Acoustical feedback energy system

[stivep]

Yeah, I expected you would say "short-circuit", nothing new to see here. Except loudspeakers do not short-circuit when no signal is feeded into them, don't you think? From which heights the British unicorns bring you zero resistance in case of an opposing soundwave? And which is not a source of DC current?

It  is not the resistance but impedance.
Impedance is made  from three factors:
- pure resistance.
-capacitive reactance between winds of the transformer
- inductive reactance  of the winding of the transformer
https://eepower.com/technical-articles/transformer-operating-principles/#

Impedance is a mixture of resistance and reactance,
Reactance like a resistance is a ratio  of voltage to current
If we eliminate reactance  in resonance we are left with pure resistance .
We can do simple test:
Simple way to eliminate reactance is to use DC.
DC doesn't recognize any reactance.
Connect any of your Transformers primary winding to 220V DC .
You'll  have exactly the same effect .
Your transformer will blow or quickly get hot and than blow.

You need to get familiar with, SRF = Self Resonant Frequency

The frequency at which the inductive impedance equals the capacitive impedance (XL = XC) is known
as the self-resonant frequency (SRF) of the component.
At this point, the phase angle of the impedance (which can be measured using the ANGL test) is zero.

The effect is that the system does not work as intended. Keeping SRF well away from the operating frequency is a key design requirement.
it means:
Your transformer selfresonance frequency must  be never   met.
or  the connection of your three  primary windings of the three transformers  powering three  pairs of speakers  must never
manifest  SRF together..
Here is SRF calculator: self-resonance-frequency-calculator Resonance
Wesley

[stivep]

To oppose  any  of yours magic energy  production  idea:
There is no energy  in given circuit without the source of it.
Circuit can't produce any  energy  as energy  can't be produced.
We have  fixed amount of energy in the  universe.- First law of thermodynamics

In other words, there has always been, and always will be, exactly the same amount of energy in the universe.

The first law thermodynamics
So any device , any circuit can only use  energy  that already exist to convert it to the form of energy
comfortable to us.
Example: Water mills harness kinetic energy from moving bodies of water (usually rivers or streams) in order to drive machinery and generate electricity.
Russian Oil sales as a source of energy till we don't  find way to stop  China and India  from buying it. The rest of the world  doesn't buy it any longer.
Most likely Russia will collapse like Soviet Union soon  making room to  many new countries .
I wish entire Russian Nation  no longer be seen as terrorists, thieves, killers, rapists and bandits in Ukraine.

I wish you personally to wake up in  one morning  thinking:
Can I just make phone call, order ticket  to New York to see Wesley and the next day
go to Australia to see some kangaroo  just because  like Wesley  I don't need visa into  entire world.
There is plenty of value in every nation and in Russians too.

Some Russians  tried to wipe me few times. I wish myself to meet you without worry that you
are some Pietrov and Bashirov.
https://news.sky.com/story/salisbury-poisoning-suspects-alexander-petrov-and-ruslan-boshirov-were-held-in-netherlands-11504028


So even if you disagree with me, you still don't  make any energy.
I wish you all the best.
Wesley

[Paul-R]

To oppose  any  of yours magic energy  production  idea:
There is no energy  in given circuit without the source of it.

N.B. Professor Harold Puthoff and the postulated zero point energy etc.

[stivep]

weslie, please answer a question: will such loudspeaker (as I've used) short-circuit if the movement of the diaphragm be hardly constrained, or the voice-coil glued to the magnet?

sound has nothing to do with it.  It is the "frequency  in the wire" - not sound pressure wave  that counts.
Frequency delivered  from the sound card should independently be delivered  to the  amplifier circuit build in the speaker without any chances for  any feedback  leakage. 
Power supply: the transformer 220V to 12V AC  should be connected to Graetz bridge rectifier using 4 diodes and than to pi filter made from  minimum 2 capacitors  (in old times electrolytic.)
But Chinese uses  some tricks to make it cheaper.
So what happened:
At the particular frequency of the sound the load presented to the transformer or to the all three transformers  powering 3 sets of  amplifiers with 6 speakers from the same outlet
in its parameters presented value  making the transformer going to  SRF = Self Resonant Frequency

