Boost Converter Efficiency Improvements

What does that have to do with tapped inductors or flyback transformers?

Only for very high volume products. Otherwise ...

Bingo!

Sure. When qties are lowish you are mostly better off with all catalog parts.

Not the Baxandall oscillator again? :-)

I have designed rather complex stuff with magnetics.

Sorry, but that ain't so. Here is a classic example of an off-the-shelf part that proves it:

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Here is another:

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I can usually get that done with four pins.

Should have looked at what was available in the US :-)

stuff.

I have to disagree. Farnell's offerings were never really complete enough for me. If I build something I want to order everything fast, meaning at one distributor if possible.

Well, then it's no wonder that you didn't get anywhere with the big companies. They normally would still accommodate you but then charge big NRE.

[...]

That's stating the obvious. Naturally one requests more than one quote.

If you pay the NRE the big companies usually take it.

After more than 25 years on the beat I know what will cost roughly how much. You get a feel for this. Typically if there is a catalog part I always use it. Later we can always re-visit and see if a custom part will save a nickel or two.

Big research labs aren't very efficient, not because of the people but because the bureacracy and the politics that usually come with them. Nowadays the real innovation is with small business, and there mostly with start-ups.

Today the biz world is all virtual. I am on GoToMeeting and similar services all the time.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg
Loading thread data ...

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Nothing - per se - with tapped inductors. Flyback transformers necessarily produce a varying voltage, and you can fudge the average voltage to the val ue that you want by pulse width modulation. There are lots of ways of varyi ng the pulse width. If you use a tapped inductor in a flyback circuit you'v e got another parameter to vary - but the way you get a variable voltage is essentially by PWM.

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og

It does make life easier. There's not a lot of economy of scale in transfor mer winding, so a custom-designed transformer isn't much more expensive tha t an off-the-shelf part, and the off-the-shelf part is almsot always going to be bigger and heavier and contain more expensive copper than the purpose designed part.

get

For some unspecified value of "rather".

You need the manufacturer's data sheet

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to make sense of what it is. It's got 12 pins, and the manufacturer claims to offer 500 variations. Digikey has 600 in stock of that particular specif ication, so presumably somebody is buying them regularly

I'd call that a common-mode choke.

But you could probably do more with more.

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At that time? Getting stuff from France or Germany was pretty much impossib le, and the US was even further away, and their wound products didn't meet European safety specifications. Delay lines were about the only wound parts I ever thought about getting from US suppliers, and the UK sources were us ually good enough.

, as

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They were the best of the UK distributors. Nobody has everything, but Farne ll came closest.

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d

At Cambridge Instruments we got a lot of attention - 100 electron microscop es a year isn't volume production, but they contained a lot of parts, some of them rather expensive. Analog Devices had Barry Gilbert come around once , but he was pushing stuff that we weren't interested in.

and

to

ion.

Primarily because the quote from EPCOS is never going to arrive, if you are n't in a more-than-10k-a-year business

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os

If you get quoted an NRE to pay.

the

If you've done enough of more or less the same design.

Or if you can throw out a lot of parts if you use a purposed-designed multi

-tapped transformer.

Companies that paid internal royalties always had to stop it because the R& D lab ended up getting more money than the rest of the company would tolera te.

Efficiency isn't really the metric here - effectiveness is what counts.

EMI Central Research's "Chief Scientist" used to be it's manager until they caught him doing an end run around the bureaucrats. It wouldn't have been a problem if they hadn't been War Office bureaucrats.

Often started up with capital from a larger firm who used to employ the peo ple who run the start-up.

--
Bill Sloman, Sydney
Reply to
Bill Sloman

That still doesn't explain what you mean with "clue".

[...]

The catalog part does not come with huge MOQ or NRE requirements and is available instantly. Both are often key.

Regarding designs with challenging inductive parts about 30-40 SMPS (I stopped counting at some point), flybacks, other architectures. Then pulsers, fuel injection circuits, fast isolation interfaces, contactless power transfer, and so on.

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That's why there is a clickable link in all Digikey parts listings.

