# [TCML] New Coil Design - and JAVATC question

Ryckmans, Thomas Thomas.Ryckmans at pfizer.com
Wed Apr 30 08:06:27 MDT 2008

```Hi Bart, everyone

Many thanks for your answer. It certainly makes sense to increase separation between primary and secondary. I have now increased radius of Primary to 9 cm (3.54 inches) and Secondary is 5.2 cm (2.04 inches) thus separation is 3.8 cm (1.5 inches). The question I have about JAVATC is the following;

It seems that JAVATC is trying to fit the number of turns to the outer diameter used as input. In practice (... only one run in my case!) I guess we try to wind a reasonnable primary, then tap onto the correct turn. Thus I'd like to have a 15 turns primary with 9cm (3.54 inches) inner radius using my 8mm (.315 inches) tubing with 8mm (.315 inches) spacing edge-to-edge. This gives me an outer radius of 33 cm (13 inches). The primary should be tuned at around 11 turns, so I calculated the corresponding outer radius (26.6 cm, 10.47 inches) and used that as input for JAVATC. However, are'nt the extra, outer turns going to influence the capacitance of the primary?

In other words... is there an option I could use in JAVATC to say "I will be using 15 turns with such and such radiuses, where should I tap"

Clear(form);
z = 1; if(z==0){form.units.selectedIndex=0; inches=true;}
if(z==1){form.units.selectedIndex=1; cm=true;}
z = 1; if(z==0){form.ambient.selectedIndex=0; fahrenheit=true;}
GetUnits(form);
z = 1; if(z==1){form.s_ws.checked=true;form.s_awg.checked=false;}
if(z==0){form.s_ws.checked=false;form.s_awg.checked=true;}
z = 0; if(z==1){form.s_Al.checked=true;form.s_Cu.checked=false;}
if(z==0){form.s_Al.checked=false;form.s_Cu.checked=true;}
z = 1; if(z==1){form.p_ws.checked=true;form.p_awg.checked=false;}
if(z==0){form.p_ws.checked=false;form.p_awg.checked=true;}
z = 0; if(z==1){form.p_Al.checked=true;form.p_Cu.checked=false;}
if(z==0){form.p_Al.checked=false;form.p_Cu.checked=true;}
z = 25; {eval(z); temp = z; form.temp.value = temp;}// ambient temperature
z = 400; {eval(z); r_height = z; form.r_height.value = r_height;}
z = 100; {eval(z); s_height1 = z; form.s_height1.value = s_height1;}
z = 152.8; {eval(z); s_height2 = z; form.s_height2.value = s_height2;}
z = 1200; {eval(z); s_turn = z; form.s_turn.value = s_turn;}
z = 0.04; {eval(z); s_wd = z; form.s_wd.value = s_wd;}
z = 101.616; {eval(z); p_height1 = z; form.p_height1.value = p_height1;}
z = 101.616; {eval(z); p_height2 = z; form.p_height2.value = p_height2;}
z = 11; {eval(z); p_turn = z; form.p_turn.value = p_turn;}
z = 0.8; {eval(z); p_wd = z; form.p_wd.value = p_wd;}
z = 0.01; {eval(z); Cp_uF = z; form.Cp_uF.value = Cp_uF;}
z = 0; {eval(z); desired_k = z; form.desired_k.value = desired_k;}
z = 7.62; {eval(z); t_inner = z; form.t_inner.value = t_inner;}
z = 30.48; {eval(z); t_outer = z; form.t_outer.value = t_outer;}
z = 160; {eval(z); t_height = z; form.t_height.value = t_height;}
form.TT.checked = true; form.TG.checked = false;
z = 220; {eval(z); x_Vin = z; form.x_Vin.value = x_Vin;}
z = 6000; {eval(z); x_Vout = z; form.x_Vout.value = x_Vout;}
z = 50; {eval(z); x_Iout = z; form.x_Iout.value = x_Iout;}
z = 50; {eval(z); x_Hz = z; form.x_Hz.value = x_Hz;}
z = 0; {eval(z); x_ballast = z; form.x_ballast.value = x_ballast;}
