Hi Dave, Id be happy to give you some more details of my coil. I will
start with the basic parameters.
Secondary Coil diameter 12.5"
Secondary winding length 54"
Secondary wire size 19 gage
Toroud 12" x 48"
Primary Coil 1/2 " OD copper wound as pan cake coil and taped on the
13th turn
Primary capacitance .08 uf
Max Break Rate 425 bps
Max Power input so far 18 KVA
Max Spark Length so far 11 feet
Power Supply 10 kva , 19500 volt pole transformer which I I'm currently
running at an output of 17500 volts
I was running this set up with a smaller transformer and at a lower
voltage but this summer I finally hooked up the bigger pole pig I got from
Bert Hickman.
The Output from it goes straight to a full wave rectifier and then to a 2
uf filter capacitor bank. In lieu of a big variac I have a big
transformer with multiple taps
that I can use to vary the voltage to the piggy. There is no Current
limiting ballast on the AC side of the system at all.
From the filter capacitors the current flows though the charging
choke witch is many windings of # 24 gage wire wound on an "I" core for an
inductance of
6 Henrys and then I have a dequing rectifier between the charging choke
and the primary capacitors to prevent current from flowing back out of the
primary
circuit into the charging circuit. Some people have had success using
solid state diodes for dequing rectifiers but I didn't have much luck with
them. I ended up using a bunch of 8020 vacuum tube diodes in parallel .
Under the right conditions you may not need a dequing diode but I think it
reduces the risk of burning
up your charging choke.
One final comment, in theory it seems that the inductance of the
charging choke would be kind of critical but I have played around with
this a lot and it
doesn't seem to be critical at all. You will run into problems if the
inductance is too small but it doesn't seem possible to make it too big.
There might be a sweet
spot somewhere that will give you the most efferent operation but if there
is I haven't found it yet.
Roger
----- Original Message -----
From: "David Rieben" <drieben@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Sunday, July 11, 2010 9:59 AM
Subject: Re: [TCML] New coil modeled after Green Monster
Hi Roger,
Yes, I have seen pics and some description of your
coil. Very nice system you have there. Now that you
have chimed in here, I would like to get a bit more de-
tail on the DC resonant charging that you employ into
your system. As you are probably already aware, the
GM simply uses the stiff, unfiltered high voltage AC
from the pole pig to power the tank circuit assembly
and around 350 to 400 bps seems to be the "sweet
spot". However, because of the unfiltered AC nature
of the power supply and the ASRSG never being
able to fully sync with the mains frequency, I do
experience the surging (wah-wah) sound of the out-
put through much of the ARSG sped range and it seems
to me if I were to filter the HV supply to a steady DC
voltage level, it would address this issue throughout the
selected RPM range of the SG motor. I do try to finely
tweak the RSG motor speed control to blend the surging
into a more steady output but it seems to me that with a
steady DC throughput to the RSG and tank circuit, there
would be a larger average power throughput and conse-
quently, bigger sparks and hey, bigger sparks is what it's
all about, right? ;^) Feel free to contact me off-list if you
feel the details would go beyond the interest of the rest
of the list.
David
----- Original Message -----
From: "Roger Smith" <rwsmith@xxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, July 10, 2010 8:45 PM
Subject: Re: [TCML] New coil modeled after Green Monster
I have built a Tesla coil that is in some ways similar to the Green
Monster. The secondary is wound on a 12.5" diameter pvc sewer pipe, and
it is wound with 19 gage wire. It is a DC resonant charging type Tesla
coil with a break rate of 425 bps and it has worked very well.
I have never built a SRSG Tesla coil
but the one thing I don't like about them is that you are limited to 120
bps. That's less than a third of the break rate of my coil. That means
that if you are going to run the same power level as my coil with 425
bps you need to put in over three times as much energy per break. That
would be hard to do without having problems.
Roger
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