Re: An Economical Magnecharger (inductive charger)

[Rod Hower <rodhower@ameritech.net>]

Lee,

I'm afraid I can't be of any assistance when it
comes to machining capabilities; however, if you 
need insulated wire for winding Xfmrs, I can send you
what you want (from very small guage to 14GA).
Also, if you need some IGBT's, Mosfets or diodes for this 
experiment, let me know, I will send them (free of charge
for your help on the list!)

Rod

Lee Hart wrote:
> 
> SteveB48@aol.com wrote:
> > Are you thinking 60hz instead of a higher frequency to keep the costs
> > down?
> 
> Yes, exactly.
> 
> > If you need some machining done, I might be able to. Can you be more
> > specific about your needs?
> 
> Not yet. The idea is in its infancy. I'm hoping discussion can refine
> the concept of what it must be / must do / must cost.
> 
> For first experiments, I'm thinking we would find a transformer than is
> reasonably cheap and available, modify it, and see what happens. This
> basically means cutting apart transformer and reassembling the pieces.
> 
> "Jim Waite" <ajbattcar@att.net> wrote:
> > I like your idea of reworking the secondary with a triac phase control
> > across the capacitor winding. Anyone who has used or are familiar with
> > ferroresonant-type xfmrs can attest to the high heat losses due to
> > their saturated core:
> 
> Well, the losses are about twice that of a normal transformer. However,
> that's still only a few percent of total power. Ferroresonant
> transformers aren't dissipating all that many watts, but they don't have
> any fans or heatsinks to dissipate that heat. Thus they run hot. Which
> is fine as far as the transformer is concerned; they don't mind heat.
> 
> > But the last used 2 to 2.5 kW Ferro I saw was around $600. Anyone got
> > a donor they'd like to supply?
> 
> We don't need a ferroresonant transformer. A conventional "hard"
> transformer is fine. We will simulate the ferroresonant effect with the
> leakage inductance (created by separating the primary-secondary
> windings) and extra capacitor winding with phase control.
> 
> Thus, we need a conventional transformer that is cheap, available in
> modest quantities (we'll never get it right the first time), has its
> primary and secondary on separate bobbins (not wound one on top of the
> other), and looks easy to modify. Power level is not critical for
> experimental versions.
> 
> > is it possible that non-ferroresonant (standard) isolation xfmr's
> > are built with the same E-I lamination arrangement, and should we
> > consider trying that first?
> 
> Yes; both conventional and ferroresonant transformers are almost all
> made with E-I laminations. The ones in ferroresonant transformers are of
> better quality and lower loss, to better handle being operated in
> saturation.
> 
> "Andre Blanchard" <andre_54005@yahoo.com> wrote:
> > I am thinking that for a prototype the paddle could be cut out of
> > the core stack by wire EDM. The stack would need to held together
> > in some manner before it is cut.
> 
> And after it is cut. Either the winding will have to be tight enough to
> bind the core laminations together, or they will need adhesives, rivets
> or screws, or the ends will need to be welded. For a start, I'd probably
> use a rivet or screw at each end. Ultimately, I'd probably pot the whole
> paddle part.
> 
> > We use 0.010" diameter wire, which cuts a 0.012" to 0.013" kerf.
> > With a 0.013" kerf and a 10 deg. included angle the core would drop
> > in about 0.15" after the cut.
> 
> We can add laminations to bring the height back up to full, so we don't
> lose cross section.
> 
> > But I think you will want a much bigger angle (maybe as much as 30 or
> > 40?) to prevent the paddle from locking in (taper lock).
> 
> This is exactly one of the things I don't know. Too close to 90 degrees,
> and it will wedge itself in so tight a crowbar couldn't remove it. Too
> much of an angle might require special laminations to have enough
> length.
> 
> For experimentation, we might disassemble two transformers, and use only
> the E's. This would in effect double the length of the center leg, so
> there's more room for the cuts and windings.
> 
> > This will be more of a problem then normal because the outer part of
> > the core will not be very stiff and will spread apart as the paddle
> > is pulled in.
> 
> I was guessing that the core is exceedingly strong, even with the center
> leg cut. In a production version, the laminations are no longer E and I;
> the secondary part of the core can be one piece, because the removed
> center leg lets the windings be slipped in after core assembly.
> 
> "Eric Johnson" <ejts@attbi.com> wrote:
> > I thought that the induced magnetic field of the secondary opposed
> > that of the primary. The windings tend to fly apart, not pull together.
> 
> No; a simple experiment will convince you that it is always an
> attractive force. Cheap Radio Shack China transformers often don't
> bother to interleave the E and I laminations; remove the mounting
> bracket and you have a loose stack of E's with the windings, and a
> separate stack of I's. Power the transformer, and it attracts the core
> piece; never repels it. It would only be repulsive if both primary and
> secondary windings were powered, on different pieces, and out of phase.
> --
> Lee A. Hart                Ring the bells that still can ring
> 814 8th Ave. N.            Forget your perfect offering
> Sartell, MN 56377 USA      There is a crack in everything
> leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen