[sdiy] Transformer question

[Scott Gravenhorst]

I think you need iron, not aluminum.  These contactless charge systems
are based on a transformer principle, one half of the transformer is
inside the device, the other half is part of the charger/holder.  In
fact, I believe that there have been implanted medical devices made that
are powered or charged this way through the skin.

A transformer has an iron core made of leaves or sheets of iron separated
by an insulating material such as varnish.  You could probably make a
device by taking a transformer apart (preferably, one with a burned out
coil so you're not destroying something useful) but remember that the
sheets of iron must remain unsulated from each other.  If you cut through
the core, you'll have to deal with that.

"Bert Schiettecatte" <bschiett at etro.vub.ac.be> wrote:
>Hi All,
>
>After getting a Braun 3D toothbrush I was impressed with the contactless
>charging mechanism that was used. I went on the net and started
>searching for some info and decided to try my own contactless charge
>transfer DIY project. To start, I took two square bars of aluminum,
>about 1cm x 1cm x 5cm in dimensions. I wrapped standard isolated solid
>core wire around them (28 turns), I think the wire thickness is like 24
>AWG or whatever the standard wire is used in solderless breadboards (a
>little thicker than wire wrap wire). I was hoping to hook up one of the
>two inductors I built to an AC power supply (say 5V, 500mA), and hook
>the other one up to a multimeter measuring volts, then bringing the two
>inductors close to each other and hoping to get some current or voltage
>transferring from one inductor to the other one. Of course it doesn't
>work. What am I doing wrong here? I am totally clueless in basic
>electronics but I can program in C++ :-)
>
>Any comments highly appreciated. 
>
>bert
>

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