John Curl's Blowtorch preamplifier part II

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#47,224
Steve Eddy said:
Of course it is. It's called Type 2 litz.



And when you take a number of strands of individual wires, twist them together, and then take a number of those bundles and twist them together, as with a rope lay, that's what you get. Each individual wire on average over a given length will occupy all radial positions from the center outward.

se
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Here is a much more detailed description of Litz wire and its optimization http://engineering.dartmouth.edu/inductor/papers/litzj.pdf There are different descriptions of Litz wire from different manufacturers that don't correlate. Your description comes from New England Wire but is not universal. There are much more complex weaves that are necessary to get benefit from fine strand larger gauge Litz wire. This stuff is used in high power high efficiency switching power supplies and HF antennas. Its pretty well understood by people who need to make a living from working with it. (Not me.)

Rope lay is not enough to describe how the cable is twisted. There are a number of rope lays: Introducing our Newsletter: Cableworks Inc. .

Thanks for forcing a crash course in wire stranding on me. I skipped that lesson (but it was before the web and Wikipedia) but I'll come up to speed.
 
#47,226
I find that chicken wire really brings out the detail in Hendrix.
 

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#47,231
Well, you could compare it to some of Mr. Curl's favorite speakers, or take home message that super flat electronics with miniscule noise floor do little for sound quality of speaker transducers.

Sure, you can listen to all electronics through same speaker, even really poor speaker, and pick out differences between electronics, or you can listen to different speakers with same electronics and pick out differences between speakers, or you can listen to music with just about any combination of speakers and electronics.
 
#47,233
Steve Eddy said:
I see nothing in that piece that either refutes what I said or supports your absurd claim that the construction I described is not even considered litz wire.

se
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It would seem your definition is pretty loose if 'rope lay" is all that is necessary to be Litz wire. Usually the frequency of operation, current requirements voltage requirements etc. all play into the design and selection of Litz wire.

In any case here Scotts Electronics Litz Wire Supplier Enameled Copper Magnet is a good source for DIY Litz wire for projects with some useful information including:

To combat the skin effect, litz wire uses lots of little conductors (strands) in parallel (forming a bundle). Each little conductor is less than a skin-depth, so an individual strand does not suffer an appreciable skin effect loss. The strands must be insulated from each other -- otherwise all the wires in the bundle would short together, behave like a single large wire, and still have skin effect problems. Furthermore, the strands cannot occupy the same radial position in the bundle: the electromagnetic effects that cause the skin effect would still disrupt conduction. The bundle is constructed so the individual strands are on the outside of the bundle (and provides low resistance) for a time, but also reside in the interior of the bundle (where the EM field changes are the strongest and the resistance is higher). If each strand provides about the same average resistance, then each strand will contribute equally to the conduction of the entire cable.

The weaving or twisting pattern of litz wire is designed so individual wires will reside for short intervals on the outside of cable and for short intervals on the inside of the cable. This allows the interior of the litz wire to contribute to the cable's conductivity.
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#47,234
scott wurcer said:
To expand a little on the Bateman issue, there is no way to make a bridge that will give the right answer for complex impedance in the transmission line sense where the real and imaginary parts are orders of magnitude apart due to there being .001 wavelenghts of line. His bridge could no more work at 10kHz than an RF bridge could at 10MHz with 1cm of line. There is simply not enough energy lost in the loss mechanisms to resolve it from the energy stored.
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Scott
Info. See the detail analysis of the terminated bridge capabilities in separating nuances btn reflected and transmitted waves here:
http://theoldcatvequipmentmuseum.org/200/202/Jerrold/JerroldABridgeMethodofSweepFreq.ImpedenceMeasurement.pdf



morinix said:
A thread, that would have a life of it's own, could be made on engineers that got screwed out of money others made on their work.
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😀


George
 

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#47,239
gpapag said:
Scott
Info. See the detail analysis of the terminated bridge capabilities in separating nuances btn reflected and transmitted waves here:
http://theoldcatvequipmentmuseum.org/200/202/Jerrold/JerroldABridgeMethodofSweepFreq.ImpedenceMeasurement.pdf

George
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George you didn't read what I said. Solve the telegraphers equation at 10KHz and get the actual complex Z where R and G matter. 0.001 or whatever tiny wavelength of line does not have enough of either and in any case he incorrectly took magnitudes which would throw it away anyway. His bridge measured the lumped L and R impedance. No line and a substitution of a 770nH L would give the same answer. I don't have the energy to post all the pics but I ran this simulation and again got the same answer at audio frequencies.
 
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