Re: [TCML] Newbie questions

[Scott Bogard <sdbogard@xxxxxxxxx>]

Hi Peter and welcome to Tesla coiling!
     You do not need two microwave oven transformers in parallel, the short
circuit current on those is close to an amp!  Using a well designed doubler
you should easily be able to take advantage of that.  With that said to the
best of my knowledge we've never had a fatal accident using MOTs, but since
the real potential is there in excess, I recommend starting with the 9 30
NST.  Anyway to be more specific for question 1, yes I believe your
assumptions are correct.  For question 2, since scope boy is blocked at
work where I write this, I don't know, but for Java TC usually they use the
RMS voltage, so if you peak voltage is 11kV your RMS would be about 8kV.
For Question 3, I have no idea, others will comment...  For question 4, A
charging reactor or ballast of some kind is absolutely essential for safety
reasons, especially when doing a doubled DC type system.  I use twin MOTs
on my best coil with no ballast and no doubler to great success, but I have
a rotary gap, a static gap will not like this low voltage high current
arrangement.  Either way, were I to touch it, I would die, start with the 9
60, that way when you learn of high voltages' curious ability to travel to
places it shouldn't be able to, it is not the hard way...  Besides it would
be terrible to spend a fortune on a .1 uf tank cap, only to not be able to
tune the thing because the tuning curve is so tight and off axis inductance
makes it not part of the primary coil...

Scott Bogard.

On Tue, Jan 10, 2012 at 5:58 AM, Peter Sutter <peter@xxxxxxxxxxxx> wrote:

> I am new to coiling and try to figure out how to build a Tesla Coil with
> the material I have available; which is:
>
> - a secondary coil of PVC tubing 160mm diameter, 73 cm high, wound with
> 1250 turns of .53 mm copper wire. JavaTC tells me that the resonant
> frequency is about 114 KHz.
>
> - about 8 m of 1/2 inch refrigeration copper tubing
> - a 6000V 30 mA NST
> - a 9000V 30 mA NST
> - several 2000 V 850VA Microwave oven transformers
>
> I would like to use the microwave oven transformers, possibly two in
> parallel with two voltage doublers, so I would get about
> 2000 * 1.41 * 4 = 11300 Volts peak and about 150 mA max current.
>
> Going through the calculations in JavaTC I notice that a bigger tank
> capacitor reduces the number of primary turns, so I try to get by with the
> 8 m of refrigeration tube. A tank Cap of .1 uF would require about 7 turns
> and a length of 6 meter, leaving some length left for tuning.
>
> Question 1: Are the above assumptions correct and would it work?
>
> Question 2: With the voltage doubler as described here
> http://scopeboy.com/tesla/**tc2schem.html<http://scopeboy.com/tesla/tc2schem.html>what Voltage and frequency would I enter in in the transformer section in
> JavaTC to calculate the transformer and the spark gap.
>
> Question 3: I am using geda gschem for drawing and would like to feed the
> data into spice. What could I use to symbolize the spark gap?
>
> Question 4: Is the charging reactor / ballast necessary to protect the
> MOTs or will a safety gap be sufficient to protect the MOTs?
>
> Thanks
>
> Peter
>
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