> lower voltage (a Variac is handy here,
it's about the only thing it is
> handy for ;-)) since the impedance of the winding will be much lower
> with the open magnetic circuit.
Can't you use an incandescent lamp in series with the filament?
I asusme you meain 'in series with the primary'. Yes, you can,
assuming you cna stil lget filament lamps [1]. You want a fair-sized
currnt thuugh, and because you only use the degauser for short periods,
it doesn't amtter if the coil would overheat if left on continuously
(most small commercial degausers of the type solde for bulk-eraisng home
audio and video tapes suffer from this too). I think th average domestic
lamp bulb will nto pass enough currnt.
[1] As you probably know, ever more types are being banned. It's things
like this, and the RoHS and WEEE directives that have caused me to claim
to be 'magenta' which is, of course, anti-green :-)
-tony