RE: Request for help with air core transformer/power transfer system

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Dave Halliday" <dh@xxxxxxxxxxxxxx>

I would try two filament transformers with an E+I core system. Pop the I
lamination off and place them face to face.

Is there a reason you cannot go through the glass?  Drilling glass is
very doable. Use brass "hobby" tube as your bit and use 600 grit
abrasive powder and water (with a bit of soap) as the cutter - build a
dam out of toothpaste to contain the slurry.  Use a drill press and feed
very very _very_ slowly.  You can then use any manner of electrical
feed-through.



> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Monday, December 06, 2004 8:01 PM
> To: tesla@xxxxxxxxxx
> Subject: OT: Request for help with air core transformer/power
> transfer system
>
>
> Original poster: David Speck <dave@xxxxxxxxxxxxxxxx>
>
> List,
> I know this isn't directly TC related, but I hoped someone with more
> transformer theory experience that I have might lend a hand,
> with Terry's
> indulgence.  Please feel free to respond privately.
>
> ->Sound enough like electricity transmission without wires ;o))  But
> respond direct if not really related to Tesla coils) - T. <-
>
> I'd like to transmit about 6 volts AC at 60 Hz and 250 mA
> through a glass
> plate about 1/4" thick without drilling a hole in the glass,
> and without
> making any really esoteric circuitry like a high frequency drive
> circuit.  I don't have a lot of time for experimentation, so
> I though I'd
> run my idea past you and see what you thought.
>
> I have space to put a 4 1/2" OD flat circular pancake coil
> (about 1/4"
> thick) on each side of the glass.  I figured I'd run 6 volts
> from a wall
> wart into the primary, and have a matching secondary directly
> opposite it,
> on the other side of the glass, from which I'd feed a diode
> bridge and
> filter cap on the secondary side..  I know similar
> arrangements are used to
> recharge batteries of implanted medical devices, but I don't
> know if they
> work at 60 Hz or higher frequencies.  My main concern is making an
> arrangement that will not burst into flames during prolonged
> unattended
> operation.
> Questions are:  Would it be better to have primary and
> secondary circuits
> with a relative few turns of heavier wire, or lots ot turns of finer
> wire.  I expect that you'd get more inductance, but more
> resistive heating
> with finer wire, but in the absence of an iron core to corral
> the magnetic
> flux, I worry about drawing too much current from the wall
> wart into the
> primary with a few turns of thicker wire.
> Is there a way to calculate the optimum number of turns and
> wire size for
> this arrangement?
>
> Is there any simple arrangement of soft iron wire or sheet
> that would help
> to constrain/direct the magnetic flux for better energy
> transfer without
> involved magnetic core fabrication?
>
> Thanks in advance for your thoughts.
>
> Dave
>
>
>
>
>