Maker Pro
Maker Pro

Winding a conventional AC line frequency transformer

M

Mark Zenier

Jan 1, 1970
0
On Sun, 13 May 2007 15:32:16 +1000, "Phil Allison"


Cricket has been explained to me many times. It still makes no sense.

As I understand it, one key point is that you don't have to run
when you've hit the ball. So part of the game is the judgement
when NOT to try to score.

Another point is that the bowler is aiming for your groin.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)
 
R

Robert Baer

Jan 1, 1970
0
Eeyore said:
It seems to have been my destiny in life to have to learn more about
transformers (and wind a fair few by hand) than I ever suspected I'd need to.

I learnt quite a bit about switchmode type transformers - I suppose actually you
could consider flyback types more like tapped inductors actually - from various
application notes and also here. Epcos's Ferrite Designer application is
additionally an excellent tool for pumping in the numbers for a wide range of
cores in various materials.

It so happens I'd like now to apply some of the techniques I've learnt to
traditional line frequency transformers.

I have several specific things in mind.

A. Reduced flux operation. Notably with toroids this can avoid the typical
'switch on surge' and it also occures to me that stray flux will be reduced both
in proportion to the reduction in magnetisation force and additionally because
operation at lower flux levels keeps core permeability values higher.

B. Improved coupling by using bifilar windings with triple insulated wire
eliminating the need for traditional insulation barriers.

C. Higher than 'typical' VA ratings for a given core size by using more
copper. Again this works well with toroids.

D. I'm sure there was something else but now I've forgotten.

The trouble is that I don't know of any single source of data on cores that's
comparable to the Epcos Magnetic designer. And then again, you can wind almost
any size core you like for toroids which will be my main area of interest.

Suggestions ?

Graham
In doing a search, i found Intusoft: Magnetics Designer, which
appears to be what you refer to.
There is a lot of "hype" or ad material, enough to make one conclude
that the software is rather expensive (in $K region or more).
Yes, they have a "free" demo (note the word "demo") , but the damn
thing is an impossibly huge 37megs.
 
M

Michael A. Terrell

Jan 1, 1970
0
Spehro said:
I'm always suspicious of endeavors that require learning a new lexicon
or require new clothes.


That sounds a lot like someone running for office the first time. :(


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jan 1, 1970
0
Robert said:
In doing a search, i found Intusoft: Magnetics Designer, which
appears to be what you refer to.
There is a lot of "hype" or ad material, enough to make one conclude
that the software is rather expensive (in $K region or more).
Yes, they have a "free" demo (note the word "demo") , but the damn
thing is an impossibly huge 37megs.


Whine, whine, whine! I have downloaded a number of test equipment
manuals that are over 100 MB So what if the slow server took almost
four hours to cough up one of the files?

Its time to take off the training wheels and get a real internet
connection.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
E

Eeyore

Jan 1, 1970
0
Robert said:
In doing a search, i found Intusoft: Magnetics Designer, which
appears to be what you refer to.

Thanks. It's the same sort of thing. I'd forgotten I'd seen it before actually. It
seems to include everything including the kitchen sink and consequently suffers from
bloat somewhat but I'll trial it again.

There is a lot of "hype" or ad material, enough to make one conclude
that the software is rather expensive (in $K region or more).
Yes, they have a "free" demo (note the word "demo") , but the damn
thing is an impossibly huge 37megs.

4.7 megs actually. A drop in the ocean.

Graahm
 
R

Robert Baer

Jan 1, 1970
0
Michael said:
Whine, whine, whine! I have downloaded a number of test equipment
manuals that are over 100 MB So what if the slow server took almost
four hours to cough up one of the files?

Its time to take off the training wheels and get a real internet
connection.
Fine; send me about $600 for the dish equipment and $60 a month for
service and i will do that.
DSL and cable are not options here.
 
T

Tony Williams

Jan 1, 1970
0
Mark Zenier said:
Another point is that the bowler is aiming for your groin.

A batsman can wear a 'box' for protection.

For possibly more serious injuries do a search on the
the infamous 'bodyline bowling', which nearly cauused
a complete rift between England and Australia.
 
