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Re: [TCML] RSG disks - who can make them ?
Hi Gary,
I strongly disagree. People who use asynchronous RSG's experiment with
various break rates all the time, by simply varying the motor RPM.
True but it is not a fair test as you are in effect misfiring at random
points in the AC wave. You cannot test anything at all if you alter more
than 1 aspect at time! Altering bps and dwell time... results are
meaningless! The only way is to keep bps the same and alter ONLY dwell time!
These are the figures I am interested in working out.
So the same question again, who has does the dwell time tests (correctly)
?... ok... I just know John is going to jump in now ;-)
It would be like rolling a car down a hill and breaking, it will go maybe
20mph... now use a even steeper hill and alter the breaking aspect and now
the car goes 30mph, so which factor has caused the increase in speed, the
decline of the hill ? or the change in breaking factor ? In theory the
breaking should remain the same and the only the decline of the hill should
change. Then you get your expected results that the car rolls faster!
I suspect the reverse is happening with tesla coils, 2st notch quench should
be better but it is not, but have all the factors accurately been taken into
account ? Now you roll your car down the hill with unknown breaking factors
( IE you altered it to some random value) and now on a step decline your car
only goes 10mph when it is supposed to be doing more like 50mph! It may not
be the best example, though if you want to study something you must only
alter one thing at a time!
Higher break rates tend to give hotter, brighter streamers (assuming that
the power supply can charge the cap fast enough) simply by delivering >more
power to the streamers. If the RPM is too low, the dwell time is extended
and it's possible to achieve multiple, smaller bangs per >presentation - an
undesirable thing.
I think I tried this also. I had my gaps set very close together and I can't
remember which way around it was, but I know I tried various RPM speeds and
gap spacing and did not find any real difference in spark output. I regret I
can't remember which way around it was, though I think it was a slow RPM
with wide gaps and a fast RPM with small gaps.
I can't really comment on higher break rates and what you state, in theory I
see no reason why this should happen. The only way it may work is to trigger
the spark gap at 10KV then spark off your coil, then the very next instant
fire at 10KV again. If lucky the sparks path will be re-ignited with the
next bang making it appear brighter and maybe even longer!
It would require a tank cap which can be charged twice on the AC cycle,
maybe 3times the current will be needed to charge the tank cap to 10KV in
just a few uS of time. Even so, so much current flowing though the gap not
being put into capacitance that the spark gap would probably just power arc
constantly and cause a whole bunch of energy drops... all swings and round
abouts.. I would think IMHO anyone who managed to get a higher BPS rate to
work in such a way must be really clever or really lucky to gain longer
sparks... I would prefer to keep things simple as possible and work from
that point. Simple matched cap to the transformer then work on RSG dwell
problems without trying to factor in multiple bangs per half cycle...
As has been previously stated, attempting to accelerate quench by reducing
dwell times by increasing RPM >is futile, as the spark will stretch
>following presentation until the gap voltage or current is insufficient,
and the gap is good and ready to quench.
I cannot see how this can happen is the system is designs well enough. My
own spark gaps shows that there is no drawn out spark after the spark gap
fires. It fires just before alignment and during alignment but not after. I
think however the problem you state gets worse with higher power coils.
Though I do not see as a problem with just a 500W based coil. If the spark
was been drawn out past the physical dwell time then the electrodes on my
gap would have been burnt both sides.
I think it is more like power arcing pas the gap, too much current, maybe
not enough current limit, or use 300bps instead of 100bps and charge the cap
up to maybe 5KV either side of the AC cycle.. will use up some the
transformer current, though think the gaps will not fire at 5kv anyway. so
other than wasting amps it does nothing at all.
I think it would be far better to lower the supply current to the tank cap,
talking easy figures for a moment, assuming the tank falls to zero in 100uS
then make sure you cap does not charge up to more than 5KV for the next
100uS or so. If the cap cannot charge then the input supply cannot power arc
anyway.
More to the problem is the trapped energy in the actual transfer. Now if you
can hit 1st notch and assume 100% energy has been transferred to the
secondary at that point, then your tank cap must not reach more than say 5KV
during the new few 100uS. otherwise the ionised gap will fire again at 5kv
then you are pulling more current across the gap and then you get the power
arc problems. .
I think there is 2 problems to deal with in anycase related to power arcing.
So if the AC cycle hits 10KV and the gap fires, assume the tank is now
empty, the transformer will try to charge the tank cap up again. As the air
is already ionised its probably the tank cap only needs to charge for a
couple of KV and the gap will trigger when it is supposed to be off. Really
there needs to be a small delay where the tank cap cannot charge.
Assuming now the tank cannot charge after the break, then there is simply no
energy there to pass over the spark gap. so as soon as the tank is empty the
supply cannot recover fast enough. So you limit power arcing as there is
just not energy there.
The next problem is the circulating energy during transfer. Unless you can
hit first notch and keep the gap off then the gap will retrigger. If all the
tank energy has been put to spark output (well designed coil) then there
will be no energy left anywhere to transfer from the secondary back to the
primary. So again the spark gap is off and no power arcing.
I am not saying it is easy, it needs a lot of thought but I do not see
anything wrong with the idea. I threw together my first coil all built on
general terms and worked well, though there is no arc after the physical
alignment of the electrodes. With low powers of 500W it probably cannot
happen, it is either that or my just is very efficient at energy transfer
and drains all the tank energy very quick. As not much design thought went
into it, either I got lucky with the design and it worked very well in spark
gap quench or 500W does not suffer with power arc problems. Maybe a bit of
both, but if designed correctly there should be no power arcing in the first
place.
So I do not agree totally with what you state as it is just not true in all
cases as already proven.
Can anyone make (for me) a 24" RSG disc
I'll not try to discourage you too much, as much can be learned even by
performing failed experiments. I've also made some large and silly failed
>attempts at an SRSG, and am wiser for doing so. Please be aware that such
a large disk at high speeds has tremendous potential to cause >injury,
particularly if made of wood!
Fail or not, I want to do the testing first hand myself, there is no harm in
doing so. I may seem a waste of time, but there is always room for
improvement.. It is one thing to say "it wont work" then list 500 reasons,
but I would like to do the tests firs hand myself and draw up my own results
and conclusions..
I think the issues is still there that 1st notch does not work, when in
theory it should work better. So as 3rd or 4th does... why is that ?
Something is still missing I think. I like things to add up in theory and in
practice... a lot of aspects seem to be a bit generalised and some points
are never really solved and just end up a matter of general opinion. I think
the challange of 1st notch quench is still out there... Though that is just
my own opinion ;-)
Chris
Regards, Gary Lau
MA, USA
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Chris Swinson
Sent: Wednesday, November 21, 2007 9:19 AM
To: Tesla Coil Mailing List
Subject: [TCML] RSG disks - who can make them ?
Hi all,
Can anyone make (for me) a 24" RSG disc and drill a range of holes for my
next range of experiments ? My engineering skills are very poor
unfortunately , so wonder if anyone has the technology out there to make
once accurately or know an engineering firm who could make one...
I was also thinking of a small disk with like a cross section of wood such
as...
|
--O--
|
( if the ACSII art comes out right)
So I can have holes in the strips to alter the break rate of the
electrodes.
It could even be made larger but I think balancing is going to be a right
pain at 3000RPM!
I know most will think it is a waste of time, though I do not think anyone
has really experimented with break rates/dwell times. I would however like
to conduct my own testing and document the results for the list...
Cheers,
Chris
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