Anyone have a use for Mu-metal?

Jeez, I could use some! My son is an aficionado of the electric guitar, and I get called upon to do a lot of guitar tech work. Lining electronic cavities with mu-metal can really cut down on buzzing from nearby beer signs, etc.

GWE

Do not forget to anneal it. Nice stuff.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

Grant Erwin wrote: Lining electronic

If Spinal Tap had had some, they would have never broken up. Hazy memory says that mumetal has to undergo a screwy annealing cycle to continue to be effective after cold working.

Kevin Gallimore

Send me your snailmail address please. My email is valid. Merry Christmas, I'll send ya a chunk.

One could build one hell of a Faraday Cage out of that stuff... like, if you had the need .

OR... A BIG transformer.

LLoyd

A better way to shield the cavity of an electric guitar is with shielding paint. The paint film must be grounded. Use a brass washer and roundhead wood screw to attach ground wire to film.

There are a number of makers. One kind I've seen used is MG Chemicals' Super Shield (catalog Number 841-340g, about $25.00 the can).

Yes. Must be annealed in hydrogen at a red heat for an hour. One must do all forming and spotwelding to final shape, anneal, then install (without putting any strain on the metal).

Shield paint does a very good job, and is far more practical.

Joe Gwinn

I'd love to have a sheet, for play.

Joe Gwinn

The paint will be effective on the electrostatic E-field, but nothing for the magnetic H-field. That's where the mu-metal is needed. Be sure to ground the mu-metal so it will shield the E-field.

Mu-metal is pricey; decades ago, a piece the size of a dollar bill cost about a dollar (if you could find a way to buy that size).

The benefit of Mu-metal for shielding is mainly on low frequency magnetic fields, so it inhibits the kind of interference/hum that one suffers from motors and transformers. For best performance, annealing in a hydrogen atmosphere was recommended (yeah, the instrument shop at the university physics department could do it. If you begged.).

So, physics and electronics industry and higher education are the main users.

Be sure

A safety note- only bond the metal on the instrument to the low side of the amplifier input through a capacitor. You don't want a low impedance connection to an amplifier that may have the chassis hot. People still get killed touching the (grounded) microphone while holding the guitar.

Kevin Gallimore

Seriously?

Hm. I'll honor the offer to send a chunk to the first guy (who I've already communicated with; it goes out Saturday) but maybe I'll put the rest on eBay and see what happens. Who knew? Amazing the stuff gets thrown away by engineering labs.