I have made a circuit to detect the material of a metallic cylinder. It is able to discern aluminum brass and steel targets, and I used a hard drive voice coil for this. This is for a machine I am developing for my small business, and I need to find a source of coils. I don't want to wind my own by hand for quality control reasons, but I'd like to get as close to the hard drive coil as possible:
inside diameter: .5 to .65 inches
length: .1 to .2 inches
number of turns: 150 to 200
My GoogleFoo is failing me. I can't seem to find anything in this range.