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[TCML] New Coil Design - ideas and criticism welcome...
Ideas and criticisms welcome...
Given the poor design of my first coil, I decided to restart from scratch -
hopefully not breaking another finger in the construction...
I am using http://deepfriedneon.com/tesla_frame6.html
for quick reference, and JavaTC for verification (JAVATC file is below)
So far, still using a 6kV 50 mA NST, and a counterpoise below the coil (no
RF ground in my apartment!) -
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
>>Shall I go for a smaller n of turns to get my D/H ratio a bit lower?<<
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
only the topload
Total capacitance at 13.3+8 = 21.3 pF [13 pF using JAVATC] gives me a
resonant frequency at 211 kHz [248 using JAVATC]
>>>The Q is 262 - should I aim for more, or less??
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
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
So far I plan to use a static gap, air cooled. I have the Terry filter
ready.
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?
JAVATC file below
J A V A T C version 11.7 - CONSOLIDATED OUTPUT
26 April 2008 19:50:51
Units = Centimeters
Ambient Temp = 25°C
----------------------------------------------------
Surrounding Inputs:
----------------------------------------------------
300 = Ground Plane Radius
300 = Wall Radius
400 = Ceiling Height
----------------------------------------------------
Secondary Coil Inputs:
----------------------------------------------------
Current Profile = G.PROFILE_LOADED
5.2 = Radius 1
5.2 = Radius 2
100 = Height 1
152.8 = Height 2
1200 = Turns
0.04 = Wire Diameter
----------------------------------------------------
Primary Coil Inputs:
----------------------------------------------------
7.2 = Radius 1
23.1 = Radius 2
100 = Height 1
100 = Height 2
10 = Turns
0.8 = Wire Diameter
0.013 = Primary Cap (uF)
100 = Total Lead Length
0.2 = Lead Diameter
----------------------------------------------------
Top Load Inputs:
----------------------------------------------------
Toroid #1: minor=7.62, major=30.48, height=160, topload
----------------------------------------------------
Secondary Outputs:
----------------------------------------------------
246.02 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
38772 Ohms = Reactance at Resonance
0.438 kg = Weight of Wire
25.083 mH = Les-Effective Series Inductance
23.559 mH = Lee-Equivalent Energy Inductance
27.001 mH = Ldc-Low Frequency Inductance
16.685 pF = Ces-Effective Shunt Capacitance
15.272 pF = Cee-Equivalent Energy Capacitance
28.882 pF = Cdc-Low Frequency Capacitance
0.1484 mm = Skin Depth
11.056 pF = Topload Effective Capacitance
147.8367 Ohms = Effective AC Resistance
262 = Q
----------------------------------------------------
Primary Outputs:
----------------------------------------------------
248.58 kHz = Primary Resonant Frequency
1.03 % low = Percent Detuned
0 deg° = Angle of Primary
951.9 cm = Length of Wire
3.33 mOhms = DC Resistance
0.79 cm = Average spacing between turns (edge to edge)
1.58 cm = Proximity between coils
0 cm = Recommended minimum proximity between coils
30.163 µH = Ldc-Low Frequency Inductance
0.01327 µF = Cap size needed with Primary L (reference)
1.37 µH = Lead Length Inductance
115.658 µH = Lm-Mutual Inductance
0.128 k = Coupling Coefficient
0.129 k = Recommended Coupling Coefficient
7.81 = Number of half cycles for energy transfer at K
15.55 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
0.47 [joules] = Primary Cap Energy
176.2 [peak amps] = Primary Instantaneous Current
67.3 [cm] = Spark Length (JF equation using Resonance Research Corp.
factors)
4.5 [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: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of sparktron01@xxxxxxxxxxx
Sent: 07 April 2008 03:21
To: Tesla Coil Mailing List
Subject: Re: [TCML] MOV destruction
Dennis
Another possibility...
How did you wire the MOV's into the circuit? If you soldered them into
a perfboard, did you HEATSINK them while soldering them?
If the MOV's are overheated during the soldering process while
assembling your Terry Filter, the MOV's operating voltage will be
degraded (read... REDUCED) to point a catastrophic failure can
happen at nominal applied voltages. I have seen this failure
phenomena in industrial equipment; so be sure to heatsink
your MOV's if soldering onto PCB's; or better yet, use mechanical
lugs for wiring these components into a power circuit.
Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA
-------------- Original message ----------------------
From: otmaskin5@xxxxxxx
> Hi, I'm trying to figure out what happened in my most recent coil melt
down and
> was hoping someone out there could help me out.? I had just replaced my
old
> capacitor bank with a 0.02uF MMC on my 15/60 coil.? I thought I had the
coil
> reasonably well tuned & was running it for about 3 or so minutes.? The
coil & it
> seemed to be behaving fairly well, producing strikes that somethime
reached over
> 50 inches...when it just stopped running.? I detected an oil type odor &
first
> thought I had blown a cap somewhere.? Eventually I found the MOVs on my
Terry
> filter were destroyed.? There was remnants of molten metal on and around
the
> MOVs, several of them had cracks or splits in them & an oily substance had
been
> ejected from the MOVs.?
>
> I tested the NST & both legs seem to be healthy, so the MOVs apparently
died in
> the line of duty protecting the NST (thankfully).
>
> I have not heard of MOVs coming apart in this manner.? From everything
I've
> heard, they just quietly do their job when there is a voltage surge.?
Before I
> replace the MOVs and start running the coil again, I'm trying to get an
idea of
> what caused this to happen & what I need to correct in the system going
> forward.?
>
> I had 8 MOVs?(1800V ZNR) in series to ground on each leg of the
transformer.?
> This essentially duplicated MOV arrays?that I have seen?others' using on
their
> 15/60 coils.? My variac maxes out at 130v - also,?I didn't see any strikes
to
> the primary or lower deck?at the time this occured.
>
> I am wondering whether I should have had more MOVs in series to handle
greater
> voltage.? If so, what is the right number?
>
> Or were the MOVs adequate, but was there some other problem that caused
this
> which I need to correct?
>
> I would appreciate any ideas.? Thanks, Dennis Hopkinton MA???
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
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