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Help, processor reset when power on large transformer.

Discussion in 'Electronic Design' started by Rock, Apr 2, 2005.

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  1. Rock

    Rock Guest

    Thanks for all the input, now that the design is done using the 'hey
    it's resetting I'll just make that part of the operatiing senario" I
    will try playing with some of these solutions.

    The board is not yet designed and these problems showed up on a hand
    wired prototype with digital section made of soldered wire wrap wires,
    so there is no ground plane it's a kludge mess.

    I think I'll start with trying some other regulators as one of you
    The relays are fired via mosfets, so I woudn't suspect any feedback
    from the relay coils, but the though that the coils in the relays are
    coupling to the transformer is an interesting observation, one that I
    failed to even consider, doh! I added resistors and caps to these
    control lines to keep the relay on during the reset time but it still

    I've never had to put a controller so close to a large transformer
    before so this is new territory for me.

    Thanks again to all who tried to help!

  2. One easy remedy (or mitigation) for a too open ground
    network is to add a number of seemingly redundant
    ground connections so as to achieve a densely gridded
    ground network. This will gain some of the same benefit
    as ground plane as the grid tends to exclude perpendicular
    AC magnetic fields, much as ground plane does. This has
    a good chance of precluding other problems you may not
    have seen yet.

    [Other approaches cut.]
    You may learn the value of ground plane from this project.
    Good luck.
  3. Fred Bloggs

    Fred Bloggs Guest

    Hahahahaaa- I like that "gap which varies to operate the relay"- damned
    moron, the very principle of operation is to "vary" the gap to "operate"
    the relay, idiot. How the hell do you pull in the armature otherwise,
    mental midget...
    Who gives a damn about your skepticism...what you seem to be missing is
    the timescale of the interference with 2us being a bit short for
    anything induced by a line frequency action- not to mention
    repeatability going against an unsynchronized activation- whereas the DC
    coil circuit is self-synchronizing. As usual, you're not even in the
    same ballpark...
  4. Fred Bloggs

    Fred Bloggs Guest

    Total garbage suggestion....
    Duh- magnetic interference ferromagnetic shield= steel box- you
    half-assed incompetent.
  5. Derf transform applied.

    Wrong again, Fred. Getting a minimal ground network
    more like a plane can readily provide shorter paths for
    currents to flow in that network, and also reduce their
    impedance. And it is well understood by many people
    that conductive loops, (easily found in a gridded ground
    network), act to exclude AC magnetic fields to a degree
    that depends on frequency, geometry, and conductivity.

    That fact that you appear unfamiliar with these facts is
    very telling with respect to your own competence.
    More Bloggs ignorance blurting out there.

    If you were to look at the work of a recognized authority
    in shielding technique, Henry W. Ott's "Noise Reduction
    Techniques in Electronic Systems", you could find a plot
    of reflection loss versus frequency in a copper shield. It
    covers magnetic fields, electric fields, and in between.
    (See page 152 in the 1st edition, in the chapter titled
    "Shielding Effectiveness of Metallic Sheets". Only the
    most electronically naive believe that a metal must be
    ferromagnetic to influence AC magnetic fields.

  6. Derf transform applied.

    When considering the magnetic circuit, it is useful to
    separate the incidental gaps due to construction from
    the gap for which the magnetic circuit exists. You need
    not get all excited thinking I meant to write a primer on
    magnetically induced motion. I merely reminded readers
    that only certain flux does any good in such a device.

    I notice that you chose to not deal with my point, which is
    that flux setup outside the relay is wasted and minimized in
    well designed relays.
    The reliable observation is the system malfunction. With
    the breadboard construction reported by the OP, that
    "about a 2 micro second low going pulse break in the
    power to the processor" is legitimately suspect. I think
    you need to learn to weight the evidence you consider.
    The OP stated "I'm switching the power anywhere in the AC
    cycle, and it doesn't always reset." This repeatability issue
    works directly against your "almost certainly" hypothesis.
    Does that mean it turns on when it turns on?
    That fancy language of yours is confusing.


    Since you seem so fond of your "solenoid field cutting the
    area" idea, I'm going to provide more detailed reasons
    for an objective person to discount that hypothesis.

    The OP mentions a problem encountered upon energizing
    a relay and mentions only 24 VDC or 5 VDC as sources
    that might be used for that purpose. Let us assume,
    (or divine, as you wish), that the highest of these is
    applied to the solenoid. (This assumption has little
    bearing on the end result since ampere-turns are held
    nearly constant for a given coil size.) The problem, as
    deduced or divined by Fred, is that a voltage has been
    induced by flux emanating from the solenoid sufficient
    to interfere with a 5V regulator powering a uP.