In the picture #1
let's calculate  some values using a  SRF calculator:
if the inductive reactance  was: 696 mH and  capacitive reactance  was 9.7uF than frequency of SRF= 61.1Hz
and  in  USA frequency of power grid is 60Hz.
calculatoratoz.com/en/self-resonance-frequency-calculator/

Another example using equation:
A transformer primary is a coil, and the opposition induced in that coil can be calculated.
If the winding in the coil is 500′ of AWG #22 copper wire, the wire has a resistance of approximately 8 Ω.
If the coil has an inductance of 0.5 H=500mH, the inductive reactance and total impedance are calculated as follows:
look at picture #2

For you to know and understand
How impedance affects wire that has 8 Ohm of pure resistance of copper   :
If the wire is not wound into a coil, the resistance of the wire alone is 8 Ω.
Because a coil has a higher impedance than a wire, the total impedance when the wire is wound into a coil is 188.7 Ω at 60 Hz.
The current capacity in the wire alone is about 23.6 times higher than the current capacity through the coil because of
the increased impedance from the inductive reactance of the coil.
The comparison of the coil and the straight conductor shows how a transformer primary can be connected to a source and act to limit the current.

The four factors that determine or control the inductance of a coil are :
the cross-section of the core,
the number of turns,
the type of the core,
and the length of the coil.

So  Aleks- try to connect 8 Ohm wire  into 220V DC and it will blow  or your 15A fuse will blow.
And now:
try to make primary winding of the transformer from the same 8 Ohm wire that becomes 188 Ohm in form of a coil.
If that  winding in this  transformer  at that frequency is not in the frequency of self resonance you can use  this transformer.

However if you take the 3  of transformers under very specific load( at the particular  frequency of the sound)
all of them have  their primary winding connected in parallel - they may fall into self resonance as impedance is dynamically dependent .
-it means is frequency  sensitive 

one more factor that may  be important :
In civilized  Western World  of Europe frequency of the grid is 50Hz.
_{if we have dynamically changing load  on the transformer and in Russia this frequency drifts we may also get effect of selfresonance.
of the transformer.
-in picture #1 you see SRF=61.1Hz. So that is 1.1Hz more than  in USA(60Hz) That little  drift  may cause problem here.
Russia during soviet union had constant every day  frequency drift in all countries under soviet terror.
Russia of today is likely third world  country  with GDP likely lower than in  Papula New Guinea 
and  Uganda or some other African countries.
Everything there is worse than it was during Soviet time and Putin is hunted by international court in Hague
like Muammar Muhammad Abu Minyar al-Gaddafi  or Saddam Husein} .

_{opinion expressed is my own.}
Wesley

[aleks]

weslie, sorry, I've lost you. You didn't answer the relevant question, the question which matters.


(Resistivity of metals is 10^-8 Ohm-meters, that's why they short-circuit easily, they have zero resistance basically, resistance of a short copper wire is in milliOhms.)


And your SRF reasoning implies that the opposing soundwave "magically" changes SRF of fixed transformer windings, that were, to begin with, predesigned for driving an audio-frequency-range voice-coil, with its mechanical inertia and associated back EMF. Sounds great in theory, but not so much in practice.


The formula for SRF of a transformer is:
f_res = 1 / (2 * pi * sqrt(L_in * L_out * C))
where L_in is inductance of 220V winding, L_out is inductance of output winding (12V I suppose), C is transformer's capacitance.


Pre-designed SRF cannot be anywhere close to 50 or 60 Hz I suppose as that would cause a resistive-load short-circuit of the mains. Considering inductance of both windings is most probably in the range 1-10H, SRF should be below 50 Hz, for a 12VA transformer. At the same time the sinewave frequency in use was above 200Hz - it was loud and audible (cheap loudspeakers do not reproduce nor resonate to anything below 100 Hz well - too small diaphragm). Something does not add up in your "SRF short-circuit" theory.