Underwater ultrasonic transducers

[kellyruperts]

Hello all,
I'm considering doing a senior project to measure water velocity
using ultrasonics and doppler measurement, and wondering if anyone
knows a good, low cost transducer (I'll actuall need two, one to
trasmit and one to receive). It seems the best ones to use are between
1 - 2.4 MHz. Also, do I need an oscillator to drive the transducer, or
can I just apply a continuous voltage? Any other help anyone can
provide would be useful (especially relating to how to construct an
underwater housing for the transducers).

Best
Kelly

 

"kellyruperts" <kellyruperts@yahoo.com> wrote:

I'm considering doing a senior project to measure water velocity
using ultrasonics and doppler measurement, and wondering if anyone
knows a good, low cost transducer

Would a marine depth sounder transducer work?

 

[Pi]

On 13 Feb 2005 21:35:07 -0800, "kellyruperts" <kellyruperts@yahoo.com>
wrote:

I'm considering doing a senior project to measure water velocity
using ultrasonics and doppler measurement, and wondering if anyone
knows a good, low cost transducer (I'll actuall need two, one to
trasmit and one to receive).
I know a n address in Poland, but you may better check in the USA (I

assume that is where you live).

It seems the best ones to use are between
1 - 2.4 MHz. Also, do I need an oscillator to drive the transducer, or
can I just apply a continuous voltage?

You can use a sine, but also pulses that make the transducer swing at
its resonant frequency. All depends on the manufacterer.

Any other help anyone can
provide would be useful (especially relating to how to construct an
underwater housing for the transducers).

There are transducers for use in water.

I did a pre-diesing of a transducer system to measure wall-thickness
of steel pipes from inside the pipes. Feel free to ask any questions.

Regards,
Pieter Hoeben
http://www.hoeben-electronics.com

 

[kellyruperts]

Hi Pieter,
Thanks for the information, I will try to give you a little more
background. My original plan was to use to transducers, 1 to transmit
and 1 to receive, but I could also just use one and do a pulse then
measure the frequency of the response, although this is a lot more
complicated for timing issues. The only transducer in the appropriate
frequency range that I have found is from Panametrics NDT:

http://www.panametrics-ndt.com/ndt/ndt_transducers/immersion/std_case_style.html

The problem is that they are a little too long and are very expensive
(each one costs $270). Does your contact in Poland have anything that
might be better? If I could keep the length of the transducer at less
than 1 inch it would make it easier to mount at the bottom of the
fluid. I talked to the sales staff and they said the housing is filled
with an epoxy so the wave transmits to water, but I don't know if it is
possible to do this in less space.

Any other suggestions from your experience would be helpful. I plan to
take the transducer output to an amplifier IC (to be determined)
through an ADC to my microcontroller.

Best
Kelly

 

[mike]

William wrote:

"kellyruperts" <kellyruperts@yahoo.com> wrote:

I'm considering doing a senior project to measure water velocity
using ultrasonics and doppler measurement, and wondering if anyone
knows a good, low cost transducer


Would a marine depth sounder transducer work?

What's the objective?
Ultrasonics?
Sound velocity measurement?
Doppler?


Seems like there ought to be ways to use any old piezo transducer
you can find on any motherboard. Might be able to break off pieces to
resonate anywhere you want.

Maybe you can fire off a flash tube under water and measure the shock wave.
I'd give you more ideas, but it's not MY senior project;-)
mike

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[kellyruperts]

Hi William,
The objective is water velocity measurement using doppler. Breaking
existing piezo transducers might not be accurate enough, I estimate at
least 500 MHz would be necessary and I don't think any amount of
breaking would get it into this range.


mike wrote:

William wrote:
"kellyruperts" <kellyruperts@yahoo.com> wrote:

I'm considering doing a senior project to measure water velocity
using ultrasonics and doppler measurement, and wondering if anyone
knows a good, low cost transducer


Would a marine depth sounder transducer work?


What's the objective?
Ultrasonics?
Sound velocity measurement?
Doppler?


Seems like there ought to be ways to use any old piezo transducer
you can find on any motherboard. Might be able to break off pieces
to
resonate anywhere you want.

Maybe you can fire off a flash tube under water and measure the shock
wave.
I'd give you more ideas, but it's not MY senior project;-)
mike

--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[mike]

kellyruperts wrote:

Hi William,
The objective is water velocity measurement using doppler. Breaking
existing piezo transducers might not be accurate enough, I estimate at
least 500 MHz would be necessary and I don't think any amount of
breaking would get it into this range.

Ok, my bad. I extrapolated to infer measure the velocity of the
ultrasonic wave in water.

I think that trying to make an acoustic wave at 500 MHz. will be
very difficult. What's the thinking behind needing a frequency that high?
What range of velocity are you trying to measure?
What accuracy do you need?
What are you going to do about turbulence?
mike


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Return address is VALID but some sites block emails
with links. Delete this sig when replying.
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Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
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