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Schematics for 5 MHz ultrasonics?

Discussion in 'Electronic Design' started by Pieter Hoeben, Dec 30, 2003.

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  1. Hi,

    I am trying to find more information on ultrasonics, especialliy on
    how to control the voltage pulse on the transducers, and how to read
    back and anlyse the data. Does anyone have experience or leads?

    Regards,
    Pieter Hoeben
    email:
     
  2. John Fields

    John Fields Guest

     
  3. Luhan Monat

    Luhan Monat Guest

    Are you sure you mean 5mhz????
     
  4. N. Thornton

    N. Thornton Guest

    I guess there must be some sort of transducer that goes that high,
    only thing that strikes me as having any chance is putting the
    electricity straight through the air. I've not heard of 5MHz
    ultrasonics before either.


    Regards, NT
     
  5. GPG

    GPG Guest

    SAW filter, surface acoustic wave
     
  6. James Meyer

    James Meyer Guest

    Medical ultrasound uses frequencies that high and much higher. I've
    been building my own transducers for 8.5 and 20 MHz using ordinary piezo
    material.

    Jim
     
  7. Bill Sloman

    Bill Sloman Guest

    5MHz is pretty typical for modern diagnostic medical ultrasound, which
    is transmission into water, rather than air. The machine that make
    nice pictres of my aortic valve seems to work around that sort of
    frequency.

    When I was working on phased array ultrasound in 1976-79 at EMI
    Central Research, I spent some time glueing together my own 2MHz
    single unit transducer out of a layer of some odd piezo-electric
    crystal that we bought from Philips, and a couple of layers of epoxy
    resin bonded tungsten power to produce quarter-wave matching layers to
    get reasonable impedance matching into water.

    Back then we had high hopes of poled stretched polyvinylidene fluoride
    plastic film, which had an acoustic impedance a lot closer to water,
    but I don't think that it ever did anything much for medical
    ultrasound.
     
  8. Fred Bloggs

    Fred Bloggs Guest

    The field is very specialized and there will be no intelligible
    literature accessible to an application engineer outside specific sensor
    manufacturer application notes and technical support.
     
  9. James Meyer wrote...
    Wow. I've done some work making my own transducers at
    5 and 10MHz, but the piezo disc was getting pretty thin.
    20MHz, please Jim, tell us more. Spill the beans for us!

    Thanks,
    - Win

    whill_at_picovolt-dot-com
     
  10. Jim Meyer

    Jim Meyer Guest

    Piezo sheets from http://www.piezo.com/en-us/dept_40.html. I was
    making little 3x7mm 'ducers. Scribe the sheets with a sharp tungsten
    carbide tool and break them just like a pane of glass or use a
    lapidary saw with a thin diamond blade. Browse the whole site for
    lots of really good info.

    Get their soldering kit too. It's got flux and solder for the
    nickle electrodes. They even throw in a small piece of piezo to play
    with. They don't guarantee what material you'll get, but the sample I
    got was the same as what I needed for the 8.5 MHz 'ducers.

    Jim
     
  11. Jim Meyer wrote...
    Good going, Jim, those are the beans I had in mind!

    Thanks,
    - Win

    whill_at_picovolt-dot-com
     
  12. Nobody else here saw the Sci Am article "KiloMegacycle
    Ultrasonics" (6/63)?

    You stick a big piece of quartz into a hole in a cavity
    resonator and feed it lots of RF. IIRC they were beaming 3
    GHz around their lab.

    Mark L. Fergerson
     
  13. ddwyer

    ddwyer Guest

    Nobody else here saw the Sci Am article "KiloMegacycle
    Ultrasonics" (6/63)?

    You stick a big piece of quartz into a hole in a cavity
    resonator and feed it lots of RF. IIRC they were beaming 3
    GHz around their lab.

    Mark L. Fergerson
    [/QUOTE]
    Iv been collecting Sci Amer from 60s so Ill go and look.
    In '61 I started work on Mil Sonar and by 70s had converted to Quartz
    resonators.
    Quartz has a low coupling coefficient so needs a lot of drive voltage at
    GHz the inherent acoustic Q is only a few 1000. Thats why SAWs are
    limited in Q at GHz.
    Lithium Niobate would be easier from a coupling coefficient point of
    view.
    YIG could be interesting.
    I remember an air powered whistle that operated at the focus of a
    parabolic mirror that ignited wool at a distance of some feet also an
    Amateur Scientist .
    Magnetostriction could well be the way for the amateur to proceed.
     
  14. Yes, for measuring wall thickness of pipes

    Pieter
     
  15. James Meyer

    James Meyer Guest

    EBay often has complete ultrasound thickness gages for sale. The prices
    are often quite reasonable. I'll bet you could find one you could afford by
    looking for a length of time less than it would take for you to build your own.

    Jim
     
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