charge-based piezo drive

On a sunny day (Tue, 16 Jul 2019 14:48:54 -0500) it happened amdx
<nojunk@knology.net> wrote in <qgl9nb$d4m$1@dont-email.me>:

On 7/16/2019 1:44 PM, Jan Panteltje wrote:
So to make the bubbles requires much less power at 40 kHz,
that is why the youtube guy has all the bubbles with a simple signal source I think.
I should not have any problems with my transducers and even
less if I use a 75 W RMS audio amp and series resonance ??
Thanks for the chart.



Yes, :)
But for chemistry you want higher frequency, many more bubbles, more
cavitation points, much more surface area.
Can anyone tell me about about Dispersion angle? Is the angle
different for a 40kHz transducer vs a 660kHz transducer?
I wonder, we pointed our 2" transducer at a convexed 4" air backed
reflector, it caused a focus of energy about 2" in front of the
reflector. At that point you had a approx 3/4" cottony froth and a
hissing from the intense cavitation at the focus.
I wonder if 40kHz would disperse, or would all the energy reflect from
the convexed reflector. About 8" away, although in some experiments we
where up to 15" away.
Click to expand...

I have not tried it, I did some experiments with beaming at very low power (44 kHz).

There is a video somewhere where they use ultrasound and a parabolic reflector to light a match a few meters away.
It was a demo outside of some exibition.

As to parabolic reflectors, it is all about wavelength, finding the wavelength is also fun,
here I reflect the 44 kHz of a piece of paper, you find the zeros (combining relfected with direct):
https://www.youtube.com/watch?v=KpeO5kYBfN0
So a fev mm , 330 / 44000 = 0.007500 m or .75 cm

So speed of sound in air / frequency,

Any parabolic shape that is bigger than several times the wavelength should work.
Maybe an old space heater, we used that very long time ago for microwaves in the lab to make a TV link
over some distance.

Mayeb even a car headlight reflector come to think of it?

Use what you have :)

Here I do some 44 kHz doppler, frequency difference depends on the speed the reflector moves:
https://www.youtube.com/watch?v=BLLIUntOc4I
 
On a sunny day (Wed, 17 Jul 2019 09:01:54 +1000) it happened Clifford Heath
<no.spam@please.net> wrote in <EHsXE.34517$7s1.23971@fx44.iad>:

On 17/7/19 3:19 am, Jan Panteltje wrote:
Actually that series resonance mode I will have to try that!
Because that would be easy with any high end audio power amp at 40 kHz and you do not need a transformer!
Now on the todo list (with a thousand other things).

How the collapsing bubble gives light? Squeeze anything hard enough and it will heat up.
Some gases may light up at high temperature,
That is the gist I get from your wikipedia link.
Because it's not a bubble. It's a vacuum cavity, so there's nothing to
buffer the shock of opposite faces impacting when the cavity closes. Any
water vapor re-absorbs instantly, and water is so incompressible that
there are huge local pressure spikes. This is what causes surface
erosion on drag boat propellors.
Click to expand...

Wikipedia disagrees with you as to
<quote>
Sonoluminescence can occur when a sound wave of sufficient intensity induces a gaseous cavity within a liquid to collapse quickly.
This cavity may take the form of a pre-existing bubble, or may be generated through a process known as cavitation.
Sonoluminescence in the laboratory can be made to be stable, so that a single bubble will expand and collapse over and over again in a periodic fashion,
emitting a burst of light each time it collapses.
For this to occur, a standing acoustic wave is set up within a liquid, and the bubble will sit at a pressure anti-node of the standing wave.
<end quote>

They later get into what sort of gasses are present in the bubble.
<quote>
In 2002, M. Brenner, S. Hilgenfeldt, and D. Lohse published a 60-page review that contains a detailed explanation of the mechanism.
An important factor is that the bubble contains mainly inert noble gas such as argon or xenon (air contains about 1% argon,
and the amount dissolved in water is too great for sonoluminescence to occur,
the concentration must be reduced to 20-40% of its equilibrium value) and varying amounts of water vapor.
Chemical reactions cause nitrogen and oxygen to be removed from the bubble after about one hundred expansion-collapse cycles.
The bubble will then begin to emit light.
The light emission of highly compressed noble gas is exploited technologically in the argon flash devices.
<end quote>

All from
https://en.wikipedia.org/wiki/Sonoluminescence
 
On 7/17/2019 9:55 AM, Jan Panteltje wrote:
On a sunny day (Wed, 17 Jul 2019 09:50:58 -0500) it happened amdx
nojunk@knology.net> wrote in <qgnckj$pct$1@dont-email.me>:

Just needed to add everything I did was in a water bath.

Yes swimming is cool.

