Litz Wire

[green]

Hi Green
Thanks,
Interesting, If im looking at things right the litz coil is at 16pf It apears to be slightly faster than the coil a at 12 pf and response to the nugget is slightly better at distance for coil E.
Its hard for me to see the colors they are so close.
I know you were evaluating the coils at the same # of turns. It would be interesting to see performance at the same inductance for these coil types.
Thanks.

Can sample the Litz sooner than the AWG28 solid, can sample the AWG28 solid sooner than the AWG24 solid. Think it's because the wire is acting as a target. Probably doesn't matter if target delay is more than 6us?

I have a hard time seeing them, I'm color blind.

Think they would chart same signal strength if inductance was the same. Still could sample litz sooner than AWG28 and AWG28 sooner than AWG24.

Think the test was done with same current profile for all coils. Coil resistance would effect current profile and Rx signal strength if current profile wasn't controlled.

[godigit1]

That goes right allong with what Im reading and starting to understand the choice of sub 40 awg wire in litz construction. The wire you used 176/46 calcs out at 23.7 awg.
Wire O.D is .021 the windings are spaced further apart, looks like a good wire space between parralel wires. So my question is why is the capacitance higher on the E coil?

Ive found a pretty complete resource for litz wire design at Dartmouth, Things just went way over my head but im going to try to injest as much as possible.

Thank you BB Sailor you gave me the right search perimeters.
Here is the link if anyone should be interested.
https://engineering.dartmouth.edu/in.../bytopic.shtml

[godigit1]

Green,
Just formed the picture of your coil in my mind ,.You may want to examine your litz coil up close with a loop at the areas where you used Foam to lock the wires in. Look for copper color right at the edge where the foam meets the wire. Really curious if your coil was damaged and if not what Foam and brand wire you used .

At least it looks like foam and I think thats what I remember you using when you construted them. Maybe your litz wire is a better quality or it is sheaved with a cotton instead of polyester. But if you look at my thread New spin on a old friend. You will see the distruction foam reeps on litz. At least the one I used That I got off Ebay.
Thinking this is the reason for higher C on coil E maybe.

[green]

Green,
Just formed the picture of your coil in my mind ,.You may want to examine your litz coil up close with a loop at the areas where you used Foam to lock the wires in. Look for copper color right at the edge where the foam meets the wire. Really curious if your coil was damaged and if not what Foam and brand wire you used .

At least it looks like foam and I think thats what I remember you using when you construted them. Maybe your litz wire is a better quality or it is sheaved with a cotton instead of polyester. But if you look at my thread New spin on a old friend. You will see the distruction foam reeps on litz. At least the one I used That I got off Ebay.
Thinking this is the reason for higher C on coil E maybe.

I'm thinking inductance is effected by the coil width(OD-ID) causing the capacitance to calculate higher with the wider coils, lower inductance. C=1/(4*pi squared*L*SRF squared). The coil made with AWG28 solid enamel coated wire has the lowest width, the highest inductance and calculates the lowest capacitance.

The vertical coil made with AWG28 solid enamel coated wire calculates 14pf.

[godigit1]

Thanks Green,
So doing the math with the SRF reading Using the probe inductively SRF 1.56MHz= 39Pf.
And if we took that coil to 300Uh and were able to keep the same SRF it would be a 12 pf Coil.

So Im still trying to learn can I ask what the significance of the Inductive measurement and which is closer to real life measurement on the coil?

Also when I zoom in on the coils your coil looks to have survived the foam. Thats the case I hope.
Makes me think I got some bade wire.

[green]

Vertical coil F, 263uH, SRF 1.56MHz, C=39.6pf. Vertical coil F, 300uH, SRF 1.56MHz, C=34.7pf not 12pf. Inductance effects signal strength, capacitance effects coil speed.

[godigit1]

Im sorry my writing is poor and Im always in a hurry for work lately.
What I meant to say a coil of the same design as yours at 300uh with a SRF of 2.6 would be 12pf.

C=1/(4*^2*300*2.6squared=.00001249 so12.5pf
My point being a coil with these specs is a good shooting point for a fast coil maybe even one fast enough to make up for the effects of shielding.
Ive known of the interaction between induction and capacitance in a coil but now thanks to you walter and Q latley I can measure it properly.
Thank You.

But my question was if you please why the probe not connected and which reading is closer to the actual C.
Is there a average?

You have to admit thats a huge differance from 2.6MHz to 1.56Mhz?
Im just trying to learn more.
Thanks

[green]

Im sorry my writing is poor and Im always in a hurry for work lately.
What I meant to say a coil of the same design as yours at 300uh with a SRF of 2.6 would be 12pf.