Oh no, that's definitely not its intended purpose. A CM choke with same capabilities (for diff lines) can be made much smaller and cheaper. One classical application for these dual inductors are SEPIC supplies.

Yes, but usually it's not necessary.

Then why could I get parts from the US in the 70's and 80's? I lived in Germany back then. For orders we use telex machines, I even used to have an old Lorenz myself. Man was that thing loud (didn't have a muffling hood).

Uhm, nope, many of them did and still do. You just had to look for the magic sequence UL/CSA/VDE (no CE back then).

I found that almost nothing could beat Belfuse and Kappa delay lines. Except for the ones we had custom-made.

Maybe in the UK.

[...]

Then you need to get on the telephone and it will arrive. I have a habit of wiggling my way up the command chain if a company I need something from behaves too recalcitrant. That does get the attention eventually, usually before it has percolated up to their CEO.

I always did. Recently I've notice large companies chickening out at times, telling me "It can't be done". A few months later we have "It can't be done" in production, but without them. As I said, real progress rarely happens in bigger places.

When it comes to converters, I have. To the point where the things start coming out of my ears, like eating a certain dish too many times.

Unless absolutely needed, that takes too long.

Venture capitalists see that a wee bit differently. And I find that this has a sobering effect on design teams, makes them do their work swiftly because there isn't a seemingly infinite amount of money and certainly no lifetime employment.

[...]

That was the case with the first start-up I was part of. But the larger firm was not large by common standards, about 300 employees.

--
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http://www.analogconsultants.com/
Reply to
Joerg

It might if you thought about it a bit harder.

The parts I got wound didn't come with huge MOQ or NRE requirements. One man and his coil winding machine don't work that way. Like I said, there's not a lot of economy of scale in transformer winding. If you are getting stuck with huge MOQ and NRE requirements, you are buying from the wrong suppliers.

Who hasn't? Why do you think that it's a big deal? I did notice that junior engineers did tend to be shy of transformers, and you had to hold their hands a bit to persuade them to use them, but once you'd got them used to the transformer equation

V1= L1.dI1/dt + M.dI2/dt and V2= M.dI1/dt + L2. dI2/dt

they usually got more relaxed.

2

I certainly couldn't find it - the clickable links gave me the circuit diagram and the pin-out, but no parameter data. Farnell does better.

If you buy 1k or so per month, that would do it. If you stop, the stock holding might drop to zero.

For a particular voltage level and power rating. More volts and you saturate the core, more current and the core gets too hot. Less of either and you are buying more core or more copper than you need.

But might be cheaper or simpler.

d).

I had to go through the purchasing department. If I threw a tantrum I could usually get an order number and phone through an order myself, but only to UK suppliers (which did include agents for US firms, who seemed to think that surface mail was the only way to shift goods).

           ... and their wound

They do now.

That was starting to happen in the late 1970's, but you couldn't rely on it.

      ... Delay lines were

I usually didn't need anything particularly good. The one time I did - for the Cambridge Instruments "Alvey" shaped-beam electron beam lithography machine - we did design our own, but the project got cancelled before we could build one.

They were pretty good in the Netherlands around 2000 - we did use other distributors, including some big German suppliers, but Farnell was fast and remarkably comprehensive.

i've spent enough time on the phone trying to do exactly that to find that claim hard to believe. You can beat the telephoe run-around if you are persistent enough, but life's too short to make a habit of it.

Or designing a circuit one way so often that you fail to realise that that particular circuit could have been better designed another way.

The usual balance of cost of design amortised over the production cycle. It helps if you are used to exploiting and designing multi-coil wound parts.

Venture capitalists are particularly short-sighted. For some innovative projects they are the right source of funding, but you need to know pretty much exactly what you are planning to make if you go to them for funding. Including market projections and a cash flow analysis that includes projected sales income.

Bell Labs and EMI Central Research had room for more speculative and open-ended projects - like the transistor and the brain-scannner.

Sure but the point is to be able to write off the start-up if it fails without writing off the parent organisation.

--
Bill sloman, Sydney
Reply to
Bill Sloman

s
152

..

