Highest Q coils ?
dex, Wed Jan 01 2014, 10:33AMHi All,
What is the highest possible quality factor (Q) range for tesla coil secondary coil?
I'd like to know both about actual msms examples and theoretical analysis dealing with maximum Qs attainable.
Re: Highest Q coils ?
Dr. Dark Current, Thu Jan 02 2014, 12:54PM
Hi,
I'm not sure what do you want this for, but usually the highest unloaded Q have coils with fewer turns of thicker wire and a topload. If you could get a thick Litz wire and make a coil with a hundred turns or so (or less) with a large topload, the unloaded Q could probably approach 1000.
However, I think what matters the most (and has an effect on efficiency) is the ratio of unloaded and loaded Q.
Dr. Dark Current, Thu Jan 02 2014, 12:54PM
Hi,
I'm not sure what do you want this for, but usually the highest unloaded Q have coils with fewer turns of thicker wire and a topload. If you could get a thick Litz wire and make a coil with a hundred turns or so (or less) with a large topload, the unloaded Q could probably approach 1000.
However, I think what matters the most (and has an effect on efficiency) is the ratio of unloaded and loaded Q.
Re: Highest Q coils ?
dex, Thu Jan 02 2014, 03:34PM
Yes, I'm interested in circumstances where the unloaded Q of secondary is maximized. Frequency range of interest 10-100 kHz. Why do you think capacitive top load must be very large? That doesn't sound right to me. Speaking of numbers, I've never heard of measured Q > 500, for tesla coil secondary.
dex, Thu Jan 02 2014, 03:34PM
Yes, I'm interested in circumstances where the unloaded Q of secondary is maximized. Frequency range of interest 10-100 kHz. Why do you think capacitive top load must be very large? That doesn't sound right to me. Speaking of numbers, I've never heard of measured Q > 500, for tesla coil secondary.
Re: Highest Q coils ?
Sulaiman, Thu Jan 02 2014, 06:41PM
in my opinion;
Tesla Coil secondaries are not optimised for unloaded 'Q' because they are intended for
A) Power Broadcasting per N.Tesla's dream
or
B) Sparks/Arcs for entertainment
in either case the loaded 'Q' is of interrest.
We make our TC secondaries long and thin (typical H/D = 3 to 5) to give space between earth/ground or the primary, and the topload, to allow for long arcs.
For a single layer solenoidal winding optimum 'Q' is when H/D is about 0.4 to 0.5,
leaving little distance from topload to surroundings.
For a given required inductance, unloaded 'Q' will increase with increasing wire diameter,
and at 10 to 100 kHz 'Litz' wire does make a significant improvement,
but there is no requirement for high unloaded 'Q' so the extra expense gives little improvement.
So if you want really high unloaded 'Q' use 660/46 "Litz' wire, (e.g.
)
with H/D = 0.5, a styrene former, and leave about one wire diameter between turns
.... unloaded 'Q' will be >500.
Sulaiman, Thu Jan 02 2014, 06:41PM
in my opinion;
Tesla Coil secondaries are not optimised for unloaded 'Q' because they are intended for
A) Power Broadcasting per N.Tesla's dream
or
B) Sparks/Arcs for entertainment
in either case the loaded 'Q' is of interrest.
We make our TC secondaries long and thin (typical H/D = 3 to 5) to give space between earth/ground or the primary, and the topload, to allow for long arcs.
For a single layer solenoidal winding optimum 'Q' is when H/D is about 0.4 to 0.5,
leaving little distance from topload to surroundings.
For a given required inductance, unloaded 'Q' will increase with increasing wire diameter,
and at 10 to 100 kHz 'Litz' wire does make a significant improvement,
but there is no requirement for high unloaded 'Q' so the extra expense gives little improvement.
So if you want really high unloaded 'Q' use 660/46 "Litz' wire, (e.g.
)with H/D = 0.5, a styrene former, and leave about one wire diameter between turns
.... unloaded 'Q' will be >500.
Re: Highest Q coils ?
Dr. Dark Current, Thu Jan 02 2014, 08:00PM
Yes. Another point, for a given frequency, the larger the coil the higher unloaded Q. Use Litz wire.