z = 0; {eval(z); x_Rp = z; form.x_Rp.value = x_Rp;}
z = 0; {eval(z); x_Rs = z; form.x_Rs.value = x_Rs;}
z = 0; {eval(z); rsg_ELS = z; form.rsg_ELS.value = rsg_ELS;}
z = 0; {eval(z); rsg_ELR = z; form.rsg_ELR.value = rsg_ELR;}
z = 0; {eval(z); rsg_rpm = z; form.rsg_rpm.value = rsg_rpm;}
z = 0; {eval(z); rsg_disc_D = z; form.rsg_disc_D.value = rsg_disc_D;}
z = 0; {eval(z); rsg_ELR_D = z; form.rsg_ELR_D.value = rsg_ELR_D;}
z = 0; {eval(z); rsg_ELS_D = z; form.rsg_ELS_D.value = rsg_ELS_D;}
z = 0; {eval(z); stat_EL = z; form.stat_EL.value = stat_EL;}
z = 0; {eval(z); stat_EL_D = z; form.stat_EL_D.value = stat_EL_D;}
z = 0; {eval(z); stat_gap = z; form.stat_gap.value = stat_gap;}
if(form.SPE.checked==true){form.SPE.checked=true;form.RGE.checked=false;}
if(form.RGE.checked==true){form.SPE.checked=false;form.RGE.checked=true;}
}

101.616 = Height 2
11 = Turns
0.8 = Wire Diameter
0.01 = Primary Cap (uF)

----------------------------------------------------
----------------------------------------------------
Toroid #1: minor=7.62, major=30.48, height=160, topload

----------------------------------------------------
Secondary Outputs:
----------------------------------------------------
244.71 kHz = Secondary Resonant Frequency
90 deg° = Angle of Secondary
52.8 cm = Length of Winding
22.73 cm = Turns Per Unit
0.04 mm = Space Between Turns (edge to edge)
392.07 m = Length of Wire
5.08:1 = H/D Aspect Ratio
54.4022 Ohms = DC Resistance
38276 Ohms = Reactance at Resonance
0.438 kg = Weight of Wire
24.894 mH = Les-Effective Series Inductance
318.907 mH = Lee-Equivalent Energy Inductance
27.001 mH = Ldc-Low Frequency Inductance
16.992 pF = Ces-Effective Shunt Capacitance
15.452 pF = Cee-Equivalent Energy Capacitance
28.698 pF = Cdc-Low Frequency Capacitance
0.1488 mm = Skin Depth
11.164 pF = Topload Effective Capacitance
147.3779 Ohms = Effective AC Resistance
260 = Q

----------------------------------------------------
Primary Outputs:
----------------------------------------------------
235.46 kHz = Primary Resonant Frequency
3.78 % high = Percent Detuned
0 deg° = Angle of Primary
1230.25 cm = Length of Wire
4.3 mOhms = DC Resistance
0.8 cm = Average spacing between turns (edge to edge)
3.38 cm = Proximity between coils
1.54 cm = Recommended minimum proximity between coils
44.318 µH = Ldc-Low Frequency Inductance
0.00926 µF = Cap size needed with Primary L (reference)
1.37 µH = Lead Length Inductance
139.297 µH = Lm-Mutual Inductance
0.127 k = Coupling Coefficient
0.129 k = Recommended Coupling Coefficient
7.87  = Number of half cycles for energy transfer at K
16.55 µs = Time for total energy transfer (ideal quench time)

----------------------------------------------------
Transformer Inputs:
----------------------------------------------------
220 [volts] = Transformer Rated Input Voltage
6000 [volts] = Transformer Rated Output Voltage
50 [mA] = Transformer Rated Output Current
50 [Hz] = Mains Frequency
220 [volts] = Transformer Applied Voltage
0 [amps] = Transformer Ballast Current
0 [ohms] = Measured Primary Resistance
0 [ohms] = Measured Secondary Resistance

----------------------------------------------------
Transformer Outputs:
----------------------------------------------------
300 [volt*amps] = Rated Transformer VA
