Re: strange observation

["Steve" <Steve-at-g8cyerichmond.freeserve.co.uk> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

This may have something to do with what Prof Eric Laithwaite called
'stiction' it's a cross between friction and sticking.  Some substances, in
particular certain polymers, dont't just slip as they move over surfaces,
they tend to stick a little. Rather than moving smoothly they move in little
jumps. Now as you wind your wire it is under tension, and stretches a little
according to Hook's law. Unless the pull you exert as you wind is perfectly
constant there will be greater tension and hence stretch at som points than
others. With hand winding I have noticed that tension gradually increases
for winding periods of reasonable length (in other words before you get too
tired or tense). Now you have a coil that is tighter at one end than the
other. The wire now 'tries' to even out the tension. Due to stiction it
happens in tiny steps. Of course the tiny movements can impart pulses of
energy to the length between the coil and the reel of wire. .
This is one of the reasons that when I wind any kind of coil I leave it for
a few days before doing anything else with it, giving it time to settle
down.
As to the period of the oscillation, ot seems very long, but there could be
an awful lot of variables.
Steve Cook
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, August 25, 2000 2:50 AM
Subject: strange observation


> Original poster: "Metlicka Marc" <mystuffs-at-orwell-dot-net>
>
> hello all,
> while wrapping the 3000 turn secondary i noticed something strange going
> on.
> after wrapping about 6" of wire onto the coil form i stopped to give my
> fingers and the motor a break, as i sat there i noticed the wire running
> from the coil to the spool would jump occasionally. i've seen wire
> running to an electric arc furnace jumping the same way with 20k amps
> surging through it. i had roughly 625 wraps on the coil-at-1432' of wire,
> on the spool there was still 17170'.
> this jumping actually looked like a wave in a pool with a forward wave
> and then a return wave, i watched it for about 15 minutes (had what
> every one calls, my thinking face on. not a pretty face i've been told),
> my girlfriend came in and watched it also.
> my question is, could i actually been seeing some sort of resonance in
> this wire? if so could it have taken the 6 seconds to traverse from one
> end of the wire to the other?
> if so, what was the driving force behind this movement?
> this action may have been talked about before, i don't know? and i'm not
> sure it means a thing, i just saw it and wondered,   marc
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