the brown noise

[Dr_Doggy]

Has anyone ever heard of it? By rumor Tesla triggered a small earthquake by using a ulf resonator on the central beam of a building.... anyone ever try to reproduce this?

how would I? I'v seen some ULF size-mic antennas and those are humongous enough, so a XtraLow Sub woofer is prolly out of the question. What about a rotating disk at a low rpm with a weight attached, or a pendulum maybe? Any theory would be great, the philosophical implications of this device are tremendous, even though I am more interested in the bio-reflex implications along with the implication of saying "i told you so!"

I need one of these!!!!

 

[carbonzit]

You know, between mentioning (totally unsourced) rumored Tesla research, "size-mic", "prolly", and just the general drift of your query ("can I create an earthquake with DIY electronics?"), I have to tell you that you owe me a new BS meter; mine had its meter totally pegged ...

 

[Dr_Doggy]

well transformers are 60 hz., couldnt a couple of em in series bring down that Fres? I'd think it was bunk too, but we have all seen what opera singers can do to glass, also there were other reports of Industrial workers getting noxious from a ceiling fan that had been wired wrong causing this ulf in the air....

 

[carbonzit]

well transformers are 60 hz., couldnt a couple of em in series bring down that Fres? I'd think it was bunk too, but we have all seen what opera singers can do to glass, also there were other reports of Industrial workers getting noxious from a ceiling fan that had been wired wrong causing this ulf in the air....

I'm afraid you're going to have to provide at least some reliable references for some of these outlandish claims if you want us to take you seriously.

If not, well, whatver, d00d, it iZ wut it iZ ...

 

[Dr_Doggy]

why is it so hard for you to believe that if wi have in vented a mic that can detect size mic shifts, then why not a speekr 2?

 

[carbonzit]

why is it so hard for you to believe that if wi have in vented a mic that can detect size mic shifts, then why not a speekr 2?

Hey, by that "reasoning", since we're able to predict solar eclipses, we should be able to cause them, right?

Just one request: can you send me some of what you're smoking? Seriously, d00d.

 

[Dr_Doggy]

like I said, I am not interested in contributing to global destruction, I just want to make the brown noise...

 

[HarveyH42]

Resonance

Should give you something to start from. Tesla's device was a small oscillator, an air powered solenoid. Doubt that it would work these days, since resonance has been figured into new constructions since that period. The 'Brown Noise' is a myth, although there maybe something to vibrations helping to move the 'matter' through, but suspect it would only work on those already holding a heavy load... The details of earthquake frequencies, and other undesirable effects most likely won't be easy to find published, nobody wants to encourage such behavior, even out of curiosity...

 

[tcmtech]

I would suggest reading up on resonance and how it relates to difernt media and physical objects and theri relative properties. Every mass has a specific resonance frequency and ever enclosed volume does too. Once you know your volume you can find its exact sonic resonance or if you know a objects mass you can also find its mechanical resonance.

As far as the "brown Note" I believe that in very specific conditions it would work. I found out first hand in high school that with a high powered set of 12" 500 watt sub woofer mounted directly behind the back seat of a car without any foam or dampening material other than the original thin seat fabric that there are certain songs that can produce a "yellow Note" with some girls.

 

[blueroomelectronics]

There was an episode of South Park where Cartman discovers the Brown Note.
**broken link removed****broken link removed**

 

[cr0sh]

Not necessarily very scientific, but mythbusters had an episode a few years back where they tried to induce the reaction ala "brown note" over different low frequencies using large amps and huge stacks of speakers; from their "experiment", nothing happened...

 

[MrAl]

Hello there,

If you would like to see one of the best examples of this kind of thing happening in real life and causing mass destruction, do a quick search for the
Tacoma Narrows Bridge


that went into resonant oscillation back in 1940. High winds caused it to start swaying back and forth and twisting and turning, and that's concrete and steel, and eventually it just couldnt take it anymore and broke up and fell into the water below. A structure like this constitutes a system or order higher than 1, and that kind of system is capable of resonance if the damping is too low.
However, that's only works for systems that have an under damped response, and the damping coefficient determines that so only systems with a certain maximum damping coefficient will go into resonance like that. That means not every system will do this, so not every structure will do this.

The way this works is that with a small amount of energy input at the right times the total energy of the system builds up over time. This happens because when the damping coefficient is low the energy released does not equal the energy put into the system so there is some net energy left when the next input interval comes along. That puts even more energy into the system and so the oscillation grows. Now some systems can still crash even with higher damping, but that takes much more energy so it isnt nearly as likely.

The conclusion then is that you can collapse some structures with a small amount of energy if you know it's resonate point, but other structures would take much more force so they are more stable and wont fall down unless a huge amount of force is applied such as an earth quake or bulldozer. Still yet other structures would fall with less energy than some direct force like an earthquake, but the energy needed is still larger than is normally seen by the structure. So we can sort of class these structures into three types: Those that require small amounts of energy applied at the right times, those that require more energy applied at the right times, and those that require a large amount of energy and the time isnt as important.

The point of application on the object could be a factor too, as some points may be more sensitive than others. This would be due to a nonlinear damping along dimensions in the directions of x, y, and/or z.