A some point someone you would need to face the fact that you have been pro ven wrong and stop arguing. You might actually learn something instead of t rying to prove you own point. You've even learned I hope that Farnell is no t the only way to go ;-)

My favorite is Digikey for parts search, Findchips.com for price and availa bility search.

Regards

Klaus

Reply to
Klaus Kragelund

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is

I

ess

68152

i...

R-

me

ne

roven wrong and stop arguing.

Sadly for your thesis, Joerg hs to prove me wrong first.

nt.

The point about the virtues Digikey's search engine was new to me, but I ha d to complain about Farnell's to provoke that response. Scarcely an argumen t for shutting up and treating Joerg as infallible (though he comes closer than most).

I've never thought that Farnell was the only way to go, but it is a represe ntative broad-line distributor, and a handy source of examples of the how t he breed behaves.

Over the years I've ended up buying more parts from Farnell than anybody el se. Digikey has gaps in it's coverage.

--
Bill Sloman, Sydney
Reply to
Bill Sloman

Looks like you can't explain your own arguments :-)

Sure there are economies of scale. Big time. At one end of the scale you have your one man with the old steam-engine, at the other you have a building the size of half a soccer stadium with myriad machines, all SCADA controlled.

[...]

How many switchers have you designed for production?

[...]

This time try it with your glasses on: Look on the left, for the word "Datasheets". Click the link next to it, says "VERSA-PAC" which is the product name. And ... voila ... full datasheet comes up.

They typically keep a few on hand then.

Cores saturate with amps, not with volts :-)

These dual inductors are quite universal. On a recent power supply that contains four switchers I use the same dual inductor for two grossly different ones (to reduce parts variety in the BOM).

More pins are simpler?

When I embarked on my first job and saw this ancient purchasing department system I started pushing for more autonomy right away, and got it. Shortly thereafter we instituted "international sourcing" and that made life a ton easier.

They even did in 1986.

Sure you could. We did have a marvelous tool: The fax machine. IIRC the older ones were called Rapidfax and had a digital protocol. I typically asked for a faxed copy of the cert.

[...]

My experience is exactly the opposite. But first you have to find out who the movers and shakers are. Like the VP of Sales, and then possibly the CEO. I became pretty good at snooping out their direct contact info.

[...]

I almost always start from a blank sheet and low-cost designs are one of my specialties.

[...]

Sure, to me that is part of engineering.

This is not reserved for large labs. How do you think this one came about?

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Very small company, venture-started, we certainly did not have a bottomless R&D account.

[...]
--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

There's a point where further explanation is flogging a dead horse.

s

A myriad machines, all making small batches of small transformers under num erical control, doesn't translate into huge MOQs and big NRE's. It doesn't take a lot of programming to change the wire size and the number of turns.

ss

One, and it was part of a thermostat. We mostly bought them in.

8152

...

That pulls up the same "data-sheet" that I found that covers 500 different devices. I was hoping for something a little more specific - as I said, Far nell does better.

Sceptical snort.

-
e
e

The core gets saturated by the magnetising current, which is volts times ti me. Typically this is quite a bit less than the current you feed into the input windings and take out of the output windings to transfer the power you are putting through the transformer. I'd have thought that you would have appr eciated the distinction, if you'd done as much magnetic design as you claim .

What - precisely - was the gross difference?

No, but the rest of the circuit might be.

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ve

Interesting. When I worked at ITT-Creed 1979-82 some of the people I was wo rking with were busy getting Group 3 fax machines from various manufacturer s to talk to one another the way the ITU specifications said they should. I t kept them busy.

it

rt

Nobody starts from a completely blank sheet. Some people get so obsessed wi th low cost that they won't use 0.1% resistors even when they do give you t he cheapest over-all solution.

is

y

But not innovation.

?

You've talked about that project before. You knew pretty exactly what you w anted to do, but you didn't have a clue if you could do it when you went af ter the capital, so your backers must have known that there was a fair chan ce that they'd lose everything that they put in.

That's what venture capital is all about.

My wife and I had dinner in Melbourne last Thursday with an old friend of m ine (we were undergraduates together, 50 years ago) who - eventually - made a lot of money (most which he's used up) out of a better way to make a con focal microscope. Tektronix put in an essentially identical - provisional - patent on the same idea three weeks before his but dropped it at the end o f the provisional period.

