Modulated Spark Gap.

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Modulated Spark Gap.
From: Tesla List <tesla-at-stic-dot-net>
Date: Wed, 19 Aug 1998 00:09:55 -0500
Approved: tesla-at-stic-dot-net

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From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
Sent:  Tuesday, August 18, 1998 10:50 PM
To:  tesla-at-pupman-dot-com
Subject:  Re: Modulated Spark Gap.

Hi Marcus,

        My latest experimental gap is design to uses a voice coil (woofer)
to move air through multiple gaps to aid cooling and quenching.  I am
studying if a resonant speaker enclosure type system will be able to move
air more efficiently through thin gaps than a vacuum cleaner or blower.  Of
course, the "volume" and frequency of such a system is trivial to adjust.
This is not quite what you are thinking of but your post certainly caught my
eye!!
        You would want a typical audio amp in the range of say 50 watts.
The speaker would be a woofer of perhaps the 8 inch variety (I am just
guessing but I have done considerable speaker work in the past).  The
mechanism needs to be "glued" to the speaker cone and needs to be as low of
mass as possible.  If one is cleaver, perhaps the moving speaker cone can be
used to direct air into the gap sections.  There is a problem that the
speaker cone's movement per given input is very frequency dependant.  The
speaker cone's movement is a resonant system just like our coils.  The
"sweet" spot could be changed by adding mass to the system or enclosing the
back of the speaker in an air tight box but this needs some real design
thought.  Probably many possibilities for such a system.  Definite bleeding
edge technology though :-))

        Terry Fritz




At 04:07 PM 8/18/98 +1000, you wrote:
>Hello All, 
>
>Ive long been considering an idea for a spark gap with very prescise control.
>It occured to me that controlling the movement in a gap could be achived 
>using the movement of a  powerful voice coil and AF amplifier. This could be 
>used to trigger sparking.
>I have thought that an AF voice coil/solenoid could push and pull on the
>outer edge of 
>a centrepivoted disc via an insulating rod of some type, kinda like a
>piston wheel. 
>A disc with electrodes arranged about the perimiter much as a rotary gap
>has, but far,
>far lighter in construction as centrifugal forces wont really be an issue. 
>Stationary electrodes would be positioned just outside the sparking range
>of their 'humming'
>counterparts while while at their resting positions. The 4 electrodes would
>be configured so 
>as to fire a series break of 8 gaps.
>Ive just never been sure what kind of solenoid/VC and amplifier Ide need to
>move the small 
>but nasty weight of around four 4.5mm dia tungsten slugs back and forth 5mm
>or so at 
>0-1000Hz + without distortion.
>There are 3 main advantages to this system, but also a few problems..
>Advantages: 
>1) Exactly controlled and easily measurable break rate/frequency with an AF
>gen.
>2) 'On the go' controll over minimum gap distance by controlling amplitude.
>3) Easy to reference frequency to mains for perfectly phase-synchronous
>operation (if desired) 
>*Maybe theres some advantage with different wave shapes but some things
>are just meant for the lab...:)
>
>Disadvantages:
>The problem with this gap is when you try to air quench it, this will most
>probaly
>cause problems with movement if the blast is as stong as it would probably
>need to be.
>*sigh* Any ideas anyone?
>Has anyone ever made anything like this? It seems to have promise. Ime just
>not in the 
>position to build one right now. 
>  
>Marcus
>
>ICQ!  #15089999 
>
>
>