Single v. Multiple Coil Transformer

LTSpice has what I consider a rather annoying feature, in which a passive component's parasitic aspects are embedded in the part. For example, the esr and capacitance of an inductor is hidden, but will nonetheless be part of the simulation. I prefer to explicitly add parasitic elements so they will be seen "in your face". Then they can easily modified, and even swept through a range of values. At a minimum you'll know they're there or not when you look at a simulation schematic drawing. A counter argument is that folks routinely forget to add parasitics to SPICE modeling, so do it for them automatically.

In this case I suspect LTSpice has a fixed winding capacitance for the coil section, so when you show five 5uH segments in series you get 1/5 the capacitance of a single coil. That's why your oscillator model starts more easily and gets up to voltage more quickly.

High winding capacitance is a killer in high-voltage high-frequency transformers. (For 60 Hz, maybe not so much.)

A common way to reduce winding capacitance is to use banked windings. Bank winding has separate short stacks of windings spaced apart from each other, sort of like your individual inductors in series.

There are many ways to create bank windings.

The picture is from Dixon page 3-10, part of TI's 2001 Magnetics Design Handbook. As you progress you wind backwards up the slope of previous windings.

Another approach is described by Brook Clark, giving advice about winding a loopstick antenna, "make 4 turns then wind backwards for 3 turns then forward for 2 turns and then backward for one turn". This makes a single bank four layers high with 10 turns. Then you space along a bit and repeat.

The picture at left of an AM radio inductor is from KJ Smith's web page, about Bremer Tully air core transformers. Here we see a plastic form to keep each bank of 10 turns or so distinctly spaced from the adjacent banks. Like the second method above, this also results in a lower capacitance than the first method, but it can be more compact.

If you ever saw a potted automobile ignition transformer in half, you'll see that they use such an approach.

Terman discusses high-frequency winding techniques in his books Radio Engineering (1937) page 34, and Radio Engineer's Handbook (1943) page 84. If you examine his sketch below, you can see how the usual way of winding a coil (left) puts turns 1 and 12, and 3 and 10 next to each other, etc., which is a high-capacitance situation, but with bank winding (right) turn 10 is all the way across the coil form from turns 1 and 3.

In closing, we can see that bank winding techniques bring a whole new meaning to the old phrase, "distributed capacitance" when describing transformer capacitance.

WOW

it looks everithing TRANSFORMERS and MAG CIRC D-Zgn need to be looked up from B4 WWII docs

i still try to locate the stuff (while i spotted this http://www.google.ee/search?hl=et&site=&source=hp&q=PHASE+SHIFTED%2C+ZERO+VOLTAGE+TRANSITION+DESIGN+CONSIDERATIONS+and+the+UC3875+PWM+CONTROLLER+BILL+ANDREYCAK&oq=PHASE+SHIFTED%2C+ZERO+VOLTAGE+TRANSITION+DESIGN+CONSIDERATIONS+and+the+UC3875+PWM+CONTROLLER+BILL+ANDREYCAK&gs_l=hp.3...5515.5515.0.9906.1.1.0.0.0.0.0.0..0.0...0.0...1c.Sd9dp-ZNF2c ... & this http://www.google.ee/search?hl=et&q=DISPOWER+Distributed+Generation+with+high+penetration+of+renewable+energy+sources+PROJECT+N%C2%B0%3A+NNE5-2001-00075&oq=DISPOWER+Distributed+Generation+with+high+penetration+of+renewable+energy+sources+PROJECT+N%C2%B0%3A+NNE5-2001-00075&gs_l=serp.3...840156.840156.0.840641.1.1.0.0.0.0.0.0..0.0...0.0...1c.1.5tflKlD97uU)

article ... remains unfound in depths of My Computer 60GB of misc. crap (yoo-hoo)

Hah, ROFLOL!

"That's good in that you don't want to run a high Q coil near it's self reasonant frequency and here we are well away from it." -- © Brooke Clarke

"Learning all the time ... Tits" -- Benny Hill (Was it a good ... Tips F;T whatever)

therewas 3 Links + 1 unfound ... sorry i dont match your hilariosity source here , ha!

yauchy wow yau wow >>>>>>>>> http://www.lessmiths.com/~kjsmith/crystal/dtest.shtml

interesting detail
(i'm so little in here)

i donno what the "ROF" means ... and this LOL is also interesting practice - so you go out (of the room) laugh loud (so the ones in (if any) can hear you do it) ??? then you return making a face like nothing happened ... what's the point

ROF-LOL, rolling on floor - laughing out loud.

actually i think you're miu maw - coz you answered to my ... inquiry Xp (& you have a sexy profile pic (HELP!)) // ((((i dont get these Earthlings G))))