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Winding a conventional AC line frequency transformer

Discussion in 'Electronic Design' started by Eeyore, May 13, 2007.

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  1. Mark Zenier

    Mark Zenier Guest

    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
    Googleproofaddress(account:mzenier provider:eskimo domain:com)
  2. Robert Baer

    Robert Baer Guest

    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.

  3. 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

  4. 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

    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
  5. Eeyore

    Eeyore Guest

    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.

    4.7 megs actually. A drop in the ocean.

  6. Robert Baer

    Robert Baer Guest

    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.
  7. 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.
  8. [snip scary stuff about 50,000A Rogowski coils]
    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.
  9. Eeyore

    Eeyore Guest

    Where are you ?

  10. 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.


  11. 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
  12. Robert Baer

    Robert Baer Guest

    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
    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
    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...
  13. Robert Baer

    Robert Baer Guest

    If you would be so kind to send info concerning those lower cost dish
    systems, i would be extremely interested.
  14. Joel Kolstad

    Joel Kolstad Guest


    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

    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...
    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

    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.

  15. Ian

    Ian Guest

    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
    as he was doing the test).

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

  16. Marra

    Marra Guest

  17. 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
  18. Robert Baer

    Robert Baer Guest

    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.
    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
    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...
    What is the frequency and (nominal) distance limit? I would expect
    the nearest Sprint tower to be over 10 miles away.
    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.
  19. Eeyore

    Eeyore Guest

    I usually do but that misses the point.

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

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

    (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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