PI Discrimination

[jon-ecm]

Hi Guys... I recently built a microprocessor controlled pulse induction metal detector
capable of discrimation (So I thought)
From what I understood, a ferrous metal should cause a longer decay and a non-ferrous
metal a shorter decay.
I did some tests today and could not observe any difference in the waveform between
ferrous and non-ferrous metals.
I played with the damping resistor to see if it was under damped or over damped but could not
ever get any differences between the two types of metal...

If you experts have any idea on what I'm doing wrong it would be really appreciated..

[Orbit]

a miracle

[bernte_one]

hello

last week i could test my surf pi at the beach. What i can say is that the tones which are generated differ dependending on the objects which are located. You should try to discriminate not for ferrous or non ferrous the discrimnation could be tuned so that you can decide massive metal (coins, rings, bracelets small or big ones - give sharp strong sound found round 10 euros eight in euro coins and rest in cent pieces) and other things like wire or tent peg (i found more than twenty tent peg and everytime i could say it before digging - have their own sound) wires a rising sound and tent pegs also a strong tone but another likes coins - because the sound lasts longer.

maybe you can start another way to discriminate
my disc for coins is my wife she can separate the coin sound from others in 90%
the rest were trolley coins