Half a croissant, on a plate, with a sign in front of it saying '50c'
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Handheld Resonator

Powerful personal touch
  (+15)(+15)
(+15)
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Percil overslept on the bus and had to get off a bit later than usual, in the seedier part of town. On the longer walk home, he was getting tailed. At an intersection, waiting for the red light to change, he casually leaned and placed his hand on the light pole.

After a few seconds, the light pole starts swaying back & forth, wider & wilder. The pole is groaning and about to break. The would-be muggers scatter in fear of his powerful touch.

Percil is, of course, bringing his work home with him. The "Handheld Resonator" is a small, battery powered device. When you place it against an object, it:

1. "Pings" the object (hits it with a small metal hammer).
2. Listens to the response.
3. Calculates the resonant frequency.
4. Rotates a small motor with a cam (maybe behind a diaphram) that pulses the object mechanically with that resonant frequency.

Doable with many metal structures which approximate 2nd order linear systems.

Should work well with light posts, stairway bannisters, parked cars, vending machines, doors, etc....

It would be difficult to actually break something, since as it moves wilder, you'd have a hard time keeping your hand on it (and it the system would experience plastic deformation, have a different resonant frequency, and/or no longer approximate 2nd order linear).

This is one idea where I will make no apologies for length. I have had it for many years, but kept it discretely inside.

sophocles, Jan 19 2006

Intro to System Dynamics: Second order systems http://www.facstaff...SysDyn/SysDyn2.html
A Bucknell University online study resource. [bristolz, Jan 19 2006]

Trager http://www.trager.com/
the active aspect of Trager is called Mentastics [JesusHChrist, Jan 20 2006]

[link]






       a very strange idea, well done [sophocles].
neilp, Jan 19 2006
  

       Didn't Tesla do this very thing in a steel framed building and later attempted to cause a whole Earth resonance?
bristolz, Jan 19 2006
  

       No, because it wouldn't be operating at the resonant frequency of your arm.
bristolz, Jan 19 2006
  

       Could it operate at the resonant frequency of the would-be mugger?   

       Could it have a timer in it, and resonate at some non-resonant frequency for Percil to wake up in time to get off at his stop?
DrCurry, Jan 19 2006
  

       No, as muggers don't approximate second order linear systems.
bristolz, Jan 19 2006
  

       Darn, I wasn't quick enough to be the first to mention Tesla.
Tesla once calculated the resonance of an unfinished steel-framed building on a construction site, and shook the thing like crazy (no damage done, though).
He made it known that he could destroy various structures with an oscillator the size of a wallet, including the Brooklyn Bridge (if I remember right).
He calculated that the resonant frequency of the earth was ~24 minutes, and with enough time he could essentially split the world in half.
But, he did not have a method of automatically calculating the resonant frequency of an object. AFAIK. I like this, I want one, [+].
roleohibachi, Jan 19 2006
  

       [bristolz] to the rescue. Correct on all points. This would not work very well on wood, bags of fluid, or other less rigid, more complicated mechanical systems like human bodies as they don't approximate 2nd order linear systems and thus have no real resonant frequency.   

       I didn't know that about Tesla. I did hear he was one real mad scientist.
sophocles, Jan 19 2006
  

       I don't know what a second order linear system is, but it sounds like fun. Could someone offer a brief explanation, or point me at a learning resource please, I wish to undumben myself :)
DocBrown, Jan 19 2006
  

       It's where you go into a restaurant and order a linear system, but they don't have the exact one you want, so you order a different kind, and they have that one instead.
Ian Tindale, Jan 19 2006
  

       This reminds me of a school physics lesson, when our teacher told us that with split second timing, and an unlimited supply of peas, a kid with a pea-shooter could cause the QEII to capsize. (personally, I think he didn't take into account the damping effect (no pun intended) of the water)

