In my ignorance, I thought the outer coller would also be a magnet with the poles opposit to those of the inner core.
I thought this would concentrate the flux through the coil, expecially if I could put a smaller coil at each end. It was intuitive to me that this would generate the largest...
My apologies for my previous post.
There is a lot of info I can get on the web which would make the post sound better. Now I see it is an incoherent mess.
I see that what I was trying to describe is a speaker driver, running in reverse.
I found the following software which should help me...
I'm making a geophone, a seismic sensor.
My plan is to get a 3/4" diameter by 1" neodymium round bar magnet. Then surround it with a collar with a space sufficient to accept a thin plastic cylinder wound with speaker wire.
I notice that in the commercial versions, the wire is wound at the top...
