[sdiy] Transformer question

[Scott Gravenhorst]

I would bet that there is an iron core in the handle.

Although this is interesting and quite curious, what is wrong with a simple plug
and jack arrangement to power a music device?  I can see the advantage for
something like a toothbrush or electric shaver since these devices can get wet so
the use of magnetic coupling is an advantage against corrosion.  But we don't
normally use our music equipment in the shower.  While this would be "cute", I
don't see it as very practical for musical use.  It will wind up being rather
expensive and inefficient compared to a simple plug and jack.  Perhaps effort
toward the actual circuit would be better expended for a good "gee-whiz" effect,
assuming that "gee-whiz" is the goal.



"Metzger, Michael A" <MAMETZGER at partners.org> wrote:
>I was able to pop the bottom off the toothbrush handle last night. Believe it or
>not, inside was as I thought - an air core coil. It is oriented to fit over the
>nub on the base. I was surprised at how large the diameter of the air core was.
>The engineer was definitely not concerned with making it fit tightly around the
>nub. Four leads from the coil go farther into the handle to a circuit board. I
>could only see the edge of the board as it was wedged next to the battery.
>
>An interesting detail is that above one side of the coil are two tiny metal
>cylinders. Theyblook like magnets. The metal is soft - I chipped one slightly.
>They are about 2mm in diameter, maybe 3mm long. The cylinders are next to each
>other and are oriented vertically, the same as the coil. They are not in the
>core but are 3mm or so directly above the loops on one side of the coil.
>
>So according to everyone's comments it sounds like efficiency is low. The handle
>sure is warm every time I pick it up. But hey - the circuit works.
>
>Mike
>
>
>-----Original Message-----
>From: owner-synth-diy at dropmix.xs4all.nl
>[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Metzger, Michael
>A
>Sent: Thursday, July 22, 2004 8:54 PM
>To: synth-diy at dropmix.xs4all.nl
>Subject: RE: [sdiy] Transformer question
>
>
>So my quick and dirty "circuit" isn't sound? Uh, no surprise there (look at
>ground, cough)  You guys have got me wanting to take the toothbrush apart now. A
>quick glance when I bought it showed the handle part to be put together pretty
>well. I don't want to break it. Maybe I can get into the base, though. Maybe
>something for this weekend.
>
>Mike
>
>
>-----Original Message-----
>From: owner-synth-diy at dropmix.xs4all.nl
>[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Paul Perry
>Sent: Thursday, July 22, 2004 7:45 PM
>To: synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] Transformer question
>
>
>You need a closed (or as closed as possible) magnetic loop,
>and for any kind of efficiency that means a core of
>transformer iron or similar.
>All I can imagine working, is two U sections, with the tops
>of the Us facing each other across the gap.
>(or, similarly, a number of these).
>
>Although, the 'receiving' side could simply be a slab of 
>'lossy' magnetic material, if you were just boiling water.
>
>paul perry Melbourne Australia
>

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