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Re: [TCML] Eastern Voltage Research VTTC Staccato Controller - puzzled on "burst" output

Hi John and all,

Hope everyone had a great holiday weekend. And some of us made some "fun

John, I have finally solved the EVR problem in a way I did not expect.
Quite simple once "I saw it".

Been working on it off and on for the past several weekends. And I was just
plain tired from being busy at work. Got frustrated several times. Tried
all kinds of things, not going to get into all details, but I could not get
any success "unlocking" the "zero lead" timing.  Kind of hard to experiment
with being on a circuit board and being inside my enclosure also. My
circuit board is somewhat "beat up" now, but it was worth it. I had to
"walk away at times".
Decided to work on some other things.
Made some more tweaks, to my grid leak increasing the performance.
Here is a couple of pictures of the grid circuit now:


I also decided to work on the "breadboard" one some more. Cleaned up
layout, changed to different equivalent components. And I also changed one
capacitor value, to squeeze out just a little more "lead time".
Giving some more background on this,
Here is several pictures of it now and the modified schematic that I happen
to be using (this is Mads'), since I have a single output transformer.
I never could get this to work well in the past, and made the major mods
quite a while ago giving the unknown then benefit of the majority of the
lead time. See the added notes on my mods. The diode and transistors
"flipping" were the biggest things that gave me the "lead time", that I
have been using for quite a while now, found from just experimenting with
the circuit. I don't think I have mentioned this before, so here it is now,
if I have not. Other changes gave better "stability" when actually running.
What you see on scope does not always work well under true running coil

Breadboard, schematic mods., scope traces of min. & max PW with even a
little more lead time than before:


Okay the EVR now, after several failures,
I thought back to the quick experiment that I did on the breadboard one,
that I was curious about, that I mentioned recently.

Here is the pic of trace again:


It got me thinking again about how the actual power input to the coil is
actually level shifted. All I need to do since my EVR has a polarity
switch, is make the PW able to be adjusted extra wide, then just switch
polarity. A simple one capacitor value change. Just can't see the simple
solution sometimes...
I can change between the "running modes" now just by "flipping the switch"
for a direct comparison of the big difference. Going from no lead to more
than plenty of lead. Speaking of more than plenty of lead, I can actually
get the PW set to only the falling portion of the level shifted sine wave,
which "kills" the output to just a very tiny spark, since voltage is going
down of course.

Here is pictures of several scope traces showing min. & max PW now and
changing polarity. And the part of the schematic that I changed to increase
PW range.


Next I will have running videos coming soon. Breadboard again, and then the
EVR in both now "switchable modes".

Hope this all makes sense and I fixed most of my typos :^)

Chris Reeland
Ladd Illinois USA

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