T

Tony Williams

Jan 1, 1970
0
[snip scary stuff about 50,000A Rogowski coils]
The point I was trying to make is that only the very small
portion of the conductor through the hole of the toroid is
affected by its magnetic field. The conductors outside this
small space serve merely to complete the circuit. There is no
appreciable difference if the conductors are wrapped tightly
around the toroid, or are routed far away from the outer surface.
Of course, tighter wraps use less wire and there is less
resistive loss.

Slightly counter-intuitive but yes, once a wire
goes down the hole it becomes a full turn. Which also
means that half turns are not possible with a toroid.

AFAIK the same thing applies to a U-I lamination
stack, which really looks like a square toroid.

On the other hand an E-I stack looks like a pair
of square toroids alongside each other, so a wire
passing down one window looks like half a turn and
has to come back up through the second window to
make a complete turn.
 
E

Eeyore

Jan 1, 1970
0
Robert said:
Fine; send me about $600 for the dish equipment and $60 a month for
service and i will do that.
DSL and cable are not options here.

Where are you ?

Graham
 
R

Robert Latest

Jan 1, 1970
0
Paul said:
The point I was trying to make is that only the very small portion of the
conductor through the hole of the toroid is affected by its magnetic field.

Actually it isn't. A properly designed toroid doesn't really create any
appreciable magnetic field outside the core. What creates a voltage in the
conductor loop is the (change of) flux through that loop. Even when you
assume a perfect toroid with zero stray field.

robert
 
M

Michael A. Terrell

Jan 1, 1970
0
Robert said:
Fine; send me about $600 for the dish equipment and $60 a month for
service and i will do that.
DSL and cable are not options here.


Its not my problem that you live in Lower Podunk. Those prices sound
rather high for Internet via satellite compared to ads I've seen around
here, anyway.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
R

Robert Baer

Jan 1, 1970
0
Eeyore said:
Robert Baer wrote:




Where are you ?

Graham
Even tho i am "in Portland OR", i am in the boonies: 3 mile walk to
the closest shopping center and so many trees that it seems i am in the
middle of a forest.

1) DSL:
The phone company lies in their ads stating 1.5M/sec or 4.7M/sec
available.
Called them and they say "we can give you only 1.5M/sec" and lied
twice concerning NGs ("yes, we have that; yes we handle binary NGs").
So on the basis of those lies (not knowing they *were* lies at the
time), i had DSL installed and it would not work at all.
They sent out a tech that spent 4 hours to get it up and the "best"
data rate was 0.250M/sec; rather shitty to say the least,for an extra
$300 for their damn modem and $30/month for "service".
Well, in the course of the first hour of attempted use, the green
internet light went out four times, each time the internet was
inaccessable for a few minutes.
The next day, i found highly variable download speeds: filling of a
large web-page changed *during* the "fill" and file downloads also changing.
So the reality was 0.250M/sec PEAK rate, with random dead periods of
indeterminite length.
That was the first lie i ran into.
Then i found there were *zero* binary NGs; second lie.
The third lie is that there were NO NGs at all in any shape, size or
color.
So that day, i made them take it all back and they better damn well
refund even the shipping and other so-called "non-refundable" fees, or
all hell will pay.

2) Cable:
I am Socially Insecure, and cannot afford $100/month for service to
begin with, and will not tolerate any more lies concerning NG support.

3) Satellite AKA dish:
$600 plus for the equipment plus unknown amount for installation, is
way out of my league, and the $60 or so per month for service is also
too steep.
And it is all subject to the weather!

Multiplexing a dozen or so phones might help, but then i would have
to pay an ameanable ISP and the phone company for all of those lines;
might as well be rich and put in a T1 line...
 
R

Robert Baer

Jan 1, 1970
0
Michael said:
Its not my problem that you live in Lower Podunk. Those prices sound
rather high for Internet via satellite compared to ads I've seen around
here, anyway.
If you would be so kind to send info concerning those lower cost dish
systems, i would be extremely interested.
 
J

Joel Kolstad

Jan 1, 1970
0
Robert,

Robert Baer said:
1) DSL:
The phone company lies in their ads stating 1.5M/sec or 4.7M/sec
available.

Actually -- if you read the fine print -- they never say you're guaranteed
anything at all in terms of speed -- it's always "up to!" Yeah, I know, small
difference, but they know as well you and I do that DSL doesn't work to
inifnite distances, and unfortunately you're at the far end of their loop and
get rotten speeds.

