# Re: Rotary Gap Design

```    I would suggest a means of controlling the frequency of the spark gap,
and crossrefrencing several industrial motors for a heavy duty design.  You
can always concern yourself later with balancing the rotor, because there
are wire connectors that are used for the motor it was designed for.  The
current rating should be better than the motor that it came from, because
the coils start at a low RPM, and call for a large amount of current.  But
once the RPM picks up, the inductive reactance of the coils start to
increase, dropping the initial demand for current.  A stepping motor gives
you the ability to control the frequency that the rotor is running at.
RPM/60 = Rotations Per Second, the number of contacts of the rotor gives you
the second factor.  If there are 30 contacts on the rotor, the equation
looks more like this, RPM/60 * 30 (The number of contacts.) = Frequency.  I
would probably pull my rotor, motor from a very old bulky disk drive.  Those
things can hit about 25,000 RPM free wheeling, and some can 35, or 40
thousand.  What you need is a driver circuit, run by a 555 timer in a VCO
configuration, a binary counter, a 1 of ten data selector (there's some
other name for that), and some power MOSFETs.

Date: Friday, August 28, 1998 9:42 PM
Subject: RE: Rotary Gap Design

>Original Poster: "Payne, Will E" <will.e.payne-at-lmco-dot-com>
>
>Excuse me, but wouldn't it be simpler to have fixed gap electrodes to put
>the current into and out of the far sides of the wheels ?  Multiple gaps
are
>desirable anyway, no ?  True, the outer two gaps would break slower, but
>would not be completely static.  They would however always be in sync with
>the central gap.
>
>Will
>
>>  >Certainly slip rings or the equivalent would be necessary - but the
>>  >voltage drop and power loss would probably be insignificant.
>
>

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