[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Sparks - Bright in the middle, how to verify it.
Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>
Paul suggests an excellent experiment. One of the problems with sparks from
AC sources (like TCs) is that there are a whole raft of visual illusions
that can occur that mask what the spark is really doing. Anyone who has
seen a big coil running outdoors in a breeze has probably noticed the "multi
stroke appearance" of the sparks. It "looks" like the wind is blowing the
succesive arcs to one side. However, it could just as easily be some sort
of afterimage effect as your eye moves, and the brain doesn't correct it as
it normally does.
Fast pulses of light really confuse the eye brain system, which really
doesn't have a bandwidth much more than 10-15 Hz (with a lot of non
linearities and odd timing behavior to boot).
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, January 22, 2001 6:58 AM
Subject: Re: Sparks - Bright in the middle, how to verify it.
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<paul-at-abelian.demon.co.uk>
>
> Charles Hobson wrote:
>
> > At the center of these sparks there is a 25mm segment which
> > is much brighter than the rest.
>
> Interesting. Never noticed that myself.
>
> Jim Lux wrote:
>
> > Sparks tend to grow from one polarity better than the other.
>
> Seems like a reasonable explanation. Ought to be easy to
> demonstrate.
>
> In response to the various suggestions, why not use a photo
> detector, or a pair, suitably collimated, and compare their
> outputs with the top voltage waveform. A suitable choice of
> detector should give a frequency response adequate to follow
> the variation of the arc's light curve at the RF frequency and
> allow comparison of the alternate half cycles. I suggest that
> this simple method might give informative results.
>
> Eg,
>
> (fixed width font)
>
> terminal arc terminal
> >>>>> \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/ <<<<<
>
>
> |
> |collimating
> |screen
> |
> \ / | \ /
> |__| | |__|
> D1 D2
> photo detectors
> *******
> *** ***
> *** ***
> * *
> ** **
> ** **
> -----------------------------*-----------------------------
> ** **
> ** **
> * *
> *** ***
> *** ***
> *******
> ^^ Top volts ^^
>
> *******
> *** ***
> *** ***
> * *
> ** **
> ** **
> **-------------------------***-----------------------------
> **** ****
> *****************
> ^^ D1 output ^^
>
> *****************
> **** ****
> -----------------------------***-------------------------**
> ** **
> ** **
> * *
> *** ***
> *** ***
> *******
> ^^ D2 output ^^
>
> It would be quite interesting to look at the light curves of arcs
> under various operating conditions. Does anyone know of any existing
> results? I don't suppose they are sinusoidal as I've shown above -
> they might start with a sudden peak as the stored charge is released,
> followed by a gradual decay.
>
> Cheers,
> --
> Paul Nicholson,
> Manchester, UK.
> --
>
>
>
>