merely illustrates the electric analogy of a magnetic circuit, it is not a suggestion to try this circuit with the Villari effect.  The electric analogy is not complete because it does not show the reluctance of empty spaces between core segments and the PM.
Not that it's bad for it but I have not thought about reluctance modulations of this circuit in the context of magnetoacoustics.  Maybe it would be useful with it and maybe it would not - I'm too tired to think about it now.

In any case, without knowing precise locations of the nodes and antinodes, the chances of doing something useful with it are very small.

itsu

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Re: Acoustic magnetic generator.
« Reply #186 on: March 18, 2014, 10:37:40 PM »

After days fiddling around with the setup i had, no noteworthy things happened.
I decided to switch over to another setup like being seen in the video (piezo flat on a glass plate, 1 ferrite rod glued on it).

Also here nothing strange found in the lower frequency regions, but when upping the frequency to around 55KHz
there started to be some sparks and something started to glow at the bottom of the piezo were it touched the glass.
I think it must be some residual flux which i had used to solder the connections to the piezo earlier.

Some movement was seen as the construction was sliding across the plate now and then pointing to some
vibrations causing also some audible tones again around 4-6KHz.

I did had some volts (3/4) on the pickup coil.

Nothing spectacular, but at last something was happening.

Video here:  https://www.youtube.com/watch?v=XpQsvv-8XCM&feature=youtu.be


Regards itsu

verpies

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Re: Acoustic magnetic generator.
« Reply #187 on: March 19, 2014, 12:43:38 AM »
That arcing is worrisome.  I never experienced it but then I had never driven my piezos above 300V.   My IMT outputs maximum 210VRMS but it delivers 5x more current than your IMT at that voltage.  The IMT has back-forth primary winding above the secondary (both spanning the whole circumference of a ferrite toroid) and it attenuates 3dB at 3.8MHz.
I like that you stood the device on a table, because the table constitutes a mechanical counterpoise for the other side of the piezo.

That the whole contraption moves on a glass table must be caused by some standing waves in it at acoustic resonance and its multiples.  Too bad, that we cannot see them. 
When acoustic reflections come back and the standing wave builds up, it squeezes the piezo turning it into a HV generator (that voltage can be high enough to cause arcing).  Note, that some cigarette and gas lighters use hammer-struck-piezos to generate HV sparks for gas ignition (see here).

Your thick rod and two return flux rods are very close to each other now, and your magnetic circuit becomes more parallel than before because the space between these rods is small enough to "allow" significant magnetic flux to take a shortcut outside of the ferrite.
If you read my previous message, you'll note that parallel magnetic circuits stand a better chance to have large flux variations on one of its branches, than series circuits ...especially if magnetic circuit nodes correspond to acoustic nodes and antinodes.

Strangely, an open magnetic circuit is more parallel than tightly looped circuits (this is most likely the reason why this guy got so lucky ;)  ...this is not to be misconstrued that open circuits produce the largest flux variations and EMF ∝ dΦ/dt.

itsu

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Re: Acoustic magnetic generator.
« Reply #188 on: March 19, 2014, 10:36:53 AM »
When acoustic reflections come back and the standing wave builds up, it squeezes the piezo turning it into a HV generator (that voltage can be high enough to cause arcing). 

Hmmm,  should i not have seen that HV on my yellow probe signal?


Quote
Strangely, an open magnetic circuit is more parallel than tightly looped circuits (this is most likely the reason why this guy got so lucky ;) 

I tried that setup lateron, see picture, and it produces similar results as the earlier setup, but then when i applied some pressure
on the magnets (probably to much on one side) the piezo shattered.

Looking at the damaged piezo, i can see where the glow came from earlier, it seems the edge where the back side "flips over" to the front site
is "eaten away" by this burning.  The back is now isolated from this front patch.

These piezo's are very bad to solder as the conductive material does not want to be soldered very well.

Anyway, still one to go, so i will revert to "clamping" the leads to the piezo as i have done before, only problem is that i have to use
the edge of the glass plate to accommodate the clamps.

Regards Itsu

verpies

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Re: Acoustic magnetic generator.
« Reply #189 on: March 19, 2014, 12:20:52 PM »
Hmmm,  should i not have seen that HV on my yellow probe signal?
Yes it should, unless the piezos has generated that HV locally at the edge.

Looking at the damaged piezo, i can see where the glow came from earlier, it seems the edge where the back side "flips over" to the front site is "eaten away" by this burning.
Acoustically heated glass can become conductive.  Are there permanent melt marks on the glass table?

These piezo's are very bad to solder as the conductive material does not want to be soldered very well.
This is a well know problem with piezos.  See this video.
Also, wires that you soldered to the piezo are too thick.  I use sub 0.5mm flexible stranded wire for a 5cm length and join/solder them to thicker wires for longer distances.

itsu

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Re: Acoustic magnetic generator.
« Reply #190 on: March 19, 2014, 01:23:39 PM »
Acoustically heated glass can become conductive.  Are there permanent melt marks on the glass table?

Yes, there are some "pits" in the glass where the glow was seen.

Quote
This is a well know problem with piezos.  See this video.
Also, wires that you soldered to the piezo are too thick.  I use sub 0.5mm flexible stranded wire for a 5cm length and join/solder them to thicker wires for longer distances.

Great tips, i have some pieces now where i can practice on   ;D

Regards Itsu

MasterPlaster

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Re: Acoustic magnetic generator.
« Reply #191 on: March 19, 2014, 08:20:22 PM »
Just a couple of random thoughts:

I was thinking that what we call the lines of magnetic force are in fact standing waves. I.E. a magnet acts like a tuning fork in the aether which
causes the lines to appear at certain locations.