The big research lab came up with the idea a few days earlier than a pair o f more isolated innovators on the other side of the Pacific, but didn't car ry it through.

--
Bill Sloman, Sydney
Reply to
Bill Sloman

In your case I often have that impression.

It usually does.

So that one thermostat made you the expert?

[...]

Maybe read up a bit on switchers? :-)

You designed one switcher. So that makes you the expert ...

Power levels different by a factor of five, output voltage range by a factor of three. Parts commonality is a major factor in overhead of a company and thus overall product cost.

[...]

I only had that problem with very long distance, across oceans. Not so much between us and headquarters which ws 6000 miles, but to places in Canada, for example. The trick was to ratchet down the transmission speed, before it gets to the point where it aborts with a transmission failure. Sometimes to 1200bd which was very painful because of the price gouging telco monopolies. At two bucks a minute that kind of matters. So we kept messages as brief as possible.

Another thing back then was that transmissions at off-peak hours tended to work better. Which is why I was glad that my fax had a scheduler built in.

[...]

I often do.

I will only use them where needed. There were designs where I backed off to 10% and even 20% (untrimmed), for consumer mass products that can matter, big time.

Sure it is. Even research has to be planned to some extent, else you can quickly see the plugs pulled.

That's how all venture capital deals work. They have to get the warm and fuzzy about the project, the market, plus the people involved. Ye olde due diligence. If only one of these isn't 100% -> no dough.

That is one of my gripes with big research, especially if taxpayer-funded. They often do stellar work and then completely bungle the commercial side of it.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

I interviewed with Tektronix's Beaverton lab in 1987, as well as HP Labs on Page Mill Rd, before going to IBM. Trust me, Tektronix was _not_ a major research lab.

Cheers

Phil Hobbs

--
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Principal Consultant 
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Phil Hobbs

[...]

No, Tektronix isn't a place I'd consider a major research lab even though they did contribute majorly. For example, their coax line pulser stuff. That was really an engineering gem.

What I meant was large gvt labs in industrialized countries. When it comes to commercialization of taxpayer-funded research results they often, well ... don't get me started. Gets my blood boiling because I am a taxpayer :-)

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Farnell was never a good alternativ to buy in Germany ferrites and even more important: bobbins, clips, spacers, enameled wire and bundled wires etc.

I don't know if

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or
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are exporting to outside EU you have to ask by email. The online browsing and searching can't compare with Digikey or Mousers. But if you look for EPCOS you may look there.

Those two above mentioned distributors had been since the early beginning the reps and distributor for EPCOS. Especially if you want a specific item like a small toroid without a thick plastic coating just the naked core, which is listed, but not stocked, you can go trough them to get an offer for a MOQ.

Although Philips had in Hamburg not far away from me their ferrite laboratory, where the ferrox was once invented, they never built up such good way offering their product line in Germany. Meanwhile they sold out many subdivisions to focus on their key biz. Seems not too much know how left: When I read last time an article about the Hue LED globe, I was suprised: the engineers did not manage to have one transformer inside working for wide range input 110VAC and 230 VAC otherwise the transformer would not fit inside :-O

rgds Joerg

--
Joerg Niggemeyer on Beagleboard running RiscOS 
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Reply to
Joerg Niggemeyer

I interviewed with HP. The guy looked at my resume and said, "The first thing you have to do is decide if you're an engineer or a programmer." It went downhill from there.

--
John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
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John Larkin

Thanks. That would be good for EU clients.

I won't do that here in the US anymore. Too many times I found that EU vendors cannot properly handle international business. To the point where on purchasing manager literally pleaded with me to change a part in my design to a domestic inductor, or at least an Asian one. I found a good source in Japan and all purchasing problems miraculously vanished.

