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60 hertz hum

Discussion in 'General Electronics' started by Dennis, Jan 3, 2006.

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  1. Ken Weitzel

    Ken Weitzel Guest

    Hi Sofie...

    Been in the UK many times as well, but not in the last 20 years...
    would like to once more if I can. Never heard crikey, either, neither
    there or here in Canada.

    My favorite expression I heard there was from someone I was doing a
    bit of a job with. I made a foolish mistake, and he accused me of
    "dropping a clanger" :)

    Ken
     
  2. It's an old expression and I was trying to be polite as a visitor to a non
    UK newsgroup.

    Otherwise I'd have said bollocks or shite. ;-)
     
  3. CJT

    CJT Guest

    FWIW, I've heard crikey used in the U.S. many times (but I don't recall
    hearing it in the U.K. during the year +/- I lived there). Perhaps it's
    a regional thing.
     
  4. I knew that would raise some rabble. Yes, of course I recognize the
    potential (so to speak) problems with opening the safety ground connection.
    However, a few interesting points exist in this particular situation:

    - The device is a laptop, and there is no direct connection from the ground
    pin through the (double-insulated) AC adapter/charger to the laptop chassis,
    so it's really not much of a "safety" ground.

    - There are two small value (10 nF) caps from each side of the power line to
    the ground terminal inside the adapter, presumably as an RFI suppression
    measure.

    - All of the audio equipment involved was plugged into the *same* outlet
    strip - it seems highly unlikely that there'd be much of ground loop within
    the 6" or so of 16 gauge wire separating the plugs

    - Finally (and this is really no excuse), my house is old enough that I'm
    not convinced that all of the three prong outlets have their ground pin
    connected to anything at all. It's not so old that it's knob-and-tube, but
    the outlets were originally two prong, and I think that many were just
    replaced with three-prong as placebos, without pulling a ground wire. At
    least the garage (with the concrete floor and the power tools) is wired
    correctly...
    --
    Mark
    "I prefer heaven for climate, hell for company."



     
  5. Ken Weitzel

    Ken Weitzel Guest

    Hi...

    As a side issue, there are testers available for only a couple of
    dollars that you can plug into your outlets that will (by way of three
    neon lamps) easily tell you whether or not ground exists, and if
    hot/neutral are reversed.

    Just mentioned it wondering if it might not increase your comfort level.

    Ken
     
  6. Alan Holmes

    Alan Holmes Guest

    How do you work that out?

    Alan
     
  7. Alan Holmes

    Alan Holmes Guest

    You obviously haven't lived!:)-)

    Used to be an everyday exclamation

    Alan
     
  8. Jasen Betts

    Jasen Betts Guest

    dunno about there in in Australia and New Zealand it's heard occasionally.

    my (aging) Concise Oxoford dictionary dosen't specifty that it's unique to
    any place.

    Bye.
    Jasen
     
  9. Karl Uppiano

    Karl Uppiano Guest

    Second harmonic of 50 Hz. A lot of the hum you hear in the US is actually
    120 Hz for the same reason. Most objects, including speakers, really don't
    radiate that well at 50 - 60 Hz fundamental, but can and do radiate pretty
    well at some of the higher harmonics.
     
  10. James Sweet

    James Sweet Guest

    I always thought the 60Hz caused core laminations, coil windings, etc to
    smack into each other at both peaks of the waveform, hence the 120Hz
    sound from a 60Hz source. I could be off on the process, but I do know
    that if I use a sound editor on my computer to produce a 120Hz sine wave
    it sounds just like the 60Hz hum from transformers.
     
  11. Karl Uppiano

    Karl Uppiano Guest

    Yeah, I think a magnet or buzzer (like in an old alarm clock) will be
    attracted by both peaks of a 50 or 60 Hz input, and oscillate at the second
    harmonic.
     
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