I did a search on this but could not find anything but came across a link that you may be interested:

http://montalk.net/notes/tuning-forks-and-megalithic-technology

armagdn03

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Re: Acoustic magnetic generator.
« Reply #192 on: March 19, 2014, 10:04:56 PM »
@ Itsu


Might I suggest shying away from ferrite based magnetic field guides. I have found more often than not playing with very very similar setups that conduction within the material is very important. While the ceramics are excellent with respect to acting as a wave guide for acoustic compression and rarefraction, they are poor with respect to transfer of a magnetic field when the material length is far greater than its width. I have several detailed experimental setups which suggest that this could very much be due to the lack of electrical conductivity. There are many reasons for this, and it was extended conversation I had when i was shortly in touch with Eric Dollard. Unfortunately neither he nor I had an adequate reasoning for this result.

Another method I have used with great success is to take two very large ceramic magnets (mine were about the size of a video cassette), and give them a tap with a very hard slightly heavy object to induce an acoustic "ring". Record this frequency for each. Build an exciter circuit at the resonant frequency of the first. Take the second and shave material off of it till it has a frequency difference from the first. Now create an exciter circuit for the resonant frequency of the second magnet. Place a coil around each of the magnets in orthogonal orientations so they are not mutually coupled. When electrically excited at the resonant frequency, the reaction from the oscillating magnetic field will place the exciter into a very high impedance mode and it will be quite efficient. The acoustic excitation of the macroscopic and molecular structure of the magnet will cause fluctuations within the magnetic field. The superimposed fields from both magnets together will create a beat frequency at the difference of frequency. F1 minus F2 = F3.

Build a large pick up coil (large in diameter, and somewhat flat) with loose coupling to the setup. For example, if your magnet setup is one foot by one foot by one foot, create the pick up to have a diameter from 2 to 3 feet. (you will have to experiment. If you take into account wavelengths of F1 and F2 and F3, along with other factors such as the quarter wave relationship with respect to Lenz reaction, you will be able to figure out exactly what you need, but for starters what I describe is a good point of beginning).  This large pick up coil should have a resonant frequency equal to the beat frequency, and when power is drawn from it, it should have filters with maximum blocking impedance at the frequencies of F1 and F2. The two initial frequencies are blocked, and the created frequency is not. Happy experimenting with the missing fundamental generator!!!

itsu

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Re: Acoustic magnetic generator.
« Reply #193 on: March 20, 2014, 10:44:59 AM »
Just a couple of random thoughts:

I was thinking that what we call the lines of magnetic force are in fact standing waves. I.E. a magnet acts like a tuning fork in the aether which
causes the lines to appear at certain locations.

I did a search on this but could not find anything but came across a link that you may be interested:

http://montalk.net/notes/tuning-forks-and-megalithic-technology

Thanks MP,  interesting link and info.

Thanks,  regards itsu

itsu

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Re: Acoustic magnetic generator.
« Reply #194 on: March 20, 2014, 10:53:12 AM »
@ Itsu


Might I suggest shying away from ferrite based magnetic field guides. I have found more often than not playing with very very similar setups that conduction within the material is very important. While the ceramics are excellent with respect to acting as a wave guide for acoustic compression and rarefraction, they are poor with respect to transfer of a magnetic field when the material length is far greater than its width. I have several detailed experimental setups which suggest that this could very much be due to the lack of electrical conductivity. There are many reasons for this, and it was extended conversation I had when i was shortly in touch with Eric Dollard. Unfortunately neither he nor I had an adequate reasoning for this result.



Great info, so i will try to avoid ferrite as the loop back medium and use some steel.


Quote
Another method I have used with great success is to take two very large ceramic magnets (mine were about the size of a video cassette), and give them a tap with a very hard slightly heavy object to induce an acoustic "ring". Record this frequency for each. Build an exciter circuit at the resonant frequency of the first. Take the second and shave material off of it till it has a frequency difference from the first. Now create an exciter circuit for the resonant frequency of the second magnet. Place a coil around each of the magnets in orthogonal orientations so they are not mutually coupled. When electrically excited at the resonant frequency, the reaction from the oscillating magnetic field will place the exciter into a very high impedance mode and it will be quite efficient. The acoustic excitation of the macroscopic and molecular structure of the magnet will cause fluctuations within the magnetic field. The superimposed fields from both magnets together will create a beat frequency at the difference of frequency. F1 minus F2 = F3.

Build a large pick up coil (large in diameter, and somewhat flat) with loose coupling to the setup. For example, if your magnet setup is one foot by one foot by one foot, create the pick up to have a diameter from 2 to 3 feet. (you will have to experiment. If you take into account wavelengths of F1 and F2 and F3, along with other factors such as the quarter wave relationship with respect to Lenz reaction, you will be able to figure out exactly what you need, but for starters what I describe is a good point of beginning).  This large pick up coil should have a resonant frequency equal to the beat frequency, and when power is drawn from it, it should have filters with maximum blocking impedance at the frequencies of F1 and F2. The two initial frequencies are blocked, and the created frequency is not. Happy experimenting with the missing fundamental generator!!!

Wow,  - "the size of a video cassette"-   those are massive magnets, and it seems this is a totally different beast.
You  must have i nice workshop when you are able to  "shave material off of it".

verpies mentioned also to try to "ping" the used ferrite rods to see how long and at what frequency the ring.
I still want to do that.

Thanks for your input,  regards Itsu