Ohm's Law Problem
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From: Michael A. Terrell on 18 Feb 2010 03:31 Joerg wrote: > > Ohm's law? I thought that had been repealed ... :-) Only in parts of Europe. :) -- Greed is the root of all eBay.
From: Ban on 18 Feb 2010 05:17 Joerg wrote: > Ban wrote: >> Joerg wrote: >>> I grew up in medical ultrasound. Back in the 80's a lot of stuff >>> around PZT-based transducers was not understood. Yet the front end >>> parts and transducers of the old machines are not that much >>> different in performance from the ones today, where we have oodles >>> of computer horsepower to simulate and calculate just about >>> anything. If we had said "Oh shoot, we don't understand the theory >>> so let's not build but keep studying until we do" a lot of people >>> in hospitals would have needlessly died. >> >> What a pathetic story. But as always just your limited experience. I >> also worked for a company(Krautkraemer) in the 80s and those guys >> from the transducer department were called "the Phds" in the >> company. They knew what they were doing. The whole principle of >> operation was actually found/invented by 2 brother professors in the >> 40s who later founded the company, hardly any "Neandertals". >> ciao Ban >> > > Krautkraemer was located pretty close to us, I used to work in > Solingen. But it seems you do not know much about medical ultrasound. > It's a heck of a lot more complicated than NDT and the competition is > very fierce. > Did you ever design parts of something like this? > > http://www.volcanocorp.com/files/pdf/datasheet-eagleeye.pdf > > I did. Actually I ran the imaging division when it was EndoSonics and > they don't let you do that with a limited experience :-) > > Hint: There are 64 transducer elements in the tip, plus five > integrated circuits. Oh, and the machine that goes with it has full > color flow capabilities despite the fact that the blood flow is > perpendicular to the beam direction. Many groups tried but we never > had any competition in electronic IVUS, they still don't. Oh, and HP > threw in the towel and shut down their IVUS business. That should > give you a taste of how difficult this stuff is. Oh my dear, I don't like to brag about my work. This US flaw detector for example still in use after 20+ years. http://www.fh-rosenheim.de/2184+M54a708de802.html Thousands of students must have pressed the buttons... In the first place it was a joint effort of all 14 design engineers and 6 softies and my colleagues were very capable and we helped each other. Then in 1986 when we did this it was challenging to make a portable and reliable instrument with digital control. I was just doing the analog front end and helped with the deflection amp for the CRT (no LCDs yet). I designed and prototyped a couple of hybrids for this, one is the 2"x1" input amp. Almost everything else is surface mount. And I can say *everybodies* life depended on it many times. Die Bahn and British Rail testing steel axles or all airplane companies, nuclear reactors, space shuttle, mines used and still use it. It is working at -20�C in Siberia with the specified accuracy as well as at +80�. And the company regained the 85% world market share it had lost before and it was sold 5 times more than projected more than 20000 units ... And again I was just part of the team tho the only consultant and without the help of Dr. Volkmann who came from R&S, I wouldn't have been able to succeed at all :-( ciao Ban
From: Joerg on 18 Feb 2010 12:56
Ban wrote: > Joerg wrote: >> Ban wrote: >>> Joerg wrote: >>>> I grew up in medical ultrasound. Back in the 80's a lot of stuff >>>> around PZT-based transducers was not understood. Yet the front end >>>> parts and transducers of the old machines are not that much >>>> different in performance from the ones today, where we have oodles >>>> of computer horsepower to simulate and calculate just about >>>> anything. If we had said "Oh shoot, we don't understand the theory >>>> so let's not build but keep studying until we do" a lot of people >>>> in hospitals would have needlessly died. >>> What a pathetic story. But as always just your limited experience. I >>> also worked for a company(Krautkraemer) in the 80s and those guys >>> from the transducer department were called "the Phds" in the >>> company. They knew what they were doing. The whole principle of >>> operation was actually found/invented by 2 brother professors in the >>> 40s who later founded the company, hardly any "Neandertals". >>> ciao Ban >>> >> Krautkraemer was located pretty close to us, I used to work in >> Solingen. But it seems you do not know much about medical ultrasound. >> It's a heck of a lot more complicated than NDT and the competition is >> very fierce. >> Did you ever design parts of something like this? >> >> http://www.volcanocorp.com/files/pdf/datasheet-eagleeye.pdf >> >> I did. Actually I ran the imaging division when it was EndoSonics and >> they don't let you do that with a limited experience :-) >> >> Hint: There are 64 transducer elements in the tip, plus five >> integrated circuits. Oh, and the machine that goes with it has full >> color flow capabilities despite the fact that the blood flow is >> perpendicular to the beam direction. Many groups tried but we never >> had any competition in electronic IVUS, they still don't. Oh, and HP >> threw in the towel and shut down their IVUS business. That should >> give you a taste of how difficult this stuff is. > > Oh my dear, I don't like to brag about my work. ... I don't either (well, ok, sometimes ...), just wanted to show that your ad hominem statement about limited experience is plain wrong. I am doing this since 1986, to be exact. > ... This US flaw detector for > example still in use after 20+ years. > http://www.fh-rosenheim.de/2184+M54a708de802.html Thousands of students must > have pressed the buttons... > In the first place it was a joint effort of all 14 design engineers and 6 > softies and my colleagues were very capable and we helped each other. Then > in 1986 when we did this it was challenging to make a portable and reliable > instrument with digital control. I was just doing the analog front end and > helped with the deflection amp for the CRT (no LCDs yet). I designed and > prototyped a couple of hybrids for this, one is the 2"x1" input amp. Almost > everything else is surface mount. Ah, hybrids. We probably did ours at around the same time. Mine were then produced at Philips Krefeld and also Turck in Halver. I had a lot of fun designing hybrids but unfortunately that era has ended :-( > And I can say *everybodies* life depended on it many times. Die Bahn and > British Rail testing steel axles or all airplane companies, nuclear > reactors, space shuttle, mines used and still use it. It is working at -20�C > in Siberia with the specified accuracy as well as at +80�. And the company > regained the 85% world market share it had lost before and it was sold 5 > times more than projected more than 20000 units ... Ok, nice, and I don't want to belittle this technology in any way. It is needed and will ensure safe operation of public transportation and other gear, as you wrote. But technologically it is a very different ballgame versus medical ultrasound. It looks like a classic A-mode system where the transducer has only one element. Or maybe several in annular array configuration for focus. A-mode is gone from medical, since the 70's. State-of-the-art is now beamforming with 64 or more channels running at the same time. <5nsec delay granularity, apodization, the whole nine yards. The one I am working on right now will support transducers with several hundred elements and will provide 3D rendering. You cannot possibly do that all in discrete, not even SMT. Which is why I had to start getting into chip design, to some extent, in the late 90's. > And again I was just part of the team tho the only consultant and without > the help of Dr. Volkmann who came from R&S, I wouldn't have been able to > succeed at all :-( Same here, there have to be real scientists involved and those are often Ph.D. with a serious physics background. Same on the project I am working on today. All I wanted to say is that there always was and still is stuff in ultrasound that's next to impossible to grasp from a science or simulator point of view. Even where it is, when a sim on the hottest screaming machine takes weeks you have to cut to the chase at some point, so you get to market in time. This is also why a lot of recipes (filler, backing material, acoustic lens, and so on) are closely guarded trade secrets. You won't find any info about this stuff here at the office, it's all destroyed the minute I don't need it anymore, only the respective client keeps it. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |