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Re: Boost Converter Efficiency Improvements
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te:
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ers
n
t

An example of a rather specialised transformer for a very specific
application. This is the catch with mass-produced transformers - there
are a lot of parameters which can vary, so the stuff which is produced
in volume is rarely what you want for your specific application.

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ttp://www.newark.com/wurth-elektronik/750311308/trans-flyback-lt3575...
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Well, 750311308 - the WURTH ELEKTRONIK- and b82802a0030a220 - the
EPCOS  fly-back transformers aren't - technically speaking - tapped
inductors, but three or four  independent windings on the same core.

The reason I wasn't able to see them for myself is that the Farnell/
Newark search engine is absolutely no help when it comes to finding
them. They were there, but they were thoroughly buried needles in a
very large haystack.

"Flyback" is the only search term that works, which is odd, because
the transformers themselves would work fine in a perfectly
conventional Royer inverter, or the slightly less conventional
Baxandall inverter, where flyback is either a nuisance - in the Royer
inverter - or evaded, as in the Baxanadall inverter

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g
ecs.
 to
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r me

Not for most of us. I'd be very surprised if you could get their
attention with less-than-mass-market production quantities

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NRE is not the whole story. People like EPCOS won't set up a big
prototyping section, that everybody can exploit - they'll limit it to
customers who can be expected to buy a lot of cores and formers, and
I'd be surprised if a low-volume producer would actually be able to
buy its services at any price.

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Nothing, but I doubt that even a big NRE will automatically buy into
that service - they'll want to keep spare capacity for people who
might buy a significant volume of cores and formers.

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 ... - as I said, coil winding
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Sure. but if you want high efficiency, flyback usually isn't the way
to go.
Getting custom transformers wound isn't such a big deal that we should
be recommending exploiting off-the-shelf transformers in sub-optimal
circuits.

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 I
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That doesn't surprise me either. The people who control the
advertising budget tend to be a long way from the people who produce
the stuff advertised. Management by walking about is a technique for
narrowing that gap, but not every manager is willing to talk to people
well down the organisation chart.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:
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Nothing "specialized" about a plain vanilla PoE flyback transformer.


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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-...http://www.newark.com/wurth-elektronik/750311308/trans-flyback-lt3575...
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So you get some windings for free. Do you also complain in a restaurant
if they give you some free pudding or a free ice cream after a meal?


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Learn Digikey. It's the only search engine that really works. The others
will never get it.


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Everyone uses push-pull CFL or flyback these days. I am surprised that
you did not know about all these off-the-shelf transformers. There are
tons of versions. Same for inductors with more than one winding. Since
years and years (I am designing power converters since 1990).


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They don't have to set it up, they've got one.


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You can. Money always talks in this market.


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If you don't like their deal you can pick out of a large selection of
other companies who are then even free to use cores from any vendor. So
what was the problem?


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If you utilize the energy that is otherwise burned off in the snubber it
can be. The main issue is getting EMI under control, that's a pain with
flybacks but for low power wide supply range stuff often you don't
really have a choice.


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If it fits there usually is not a significant penalty and using COTS is
the smart thing.


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It rather boils down to hiring really smart engineers, the managers are
less important (other than not getting in the way too much). Engineers
who truly understand the materials properties and trade-offs. And who
are most of all keeping in touch with new ferrite materials.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements

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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-...http://www.newark.com/wurth-elektronik/750311308/trans-flyback-lt3575...
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Sloman is obsessed with the Baxandall thing. He's been working up to actually
building one for about a decade now. He claims to have spent thousands of
dollars getting a custom transformer wound.

Weird.


--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
On Saturday, 8 June 2013 02:22:06 UTC+10, John Larkin  wrote:
:  
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wrote:  

<snip>
  
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I'm in good company. Jim Williams wrote application notes AN45, AN49, AN51,
 AN55, AN61, and AN65 about the Baxandall class-D oscillator.

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I built one back in 1968 - it's described in my Ph.D. thesis, though I neve
r actually built it into the LVDT driver circuit I'd built it for. The UK M
ilk Marketing Board got another in 1975, and my particular variant of the c
ircuit got shipped with a few GaAs crystal-pullers around 1987. What I'm fu
tzing around with at the moment is rather different low-distortion sine wav
e oscillator.