C=1/(4*^2*300*2.6squared=.00001249 so12.5pf
My point being a coil with these specs is a good shooting point for a fast coil maybe even one fast enough to make up for the effects of shielding.
Ive known of the interaction between induction and capacitance in a coil but now thanks to you walter and Q latley I can measure it properly.
Thank You.

But my question was if you please why the probe not connected and which reading is closer to the actual C.
Is there a average?

You have to admit thats a huge differance from 2.6MHz to 1.56Mhz?
Im just trying to learn more.
Thanks

When I did that test I was trying different ways to measure coil resonance. Measure coil resonance, coil only(no shield and no leads), coil with shield(no leads) or coil with shield and leads. The detector sees the coil with shield and leads, lead capacitance is typically greater than fast coil with shield capacitance. The other measurements are to learn something. Connecting scope probe(scope 5mV/div) to ground lead making a loop and laying the loop on the test coil while exciting resonance with an operating PI is the best way I have for measuring SRF. Tried a bundle coil this afternoon to compare with a flat spiral. Both are 26turns, 8inch mean diameter wound with AWG28 solid enamel coated copper wire. Coils no shield, no leads. Flat spiral: 336uH, 2.82MHz SRF, 9pf. Bundle wound: 420uH, 735kHz SRF, 112pf.

[waltr]

The scope probe loop method has the least interaction with the coil under test. Any direct connections to the coil, leads, etc change the characteristics of the coil therefore the measurement of SRF is off.

[godigit1]

Awesome thank you both that totally makes sense now.

I was wondering about testing with this method instead of a signal generator. Seems much easier.

The flat spiral coil has very good SRF and Capacitance, should be very fast I would think. It will be interesting to see how it performs.
Did you add any spacing between wraps?

Im kinda suprised to see that much differance in inductance between the the two though.

Thats one of the things I think all your testing shows is the spiral coils seem to have a better SRF and performance is right up there.

I was heading towards some more spiral coils and retesting the ones I have made in the past but I have two more 3dss experiments that have been on the back burner for a while and I have the forms allready.
Thanks again you all.

[green]

Awesome thank you both that totally makes sense now.

I was wondering about testing with this method instead of a signal generator. Seems much easier.

The flat spiral coil has very good SRF and Capacitance, should be very fast I would think. It will be interesting to see how it performs.
Did you add any spacing between wraps?

Im kinda suprised to see that much differance in inductance between the the two though.

Thats one of the things I think all your testing shows is the spiral coils seem to have a better SRF and performance is right up there.

I was heading towards some more spiral coils and retesting the ones I have made in the past but I have two more 3dss experiments that have been on the back burner for a while and I have the forms allready.
Thanks again you all.

The bundle wound calculates 424uH using the coil calculator(Sticky in coils), measured 420uH. The flat spiral calculates about 300uH with the coil calculators I tried, measured 336uH. No spacing with the flat spiral, think spacing would lower inductance with same number of turns and might increase capacitance.

[godigit1]

Hi Green,
Noticed the coil calculator gave you a different Inductance for the two coils? Is there a formula you use to calculete the differance in wire lenght for Flat coils As each turn increases in radius?
Just curious as Im getting ready to make a flat DD and wanted to be accurate with the form.
Thanks

[green]

Hi Green,
Noticed the coil calculator gave you a different Inductance for the two coils? Is there a formula you use to calculete the differance in wire lenght for Flat coils As each turn increases in radius?
Just curious as Im getting ready to make a flat DD and wanted to be accurate with the form.
Thanks

www.deepfriedneon.com/tesla_f_calcspiral.html

http://crystalradio.net/professorcoyle/index.shtml

Couple I've been using.

Just guessing, if I were making a not round coil I would start with circumference, convert to round, use calculator to calculate required turns, add 15 to 20% more turns and remove wire if needed. Let use know what works.

[godigit1]

Once again awesome thank you so much I had not found either of those sites.

Thinking Hollow core 3DSS DD and to compare to a Flat coil DD with two layers comprised of a twisted pair or pairs upper layer occuping spacing between lower layer.
My goal is to find a wire configuration to make a unshielded DD that will operate at 6 to 8 us cleanly and hopefully in hot ground.
But shielding may be required so i want to make it as fast as possible. Alot of work ahead.
You are a inspiration and a wealth of information as well as a teacher one of the true guru's.

[green]

Once again awesome thank you so much I had not found either of those sites.

Thinking Hollow core 3DSS DD and to compare to a Flat coil DD with two layers comprised of a twisted pair or pairs upper layer occuping spacing between lower layer.
My goal is to find a wire configuration to make a unshielded DD that will operate at 6 to 8 us cleanly and hopefully in hot ground.
But shielding may be required so i want to make it as fast as possible. Alot of work ahead.
You are a inspiration and a wealth of information as well as a teacher one of the true guru's.

Think might need shield with delay at 6 to 8us. Maybe not with DD? Interested in what you learn.