Some coins are mild steel with a nickel coat.
So at the final op amp filter output the ..
Nickel is trying to push a positive signal - which if nickel alone would "ping"
Iron is trying to push a negative signal - which if Iron alone may give a "clip" sound - rejected"
In this special case the Plus from the Nickel and the minus from the Iron - - these sum to zero and the comparator does not get tripped and you dont hear anything. Ive had that with these designs.
S
So at the final op amp filter output the ..
Nickel is trying to push a positive signal - which if nickel alone would "ping"
Iron is trying to push a negative signal - which if Iron alone may give a "clip" sound - rejected"
In this special case the Plus from the Nickel and the minus from the Iron - - these sum to zero and the comparator does not get tripped and you dont hear anything. Ive had that with these designs.
S
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