One objection - wouldn't the muggers know they were in no direct danger from the resonator?
coprocephalous, Jan 19 2006
  

       and if the Resonator (which I like a lot) failed to deter them, you could deploy device number two - a Reasonator - I suggest a large ball bearing in a sock, swung with angular vigour +
xenzag, Jan 19 2006
  

       Didn't James Bond have a high frequency one of these built into a ring?
st3f, Jan 19 2006
  

       In short, [DocBrown], the expression "second order linear system" comes from studies in linear algebra and calculus where equations are used to model physical behaviors, system dynamics and phenomena that are capable of exhibiting oscillation (and overshoot and damping tendencies) as a reaction, an acceleration, to an input of force.   

       I conducted a small search to see if there was a resource online that had a simple explanation but, alas, all I found required at least a rudimentary understanding of calculus. Of these, I've posted the simplest explanation I found.
bristolz, Jan 19 2006
  

       The tiny reaction does act on your arm, no-one disputes that.
AbsintheWithoutLeave, Jan 19 2006
  

       It would only work in systems with very low damping. Before you can put any energy into increasing the magnitude of vibration, you've got to replace all the energy that is being lost as heat within the system. Very rapidly, you will exceed the power available from a small system.   

       ...based on that, methinks Tesla's claim (or the claim attributed to him) is flawed. The energy required to split the earth in two would be massive; all a resonator does is give you a kind of leaky bucket to store the energy up in.
david_scothern, Jan 19 2006
  

       There are many of Tesla's claims that seem unlikely to my way of thinking.
bristolz, Jan 19 2006
  

       The cam idea was eliminated by Tesla to reduce friction losses and he ended up with something like a slug in a solenoid but he didn't have as efficient of motors &/or batteries as we do today. You may want to have some sort of auto shut-off device to prevent the sledge hammer emergency stop that Nikola developed further hilighting the point of determining the dampening effects mentioned above. Your second generation version might want to check this too perhaps with some sort of shoe mounted bluetooth ultrasound.   

       The last point to worry about is the alleged "laxitive" effect of maintaining direct contact with an object properly vibrating near it's resonant frequency. That may be a worse outcome (so to speak) than handing you wallet over.
Seven, Jan 19 2006
  

       //It's where you go into a restaurant and order a linear system, but they don't have the exact one you want, so you order a different kind, and they have that one instead.//   

       ha ha   

       by the way, big hello to all the FBI and/or NSA agents who are now once again lurking in the bakery. Welcome. Stick around, enjoy yourself, this place can be pretty entertaining.
oxen crossing, Jan 20 2006
  

       You can do this by meditatively vibrating your body. I predict this will be the next rage with terrorists. See link for a physical therapy technique that teaches this kind of body vibration.
JesusHChrist, Jan 20 2006
  

       Not sure I believe the "laxative" allegation, either.
bristolz, Jan 20 2006
  

       //Handheld Resonator//   

       Indeed! There are websites for this sort of thing! We do not need more smut around here, thanks!   

       I suppose you will say it comes with a rotating head, next!
Parmenides, Jan 20 2006
  

       //once again lurking in the bakery// Welcome back, [oxen].
Shz, Jan 20 2006
  

       //big hello to all the FBI and/or NSA agents who are now once again lurking //
Why are they lurking here?
Haven't they got better things to do?
coprocephalous, Jan 20 2006
  

       Many thanks [bris]. I shall go and have a read.
DocBrown, Jan 20 2006
  

       [bristolz] Simply citing again more Teslanian lore about Nikola's demonstration to of sympathetic vibrations to Samuel Clemens. Mark Twain was known for being full of it, perhaps the events were unrelated.
Seven, Jan 20 2006
  

       [Parmenides] If you have a dirty mind, you can read a lot more into this idea than just that.
sophocles, Jan 20 2006
  

       [Seven], Oh. I didn't know that the laxative rumor started with Twain. I'm just skeptical (septical?) about that notion.
bristolz, Jan 20 2006
  
      
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