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Re: Rotary Spark gap


---------- Forwarded message ----------
Date: Wed, 01 Oct 1997 19:10:02 +1000
From: Peter Electric <elekessy-at-macquarie.matra-dot-com.au>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Rotary Spark gap

Tesla List wrote:

> ---------- Forwarded message ----------
> Date: Mon, 29 Sep 1997 12:37:06 -0500 (CDT)
> From: Kevin Radtke <umradtke-at-cc.UManitoba.CA>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Rotary Spark gap
>
> Hi All,
>         OK one last try.  I've asked a few questions regarding
> improving
> my understanding of rotary spark gap construction and have only
> recieved
> TWO replies.  A thousand thank you's to those two who have tried to
> help
> me so far.  The problem is that the two answers I recieved were sort
> of
> brief and I still don't get it.  Sorry. :)
>         First of all I've never seen a "sync" motor and I'm not sure
> what
> they do.  ie. Why do I want to use a sync motor in a rotary spark gap?
>
>         What is a good target range for BPS?  Around 200-400?
> OK last question (which requires most detial)  If I wanted to modify a
>
> motor to run snyc, I understand that flats need to be filed on the
> armature, is there somewhere I can see pictures that detail this sort
> of
> work.  Its very hard to "visualize" what to do from a short text
> paragraph telling me to file flats 1/8 the size of the armature etc.
>         Thanks so much for the reems of usefull info on the list,
> hopefully my understanding of TC's will grow to the point where I may
> have info to contribute.  But for now I'm just trying to learn from
> all
> of you.  Thanks for the help.
>
> Radtke

When running a TC using Neon sign transformers, it is of great advantage
to be able to get the cap to fire across the primary of the TC at the
peak of each phase of the AC sine wave - ie at the peak of the first
positive peak then the peak of the next negative peak etc. This equates
to 2 firings per AC sign wave - or 120 breaks per second (BPS).

This is where the Synchronous motor comes in. You modify the motor to
get the armature to "lock in" with the AC sine wave. On a 3600 RPM motor
this allows you to place two electrodes on the rotor and by carefull
adjustment, you can get the electrodes to align with a stationary pair
of electrodes precisely twice on every cycle. If you do your math you
will also realise that it will take 4 electrodes on an 1800 RPM motor to
achieve the same effect. Just use whatever speed motor you can get hold
of.

See John Freau's excellent posting on exact details of how to file the
flats.

Cheers,

Peter E.