Building a sync RSG... But how? (fwd)

---------- Forwarded message ----------
Date: Tue, 12 Oct 1999 22:24:52 +0300
From: "Antti [iso-8859-1] Koskipää" <antti.koskipaa-at-nic.fi>
To: tesla-at-pupman-dot-com
Subject: Building a sync RSG... But how?

Hi all,

After searching the entire tesla ring, I found no information on how to
exactly calculate and build a synchronous rotary spark gap.

Here's the current coil specs:

8kV 100mA (NST) into 20nF and 8 turns, 1000 turn 4" diameter secondary
with 0.4mm copper wire, multigap spark gap w/copper pipes (7 gaps), 28"
arcs from the toroid.

And here are the questions:

How do I calculate a motor's rpm if I know the number of "magnetic
poles" in it?
(motor will be a salient-pole type, 3-phase, 50hz)

How do I calculate the number of electrodes and their spacing?
I want 100bps (-at-50hz). I haven't figured this out on my own. If I put
the spacing a little bit wrong, wouldn't the sparking drift out of sync
after running for a while and then again into sync etc...?

I found some 3-phase, 90W 660/670rpm motors from the local scrap yard,
can I
use these? (with a phasing capacitor of course, I want to use a 1-phase

Would this improve the coil's performance? everything else has already

Or should I just go for a fast-rotating, non-sync rsg? I want to build
an rsg
anyway so I could use it in future coils...

Thanks in advance,
- Antti