OK, not everything, our 660kHz experiments were in a water solution. :)
Click to expand...

Mikek
 
On a sunny day (Wed, 17 Jul 2019 09:50:58 -0500) it happened amdx
<nojunk@knology.net> wrote in <qgnckj$pct$1@dont-email.me>:

> Just needed to add everything I did was in a water bath.

Yes swimming is cool.
 
On 7/17/2019 2:31 AM, Jan Panteltje wrote:
On a sunny day (Tue, 16 Jul 2019 14:48:54 -0500) it happened amdx
nojunk@knology.net> wrote in <qgl9nb$d4m$1@dont-email.me>:

On 7/16/2019 1:44 PM, Jan Panteltje wrote:
So to make the bubbles requires much less power at 40 kHz,
that is why the youtube guy has all the bubbles with a simple signal source I think.
I should not have any problems with my transducers and even
less if I use a 75 W RMS audio amp and series resonance ??
Thanks for the chart.



Yes, :)
But for chemistry you want higher frequency, many more bubbles, more
cavitation points, much more surface area.
Can anyone tell me about about Dispersion angle? Is the angle
different for a 40kHz transducer vs a 660kHz transducer?
I wonder, we pointed our 2" transducer at a convexed 4" air backed
reflector, it caused a focus of energy about 2" in front of the
reflector. At that point you had a approx 3/4" cottony froth and a
hissing from the intense cavitation at the focus.
I wonder if 40kHz would disperse, or would all the energy reflect from
the convexed reflector. About 8" away, although in some experiments we
where up to 15" away.

I have not tried it, I did some experiments with beaming at very low power (44 kHz).

There is a video somewhere where they use ultrasound and a parabolic reflector to light a match a few meters away.
It was a demo outside of some exibition.

As to parabolic reflectors, it is all about wavelength, finding the wavelength is also fun,
here I reflect the 44 kHz of a piece of paper, you find the zeros (combining relfected with direct):
https://www.youtube.com/watch?v=KpeO5kYBfN0
So a fev mm , 330 / 44000 = 0.007500 m or .75 cm

So speed of sound in air / frequency,

Any parabolic shape that is bigger than several times the wavelength should work.
Maybe an old space heater, we used that very long time ago for microwaves in the lab to make a TV link
over some distance.

Mayeb even a car headlight reflector come to think of it?

Use what you have :)

Here I do some 44 kHz doppler, frequency difference depends on the speed the reflector moves:
https://www.youtube.com/watch?v=BLLIUntOc4I


Just needed to add everything I did was in a water bath.
Click to expand...

Mikek
 
On 17/7/19 5:31 pm, Jan Panteltje wrote:
On a sunny day (Wed, 17 Jul 2019 09:01:54 +1000) it happened Clifford Heath
no.spam@please.net> wrote in <EHsXE.34517$7s1.23971@fx44.iad>:

On 17/7/19 3:19 am, Jan Panteltje wrote:
Actually that series resonance mode I will have to try that!
Because that would be easy with any high end audio power amp at 40 kHz and you do not need a transformer!
Now on the todo list (with a thousand other things).

How the collapsing bubble gives light? Squeeze anything hard enough and it will heat up.
Some gases may light up at high temperature,
That is the gist I get from your wikipedia link.
Because it's not a bubble. It's a vacuum cavity, so there's nothing to
buffer the shock of opposite faces impacting when the cavity closes. Any
water vapor re-absorbs instantly, and water is so incompressible that
there are huge local pressure spikes. This is what causes surface
erosion on drag boat propellors.

Wikipedia disagrees with you as to
quote
Sonoluminescence can occur when a sound wave of sufficient intensity induces a gaseous cavity within a liquid to collapse quickly.
This cavity may take the form of a pre-existing bubble, or may be generated through a process known as cavitation.
Sonoluminescence in the laboratory can be made to be stable, so that a single bubble will expand and collapse over and over again in a periodic fashion,
emitting a burst of light each time it collapses.
For this to occur, a standing acoustic wave is set up within a liquid, and the bubble will sit at a pressure anti-node of the standing wave.
end quote

They later get into what sort of gasses are present in the bubble.
quote
In 2002, M. Brenner, S. Hilgenfeldt, and D. Lohse published a 60-page review that contains a detailed explanation of the mechanism.
An important factor is that the bubble contains mainly inert noble gas such as argon or xenon (air contains about 1% argon,
and the amount dissolved in water is too great for sonoluminescence to occur,
the concentration must be reduced to 20-40% of its equilibrium value) and varying amounts of water vapor.
Chemical reactions cause nitrogen and oxygen to be removed from the bubble after about one hundred expansion-collapse cycles.
The bubble will then begin to emit light.
The light emission of highly compressed noble gas is exploited technologically in the argon flash devices.
end quote

All from
https://en.wikipedia.org/wiki/Sonoluminescence
Click to expand...

