Hi Duffy,
Thanks for your reply. My mentor did advise me earlier to use short multilayered coils and I presume this reduces the reluctance significanty; I decided to use single layer as I was unsure of the response from mulilayered coils with an increase in frequency (skin effect and capacitance between layers). I am not very sure about the frequency change: the frequency determined by the source frequency which is set manually (unless you were talking about an oscillator).
With single layered coils I did not see any significant change in amplitude or frequency when it was connected in series to a pull up resistor and powered by an AC source after trying various british coins.
Thanks for your reply. My mentor did advise me earlier to use short multilayered coils and I presume this reduces the reluctance significanty; I decided to use single layer as I was unsure of the response from mulilayered coils with an increase in frequency (skin effect and capacitance between layers). I am not very sure about the frequency change: the frequency determined by the source frequency which is set manually (unless you were talking about an oscillator).
With single layered coils I did not see any significant change in amplitude or frequency when it was connected in series to a pull up resistor and powered by an AC source after trying various british coins.