Re: Rotaries and Neons (fwd)
---------- Forwarded message ----------
Date: Fri, 7 Aug 1998 09:17:14 EDT
Subject: Re: Rotaries and Neons (fwd)
In a message dated 98-08-07 00:07:55 EDT, you write:
<< Actually it is. Elsewhere I stated that I would uput a static gap
> across the rotary to catch misses. I would definitely want to
> resonantly charge Cp although I'd expect the value of Cp to be chosen
> according to breakrate. I guess my main point is: if the zero current
> crossing spikes in the gap are the real nemesis for NSTs and these
> are adequately filtered, all should now be well, shouldn't it?
> Malcolm >>
Well, that's what I get for assuming.... :)
I thought that usually with NST's, the cap size that is best for
resonant charging, draws so much current, that only one break
per half cycle was possible, but I may be wrong about that. If you
want 2 or 3 breaks per half cycle, the cap may have to be small
enough that there won't be much resonant effect. Again, I haven't
really checked this out. (actually I did, but don't remember offhand).
I would guess you'd have to run at least 150 true breaks per second
(maybe 220 BPS calculated), to obtain smooth operation...again I
haven't tried this with a neon, so I'm not sure. I did run an NST
async one time, but I don't remember the cap size, or break-rate, etc.,
it ran poorly, but the cap may have been too big. I've seen instances
in which folks used multiple neons, driving a relatively small cap, and
obtained smooth operation...I'm guessing not much resonant charging
was happening. Much speculation in my response here, I'm afraid.
I'm sure you've considered all this anyhow.
But I do agree that the neon would probably be safe from destruction
using your methods (as safe as it can be anyway). You're protecting
it from simple overvoltages, and RF overvoltages, the only thing not
protected against is current overloads...and I think NST's can withstand
current overloads if the run times are reasonable.