Dr. Dark Current, Thu Jan 02 2014, 08:00PM
Yes. Another point, for a given frequency, the larger the coil the higher unloaded Q. Use Litz wire.
Re: Highest Q coils ?
dex, Fri Jan 03 2014, 08:34AM
By unloaded Q I meant spark uloaded. I didn't know about H/D ~ 0.5 condition... No wonder unloaded Q of usual TC secondary is below 500 since it is made H/D>>0.5 and without Litz wire.
dex, Fri Jan 03 2014, 08:34AM
Sulaiman wrote ...
in my opinion;
Tesla Coil secondaries are not optimised for unloaded 'Q' because they are intended for
A) Power Broadcasting per N.Tesla's dream
or
B) Sparks/Arcs for entertainment
in either case the loaded 'Q' is of interrest.
We make our TC secondaries long and thin (typical H/D = 3 to 5) to give space between earth/ground or the primary, and the topload, to allow for long arcs.
For a single layer solenoidal winding optimum 'Q' is when H/D is about 0.4 to 0.5,
leaving little distance from topload to surroundings.
For a given required inductance, unloaded 'Q' will increase with increasing wire diameter,
and at 10 to 100 kHz 'Litz' wire does make a significant improvement,
but there is no requirement for high unloaded 'Q' so the extra expense gives little improvement.
So if you want really high unloaded 'Q' use 660/46 "Litz' wire, (e.g. )
with H/D = 0.5, a styrene former, and leave about one wire diameter between turns
.... unloaded 'Q' will be >500.
Thanks!in my opinion;
Tesla Coil secondaries are not optimised for unloaded 'Q' because they are intended for
A) Power Broadcasting per N.Tesla's dream
or
B) Sparks/Arcs for entertainment
in either case the loaded 'Q' is of interrest.
We make our TC secondaries long and thin (typical H/D = 3 to 5) to give space between earth/ground or the primary, and the topload, to allow for long arcs.
For a single layer solenoidal winding optimum 'Q' is when H/D is about 0.4 to 0.5,
leaving little distance from topload to surroundings.
For a given required inductance, unloaded 'Q' will increase with increasing wire diameter,
and at 10 to 100 kHz 'Litz' wire does make a significant improvement,
but there is no requirement for high unloaded 'Q' so the extra expense gives little improvement.
So if you want really high unloaded 'Q' use 660/46 "Litz' wire, (e.g.
)with H/D = 0.5, a styrene former, and leave about one wire diameter between turns
.... unloaded 'Q' will be >500.
By unloaded Q I meant spark uloaded. I didn't know about H/D ~ 0.5 condition... No wonder unloaded Q of usual TC secondary is below 500 since it is made H/D>>0.5 and without Litz wire.
Re: Highest Q coils ?
Uspring, Fri Jan 03 2014, 12:04PM
Q for secondaries without arc load is given by
Q = sqrt(L/C) / R
omitting some other smaller effects. R is the resistance of the secondary winding. A large L and a small C will increase Q, as well as a thicker winding, which will reduce R. A larger L means more windings, and thus a bigger R, so adding more turns might not change much wrt Q. JavaTC calculates these values.
For TCs, the loaded Q plays a much bigger role. A litz wire winding doesn't increase loaded Q to any reasonable extent.
Uspring, Fri Jan 03 2014, 12:04PM
Q for secondaries without arc load is given by
Q = sqrt(L/C) / R
omitting some other smaller effects. R is the resistance of the secondary winding. A large L and a small C will increase Q, as well as a thicker winding, which will reduce R. A larger L means more windings, and thus a bigger R, so adding more turns might not change much wrt Q. JavaTC calculates these values.
For TCs, the loaded Q plays a much bigger role. A litz wire winding doesn't increase loaded Q to any reasonable extent.
Re: Highest Q coils ?
dillon, Sat Aug 08 2015, 05:22PM
until the spark does break out, its the unloaded q that develops the voltage rise. same for a spark gap coil. put a large toroid to keep the coil to develop a high hv breakout ,but its the q that causes resonant rise until breakout
dillon, Sat Aug 08 2015, 05:22PM
until the spark does break out, its the unloaded q that develops the voltage rise. same for a spark gap coil. put a large toroid to keep the coil to develop a high hv breakout ,but its the q that causes resonant rise until breakout
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