Talking about magnets and skin depth, I recall an incident back in the early to mid 60's. I was living on Long Island at the time and had many friends who worked at Brookhaven National Laboratory. Needless to say I had numerous tours of the facility. At one time I was given a tour of the cryogenic lab, and was shown a magnet that they were using. To my surprise the magnet was wound with un-insulated wire. Naturally I had to ask about that, and was told that at cryogenic temperatures the contact resistance is so much higher than the actual wire resistance that they do not bother. This way they claimed they could get more turns on a given solenoid. Another interesting thing was an LC at cryogenic temperatures. This thing was oscillating on its own, after it was excited. I guess the Q must have approached infinity with such a low R. It was interesting. - Mike
Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Lux Sent: Friday, July 04, 2008 8:57 PM To: Discussion of precise time and frequency measurement; Bruce Griffiths Subject: Re: [time-nuts] Rb references for audiophiles? Quoting Bruce Griffiths <[EMAIL PROTECTED]>, on Fri 04 Jul 2008 05:47:53 PM PDT: > Jim Lux wrote: >> >> That one I'm familiar with.. (SpaceWire cables, for instance, have 4 >> shielded twisted pairs, 2 in each direction, with the shields grounded >> at the sending end for each pair of pairs)... >> >> >> These were just plain old two (gold/palladium plated) pins for each >> "cable" (granted, the cable is some complex braided combination of >> silver ribbons, which is a fairly exotic form of Litz wire, I >> assume... but no shield) >> >> >> > Unless each individual strand is insulated from all the others (as it is > in true Litzendraht) braiding the wire is ineffective in reducing skin > effect. > > Bruce It was unclear from the literature I saw, but I have to assume that they know this (Litz wire and all it's properties have been "fashionable" in one sense or another for the audiophile biz for decades... I had friends who made their own). On the other hand... I did run across an interesting product for high end audio (not recently)... air core tape wound inductors (i.e. a pancake shaped coil with the winding of thin tape, instead of wire) in both silver and copper. Very interesting stuff. A friend was looking at using them for magnets for a rail gun type system (since they have have a hole in the middle for mounting)... Jim _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