Yeah, the old Valvo. That is a sad story, it used to be a true electronics powerhouse. They were very good to me as a student in Germany when I needed parts and databooks. Still have most of those databooks because many transistors and diodes didn't change over the last 25 years. Actually I got into electronics via Philips, the EE-20 experimenter's kit:

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When I see how universities are nowadays teaching that is not at all a surprise. Although it probably won't matter for screw-in bulbs because the sockets are slightly different between the US and Europe. Not much though, I have several German lamps with 120V bulbs and American CFL here, one right next to the PC.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Obviously not. Like I said, we didn't design many switchers. There were qui te a few other wound components, and a few more that got designed and bread

-boarded, but not built.

You may not see what I'm saying, but it's a valid distinction - essentially what makes transformers better devices for getting power across an isolati on barrier or a voltage difference than simple fly-back-coupled inductor pa irs.

It's not the only one I designed, merely the only one I got into production . I'm not claiming the credit for stuff that other engineers turned into pr oduct.

So you could trade off having more magnetising current in the higher voltag e part (in the primary coil), as opposed to having a bigger power-shifting current in the higher voltage part (flowing through both primary and second ary coils)?

Up to a point. And not for parts being used in volume. At some volume, payi ng for a more expensive part is going to be more expensive than tying up a buyer for an extra hour every month and finding room for another bin in sto res.

So you think about using valves for the job, and search the web for every p ossible new integrated circuit that might have been introduced since you di d a similar job? You can't - and shouldn't - set aside everything you've do ne before, and you shouldn't fool yourself about our innate tendency to dis tort problems into variations of problems we've solved before.

But not when parts commonality is crucial.

That "some extent" is the tricky bit.

The point about research is that you don't know what you are going to find

- otherwise it wouldn't be research - and you can't plan how you are going to exploit a break-through if you don't know what kind of break-through you r research is going to uncover.

That's exactly what happened there - the Australian patent was eventually s plit between my mate and his co-inventor, who happened to work for CSIRO - the big Australian-government-funded Commonwealth Scientific and Industrial Research Organisation. CSIRO did nothing with it.

CSIRO does have it's commercial successes. Not every development is bungled .

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h_Organisation

Varian bought up their atomic absorbtion spectroscopy invention fairly earl y on - in 1969 I tried for, but didn't get a job with the Frew family that got the first machines onto the market. CSIRO's developers used the Cambrid ge Instruments EBMF 10.5 to create the holograms that went into the first p olymer banknotes, which is how I got to know about that one.

EMI essentially went bust because they stuck too much capital into their bo dy-scanner and couldn't get the machines into the customer's hand quite fas t enough - Jimmy Carter didn't help - so commercial research labs aren't pe rfect either.

--
Bill Sloman, Sydney
Reply to
Bill Sloman

[...]

One is in a SEPIC, the other in a buck where the 2nd winding is merely used to generate a piggy-backed negative voltage almost for free.

[...]

What I meant is starting with a clean slate when doing a design. Of course everybody draws on their education, previous experience, and so on. And we do not have to start each project with Maxwell's equations.

Haven't done a tube design in ... almost forever. But they sure were fun. RF stuff, BIG.

Sure, even then. Example: You have 10k pull-ups for logic stuff but otherwise no 10k resistors in dividers or other ciruits that require high precision. So I told them to ease off to 20% for those.

Then we have different definitions for the word research. To me, for example, trying to find a cure or treatment for a disease is research. Because when you start you don't know how to get there. But you can still plan your path, define a budget, and so on. It's done all the time in industry.

[...]

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Sometimes I wonder where the taxes going to such large organisations are really a wise investment. Aside from botched commercializations these enties often become heavily politicized, as outlined in your link.

However, society needs some folks who do basic research. One should just not overdo it.

Big ones often aren't. They tend to become bureaucratic and there is too much tenure going on.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

George Kent had a wide range of parts - pretty much every E12 resistor, exc ept 18k, until my boss got peeved and designed a circuit with 18k resistor where everybody else was using 10k. We didn't pay much for our standard 1%

600mW 18mm pin-spaced (actually 0.7 inch) resistors, so adding a looser to lerance part to the range wouldn't have saved much money.

It's applied research, and since it is almost always driven by doctors, it is rarely scientific research. Most "medical" breakthroughs come from non-m edical biological research, trying to work out what's going on, rather than an explicit search for a cure or a treatment.

