"Paul B. Webster VK2BZC" wrote:
>
> Walter Markiw wrote:
>
> >  I need to build a coil to provide an inductance in the range of 0,001
> > to 0,1 Henrys.
> > It is for a frequency filter I am planning to build.
>
>   Audio (it is audio, isn't it?) frequency filters use active "gyrator"
> circuits to synthesise inductance with op-amps and capacitors.  That's
> how variable inductance is emulated.
>
>   Generally, this is part of a well-recognised filter type using
> op-amps, and I presume you should be pursuing a reference for these to
> find your design.

I would suggest this way too.

Take a look into a good book about op-amps/electronics. Also you may
want do
a search at the National semiconducter Web-Site for applictaion-notes on
op-amps.

        Stefan