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John-out-of-touch-with-reality-Larkin gets it wrong again. The inductors an
d transformer I got wound for the low-distortion oscillator didn't cost any
thing like that much - unless of course the US dollar has fallen precipitat
ely against the euro in the last few hours. And it's certainly not any kind
 of Baxandall oscillator.
  
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Very weird. John Larkin isn't usually quite this demented.

--  
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
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rote:

<snip>

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If PoE is what you want. It's not going to be the right turns ratio,
voltage or current rating for any other application.

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....

They still aren't "tapped inductors" and you've got to couple the
windings yourself - using up two pins - to get the reuslt that you get
from one pin on a real tapped inductor.

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That's useful to know. Their catalogue was always perfectly useless,
organised strictly by manufacturer.

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The off-the-shelf transformers that I knew about were all pulse
transformers, and pretty much always transmission line transformers
with high - but unspecified - intervwinding capacitance. PoE seems to
have become ubiquitous enough to support off-the-shelf inverter
transformers, and I don't - these days - learn the contents of the
Farnell catalogue cover-to-cover any more. I never set out to learn
their catalogue, but if you spend enough time with it, the content
tends to stick.

<snip>

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r

Learn to read more carefully - that sentence doesn't imply that EPCOS
hasn't got coil winding facilities, it's a prediction about the
customers that can expect to be able to get at it.

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it to

But the money that talks is the sum that you can spend on cores and
formers.

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Getting EPCOS to do it. I was exploiting recommending local coil
winders rahter than trying to get wound parts from EPCOS.

<snip>

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t
ss
r"
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,

Big if.



"Not getting in the way too much" is the whole art of management, and
the only management course that I was ever involved emphasised just
that.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:
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Seriously, I think you should read up on flyback converters. The turns
ratio in a flyback has a much lesser importance than in pretty much any
other architecture.

Or ask yourself this question: How do you think we design switchers that
take anything from 80VAC to 260VAC and make a regulated 12VDC or
whatever out of that, at EPA mandated efficiencies?


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C'mon. All that requires is a soldering iron. I hope you aren't this
picky with food :-)

Hint: Nearly all "tapped" inductors have four pins. Guess why ...


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I can't even remember the last time I used a paper catalog. Oh wait,
it's right in front of me: The AMP Connectors hardcover 1991 edition,
used to get my flatscreen monitor to the correct height.


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It happened long before PoE. You could always buy flyback transformer
for small primary switchers, for a few bucks.

Even in the 60's you could but those were bigger and cost a lot more, as
they were for TV sets and thus had a fat profit margin calculated in.


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Farnell is not necessarily the best place to learn about this kind of stuff.


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Read your own writings more carefully. Quote "Sadly, EPCOS won't wind
prototypes for you".

This clearly means "they won't do it for me" and that is incorrect.


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Naturally. They have to pay their bills just like any other corporation.
You request a quote and then decide whether to accept it or not.


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In the end it won't matter who does it. It boils down to cost, the
quality of their engineers, and (in my line of work) how far they are
willing to veer off the trodden paths and embrace something new.


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Again, take a look what's out there. Tons. I'd say more than 95% of the
larger inductors I use in switcher designs are COTS parts.


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Yeah, I wish more people would understand this. Give people the power to
make decisions. They'll screw up once in a while. But so have we, and
learned from it.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
wrote:

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wrote:
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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-......
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ISDN transformers are cool. We stock one with four independent
windings, 1:1:2:2. That's handy for all sorts of things.


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I treasure my hardcopy Digikey and Mouser catalogs, even as they age.
Searching for a cap or an inductor is way easier in the hardcopy.


--  

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Re: Boost Converter Efficiency Improvements
John Larkin wrote:
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[...]

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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-......
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Yup. Although I favor LAN transformers because ISDN is on its way out.
It was a fairly short-lived technology, not enough bang for the buck.

What is also very useful are the VersaPac ferrite transformers with six
independet windings. I've designed a lot of ad hoc circuits with that,
plus some for production.