120000 [ohms] = Transformer Impedence
6000 [rms volts] = Effective Output Voltage
1.36 [rms amps] = Effective Transformer Primary Current
0.05 [rms amps] = Effective Transformer Secondary Current
300 [volt*amps] = Effective Input VA
0.0265 [uF] = Resonant Cap Size
0.0398 [uF] = Static gap LTR Cap Size
0.0692 [uF] = SRSG LTR Cap Size
20 [uF] = Power Factor Cap Size
8485 [peak volts] = Voltage Across Cap
21213 [peak volts] = Recommended Cap Voltage Rating
0.36 [joules] = Primary Cap Energy
127.5 [peak amps] = Primary Instantaneous Current
67.3 [cm] = Spark Length (JF equation using Resonance Research Corp. factors)
3.7 [amps] = Sec Base Current

----------------------------------------------------
Rotary Spark Gap Inputs:
----------------------------------------------------
0 = Number of Stationary Gaps
0 = Number of Rotating Electrodes
0 [rpm] = Disc RPM
0 = Rotating Electrode Diameter
0 = Stationary Electrode Diameter
0 = Rotating Path Diameter

----------------------------------------------------
Rotary Spark Gap Outputs:
----------------------------------------------------
0 = Presentations Per Revolution
0 [BPS] = Breaks Per Second
0 [kmh] = Rotational Speed
0 [ms] = RSG Firing Rate
0 [ms] = Time for Capacitor to Fully Charge
0 = Time Constant at Gap Conduction
0 [µs] = Electrode Mechanical Dwell Time
0 [%] = Percent Cp Charged When Gap Fires
0 [peak volts] = Effective Cap Voltage
0 [joules] = Effective Cap Energy
0 [rms volts] = Terminal Voltage
0 [power] = Energy Across Gap
0 [cm] = RSG Spark Length (using energy equation)

----------------------------------------------------
Static Spark Gap Inputs:
----------------------------------------------------
0 = Number of Electrodes
0 [cm] = Electrode Diameter
0 [cm] = Total Gap Spacing

----------------------------------------------------
Static Spark Gap Outputs:
----------------------------------------------------
0 [cm] = Gap Spacing Between Each Electrode
0 [peak volts] = Charging Voltage
0 [peak volts] = Arc Voltage
0 [volts] = Voltage Gradient at Electrode
0 [volts/cm] = Arc Voltage per unit
0 [%] = Percent Cp Charged When Gap Fires
0 [ms] = Time To Arc Voltage
0 [BPS] = Breaks Per Second
0 [joules] = Effective Cap Energy
0 [rms volts] = Terminal Voltage
0 [power] = Energy Across Gap
0 [cm] = Static Gap Spark Length (using energy equation)

-----Original Message-----
From: Thomas Ryckmans [mailto:thomas.ryckmans at virgin.net]
Sent: 30 April 2008 07:48
To: Ryckmans, Thomas
Subject: FW: FW: [TCML] New Coil Design - ideas and criticism welcome...

-----Original Message-----
From: bartb [mailto:bartb at classictesla.com]
Sent: 30 April 2008 03:39
To: Thomas Ryckmans
Subject: Re: FW: [TCML] New Coil Design - ideas and criticism welcome...

Hi Thomas,

Thomas Ryckmans wrote:
> Hi Bart,
>
> Any chance you could have a look at these numbers? I am worried about H/D
> ratio (5.1) and Q factor (262). Are these values acceptable?
>
> Many thanks
> Thomas
>
> New secondary: diameter 104 mm (4 inches)(R=5.2 cm); using SWG 27
(diameter
> 0.4 mm - almost similar to AWG 26) which give me a height of 528 mm (52.8
> cm) for 1200 turns. H/D is 5.1
> This gives me L=26699 uF and self capacitance 8 pF
>
The secondary is fine. The 5:1 h/d is good and the Q is in the ballpark.
