If you are not in a rush, see if you get any more suggestions here, and do have a really good search with google.
Im not in a rush :-) i have time but the thing is the programming is not the problem becorse i like programming (im doing it in perl (Win32/Linux))
You must know that i search with a metal detector for several years now and i thougt i can also make a metal detector but do the minimum on electronics and the most by software so that i can do what i want with the data and even make data filters, time readings etc even collect the readings where i have been on the field. But that is not all, i can also do better messurements by digital data.
Shortley it is a cool project for me!
Im also looking at google and im going to collect some more information. But i need to be pacient to collect all information. Im also lerning electronics and i have also some other idears but this is the thing where i want to work to it!
Mayby i just need to start with binding a coil ;-)
But i think this is almost the way to build the standard circuit, to have a coil, strongen the signal, convert it to an digital signal and input it to the arduino for reading. The second thing is to make a signal, make the signal stronger and bring it to the coil. but if it is to make a pulse by using the arduino i dont know. Mayby i should use a continus puls generator in analog technique. but only say by computer so from, start send stop sending.
It are a lot of questions to be honest :-/ sorry.