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Re: I gots a question!

PostPosted: Sun Jul 31, 2016 3:32 pm
by Paul Gagon
deltafred wrote: Thinking back to my old days playing with RF if you want to raise the inductance of a coil you used a core of compressed iron dust or ferrite, and brass to lower it. I seem to recall it was because of the eddy currents getting shorted out acting as a partially shorted turn (on a virtual secondary winding within the core). IIRC any non ferrous metal will lower the inductance by an amount depending upon it's conductivity.

Aluminium was used as the drag cup in mechanical speedometers, the rotating magnet caused eddy currents in the cup (which increased with speed) which then acted as weak magnets and dragged the cup against a return spring. The needle was attached to the cup to indicate the speed. (Hope all this makes sense.)

Wow! Thanks deltafred. Sounds like you're way more knowledgeable about this then I am. I really appreciate all you guys jumping in and adding your experience and wisdom here. I have spent a lot of time experimenting with, and doing diagnostics on, pickups but there are always things that come up that make you scratch you head and wonder.

Your explanation of the eddy currents would explain why I was reading a drop in pickup inductance, which caused the pickups resonant frequency to rise. Makes perfect sense now. You know.....I really can't express my gratitude enough to all you guys that post here at Bassesbyleo and Ken for allowing me an opportunity to share some of the stuff I've been doing over the last 36 years of my life. I'm just hoping that I can add some helpful ideas or excite someone to dig deeper or maybe learn something new. Thanks guys.

Re: I gots a question!

PostPosted: Mon Aug 01, 2016 2:22 am
by deltafred
No problems Paul, glad to be of assistance. It should really be us thanking you for taking the time to come over here and share your very in depth knowledge of all things G&L with us.

(I worked in an R&D lab as an apprentice with ex radar and radio engineers (long time ago as I'm retired now), I learned a lot from them.)