R
RST Engineering \(jw\)
- Jan 1, 1970
- 0
I plan on using two junk CDROMs in my basic science class as a variable
capacitor for a crystal set -- shim brass cut to cover a little less than
half of each cdrom, glued to the surface, with a vinyl grommet in the middle
to hold the disks together and a disk of mylar cut from a sheet protector
between the brass plates as the dielectric.
Each student is going to have to prepare two disks each, so it isn't a
onesie-twosie job. I need a method that I can use fifty times a semester
every semester.
The problem is removing the metal "plates" that are there now. First
thought was to soak the disks in drano or aqueous lye and dissolve the
aluminum, but further reading and experimentation shows this isn't quite
enough. Apparently there is a lacquer or epoxy coating over the aluminum
and a nickel flash under the aluminum. This is only hearsay, but I know
from experimentation that a caustic solution by itself isn't enough.
Anybody KNOW what the various layers are on the disk and any suggestions on
how to remove them without destroying the plastic of the disk itself?
Jim
capacitor for a crystal set -- shim brass cut to cover a little less than
half of each cdrom, glued to the surface, with a vinyl grommet in the middle
to hold the disks together and a disk of mylar cut from a sheet protector
between the brass plates as the dielectric.
Each student is going to have to prepare two disks each, so it isn't a
onesie-twosie job. I need a method that I can use fifty times a semester
every semester.
The problem is removing the metal "plates" that are there now. First
thought was to soak the disks in drano or aqueous lye and dissolve the
aluminum, but further reading and experimentation shows this isn't quite
enough. Apparently there is a lacquer or epoxy coating over the aluminum
and a nickel flash under the aluminum. This is only hearsay, but I know
from experimentation that a caustic solution by itself isn't enough.
Anybody KNOW what the various layers are on the disk and any suggestions on
how to remove them without destroying the plastic of the disk itself?
Jim