    Most people familiar with the elementary theory of
    induction, back EMF, magnetics, and the like can see
    that the flux linking that solenoid will then change
    at a maximum rate of 24/N Webers/Second, where N is
    the number of turns on that solenoid. Those people
    can also see that the maximum voltage this changing
    flux may induce in a single circuit loop outside of
    the solenoid itself is k * 24/N Volts where k is the
    fraction of flux that manages to escape the closed
    magnetic circuit I mentioned ealier as being the most
    probable form of that solenoid.

    Consdering that the only flux that acts to operate a
    solenoid is that which is in the volume that changes
    as the intended motion occurs, it should be obvious
    that suffering the IR losses necessary to establish
    similar flux levels in many times that volume would
    be very wasteful. A brief examination of how most
    relays are constructed reveals that their designers
    are not that incompetent. They arrange that most of
    the flux path is either iron, (which conveys the flux
    without much stored energy or required MMF), or air
    which develops useful force due to that flux.

    Having never yet seen enough flux linkage to worry
    about, I have not measured the k value for any relays
    yet, but values in excess of 0.1 would surprise me a
    lot if exceeded by any but a small fraction of relay
    designs out there. (I exclude reed relays from this;
    they are inefficient and irrelevant to the OP's issue.)
    This estimate is based on common constructions I have
    seen and the idea that, when driven at their intended
    levels, the iron in the path tends to not saturate during
    energization. (The magnetic circuit is gap dominated.)

    I have unwound a number of solenoids wound for 12 V
    and 24 V service. They invariably have many dozens
    if not a hundred or more turns. A 24V coil with as
    few as 25 turns would be most unusual.

    Based on these estimates and observations, I expect
    the ordinary magnitude of Fred's "almost certainly"
    induction to be less than 0.1 * 24V / 50 turns = 48 mV,
    and most likely much less.

    But of course, in Bloggs World, we must make a few
    concessions to the vast variability of the "real"
    world. So, let's allow that the relay designer was
    able to get only half the flux where it could ever do
    any good, (and a much smaller fraction of the field
    energy there), and make it a truly high powered coil,
    having, say, only 10 turns. Under those conditions,
    we might see 0.5 * 24V / 10 = 1.2 V. By gosh! That
    *must* be it!. The OP has spread out the feedback
    for his three-terminal regulator over enough area to
    capture a significant fraction of that wasted flux!
    And it is seeing the 1.25 V (or so) that it wants
    when there is not a proportionate output but merely
    the illusion of it induced by that humongous and hot
    coil designed by one of the multitude of idiot relay
    designers sadly allowed to live in Bloggs World.

    Another mystery resolved by astute divination.
  7. Fred Bloggs

    Fred Bloggs Guest

    Nah- your so-called gridded ground plane is only effective against
    fields if it encloses them- a kluged wire wrap network that does not
    enclose his circuit will be as worthless as you are. You should have
    stuck to SEB with your bullsh_t and worthless advice- because it doesn't
    fly here.
    That is only for *high* frequency- at line frequency, it is not a shield
    you want to build, but a field shunt- and that means ferromagnetic. Take
    another look at Ott and see if this is not the case. A second point of
    confusion you have is that you're too damned dumb to know the difference
    between a *radiated* field and an induction field. At line frequency,
    the field is induction. Want to try reading me the book again, you
    half-assed inferior p.o.s. and idiot?
  8. Fred Bloggs

    Fred Bloggs Guest

    What a joke example of your extreme narcissism- like the world is
    watching the great Larry-Fairy and taking notes on everything he says,
    keeping score of his words of wisdom. No one is reading your worthless
    bullsh_t- you have been exposed as a fraud who can't do anything except
    babble- you're a dull and uninteresting person.
    It is there in considerable quantity if it's mounted right on the PC
    board with the PIC.
    I am not going to argue over what the OP said- he doesn't have the
    intelligence to think himself out of a wet paper bag. Like how damned
    hard is it for the reptile to disconnect the drive to the transformer.
    Plus these f___g OPs lie quite often. That is why I never argue about
    what some idiot OP might have meant. So it looks like you loose the
    chance to post 10,000 words of conjectural bullsh_t...too bad.
    Right- the non-repeatability does go against the relay- but like I said-
    these OPs lie quite often- so I discounted it.
    There would be no other reason for having a 24VDC supply other than
    using that to drive the relay, idiot.
    No- that is nonsense- only holds for a single layer coil with no leakage

    [...snipped the usual over-simplified elementary textbook garbage barfed
    by Brasfield...]
  9. Fred Bloggs

    Fred Bloggs Guest

    None of that applies at line frequency, idiot...
    Only a saturable reactor could approach that time interval-which a
    stepdown core is not- and even 20x60Hz is a measly 1200Hz. You just
    don't get it, idiot, and as usual your advice is pure babble.
    Yeah- I agree- mainly because it will keep him busy and not because it
    will do a damned bit of good.
    This why they make such enclosures...
    I believe the traditional term for the type of field interference here
    is "quasi-static", which means time variation involved, but no
    radiation. You are a true idiot to think there is a near/far field
    partitioning here- you have already demonstrated you don't know squat
    about transmission lines, and now we know you don't squat about field
    Well -why the hell don't you try actually understanding the material and
    remembering it, instead of regurgitating graph numbers that are not
  10. Rock

    Rock Guest

    I can't put a ground plane on the circuit board. For one it would raise
    the costs, for 2, it would complicate the certification process with
    UL. For my UL, non isolated power boards I put no extra copper on them
    at all, just the traces, nice and wide and far apart so the UL Guy
    goes, "Yeap no Prob.".