Ahh, interesting. So it looks like the microscopic amount of gas
remaining in the bubble is heated to incandescence for an instant, prior
to any total collapse that may occur. The incandescence is still a
result of a massive pressure spike. That makes perfect sense, and now I
understand the phenomenon, I feel no need to reproduce it.

Clifford Heath
 
On Tuesday, July 16, 2019 at 8:56:01 AM UTC-7, amdx wrote:
On 7/16/2019 1:53 AM, Jan Panteltje wrote:

'anti resonance' could mean?
[1] Using it out of resonance (that is easy).
[2] Or some magical thing? Then it is bull.
It is either in resonance or it is not, as simple as that.
Click to expand...

No, you're talking about beepers, not about thick transducers.
No bull, the thick ones have a peak *AND* a notch in their impedance
graph vs freq., the resonance and the anti-resonance. As if
they can act as either a parallel RLC or a series RLC depending
on drive freq. IIRC, the thin PZT beepers don't do this.

Ya, you have me wondering if I used the wrong term, but it is the low
impedance point on a an impedance curve.
Click to expand...

Yep, a resonant notch, rather than the usual resonant peak
that we all expect.

Search: transducer antiresonance

http://www.ultrasonic-energy.com/shop_talk.html

For sonoluminescence, I think they tracked that glow to the natural
atmospheric Argon contamination. Then enhanced the effect by
bubbling some argon through their water. Heh, modify the
color of the glow by using Neon? Or Strontium salts, etc.?
 
On Sunday, July 21, 2019 at 4:30:40 PM UTC-7, Clifford Heath wrote:
Ahh, interesting. So it looks like the microscopic amount of gas
remaining in the bubble is heated to incandescence for an instant, prior
to any total collapse that may occur. The incandescence is still a
result of a massive pressure spike. That makes perfect sense, and now I
understand the phenomenon, I feel no need to reproduce it.
Click to expand...

Then you'd miss the problem where, if water is degassed and
then filled with N2 (no argon,) the glow doesn't occur. It
seems associated with argon, not with mere incandescence.
That, or N2 chemistry is reducing the peak pressure by creating
losses, as it does with high voltage sparks (compare sparks in
air with sparks in argon at 1ATM , 1cm becomes 30cm.) So once
the chemistry stops, and dissolved nitrides/oxides are out of
the bubble, then the water can bounce, and peak pressure
doubles.

What I really want to know is, if the water is full of methane
or even alcohol + O2, will it continue to self-oscillate as a
sort of Diesel engine; driving its own repeating compression
cycle until the fuel was eventually consumed? This would
probably need a parabolic reflector, or a spherical flask, or
a very smooth-bore pipe with flat reflective endcaps. Or if
not oscillate, at least measure the system Q for various
water contaminants, to see if exothermic chem inside the bubble
can add detectable acoustic energy.
 
On 7/22/2019 3:48 AM, Bill Beaty wrote:
On Tuesday, July 16, 2019 at 8:56:01 AM UTC-7, amdx wrote:
On 7/16/2019 1:53 AM, Jan Panteltje wrote:

'anti resonance' could mean?
[1] Using it out of resonance (that is easy).
[2] Or some magical thing? Then it is bull.
It is either in resonance or it is not, as simple as that.

No, you're talking about beepers, not about thick transducers.
No bull, the thick ones have a peak *AND* a notch in their impedance
graph vs freq., the resonance and the anti-resonance. As if
they can act as either a parallel RLC or a series RLC depending
on drive freq. IIRC, the thin PZT beepers don't do this.

Ya, you have me wondering if I used the wrong term, but it is the low
impedance point on a an impedance curve.

Yep, a resonant notch, rather than the usual resonant peak
that we all expect.

Search: transducer antiresonance

http://www.ultrasonic-energy.com/shop_talk.html

For sonoluminescence, I think they tracked that glow to the natural
atmospheric Argon contamination. Then enhanced the effect by
bubbling some argon through their water. Heh, modify the
color of the glow by using Neon? Or Strontium salts, etc.?
Click to expand...
I get a 404 error for your link, I truncated it and then get a few
links but no search bar to look for transducer antiresonance.

Mikek

btw, something I just found out but should have known, they are using
ultrasound to do Coolsculpting. As in "melting' fat away, not sure if it
breaks the cell wall and then your body removes the debris or just how
it works. Strange how many times I see how many inches are lost, but
not any pounds, although I'm sure it takes time for your body to remove
the debris. I think it quite possible your body actually uses the debris
in your blood stream as fuel, so maybe you need to diet also!

Mikek
 
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