ultrasonics

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Or simply get a 40KHz ultrasonic transducer -- if you only need one frequency and 40KHz is it, it's perfect and peaked out for performance.
 
yes thnx, is there a place I can get lots of the transducers for cheap? also do i need to consider "volume"? I was reading that an array of these can create a kinetic force?
 
another question?? Why can't I use a LC circuit? say a 5187.78 uH air coil with a 1nF capacitor.?
 
also is it correct that λ = c/f

does that mean that a 40khz ultrasonic wave is 90m long?
 
No on the wavelength. You have the equation for the wavelength of a radio signal, not an audio soundwave.
 
but why no? what frequency does it cross from a sound wave to a Radio one? and is there a point where an audio wave crosses to RF, or vice versa? or maybe im looking at this wrong?

is there a max/ min limit on acoustic wavelengths(Imean besides mammal audible ranges)? and what happens when we try to cross that acoustic limit?
 
You are confusing two different phenomena.
Radio waves are electromagnetic radiations, and essentially travel at the speed of light. Sound is a variation of air pressure, and travels at roughly 1000ft/sec.

There sre calculators for the wavelength of both types of wave here; Wavelength frequency convert lambda Hz sound conversion acoustics acoustic audio radio speed of sound and radio waves wave length light vacuum equation formula speed of light - sengpielaudio Sengpiel Berlin

But as you can see, there are two entirely separate calculators involved.
 
doggy__ said:
is there a max/ min limit on acoustic wavelengths(Imean besides mammal audible ranges)? and what happens when we try to cross that acoustic limit?
Click to expand...
The only limit is in trying to get a mechanical device to vibrate at the very high frequencies needed to generate short wavelength sound waves. Specialized applications use sound waves in the several MHz region. There is no hard limit.
 
YEA I am confused! and i understand the difference ok, but there is something i am getting lost,

let me start: i gots my singen, so i wire it to a speaker, turn up the f and eventually go above audible, but it is still sound(airpressure)? eventually i go up out of tweeter range, but then what about these transducers, they are acoustic too?, do we ever use RF in 40khz range?

myabe my question is what is the max freq that won't get dampened out by the air?
 
doggy__ said:
myabe my question is what is the max freq that won't get dampened out by the air?
Click to expand...

I believe that can be calculated from the mean distance of air particles (6.917×10^-8 meters) and the speed of sound (343.174 m/s). That would give an estimate of couple of gigahertz.
 
ok, so a Mhz sound wave wouldn't be an EMF, and wouldn't travel at the speed of light? and would NOT INTERFERE WITH RADIO? so going back if I had an inductor coil, it will generate a emf, shrinking that coils induction would help it to respond to higher frequencies? BUt a speaker just displaces the air?

I am interested in the special methods to get the devices to vibrate at high frequencies, are we talking crystals and such?
Is this getting back in to the natural resonance stuff? or maybe more like a magnetron(which is emf right)

Would a tweeter do 40khz acoustics(ynot)? could i use a choke, with a small back magnet? Is there anything i can get on freq response design for speakers or transducers?

(lol, also wouldn't a speaker coil cause EMF!?)
 
You can generate either an acoustic wave or an EM wave at 40KHz (the NIST station from Boulder broadcasts a 60KHz EM signal that "atomic" wall clocks use for synchronization). The type of wave you generate just depends upon the transducer. If you feed the 40kHz electrical signal into an appropriate antenna then you will generate and radiate a 40kHz EM wave in space (no air required). If you feed the 40kHz electrical signal into an appropriate speaker, then you will generate and radiate an acoustic wave in air (air required).

Edit: Yes a speaker coil will generate some EM also but the speaker is such a poor antenna at those frequencies that the EM wave has no measurable power except perhaps very close to the speaker..
 
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okko, that makes sense, thanks for clarification, so which of these waves travel linearly, that we(an bats) use for sonar, that would be acoustic..... but then why wont a button magnet and a small coil work? I guess the transducers are better.....

still is there a place to get alot 4 cheap, do i need to consider power output??
 
yes , but i only need a ton of transmitters like 100 or so, no receivers. so i need to find a bargain, plus i need to consider driving, it says 60v p-p, any driver suggestions?

thnx again!
 
Why are you trying to create a high power ultrasonic transmitter?
Are you aiming to deafen all bats, within a 10 mile radius for example.
Or trying to call your dog from the next town??....
 
Personally, I think the O.P. is kind of a nutcase (albeit a likeable one) who's overly influenced by golly-gee-whiz-bang stuff like Tesla coils, trying to cause earthquakes, perpetual motion, and other such pseudoscientific stuff.

But hey, what do I know?
 
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