shielding inductors

I would like to know if I have to use extra shielding with those inductors:



I´ll be using extra shield foe the toroidal types, for sure, but what about the others?

Hook 'em up to the input of a sensitive amplifier, immerse in an 50Hz or 60Hz electromagnetic field, and you'll have your answer. Test with and without extra shielding.

nice way!

As I understand any power transformer conneceted to the wall will work as a 60Hz magnectic field, no?.

I´ll try it...

Actually, I think a filament transformer, feeding a lamp through a big loop of wire, might be the ticket. The lamp is just acting as a load for the transformer, so it's not working into a near-short. I'm picturing something kinda like a "degausser coil."

OK, I just found this in Tremaine and scanned it:
74kB PDF

Thing is, in order for any such "measurement" to be meaningful, we have to be comparing it against something. Any inductor is going to pick up hum. You would almost need to know the strength of field inside the piece of equipment you're going to build, to be able to say for sure whether or not your inductors are going to need additional shielding. And you'd need a baseline level of "acceptable" pickup to measure against.

Of course, you could always just build your circuit and see if you end up needing extra shielding or not.

Thanks for all the info, Dave.

I think I´ll just build the thing and see how it turns out without any extra shileding. As the passive eq part will be PtP anyway, I can always get it apart if there is a problem.

Do they sell Altoid mints in Brazil? The cans make great little shielded enclosures. They're ferrous and you can even solder to them quite easily.

That torroid looks pretty even as far as the winding, which means the external fields are supposed to cancel, which means you will get Some cancelation. Theory never matches practice, so give it a try.