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Re: Solid state t.c.'s

Very interesting article! I'm interested in schematics.
Is that configuration usable for lower dc input, I mean powered from truck
acccumulator?
What do you think about Siemens IGBTs and BUP-IGBTs?
Stefan Richter, Germany


Tesla List wrote:

> Original Poster: "Kennan C Herrick" <kcha1-at-juno-dot-com>
>
> A few more comments/responses:
>
> Alan Sharp:  The patent has been approved but not yet issued (it's
> "pending").  As soon as it's issued I'll post its no. on the List.  As to
> availability of my circuit:  As I have said, I'll want to first prove
> out--more thoroughly, tho I've done this already with prior
> manifestations of my scheme--the notion of incorporating more transistor
> pairs/power sources into my 1-turn loop.  Then I'll clean up my
> documentation & offer it as a package.  From the patent, of course, one
> can understand the basic scheme--but, believe me, there's lot of sweat
> involved in getting from what the patent describes to a finished article!
>  I've blown my share & more of power MOSFETs.
>
> "B2":
>
> I drive each 6 pair of MOSFETs in push-pull parallel with circuits of my
> own devising.  For each 6 pair, a 6-transistor H-bridge is driven from a
> 2-phase logic-level pulse-burst signal from the single gated amplifier.
> That, in turn, drives a 2-transistor crossover-control circuit via an
> isolation transformer.  The output of that circuit drives the 2x6 MOSFETs
> in push-pull.  The gated amplifier also drives however-many other
> H-bridges are in the circuit; my current design will incorporate 6,
> total, driving two 1-turn current-loops arrayed in parallel in a flat
> configuration at the bottom end of the secondary, with each loop
> incorporating 3 pairs of MOSFET/power source circuit boards arrayed
> around the loop.
>
> I've tried to stay away from surplus in this project so as to make it
> easier for others ultimately to follow my plans & get the parts.  Absent
> surplus, those humongous MOSFETs are pretty expensive and not, perhaps,
> readily available.  Also, they are somewhat slow: at 125 KHz one only has
> a 4 us on-time for each half-cycle.  Out of that, it's not too good to be
> taking 1 us or so to rise & fall.
>
> I shouldn't have written 100/s as a max. spark rate.  10/s is more like
> it, with a 6 ms on-time:  At 10/s, that's 100 ms between pulse-bursts.
> 6/100 = a 6% duty cycle.  Multiplying the 250 A pulse-burst current I
> presently see by that 6% yields 15 A line current from the (U.S.) 115 V
> mains, to recharge the power-source capacitors between sparks.  That's
> about all my circuit breakers will handle.
>
> When I finally get to realizing the final configuration, I'll be pulsing
> some 750 A of current.  So either I cut that maximum spark rate to 3/s or
> so or I diminish the pulse width.  I like the 6 ms because it gives time
> to fatten up the spark and cause it to branch.  I suspect that, all else
> working out OK, I'll be happy with big, fat, loud sparks but at a mere
> 3/second.  Especially when I can just plug the machine into a wall
> socket--and not worry about getting fried if I inadvertently contact the
> primary.  I may not have made clear that at no time does any voltage on
> any part of the primary apparatus, as measured to ground, exceed 160 VDC
> or 320 VAC at 125 KHz--with the latter only occurring during each 6-ms
> pulse-burst.
>
> Were I of a sardonic turn of mind, I might have commented that my scheme,
> while not perhaps employing 21st-century hardware, surely employs that of
> the 20th--in contradistinction to most of you other coilers who are back
> in the 19th.  But I would never say that.
>
> As to trying this with another secondary, I have not done that.  I don't
> have one, for one thing: I have just the pie-wound one.  There's no
> reason at all why it wouldn't work fine, as long as its resonant
> frequency was not too much higher than 125 KHz (so that the pulse's
> on-time would not become too much shorter than the 4 us).
>
> Someone else commented that perhaps my MOSFET scheme could be scaled up
> for larger coils.  No reason why not.  One can pump X-number of amperes
> through a 3' diameter current loop just as readily as through a 1' one.
> Since the loop impedance would go up, more hardware would be needed to
> get the same current, of course.  And a larger secondary would exhibit
> quite a bit lower resonant frequency, so pulse width would be longer, so
> slower/cheaper MOSFETs could be employed--but more of them ("there's no
> free lunch").  Such a coil would more efficiently be operated (in the
> U.S.) from a 220 V split-phase mains, which most people have, I think.
> Each current loop, of a pair of them in parallel, would be powered from
> one side of the line, keeping MOSFET and storage-capacitor voltage
> ratings still at reasonable levels (500 V for the MOSFETs, 200 for the
> capacitors).
>
> Anyone hot to trot?  You'll have to wait a while, at least for my plans;
> perhaps 6 months.
>
> Ken Herrick
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