><My first thought was something like a small compass near each bit. I want
><to avoid lights since I think they are less engaging, less an indicator
><that something has happened. Ideally this should be an attractive looking
><toy, that sparks curiousity.
>
> The ferrite would not show enough external field change to be a reliable
> indicator. However when the wires were driven they indeed would!
OK, how about it. Put a ring of compasses around the wire with needles strongly
enough magnetised that they will stay pointing N-S around the ring regardless of
the Earth's field.
Can you then flip them with a current? A very good visual demonstration of how
core works!
Philip.
BTW Siemens make some torroidal cores down to 1mm thick ferrite, slightly larger
in other materials. RS Components stock some -
http://rswww.com/ and go in
through the catalogue: "Electronics", "Transformers/Inductors/Ferrites",
"Ferrites", "Torroids" (sic). There are even data sheets but I didn't manage to
download them.
Received on Mon Apr 26 1999 - 12:25:23 BST