> > Pot cores which come apart in 2 halves are available. Each half can hav=
e
> > its own
> > coil and they couple quite strongly when near enough.
>
> Do you have any examples?

Some years ago:
(Searches archives - hmmm - 1999)

I used U cores .
I can provide a photo if desired.
Can be wound without bobbin direct on limb(s) of U.
TX was a resonated current loop.
100m of TPS mains flex in one demo.

Resonance is very very very (...) worthwhile in achieving range and
power transfer.

A prototype with dozens of units used ?5% tolerance Mylar caps and
coils wound to same number of turns but with some inductance variation
due to mechanical variations. Most receivers just drove an LED. Some
had full duplex coms and a serial connector to allow a PC to connect
remotely.

I can give rough details of basic LED units. Very simple.
Half wave diode rectification and a reservoir cap allows much more
real things to be done. Cost addition per unit is small.
Resonance adds very substantial voltage and achievable energy output.
I could get Watts from cores of "a few" cubic cm volume.
Frequency unremembered but probably a few hundred kHz or less.

TX circuit should also be resonated (series or parallel as appropriate).
Some people patented both series and parallel resonance in this
context ( :-(  ) (no names) but I can demonstrate proof of prior art
(not mine) from early 1970s if this ever became an issue.



         Russell McMahon
--=20
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