> The topload will be a aluminium toroid 76.2 mm by 304.8 mm (3 by 12
inches)
> with capacitance around 13.3 pF (DeepFried Neon) and 13.1 pF with JAVATC
for
Yes, but realize these numbers are sort of meaningless. They are the
capacitance of a toroid without any external effects.
> Total capacitance at 13.3+8 = 21.3 pF [13 pF using JAVATC] gives me a
> resonant frequency at 211 kHz [248 using JAVATC]
>
Sorry, they won't add like that. It's not as simple as putting the
toroid in parallel with the selfC of the coil. Note that when you insert
a toroid into Javatc and run the program, the Toroid "effective"
capacitance will be lower. In your case, 11pF. This is where Javatc is
"special" as it accurately accounts for the capacitive distribution with
toroid, coil, ground, primary, strike ring (whatever you throw into the
mix).

In days past, (old Javatc 9.1 and earlier or John Coutures JHCTES
program), we used what we called a "topload reduction percentage" to try
to empirically predict the effect of the topload. Sometimes close, many
times not. We don't have to rely on those factors any longer thanks to
Paul Nicholson who wrote Geotc.js for FANTC. Of which I ported over into
JAVATC at version 10. Paul's the real brains here that made this
possible. A very big step for TC design programs.

> The Q is 262 - should I aim for more, or less??

262 is fine (and this is a ballpark number anyway). It's always nice to
aim for high Q, but Q is highly dependent on frequency and wire size.
H/D and turns are also important. So in the end, Q will usually end up
between 250 and 300 for most "decent" coils. It's more of something to
keep your eye on just in case it goes low.

> For the primary, I will use 8 mm copper tube, with spacing (centre to
> centre) of 16 mm. Starting at Secondary radius + 2 cm = 7.2 cm
>
The primary is very close to the secondary. I know your running a low kV
supply, but when that gap conducts, it will be about 9kV or greater. You
need about 1.5" distance between primary and secondary on this coil.
Take a second look at the primary in that area (start the inner winding
at 1.5" which will prevent sec to pri breakdown). If coupling is low and
you don't want to adjust the secondary, consider a slight inverse cone
shape. This might be a coil that would truly benefit from a conical shape.

> This gives me L around 31 uH at 12 turns
> Thus I would need a MMC of 0.018 uF to 0.013 uF to reach resonance
> Using CDE capacitors 942C20P15K-F (2000Vdc 0.15 uF) I would need a single
> string of 11 caps to reach 0.013 uF and have a (recommended) voltage
rating
> of 22kV.
>

No problem with the cap. Your over 2.5 x Vp of your power supply and
power dissipation is low. You will be running STR, so bps is likely to
be high since your NST is only 6kV rms and high current (small cap and
hefty current = high bps). I expect something in the 350 to 400 bps
range. Probably some losses there. From a cost standpoint, I would stick
with the .013uF size for now. If you upgrade to say .035uF or near
later, you still have plenty of primary turns to tune the coil. The only
benefit in this coil with upgrading the cap to LTR would be to reduce
gap losses. Toss a coin in the air (hard to say if it would help which
is why I recommend sticking with the .013uF, at least to start).
> So far I plan to use a static gap, air cooled. I have the Terry filter
>
> Is the design sound, will it work, will it last more than 10 minutes
before
> frying, what kind of sparks will I get out of it.
>

Yes, it's fine (minus what I mentioned) and a good secondary (turns) for
a low kv supply. You can expect about 25" sparks at "best". Sparks are
"mostly" power dependent. The fact is, your supply is 300VA and that's
where the limitation is. Same is true for any coil. Our coil designs,
building techniques, and experience, help to make whatever coil we build
more efficient at processing the power we supply to the coil, but big
power is needed for big sparks (always has been and always will be).
Efficiency would really have to take a giant leap to change that, and so
far, that hasn't happened (including any of the solid state designs,
well, slightly maybe).

Take care,
Bart

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