Transducer design

[Per Jonsson]

Hi everyone !

I've just started my project building a SSS.
First plan is to make a Dan Fountain "copy" to learn and make tests. I'm using a Fuso 108D writing echosounder. It's operating on 200 kHz and has a range of 150 m. Do not know the output power yet but I will measure it soon.

As a start I will use 5 cheap Thru-Hull transducers from Airmar. My plan is later on to design and construct my own transducer.

Has anyone tried to make a transducer from Piezo Film?
I have been studying the material from Measurement Specialties Inc (www.msiusa.com).
They are selling the film in "raw" sheets as well as tiles (film laminated with aluminium) 1" x 1". The tiles are made to fit sonar designs and comes out in only $25USD.

My plan was to buy a sheet (8" X 11") and cut into a suitable size to get desired beam angle.
Then laminating it onto some material to get desired resonance frequency.

I know Piezo Film has some disadvantages but also some very great advantages as very high sesibility.

Anyone tried to use Piezo Film transducers?

Also have some ideas about materials to use as acoustic window and absorber. What about using stearine as window? Of coarse it's sensitive to mechanical damage but it got a suitable speed of sound (1380 m/s) and is easy to apply (without bubbles) and to remove if wanted. I also belive its very good to keep water out of transducer. As absorber I was thinking of some kind of rubber (40-149 m/s).

Anyone has any suggestions or ideas about this?

Another plan is to digitize the signals from the transducer utilizing the sound card (line input) on my PC. It is fairly easy to write a software in VB for this. I will make some experiments this summer with a PC oscilloscope software called OSCI which uses the soundcard as input device.

Keep up the good work,
Best regrds,
Per

[Mark]

Re: Transducer design

I've made hydrophones from Piezo Film, and indeed they work fine. The material is not usable for transmitting, but makes a good receiver.

They used to make, and probably still have some stock of the hydrophone cylinders.... these are going to be more sensitive than the tiles, but will also have a 360 degree beam pattern.

Mark

[John]

Re: Transducer design

Hello Mark,
I am increasingly becoming interested in sidescan sonar, as I want to gain my knowledge in the field to eventually become another avid sonar scanner interested in preserving wrecks and the like. I have education in various fields, which can be related to scanning.
I lead a very busy life and have little time for adventure, but I hope to change that in the near future. I'm reading your reply to Per's comments and am wondering if you would be kind enough to refer or personally give some info as to general sonar operation and technology?
I want, like a few folks I have read about, to start to gather and build my own small experimental sonar and ultra sound ideas, but am just starting now to explore the possibilities. A reply would be wonderful, and I wish you luck with your own ventures.
Kind regards,

John.

[John]

Re: Transducer design

Hello again Mark,

It looks like I got exited at the "find" of this page, I am sure to find the various subjects I am seeking here. You do not have to reply to my former question , but if you do, I will appreciate that.


Thanks anyway,

John.

[Mark]

Re: Transducer design

I haven't done any work with SSS, but like the vast vast majority of the people here, am interested, but with nothing particular to add. I'd personally love to be able to make charts of local scuba sites. I'm an professional electronics designer, and have done some underwater work....

There really hasn't been any significant 'content' presented by anyone here in a long time... most everyone is asking questions with very few solid answers. I think most of us are lurking, waiting for someone to offer a great low cost kit, or DIY plans



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[John]

Re: Transducer design

Hello Mark,

Thanks for the reply, something a lot of people dont have the courtecy to do.
I am very interested in hydrophones as well, and when I read your reply to Per's comments I thought I'd drop you that line. I see that there is , however, a lot of material on the subject and got real happy fast. Again....Thanks

John.

[Per Jonsson]

Re: Transducer design

Thanks for answers and new ideas...

Very intresting link you left here Mark,
since I'm also doing some underwater photgraphy and have been planning to make my own very compact underwater camcorder.
Building the house is not really a problem but the tricky thing is to gain access to the controls outside the house. Maybe there is something I have to start working with again....
I'm using a Sony DCR-PC110....

[Wayne Keller]

Re: Transducer design

Interesting. I have the same interests and also have the same sony camera. I am currently building a small shallow water rov, with additional interests in hydrophones and sidescan.

I live on Louisiana's only inhabited barrier Island, Grand Isle. I am a sailor and director of the local Port Commission.

Would love to share knowledge, (mainly yours as I am early in the research stages of many of these interests)



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[fganje]

Re: Transducer design

Just caught your message re:designing transducers and thought I would throw in some info from my medical electronics experience. We built prototype transducers using lead metaniobate (spelling? crystal because of the high efficency and mechanical strength. A straight edge and razor blade can be used to cut the material into segments for electrical isolation of individual elements. Deeper grooves could be made using a diamond saw to improve mechanical isolation. Alminum oxide powder stirred into 2 part epoxy formed an absorbtive non-conductive backing for the transducer. Air bubbles were removed from the mixture by pulling in a vacuum jar. A 1/4 wavelength plastic face plate could be bonded to the front face.