    But I really don't understand the war that is going on over this
    posting, I don't think either of you has said anything that seems out
    of the question for a solution, but your going at it like it's some
    kind of holy war.

    Chill dudes, act like professionals, and I don't mean in the wrestling

  11. John Fields

    John Fields Guest

  12. Mark Jones

    Mark Jones Guest

    Yeah, sounds real "professional" doesn't it? I wonder if his circuits are built
    the same way: "Scrape the fucking garbage oxide off this resistor to get it up
    to 1.255k, who cares about goddamn parasitic inductance, I can do LaPlace
    transforms in my head so _You_ must be a slack-jawed simpleton..."

    Win is a professional. So is Joerg, Terry, Spehro, Guy, and a few others.

    -- "God might not play dice with the universe, but he sure can bowl when it's
    raining!" MCJ 20041222
  13. John Fields

    John Fields Guest

    Galls you, doesn't it? You have a picture in your head of what you
    think professionals should do and how they should behave, and then
    when someone doesn't act according to your preconceived notions of
    what you consider to be propitious, then there's no way they could be
    professionals, huh?

    Anyway, what's it to ya?

    I was replying to Rock's series of off-topic bullshit posts so it
    really has nothing to do with you, unless you find what I post
    offensive, and then I assume you know how to use a kill filter.
    If you've got anything to say about my technical abilities, then the
    proper way to do that would be to find a technical error in something
    I posted and comment on that. Otherwise, you're just venting and who
    gives a shit? Not I.
  14. Yeah.

    "Unconditional Love? Oh Kay, Love DIS!<snarf!>"

    "I can be as poopy as I want to, and there's nothing you can do about it,
    nanner nanner nanner!"

    I wouldn't **** you with Pynerapr's dick.
    Meet Elmer, young son of the Thorpes,
    Afflicted with psychotic warps.
    His idea of fun
    Is to bugger a nun,
    And then vomit all over the corpse.
  15. Mark Jones

    Mark Jones Guest

    No, that is, professionals don't act like rabid animals recently escaped from
    the zoo. ;)

    (Add Kevin and Wouter to the list of professionals. I'm still missing a few

    Don't get me wrong, you obviously are intelligent John. It's just that your
    social skills are... not very professional. (If I impart the voice of reason,
    who will?) Chosing to use "****" and "goddamn" about anyone is not professional,
    at any time and for any reason. Call it a mold if you like, but I bet you don't
    talk to your clients that way... if you have any clients. It's supposed to be
    about decency and courtesy - something you must be above (or below.) So if you
    don't have any courtesy and decency for me, then I don't have any for you, and
    soon everyone's all saying "f-you" and engaging in primitive testosterone &
    cortisol-overload. I for one, am not going to fit THAT mold.

    Getting some physical excercise is great for the body, and mind, and soul.

    Rich will say that The Mother agrees, so it must be true! :)
  16. Please don't use such disgusting expressions on this NG. (;-)
  17. Rich Grise

    Rich Grise Guest

    That's why I have aliases, for when I want to futz around vs. when I'm
    presenting something that I believe might actually be on-topic. ;-)

  18. Actually, at the moment, in response to this particular post, she's
    saying, "Well, yeah, but in moderation!" Pumping iron is kind of like
    abuse, but - - -

    Here's Mother:
    "If it feels right, it's right."

    I've come to the conclusion that I've been channeling The Mother since
    I opened my root chakra. She doesn't speak English. Sometimes she speaks
    Kundalini, sometimes she speaks Dance - she's very spontaneous, when you
    let your own fragment of her heal. :)


    for further information, please visit
  19. Well, you've gone and got me chided again for making too much noise in
    my cubicle! ;-)
    "Based on what you know about him in history books, what do you think
    Abraham Lincoln would be doing if he were alive today?
    (1) Writing his memoirs of the Civil War.
    (2) Advising the President.
    (3) Desperately clawing at the inside of his coffin."
    -- David Letterman
  20. I read in that Rich The Philosophizer
    What's that, and please don't refer me to the godchannel site, because
    it makes my brain hurt. There are words there, lots of words, and I read
    them, and I find no content in the words. Maybe I'm just beyond
    Where is that language spoken on Earth?
    You mean 'dance' as in 'jig about'? How can you speak that?
    Maybe if there was any chance I could cut through the waffle and find
    the Truths you declare to be there....
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