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I keep them as well, just in case. But I've found that the PC is simpler
for browsing caps and stuff. Just like the vellum pad gets less and less
use. Nowadays almost everything starts right on the screen, sometimes
with GoToMeeting and similar collaborative tools. I just wish they had a
better whiteboard.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
wrote:

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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-......
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Real engineers don't need no wussy mousey things!

https://dl.dropboxusercontent.com/u/53724080/Otis/No_Mice.JPG



--  

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Re: Boost Converter Efficiency Improvements
John Larkin wrote:

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LEts see, that looks like a TI-30 or an HP calculator on the right and
as for the schematic, looks like a digital programmable gain loop for  
the amp you're using. The programming looks like you're using something
like a 4 or more lines input, possibly from a 4 or more row thumb wheel
R scalar or some other means like a parallel IO source.

  Most likely a unity buffer amp on the output with some filtering (Cap).

  3 terminal reg supply down at the lower right and at the top, looks  
like you have another amp input going to an IC I can't make out,  
possibly the input is a comparator for the generation of shaped pulses  
for the following IC instead of an amp? FF maybe for the IC?, etc..

  How close did I come ? :)

Jamie


Re: Boost Converter Efficiency Improvements
On Fri, 07 Jun 2013 21:03:57 -0400, Jamie

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A original HP35. Still works.

and
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Given the fuzziness, I wouldn't expect you to. Here it is:

https://dl.dropboxusercontent.com/u/53724080/Circuits/Driver_Sh_1.JPG


Nothing interesting, except maybe the 4051 analog logic.


--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
On Fri, 07 Jun 2013 20:24:54 -0700, John Larkin

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Which has a bug, which any Master Circuit Designer will immediately spot.




--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
John Larkin wrote:
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[...]

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Now what about that beer coaster? :-)

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements
John Larkin wrote:
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Still not very clear but I can at least see a better view of it now..

  It seems you're wasting lots of channels on the 4051, maybe something
like a 4066 could work, too ... :)

  But I did get the upper IC's pretty much close, at least they have a Q  
and /Q  with signal shaper coming in.

Jamie


Re: Boost Converter Efficiency Improvements
On Sat, 08 Jun 2013 19:33:03 -0400, Jamie

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others
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Yes, but the 4051 is decoding three inputs, so it's doing logic, too.
It's an analog LUT.

Come on, Jim, point out the bug.


--  

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Re: Boost Converter Efficiency Improvements
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 wrote:
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e
d

Since my first serious digital project was 10-bit PWM D/A converter,
back in 1975, I think I can claim to have known the answer to that
question for a few years now. There are always trade-offs in getting
voltage step-down or step-up by PWM - getting the right turns ratio
minimises them.

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......
.
t

Interesting wound components are often pin-limited.

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They've been designed by unimaginative engineers to go in square/
rectangular packages ..

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rs

But it made sense to specify ityourself, for your application. The off-
the-shelf parts weren't cheap enough to be all that interesting, if
you could find them.

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e
ff.

So where would you suggest?

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for

They've done it for you? What was the projected production volume? And
did the projection come true.
I still doubt that they will wind parts for David Jordan's particular
application.

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t it to
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nt
o

No argument there. Would EPCOS be the place where you'd expect to find
innovative engineers?

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ch
hat
,
ross
ver"
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Hz,
e
fs
it
h
d

So you are designing stuff for a well-established market.

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e
e

It's not just that. The engineers at the sharp end have to immerse
themselves in the fine details of the project. Educating management to
undersand these details takes time - that they usually haven't got.
Our rule of thumb was never to write anything longer than two A4 pages
for management, and figure that they were only going to pay attention
to the first page, so you put your cover-your-back details on the
second page.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:
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wrote:
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Not sure what a D/A converter has to do with this. But if you claim to
have understood flybacks since 1975 I really do not understand why you
said "It's not going to be the right turns ratio, voltage or current
rating for any other application".

The turns ratio only really matters to optimize the thing so the lowest
cost parts possible can be used.


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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-......
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Nope.



They have been designed by smart engineers who wanted to maximize
markets for this part. For example, as John said, you can also use them
as iso transformers. That use would be precluded it it had three pins,
so less pins is not smart.

The other reason is one I regularly use on designs: I often need a
negative supply, in other cases I need a higher voltage supply above
logic level for amps and stuff. I can do both with the same part. With
your three-pin device that ain't possible.


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I have found them and shown you. You still don't see it? And no, they
won't be in a 1975 Farnell catalog :-)


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I already said that: Digikey.


