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Magnetic disturbance

Discussion in 'Electronic Design' started by [email protected], Oct 26, 2012.

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  1. Guest

    how sensitve is it? ?

  2. Jamie

    Jamie Guest

    Once in a great while, we have a series of events where our machines
    with beam scanning functions in them will all be steered out of place
    enough to trigger alarms and shut the units down.

    It does take a lot of magnetic disturbance to force these out of
    alignment, but there is no other equipment adjacent, on the roof nor in
    the ground. This area of operations are on ground level cement slab and
    the roof is tin with nothing but static vents. Power feed transformers
    are far away.. There was no near by strikes which has never cause this
    in the passed.

    The strange thing is, we had to wait ~ 20 mins for a restart because
    we kept on getting an error in steering, on all the machines, then it
    finally cleared up..

    All these machines are independent of each other..

    Is there any geological events that can take place to cause this in the
    ground or maybe solar charge of some kind? It's almost like some one was
    hanging a large magnet over our plant.

  3. Does this help, er match up with your distrubance? It's a CME
    prediction model.

  4. Phil Allison

    Phil Allison Guest

    "Jamie" <= Radio Ham Jerkoff " Maynard A. Philbrook "

    ** FFS - wot a pathetic wanker!!!

    Do your own fucking testing.


    1. A compass needle will respond to static variations in the local magnetic

    2. The trace on an analogue scope also responds to the local magnetic
    field, be it static or otherwise - budget scopes have CRTs with no mag

    ..... Phil
  5. Jamie

    Jamie Guest

    I wouldn't know about budget scopes with CRT's, we only have one CRT
    scope and that is at home base and it's a Tek 350hz model. The rest of
    our scopes are all TFT/LCD, Regol, Tek and Lecroy and thinking about
    getting an Agilent.

    As for the compass needle, We use a flux differential array sensors
    and that went very screwy.

  6. Phil Allison

    Phil Allison Guest

    "Jamie" <= Radio Ham Jerkoff " Maynard A. Philbrook "

    ** You are pig ignorant, shithead.

    ** There is no point in giving a bullshitting **** like you any kind of


    ..... Phil
  7. Jamie

    Jamie Guest

    Interesting site, looks like a good candidate for an application that
    could read and display those numbers graphically with a geological plot.

    I book marked it, thanks.

  8. Jamie

    Jamie Guest

    Which only means you don't know what I am talking about, that's fine,
    I wouldn't expect it from a down under.

    I understand the branches on the trees down there don't spread out
    much and kangaroos are in season.

  9. Gib Bogle

    Gib Bogle Guest

    Seek psychiatric help.
  10. Phil Allison

    Phil Allison Guest

    "Gib Bogle" = ASD fucked MORON

    ** Get cancer and die -

  11. Robert Baer

    Robert Baer Guest

    ** Copy of previous posting elsewhere **

    Err...What about the possibility of an extremely nasty solar flare
    storm - one that can literally fry all satellite electronics, and zap
    almost all ground-based electronics?
    1) EE Times Sep 17,2012 pp 20-22 "Girding for the next 'solar max' "
    2) Science Fact article in Analog SF&F Nov 2012 pp21-27 "The Day the Sun

    Could be serious enough to totally crash all banking in the
    world,leaving the "Third World" nations in a superior position.
  12. Robert Baer

    Robert Baer Guest

    ??350hz?? Rather oddball powerline frequency..
  13. Gib Bogle

    Gib Bogle Guest

    I'm serious. You are bad for yourself and for people around you.
  14. Martin Brown

    Martin Brown Guest

    They are. Or rather the planet has a pretty huge magnet inside it and
    the solar wind can buffet it enough to cause trouble for sensitive gear.
    More so in the US and Canada than in Europe since magnetic North is on
    your side of the planet.

    Any geomagnetic record for your neck of the woods would show if it was
    from a CME event. This one goes back a few days

    Place to look next time it happens.

    You might want to make a simple magnetic disturbance monitor to
    determine independent of your kit if there is a magnetic storm.
  15. Phil Allison

    Phil Allison Guest

    "Martin Brown"

    ** Thanks Martin.

    Despite the OP's staggering lack of insight, the motive for my two
    suggestions re the magnetic compass and simple CRT type scope was the very
    same idea.

    I also suspect the notion alluded to in the heading is pure hogwash.

    ..... Phil
  16. Martin Brown

    Martin Brown Guest

    Rubbish. Dipole field falls off as 1/r^3.

