metal detector in the manual questions

[science_geek]

i was looking at the metal detector program in the propellor tutorial manuals (i dont know what its called), i now have questions...
1. Does distance affect the output of the metal detector?
2. If i had a piece of steel and it gave a certain reading, and then i cut it, would the size change readings or would i be able through trial and error figure out a vast range of metal types and be able to scan certain object to find out what there made out of?
3. Has anyone actually used this for anything, and if so, can they give insight in the areas where problems occur?

[Beau Schwabe (Parallax)]

science_geek,

This type of metal detector can only discriminate against metal and non metal by changing the inductance of the coil. The readings are exponentially proportional to the distance between the coil and metal. When the PE-Lab was put together all of the components had already been pre-selected and this method for detecting metal was contrived with the stipulation that we couldn't add any "new" components or parts to the lab kit. It's design is from an educational standpoint.

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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.