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Epcos has not done it for me personally. But I had a talk with them and
they would have. Volume was several k/month. The reason we didn't go
ahead was that we needed another company's ferrite material.


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Before you actually ask, such doubts are meaningless. Epcos is a pretty
good company.


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Most companies have them. But this wasn't about that. The fact is, Epcos
can make custom parts.


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Generally not.



In my experience out-of-the-box thinkers are mostly found in small
business, that's where I go first for difficult projects.

My strategy for proposals and such is this: The first section contains
an executive summary of my ideas. 1/2 to 3/4 page. Then 3-5 more pages
with details. So if a busy executive gets curious and wants to no "No
how on earth is this supposed to work?" he or she can dig deeper before
having to call or email. But they don't have to.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Boost Converter Efficiency Improvements

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wrote:
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http://www.newark.com/epcos/b82802a0030a220/inductor-flyback-40uh-10-......
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OK as a parts search engine, but buy the parts from someone with better prices,
and who actually stocks them.


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I jump in and get technical fast. If a PHB can't understand it, he'll be
impressed!


--  

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

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Re: Boost Converter Efficiency Improvements
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e> wrote:
<snip>

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at

It's the fact that it used PWM to produce the output voltage we wanted
that should have been the clue.

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You optimise transformer design for the application - you don't buy
more core or more copper than you have to - unless you insist on
designing your power-supply with the nearest transformer/inductor that
you can buy off the shelf that won't actually burn out.

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Lowest parts cost is one aspect of optimisation.

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t

Then you haven't designed the kind of stuff I did, and taken full
advantage of your wound components.

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Unlikely. Off-the-shelf parts are optimised for one specific
application, which buys almost all of the parts produced. Anything
else is a boutique part, and costs a lot more.

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Fewer pins than four wouldn't be smart. My last transformer got
stalled when Farnell sent me 10-pin formers when I'd ordered 12-pin
formers.

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With a four pin device it often isn't possible too. Twelve pins can be
handy.

<snip>

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IIRR the 1975 Farnell catalogue did include pulse transformers - but
they were transmission line tranformers with horrible interwinding
capacitances.
I'd found them all right.

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as
the
stuff.

A catalogue that's rigidly organised by manufacturer isn't really a
good place to browse, and while Farnell wasn't good on printing extra
parametric data, Digikey was worse.

<snip>

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Several k/month is bigger than my 10k per year volume estimate of
minimum interesting volume. I've never work on anything that was
expected to sell more than 1k per year.

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An excellent company, but big. And my doubts aren't meaningless -
realistic is the word you hould have chosen. David Jordan could always
ask for quote from them, but he'd be mad not to explore more realistic
options at the same time.

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mit it to
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d
n.

But you don't hang around waiting to find out if they will give you a
quote you can live with, and you go for quotes from other suppliers.

<snip>

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But they are very unlikely to do it for you if you can't realistically
project 10k per year volume.

 <snip>

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e

How often do you do a parallel design for a a custom transformer and
see how the costs would have compared? Time-to-market and short
product life-cycles do tend to discourage this, but presumably you do
design stuff that stays in production for long enough to make a bit of
cost-engineering feasible.

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EMI Central Research was full of them, and Bell Labs too, but that
style of blue-skies R&D has gone out of fashion. It paid off hugely in
the long term, but accountants like to do their discounted cash flows
on more predictable profits.

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Mine were written where the busy executive could walk to my desk or
tell me to walk to his office if he felt curious - back then they were
all male.

--
Bill Sloman, Sydney

Re: Boost Converter Efficiency Improvements
Bill Sloman wrote:
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wrote:
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What does that have to do with tapped inductors or flyback transformers?


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Only for very high volume products. Otherwise ...


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Bingo!


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


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Not the Baxandall oscillator again? :-)

I have designed rather complex stuff with magnetics.


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

http://www.digikey.com/product-detail/en/VP1-0190-R/513-1191-2-ND/668152

Here is another:

http://www.digikey.com/product-detail/en/SRF0703-4R7M/SRF0703-4R7MTR-ND/2458494


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I can usually get that done with four pins.


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


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stuff.
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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.


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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.

[...]


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


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


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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.


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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.


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

--  
Regards, Joerg

http://www.analogconsultants.com/

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