    They are not all that powerful at a distance. At least up to the sizes
    used for magnetic clamps. You don't want one in a pocket though. I
    became attached to a supermarket checkout till once after someone put
    one in one of my pockets. They will nip flesh rather painfully - big
    ones destructively. Didn't harm my bank card at all.

    Superconducting NMR magnets are in a different league altogether. I know
    of one where the outer shell has a dent from snatching the end of a
    passing scaffold pole from outside the building.
    Again you have to be quite close to magnetise the screen and any damage
    is fairly local. The one thing I found did zap bank cards was the
    initial power on degauss coils of big reference colour monitors in the
    old days if you were leaning over or working on them at switch on.

    There was a hefty boing noise from the coils responding to the degauss
    waveform. That really did for bank cards if you forgot.
    Trams? Large arc welding kit nearby.
    Seen that destroy some early CNC kit after the machine went beserk.
  17. Mac Decman

    Mac Decman Guest

    Our magnetizer at work will erase those club discount cards that
    stores give out if you stand within a few feet of it. I think it
    makes a 1.3T pulse 150ms long with a coil ID of 8 inches. Never had
    any credit cards get erased though.

    Mark DeArman
  18. Robert Macy

    Robert Macy Guest

    solar flares cause massive disturbances to the earth's magnetic field.

    Take a look at the Noise Floor of the Earth's Field:
    the field noise data cmoes ffrom actual meaurments of sites
    From paper, here is its bibliography:

    1. E.L. Maxwell and D.L. Stone, "Natural Noise Fields 1cps to 100kc",
    IEEE Transactions on Antennas an Propagation, Volume AP-11, Number 3,
    pp 339-43, May 1963.
    2_ D.A. Chrissan, A.C. Fraser-Smith, Seasonal Variations of Globally
    Measured ELF/VLF Radio Noise, Technical Report D177-1, Stanford
    University Dept of Electrical Engineering, STAR Lab, December 1996.
    3_ R. Barr, D. Llanwyn Jones, C.J. Rodger, "ELF and VLF radio waves",
    Journal of Atmospheric and Solar-Terrestrial Physics, Volume 62, Issue
    18, pp 1689-1718, November 2000.
    4_ Kenneth Davies, Chapter 9, Propagation of Low and Very Low
    Frequency Waves, Ionospheric Radio Propagation, New York, N.Y., Dover
    Publications, Inc., 1966.
    5_ M. Balser and C.A. Wagner, "Observations of Earth-ionosphere cavity
    resonances", Nature, Volume 188, pp 638-41, 1960

    Magnetic fields are insidious, once created you can't destroy them,
    simply redirect them. And, low frequency are the worst, because they
    penetrate EVERYTHING! Using mumetal can get expensive, and if not done
    properly can easily exacerbate the problem by 'sucking' in magnetic
    fields and actually intensifying them locally, so even that type of
    shielding must be done carefully.

    from those charts:
    at 1 Hz the noise spectral density is 'normally' 1pT/rtHz, and it has
    a 1/f distribution [I think]
    at 0.01Hz it has climbed to over 1nT/rtHz.

    If your e-beams are low speed, circa 10-20kV and the run path is long,
    it doesn't take much field to deflect the beam over 100nm down at the
    target, which in today's geometries is HUGE!

    Has anybody produced the calculations for you? It should be part of
    your equipment's performance spec - specifying the operating ambient
    fields that are allowed. Then it'sup to you to prove your fields are
    less than that.

    Anyway, the number in those charts is 'average' which means during
    solar storms it can easily go above 10X that value - for days! and
    even into the 100X for short periods.

    Do you have ambient magnetic field instrumentation monitoring the
    fields? They are purchaseable items.
  19. Robert Macy

    Robert Macy Guest

    You have to find the frequency values of the disturbance, could be
    related to a bad AC mains return cable going intermittent on you.
    Those fields can get into the 100's of microTesla ranges and THAT will
    deflect even an old monitor's traces.
  20. Robert Macy

    Robert Macy Guest

    Just thought of something, our satellite reception went wonky the
    other night/day? during 'good' weather. The satellite company claims
    moisture in the air during a rainstorm reduces the uWave signal and
    you get signal breaking up. We got signal breaking up but the weather
    here was SUNNY and clear! Anybody else experience that? Maybe we can
    correlate the disturbances we saw to what happened to Jamie.
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