Statistically, though, probably better than 90% of DSL subscribers do get the
advertised speed. I do, and I'm kinda out in the boonies as well: DSL was
advertised as 1.5Mbps and I get about 1.4, cable modems were advertised as
4MBps and I got about 3.6 (using dslreports.com).

It does sound as though:

1) The tech was clueless and probably should have been able to determine you
weren't gong to be able to get any reasonable speed with reliability and just
told you as much and initiated the refund process.
2) Whoever told you they had newsgroups was also clueless, and yeah, they did
lie to you. (Unfortunately the many people today seem to consider lying a
better alternative to admitting ignorance. :-( )

BTW, if this was with Qwest, any old $50 DSL report will work fine with
them -- no need for some fancy $300 job. Qwest also has a 256kbps "tier," I
believe (cheaper than 1.5Mbps, of course), and *if they could get your
connection to be reliable* it might be worth it for you. The Internet is
still quite usable at 256kbps...
2) Cable:
I am Socially Insecure, and cannot afford $100/month for service to begin
with, and will not tolerate any more lies concerning NG support.

It's more like $65 a month you're not getting cable TV as well ($55 with).

You missed one alternative: Sprint (or other) broadband cards. You, a laptop
or desktop (with a cardbus adapter), and a log periodic antenna aimed at your
nearest Sprint tower will get you ~200-300kbps, for about $60/mo. Not that
much better than satellite speed-wide, but portable and somewhat lower upfront
costs.

If you have any neighbors within, e.g., a couple of miles, it's probably worth
asking them if they have reliable high-speed Internet via cable or DSL and
asking if you could link to them via WiFi (again, you'll need a gain antenna
if they're more than 1000' or so feet away) for some small monthly fee.
Access points are quite cheap these days.

---Joel
 
I

Ian

Jan 1, 1970
0
Robert Baer said:
Even tho i am "in Portland OR", i am in the boonies: 3 mile walk to the
closest shopping center and so many trees that it seems i am in the middle
of a forest.

1) DSL:
The phone company lies in their ads stating 1.5M/sec or 4.7M/sec
available.
Called them and they say "we can give you only 1.5M/sec" and lied twice
concerning NGs ("yes, we have that; yes we handle binary NGs").
So on the basis of those lies (not knowing they *were* lies at the
time), i had DSL installed and it would not work at all.
They sent out a tech that spent 4 hours to get it up and the "best" data
rate was 0.250M/sec; rather shitty to say the least,for an extra $300 for
their damn modem and $30/month for "service".
Well, in the course of the first hour of attempted use, the green
internet light went out four times, each time the internet was
inaccessable for a few minutes.
The next day, i found highly variable download speeds: filling of a
large web-page changed *during* the "fill" and file downloads also
changing.
So the reality was 0.250M/sec PEAK rate, with random dead periods of
indeterminite length.

I'm also fairly out in the boonies. Try and find out how far it is to your
exchange, I'm at least a couple of miles away probably a fair bit more
depending on the routing.
I had trouble initially very similar to what you report, but the engineer
put a better filter/terminator right at the inlet to the house wiring system
and it has been fine since. I only have a 512k service, but I know the
S/N is good for quite a lot higher than that (I was looking over his
shoulder
as he was doing the test).

Once you have net access the rest does not have to be via your lack of
service provider.

Regards
Ian
 
M

Michael A. Terrell

Jan 1, 1970
0
Robert said:
If you would be so kind to send info concerning those lower cost dish
systems, i would be extremely interested.


I threw them into the recyling bin a month ago, but I'm sure I'm
still on the mailing lists. They have popped up in my mailbox about
every other month for the last two years. I'll keep an eye out for the
next one.

I use Brighthouse (Time Warner) cable to get basic cable TV and
broadband internet for $63.11 per month, with a 7 Mb max datarate. It
went from 3 to 5 to 7 over tha last two years without a change in the
monthly broadband fee. there is a Lite version of RR at a lower monthly
rate, and some of the sat services offer different tiers, as well.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
R

Robert Baer

Jan 1, 1970
0
Joel said:
Robert,




Actually -- if you read the fine print -- they never say you're guaranteed
anything at all in terms of speed -- it's always "up to!" Yeah, I know, small
difference, but they know as well you and I do that DSL doesn't work to
inifnite distances, and unfortunately you're at the far end of their loop and
get rotten speeds.

