Russell McMahon wrote:
>
> I'm pleased to see that after a longish digression into electromechanicals
> (slip rings and ball bearings) we are starting to get back on track with
> rotary transformers :-)
> So, I'll ask again -
>
>         ????  How much power is this design meant to  ????
>         ????  transfer to the rotating head?                    ????
>
> The answer probably has a significant affect on which is the best. solution.

Peter L. Peres wrote:

>You'd be hard pressed to pass enough power to light a LED with those.


That would seem realistic at first thought, but i'm
not sure it's true. After doing that 2-transistor SMPS
using the tiny RF inductor I was surprised to get 150mA
and more with no problems.

Sure the VCR rotary transformer only carries uV and uW,
BUT it has a decent pair of coils, and beefy ferrite
cores that make what looks something like a standar round
ferrite former, but with tiny precision air gap (where
it rotates!). These are very precise units, with minimal
losses, and decent coil sizes, all because it HAS to
be efficient enough to get that tiny signal through.

Based on getting 150mA ok through an inductor 10x smaller,
and that i've used round ferrite cores a little larger good
for a couple of amps at 5v, i'm *guesstimating* you could
get 200mA to 500mA at 5v through these VCR units, maybe
considerably more. :o)
-Roman

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.