Hi Chris,
I've seen the very raspy growling sound when the grid feedback is too strong. I think in this case the grid can go too positive and itstarts behaving like the tube plate and attracts theelectron flow to it. I'm not sure if I have the explanation exactly right because it was a longtime ago that I looked into this. I had one VTTC(no staccato) where as I turned up the power,it would begin the nasty rasp, then I hadto keep turning it up more "past" that stage,and the raspy sound would stop, and the sound became smooth, and the spark lookbecame normal again, and shot up muchlonger, but I was alwaysnervous doing that. It always seemed likesomething was about to be destroyed.
The extra wide pulse on the staccato doesnot cause any bad behavior, things run supersmoothly, it just limited the pulse rate to 30ppsif the bypass was not activated.
The bad firings using staccato, I wasn't referring to theraspy sound, but just to the occasional shorter branchedsparks along with a sound that sounds "soft",not solid. I heard these on your EVR board inyour video, and I used to hear them at timesin my various VTTC's. By branched in this caseI just mean split in two or so rather than a singlesword, and shorter/weaker. But not fuzzy, gnarled,or raspy.
I always did all the tuning and grid adjustmentswithout staccato. I only added staccato afterthe coil operation was optimized.
John
-----Original Message-----
From: Chris Reeland <chrisreeland@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sun, Oct 27, 2019 10:43 pm
Subject: Re: [TCML] Eastern Voltage Research VTTC Staccato Controller - puzzled on "burst" output
Hi John,
Just a quick update, grid repaired, tweaked grid leak a little, all running
good both interrupters. Actually have a slight improvement in streamer
length in both. As I said previously I knew off a little, since the recent
primary and cap change. Still wandering of course on EVR. Did grid winding
a little different since I think I am done changing and I feel this amount
of turns is permanent now. Previous setup was mainly for ease of "quick and
dirty" changes. Did not mind cutting wire away to extremes during testing.
Also winding crazy lengths on to see what happens. Got damaged during the
extreme long. Again not unexpected. Learned things again.
Also during this grid experimenting I did, I experienced at times, I think
you mentioned, nasty "snaps" with very branchy not real long discharges.
Steve White mentioned these also if I remember correctly. So, to me the
grid if not quite right, these can occur at times. For you John, some other
factors could be in play, since extra wide pulse. Another unknown...
I want to add, now both interrupters are running and transitioning very
smooth everywhere as far as I know. Thoroughly tested both for several
hours. No nasty snaps.
These are definitely nasty looking and sounding in a bad way. And I think
you both would agree these are not good at all, and could be very damaging
somewhere. I have just a guess here, but I am going to call this having
something to do with the grid "losing control". Again just a guess.
I don't think I will get to input current checks and the secondary current
on the scope tonight. Not enough time in the day... next weekend.
I am going to be doing some thinking and scope things on the "breadboard"
interrupter. Have some ideas running through my head. I will eventually
float some of these to you, John when ready, with questions most likely
also. Going to tinker with it and just scope some the rest of the evening
on it.
Chris Reeland
Ladd Illinois USA
Sent from my LG V20
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