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Re: [TCML] New coil modeled after Green Monster
Hello,
Just for clarification what do you mean by
"Another trick I did with my choke was after each layer of wire was wound I would switch back to
the other side before I started the next layer."
are you saying that you only built up the windings in one dirrection, like only from top to bottom having a wire run down the length of the coil?
Thanks,
John "Jay" Howson IV
----- Original Message -----
From: "Roger Smith" <rwsmith@xxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, July 14, 2010 9:24:37 AM GMT -05:00 US/Canada Eastern
Subject: Re: [TCML] New coil modeled after Green Monster
Hi David. when the capacitors for the primary circuit are charging, the
charging choke may cause them to charge to a higher voltage than the dc
power supply voltage . If the rotary spark gap doesn't make when the
voltage reaches its peek current will start flowing back into the charging
circuit from the primary capacitors. The dequeing or "de-Q-ing" diode will
prevent this. Here is a link to some more info on this
http://www.richieburnett.co.uk/dcreschg.html
I just noticed for the first time on Richie's
web page that we has the de-Q-ing diode between the charging choke and the
DC power supply. I guess a solid state diode would have a better chance of
surviving there than between the charging choke and the primary capacitors.
You are right that the charging choke protects the everything down stream of
it from high voltage transients. That is on of the things I like about this
set up. Your Pole pig will last forever! However the charging choke takes
some abuse and has to be made "bullet proof". On my choke I put a layer of
insulation between each winding layer. I can't remember how many winding
layers there are. I think it might be about 30. Another trick I did
with my choke was after each layer of wire was wound I would switch back to
the other side before I started the next layer. This keeps the voltage
between layers even all the way across the layer.
In the power supply circuit I have two filter capacitors that are
connected in parallel and are 1 uf each . I got them at one of DC Cox's
Teslathons. They look like they might have been power factor correction
capacitors used by a utility company. Now that I am talking about
capacitors, this would be a good place to mention that with a DC resonant
charging Tesla coil the capacitors create a serious hazard as I'm sure you
can imagine. At the very least, a person should have good bleeder resistors
across both the filter capacitors and primary capacitors and they should
test for voltage before working on the coil.
Roger
----- Original Message -----
From: "David Rieben" <drieben@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, July 13, 2010 4:15 PM
Subject: Re: [TCML] New coil modeled after Green Monster
> Hi Roger,
>
> Thanks for the info. Since this subject matter is quite re-
> lavent to coiling in general, I'll keep this response open
> to the entire TCML. I'm not sure I fully understand the
> concept of the "dequing diode", though? I thought pre-
> vention of the nasty feedback transients of the tank
> circuit from feeding back into the charging circuit was
> one of the main purposes of the inductive choke (6 H,
> in your case)?
>
> I do have a current limiting ballast on the LV AC side
> of my control panel but I could see where the DC Res
> charging setup could preclude the need for this feature.
>
> Also, could you share a bit more info on the capaci-
> tors that you use in the 2 uFd filter cap bank?
>
> David Rieben
>
> PS: That 10 kVA rated, 19.5 kV pole pig is a true
> treasure find for an old time ARSG coiler ;^) My
> pole pig is 10 kVA also, but the more standard 14.4
> kV.
>
>
>
> ----- Original Message -----
> From: "Roger Smith" <rwsmith@xxxxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Sunday, July 11, 2010 7:03 PM
> Subject: Re: [TCML] New coil modeled after Green Monster
>
>
>> 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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>>
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>
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