Re: Passive Ballasting for DRSSTC - My thoughts before Ed Wingates Teslathon

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jimmy Hynes <jphynes@xxxxxxxxx>

I'm gonna try sending this again, since it didn't work the first 
time. Sorry if it comes through twice

Hey,

On 8/25/05, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: "Mccauley, Daniel H" 
<<mailto:daniel.h.mccauley@xxxxxxxx> daniel.h.mccauley@xxxxxxxx >

Apparently, there has been an offlist discussion (without me of course)
regarding my ideas of a "passive ballast" for use in a DRSSTC.  Also, i
received word that Steve Ward was planning on basically debunking this
theory to fellow list members at the upcoming Teslathon this weekend,
again without me being present to provide my feedback on the subject.
Anyways, i thought I would add my thoughts on this practice ahead of
time so you can hear my side of the story.



Hmmm? I talk to Steve all the time on AIM, and am not aware of any 
'plans' to talk about stuff behind your back. I'm sure if it comes 
up, he would share his opinion, but I doubt he's scheming against you 
so he can attack when you are defensless :P


Firstly, regarding the passive ballasting action of the DRSSTC, it
works.  Perhaps not in the way i think it works, but it does in fact
work.  Now, i'm much more of a practical engineer, than one that dives
into the hard core theory behind everything, so i'll be the first to
tell you that my theory could be incorrect.  But again, regardless, it
does work.


I'm sorry if i wasn't very clear on this before, but I wasn't arguing 
that it didn't work for you. I was basically arguing that its not 
doing what you think, and doesn't necessarily always work.



Here are several of my arguments so you can get my side of the story
before you hear someone elses ideas.

1.  The first argument Steve and Jimmy provided was that the ON time in
both of my experimental data was different.  Okay, this is a valid
argument.  I checked the data and in fact the ON time *is* different.
However, i was sure my drive pulsewidth was constant.  To verify this, i
had my technician re-check this data.  Again, the data was identical.
Even when the drive pulsewidth was identical, the ON time (primary
current) differed in each one.  Perhaps, this is more of a clue to why
the ballasting effect occurs.


First of all, I don't see how the drive pulsewidth can be different 
than the ON time, especially if you are not using a JK flip flop to 
ensure a soft turn off. Even given a constant ON time, there was a 
noticable effect. I wasn't claiming that the effect was purely 
different ON time, but that if you are gonna try to compare them, you 
should at least compare them honestly and not try to cheat a few cycles.


2.  The second argument is that somehow the length of the wire affected
tuning or coupling.  Again, a good point, however i no longer use longer
wires when ballasting.  I use same length as original 4 AWG cabling, but
just use 8 AWG instead.  Steve also made a comment that perhaps I do not
retune when switching the wire sizes.  I personally can't see how
changing an identical wire length to a smaller gauge would affect
tuning.  Again, his point his valid, and this is something i can explore
further.


Do you still notice the effect when you don't change wire length? I'd 
find that hard to believe. The only other change is the resistance, 
which is a simple ohms law calculation.


3.  The third argument proposed to me was that this was a fluke.
However, I have built (well, my technician working for me) has built
five identical DRSSTC II coils in the past year.  Three of which are
used for demonstrations i do during the year, and two which were sold.
In every case, this ballasting effect occurred and is measurable.


Not really a 'fluke', just that it works with your coil, with your 
tuning. Of course identical set ups will perform identically. It 
depends on how you tune the coil in the first place (running a 
slightly lower tuning effectively cancels out your 'ballast' 
inductance). In other designs, it may not be effective, and in the 
case of primary current feedback, it will do nothing, since it will 
simply drive it a bit slower, and keep building up current.


4.  The fourth argument is that this passive ballasting is inefficient
and lossy.  This again is not true at all.  Power input to my coils
barely change at all when switching from the 4AWG to 8AWG primary wire.
Spark length also remains unchanged and in fact, the ballasting effect
only appears to work during ground strikes when currents peak to their
highest.


First of all, any increase in resistance will increase loss. If you 
arent going for a resistive ballast, then you dont want unnecessary 
loss. If the effect were to be purely resistive, the loss would be 
enourmous. The effect you are seeing is NOT resistive, and therefore 
you do not see the loss.


Again, i don't claim to me an expert on theory and i'll be the first to
tell you that i am not. My theory behind why this actually occurs may be
incorrect, but the so called passive ballasting does work.  You can
argue with me and debate this as much as you want, but my experience and
measured data show it to exist.


Ok, I'll try to dive into some theory here...

First of all, we have to look at the possible effects of adding some 
small wire to the setup. The effects can be inductive, or resistive, 
or a combination thereof.

The extra inductance both changes the primary resonant frequency (as 
does changing the tap point), and reduces the coupling (as does 
raising the secondary). Therefore, you shouldn't add thin wire for 
the inductive effect, since you can simply retune (and raise the 
secondary, although it's probably more about the tuning), and thinner 
means more loss.

Resistive limiting is not practical. Either the loss is small and the 
regulation is horrible (as in your case), or the regulation is 
decent, but the loss is horrendous, or you can have the worst of both worlds :P

<http://www.hot-streamer.com/chunkyboy86/resistiveballasting.jpg>www.hot-streamer.com/chunkyboy86/resistiveballasting.jpg

The "minimum loss" box is where you're running with a few extra 
milliohms from "only" 8 gauge wire. You don't lose much, but the 
short circuit current is many many times the nominal current. The 
"max power" box still loses 50% of the power input, and has a short 
circuit current of 2x the nominal current. The "max regulation" box 
limits the short circuit current to a little over the nominal 
current, but the power lost is way more than power out. Since you are 
running in the first box, you do not see the huge loss, but 
resistance is not doing anything to limit the peak current either. A 
few milliohms has a short circuit current of thousands of amps!

Since there is a noticable effect, it has to be inductive, and can 
also be tuned out. Since you are using secondary feedback, if the 
primary frequency is off, it will not build up as much, and may not 
have a drastic (although it is noticeable in your pictures) effect 
under normal circumstances. How did you go about tuning the coil in 
the first place?


Now there are two ways to answer this post.  One is to be close minded,
act with attitude, and tell me that passive ballasting is impossible,
wastes energy, and does NOT work - as has been the typical response.
The second would be to try to discuss this in a positive manner and
perhaps provide insight to why i am getting these results.  Perhaps the.
action isn't purely resistive or inductive as in a typical ballast - as
i originally thought.  But you guys tell me.  What are your thoughts.
I'm open ears.


I'm trying to explain the theory and provide some insight on why 
you're getting your results, so hopefully you'll see this as the second type!


Also, keep to the subject.  We all know active current limiting is the
ideal way to go (albeit at the expense of being a bit more complex) so
please don't turn this into an Active Limiting vs. Passive Limiting
thread.



Active is better :P


Dan