Someone recently published a meta-study showing that about two thirds of pu blished papers on cures and treatments couldn't be replicated. Medical rese archers often aren't good at science.

The trick is to be aware that the path you have planned is through unexplor ed territory, so you should be prepared to change it as you get to know mor e about the territory you are exploring. Managers who confuse the initial r ough map with the territory can miss opportunities.

The military adage is that no battle plan survives contact with the enemy.

earch_Organisation

Any government-funded organisation comes under pressure from politicians - CSIRO is no worse off that the universities and the research councils.

Now that industry has given up on funding places like Bell Labs and EMI Cen tral Research we are stuck with the politician's silly ideas, which are no sillier than the average industrialist's, if different.

If we could find a better way of picking the people to do basic pure resear ch, we could perhaps usefully spend more. That might be a useful area of ap plied research.

Tenure is one of the mechanisms that frees people to do basic pure research where there's no obvious immediate payoff. Bureaucrats hate it.

As someone said, the point where scientific revolutions start isn't when so meone says "Eureka", but much earlier, when they say "That's odd ...". It t akes a lot of "That's odd .. " to generate one "Eureka".

--
Bill Sloman, Sydney
Reply to
Bill Sloman

That was probably because you never designed electronics for the consumer market. It's a very different ballgame.

Not true. Visit a large pharmaceutical company and take a tour.

The break-throughs I was involved in almost all came out of engineering groups. Like the one in the link. It enabled procedures that weren't possible before. Occasionally one comes out of university research which I greatly support.

[...]

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Except that industrialists are typically vastly more competent, they get results.

Huh? Tenure is all bureaucrats are usually after. Tenure plus fat pensions, ideally combined with iron-clad job protection where you can't even get fired for gross incompetence or even misconduct.

There is an old saying: Tenure breeds incompetence.

Sometimes it starts with "oh-oh" or *PHUT* :-)

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Most of the non-reproducible publications I mentioned seem to have been pub lishing the results of clinical trials of new products produced by large ph armaceutical firms.

Whatever they are doing, it isn't science. It may be dressed up with white coats and spiffy-looking spread-sheets full of ostensibly clinical data, bu t they get the results that suit them rather too often for the whole edific e to be all that credible.

You are an engineer - and seem to be a good one. What kind of break-through s would you expect and engineer to be involved in?

University research tends to be driven by a desire to work out what's going on - for one thing, if you can dream up a more plausible and comprehensive explanation of what's going on in any particular area, you've got somethin g that is easier to teach to under-graduates, which is what universities ex ist to do.

The emphasis on university research reflects the fact that good researchers are better teachers than their less insightful colleagues. It certainly st uck out a mile in my undergraduate courses.

esearch_Organisation

Not the ones I worked for. You may argue that they had to have been atypica lly incompetent to hire me in the first place, but the ones that hired me w ere actually better than average, and tended to move on when the average id iots managed to screw things up for all of us, as they did from time to tim e.

All bureaucrats would like that. Some jobs are sufficiently exposed to publ ic scrutiny that it wouldn't be worth taking them on if there wasn't a lot of built-in protection against influential nut-cases trying to force people to make the decisions that suited them. University lecturers are continuou sly exposed to parents who don't want their kids exposed to points of view the parent don't like.

If there is, Google can't find it. Tenure can protect incompetence, but it usually isn't granted until after the recipients have spent some time provi ng their competence. If they later lose competence - by becoming incapable for some reason or other - you can usually force retirement.

Example?

--
Bill Sloman, Sydney
Reply to
Bill Sloman

The development of medications such as Lipitor were not science? Have you lived on a boat in the middle of the ocean all this time?

Many. Medical ones are just an example. I have witnessed technologies being developed where people on life's "death row" signed up for a new experimental treatment and then got their life back. Via medical devices designed by engineers.

How do you think passenger airplanes came about? Or engines? Or cars? Or trains?

My experience is quite different. I have witnessed real break-through research from universities, stuff society can use. A downside is the dreaded publish-or-perish mandate in academia which leads to excessive concentration on publishable results.

[...]

If better than average, why did you main employer go belly-up?

[...]

Many. Here are a few:

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--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

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