Fisher Lab CZ-21 QuickSilver Operating Manual page 19

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8. Most silver rings will give a high tone. Most gold rings
will fall into the pull tab/foil mid-tone category. This is
due to the unavoidable fact that most gold rings are
conductively similar to aluminum foil and pull tabs.
Some are more closely identical to the U.S. 5-cent
piece; however, the CZ-21 does have the unique
ability to separate those signals from the aluminum
trash signals.
9. Now increase the DISC control to "1." You will find
that the CZ-21 rejects the small, iron targets and no
longer responds with an audio tone.
10. Continue to increase your DISC control, noting
that with each successive step up, more and more
targets are rejected. At DISC = "4" for example, a
"coins-only' mode will ignore iron, tabs and foil while
accepting U.S. coins.
11. The target I.D. decal on the left underside of the
control housing graphically displays which items
are rejected and accepted at each DISC level. For
example, "foil" is placed between DISC = "2" and
DISC = " 3." This means that foil is accepted at "2"
Figure 8. Typical CZ-21 Audio Responses
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