There are some buildings that actually have active damping. That means a huge mass inside the building is made to move using mechanical actuators (like motors) in accordance with a control law for the building such that it sways less with a disturbance such as wind. The mass moves to minimize the movement of the building in the plane of x and y. This keeps it much more stable, so a building like that would be impossible to topple with a small amount of energy unless the designers made a mistake and you know what that mistake is and take advantage of it.

 

[DerStrom8]

By rumor Tesla triggered a small earthquake by using a ulf resonator on the central beam of a building.... anyone ever try to reproduce this?

how would I? I'v seen some ULF size-mic antennas and those are humongous enough, so a XtraLow Sub woofer is prolly out of the question. What about a rotating disk at a low rpm with a weight attached, or a pendulum maybe? Any theory would be great, the philosophical implications of this device are tremendous, even though I am more interested in the bio-reflex implications along with the implication of saying "i told you so!"

I need one of these!!!!

Hi, doggy.
I read about this experiment, as well. Tesla supposedly created an oscillator that resonated with his workshop, but it actually destroyed one whole side of the building, as well as the police station downtown. When the police came to see what was going on, they found Tesla with a beam in his hands, and the oscillator lay destroyed on the floor. That is what the book said, anyway. I'm not sure about its credibility, though.
The moral of the story: Don't try it. If you manage to duplicate Tesla's experiment, things are likely going to get out of control.

Not necessarily very scientific, but mythbusters had an episode a few years back where they tried to induce the reaction ala "brown note" over different low frequencies using large amps and huge stacks of speakers; from their "experiment", nothing happened...

I have found the mythbusters to be fairly unreliable. They don't think their experiments through and do not eliminate all but one variable. They are special effects creators, not scientists. for example, for the "brown note" episode, they only changed the frequency. They did not think to adjust the duty cycle as well.
I don't know if there really is a "brown note," but if there is, I wouldn't trust the mythbusters to find out.

 

[audioguru]

School kids guessed that the Tacoma Narrows Bridge collapsed due to wind causing it to vibrate at its resonance but scientists blame "aeroelastic flutter". The bridge was an engineering blunder because the wind wasn't even very strong that day.

Mythbusters used "PA" or "Guitar" speakers that did not produce the very low frequencies needed to cause a Brown Mess. They should have used high quality sub-woofers.

 

[misterT]

Mythbusters used "PA" or "Guitar" speakers that did not produce the very low frequencies needed to cause a Brown Mess. They should have used high quality sub-woofers.

Mythbusters used twelve high-power sub-woofers specially modified for lower frequencies than normal sub-woofers. I believe the information at wikipedia (about Mythbusters' test) is correct Brown note - Wikipedia, the free encyclopedia

 

[MrAl]

Hello audioguru,

School kids guessed? Where did you hear that? The bridge was unstable dynamically and aeroelasticity could easily have played a role, but by its very definition aeroelasticity implies that aerodynamics plays a role at the very least in starting the problem, and that's exactly how it's described in every text i've seen. Some say gale force winds, but even a relatively light wind could start it oscillating.

 

[cr0sh]

I have found the mythbusters to be fairly unreliable. They don't think their experiments through and do not eliminate all but one variable. They are special effects creators, not scientists. for example, for the "brown note" episode, they only changed the frequency. They did not think to adjust the duty cycle as well.
I don't know if there really is a "brown note," but if there is, I wouldn't trust the mythbusters to find out.

I never said they were scientists - I never even implied it...

Not necessarily very scientific, but mythbusters had an episode a few years back where they tried to induce the reaction ala "brown note" over different low frequencies using large amps and huge stacks of speakers; from their "experiment", nothing happened...

In fact, via the bolded sections above, I tried to indicate that the tests the mythbusters performed were anything but scientific; I recognize the show for what it is - mass market entertainment with a smattering of "science" thrown in (because anything more makes the poor brain's of so-called educated America hurt as it upsets their worldview - but the hurt is lessened on Wednesday's and Sunday's - poor dears).

I don't disagree with your assessment of the "experiment", though.

 

[DerStrom8]

I never said they were scientists - I never even implied it...

In fact, via the bolded sections above, I tried to indicate that the tests the mythbusters performed were anything but scientific; I recognize the show for what it is - mass market entertainment with a smattering of "science" thrown in (because anything more makes the poor brain's of so-called educated America hurt as it upsets their worldview - but the hurt is lessened on Wednesday's and Sunday's - poor dears).

I don't disagree with your assessment of the "experiment", though.

Yes, I apologize if I sounded like I was disagreeing with you. I was actually explaining why I agree, though my phrasing was not very well thought-out. Sorry for the confusion.
Der Strom

 

[audioguru]

I watched the TV show about Mythbusters trying to make a Brown Note and I didn't see any high quality Meyer sub-woofers. I saw cheap (Electrovoice?) PA speakers in plastic enclosures.

 

[ericgibbs]

. Some say gale force winds, but even a relatively light wind could start it oscillating.

hi Al.
I know that you know this already.
The actual wind speed is critical, its not the greater the wind force, the greater the chance of oscillation.
If you overdrive an oscillating structure by applying much more force that thats required to maintain that oscillation, the oscillation will cease or the period of the oscillation will change.

The Tacoma Narrows Bridge used to oscillate at moderate certain wind speeds.

Eric