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Electrostatic discharge on bus?

Discussion in 'General Electronics' started by Acceed See, Apr 15, 2005.

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  1. Acceed See

    Acceed See Guest

    I have discovered several times after I leave the bus seat and grab the
    stainless
    steel pole, there was a pak sound. Is that a ESD? Are the charges from my
    hand
    or the pole?
     
  2. oðin

    oðin Guest

    I have discovered several times after I leave the bus seat and grab the
    I do not give a ****.
     
  3. John_H

    John_H Guest

    From your clothes, via your hand.

    To eliminate the effect try grabbing the pole, or any other earthed
    (to chassis) part of the bus, while your bum leaves the seat -- which
    is the point at which your clothes become charged.

    Works for me everytime -- car or bus.
     
  4. Don Taylor

    Don Taylor Guest

    Certainly could be static discharge, two different materials,
    like fabric and plastic, rubbing against each other can
    transfer charge.

    If you can still find an old fashioned neon bulb, a tiny little
    glass container with two wire electrodes separated by a bit of
    neon gas inside, you can hold one lead of the bulb and let the
    other get close to the pole. You might shield the bulb from
    the light in the bulb, so you can still see it but it won't be
    overwhelmed by the lights on the bus, then you might be able
    to see a brief flash in the bulb as the sparck jumps from the
    pole to the free lead. There are more sensitive detectors but
    this might be enough for your testing.
     
  5. Pharmanaut

    Pharmanaut Guest

    I thought that in a car it was the air rubbing electron off of the
    car, which is insulated from ground by it's tyres, that caused you to be
    charged. And that you earth the car to ground as you step out... bloody
    painful sometimes!

    Pharm..

    --
    Drop the dex to reply.

    "...The people can always be brought to the bidding of the
    leaders. That is easy. All you have to do is tell them they are being
    attacked, and denounce the pacifists for lack of patriotism, and
    exposing the country to greater danger "
    -- Herman Goering at the Nuremberg trials

    "They that can give up essential liberty to obtain a little
    temporary safety deserve neither liberty nor safety."

    - Benjamin Franklin, 1759
     
  6. Guest

    That doesn't work. I know from experience. I would really
    like to find a way to degauss myself at will. I get out of
    my car and touch my winter coat-wrapped elbow to the car; get
    a poke. I still get a huge poke when I remove the
    key from the lock.

    I also have the problem that walking around in the grocery
    store charges me up to the point that I get a surge that
    feels like an electric fence when I touch the checkout
    counter.

    /BAH

    Subtract a hundred and four for e-mail.
     
  7. Guest

    Discharging once doesn't work, so I figure there has to be
    something else that turns into a charge.
    They are leather boots. I don't know what the soles are.
    When JMF decided to show off the second to last CPU he worked on,
    I had to put a collar thingie around my shoe to prevent an
    inadvertant teensy little spark while walking around on the
    machine floor. I still don't know exactly what that was. I still
    have the shift he had to wear.

    /BAH


    Subtract a hundred and four for e-mail.
     
  8. tadchem

    tadchem Guest

    Investigations into the urban legends of cell phones sparking explosions at
    the gas pump have fingered the *real* culprit - static electricity generated
    when someone wearing synthetic fabrics *slides* out of the driver's seat
    (also fabric covered) and touches the pump handle, usually after the tank
    has been filled.

    Doesn't happen much with cotton, though. Or to people (like most men) who
    don't get back inside the car while they are pumping.

    There is no significant "air rubbing" when the vehicle is parked at the
    pump.

    "No, dear, that dress does NOT make you look fat, but just to be on the safe
    side, use the full-service pump."

    Maybe the OP should wear cotton or denim on bus rides.


    Tom Davidson
    Richmond, VA
     
  9. bz

    bz Guest

    degaussing won't work, that removes magnetic fields.

    You probably have plastic or rubber soles on your shoes.

    If you had leather soles, the charge would probably leak to the floor
    through the shoes.

    You could probably modify your shoes to provide a high resistance but still
    conductive path to ground.



    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  10. bz

    bz Guest

    If you carry a coin in your hand, grip it tightly between thumb and
    finger, and touch the edge of the coin to the checkout counter, you should
    feel less of a jolt. The noise may surprise some people, however.
    Perhaps JMF can get you a bit of the conductive foam that chips are
    sometimes shipped in. If you use that instead of the coin, in the way
    mentioned above, you should avoid jolts and noisy sparks.

    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  11. tadchem

    tadchem Guest

    An Electronic Engineer of my acquaintance used to strip one foot to bare
    skin and keep his foot on the tile floor (concrete foundation) while working
    on sensitive Integrated Circuits (ICs, such as instrumentation amplifiers).
    Some of these had input impedance in the gigohm range, and could be fried by
    a spark you couldn't even feel.

    I would not recommend that on the bus - OR at the gas pump.


    Tom Davidson
    Richmond, VA
     
  12. tadchem

    tadchem Guest

    Your winter coat could be the problem...

    Is it made with a synthetic fiber?


    Tom Davidson
    Richmond, VA
     
  13. tadchem

    tadchem Guest

    Sound like a grounding strap.

    Fuel trucks drag a short chain underneath to provide a path to earth for
    static as it is generated. Same principle...


    Tom Davidson
    Richmond, VA
     
  14. John_H

    John_H Guest

    Vehicles on rubber tyres can certainly become charged, though I'd
    suspect the culprit is dust rather than air. In such cases, the
    occupants won't be affected while they remain in the vehicle (as
    Faraday demonstrated in his classic experiment).

    The example given here occurred inside the bus -- ie the occupant
    carries the charge relative to the bus. The discharge took place
    before the "victim" touched true ground.
     
  15. John_H

    John_H Guest

    One of the worst "vehicles" for generating static electricity
    (understandably) is a combine harvester (header).

    Many operators drag an earth chain to keep their windows clean!

    Experience tells me that it works. :)
     
  16. Guest

    Yup. That's what it was called; thanks :).
    Sure. But a chain is metal and can conduct. I never understood
    how this non-metal thingie would work. I'm not sure what the
    material was. I thought rubber but then lots of plastic feels
    like rubber these days. And the thing only touched my shoe, not
    me. The shift's material has a funny feel to it.

    /BAH

    Subtract a hundred and four for e-mail.
     
  17. Guest

    Wow! You had windows? ;-)

    Charge can be deadly when filling silos.

    /BAH


    Subtract a hundred and four for e-mail.
     
  18. Guest

    Well, I rather ruled that out when I'd get a poke without it
    on. Same thing with my boots. I get a poke when I wear shoes.

    The instances do diminish in the summer time but then that's
    normal.
    Yup. What I don't understand is why I don't ground out completely
    with the first poke. One of these days, I'm going to remember to
    not turn around to lock the car and see if that recharges me. I
    know it's a silly notion, but I have to rule out them out, too.

    /BAH

    Subtract a hundred and four for e-mail.
     
  19. Guest

    Right. So why can't I manage to get a discharge a second time
    through my coat? If I can't do this a second time, then I'm
    a walking spark when I pump gas. So far I always lock my car
    before I pump gas to make sure I don't spark.


    This is one of the many reasons I put hardware on my list as a
    "guy thing".

    /BAH

    Subtract a hundred and four for e-mail.
     
  20. bz

    bz Guest

    They include a conductive filler in the plastic when they make it or they
    add a conductive coating after the garment is fashioned.

    The 'ohms per square' of the material can be rather high and it can still
    act as an effective discharge device.



    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
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