Statistically, though, probably better than 90% of DSL subscribers do get the
advertised speed. I do, and I'm kinda out in the boonies as well: DSL was
advertised as 1.5Mbps and I get about 1.4, cable modems were advertised as
4MBps and I got about 3.6 (using dslreports.com).

It does sound as though:

1) The tech was clueless and probably should have been able to determine you
weren't gong to be able to get any reasonable speed with reliability and just
told you as much and initiated the refund process.
2) Whoever told you they had newsgroups was also clueless, and yeah, they did
lie to you. (Unfortunately the many people today seem to consider lying a
better alternative to admitting ignorance. :-( )

BTW, if this was with Qwest, any old $50 DSL report will work fine with
them -- no need for some fancy $300 job. Qwest also has a 256kbps "tier," I
believe (cheaper than 1.5Mbps, of course), and *if they could get your
connection to be reliable* it might be worth it for you. The Internet is
still quite usable at 256kbps...
YUP! It is Qwest, and (with zero info from them) found that there aer
two DSL modulation schemes: CAP and DMT; and with zero info from them
found that they support CAP only for existing customers.
On the net, i found a number of CAP modems, some (new ones!) for as
low as $20 - but the DMT modems started within $10 of the Qwest $300 price.
Oh, yes, during my "talk" with the Qwest rep concerning the removal
of service, they "offered" a $5 reduction in the monthly fee for that
so-called 256K tier; *zero* accomidations for outages or massive slowdowns.
I gave them a firm "NO" in that i would be paying at a gold rate for
decomposing tin.
It's more like $65 a month you're not getting cable TV as well ($55 with).
Oh, just like the damn phone company: "you are paying $12/mo for
service" nevermind with all of the damn taxes it is closer to $35/mo and
they refuse to talk about what the taxes are or even the approximate amount.
The cable guys also refuse to talk about taxes, refuse to give any
guarantee or warantee, refuse to talk about actual data rates, etc ad
nauseum.
Even tho i do not know spit about cars, i bet i could do fairly well
goung to a auto wrecking yard and buying any random rust bucket that
had 4 wheels without looking under the hood to see if any metal was there...
You missed one alternative: Sprint (or other) broadband cards. You, a laptop
or desktop (with a cardbus adapter), and a log periodic antenna aimed at your
nearest Sprint tower will get you ~200-300kbps, for about $60/mo. Not that
much better than satellite speed-wide, but portable and somewhat lower upfront
costs.
What is the frequency and (nominal) distance limit? I would expect
the nearest Sprint tower to be over 10 miles away.
If you have any neighbors within, e.g., a couple of miles, it's probably worth
asking them if they have reliable high-speed Internet via cable or DSL and
asking if you could link to them via WiFi (again, you'll need a gain antenna
if they're more than 1000' or so feet away) for some small monthly fee.
Access points are quite cheap these days.
Shoot, it is about 500 feet to just the local road that goes by...
And (after checking) nobody within 1/2 mile is on WiFi or interested
(even with hint of bribes)..

What it really boils down to, is if i was really rich, i would have
Verizon run a fiber line from Hillsboro to a "shack" near here with a
bunch of equipment that would allow up to 150M/sec service to anyone in
the area that wanted such service; no setup charges, no equipment fees,
no tax bullshit, just flat at cost service charge.
Then see the fur fly when Qwest, etc find out and let them try to do
anything to squash it; would be worth it.
 
E

Eeyore

Jan 1, 1970
0
Marra said:
You could always use a thermistor in series with a toroidal core to
reduce switch on currents.

I usually do but that misses the point.

You *can* design toroids so that switch-on surge simply doesn't happen.

Graham
 
J

John Popelish

Jan 1, 1970
0
Eeyore said:
I usually do but that misses the point.

You *can* design toroids so that switch-on surge simply doesn't happen.

Here is a completely seat of the pants (no actual analysis)
idea.

(deep breath)
If you connect a capacitor across the primary (perhaps as
part of the line filter) that does not get disconnected by
the power switch, and the power is switched off at the worst
case (for start up surge) at the voltage zero crossing, the
magnetizing current that peaks near that point would drive
the capacitor voltage through zero and apply some
demagnetizing volt seconds to the core.
 
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