Coil Question for Tom

I am kinda new to the hobby, and have done a little reading ( could be dangerous). Are all coils designed with two windings? I know the size of wire and number of windings depend on the frequency that will be applied. My main question is .... Is it possible to design a coil with multiple windings that relate to coil size? It would require a selector switch that could be changed "on the fly" to meet hunting needs.
If this is possible a single coil could take the place of two or more coils of different sizes. This is just a newbie question so take it easy......

Pulse Induction metal detectors can (primarily) use a monoloop. VLF units (which is what most metal detectors that we are familiar with) .....yes, use 2 windings. A transmit coil..........and a receive coil.

If I understand your question correctly........................Garrett metal detectors does indeed have what you are in reference to. Multiple coil sizes in one housing. . . . . . and ,,,,, you can switch coil 'size'.............on-the-fly. It is not very effecient; subsequently, not popular.

Resonance, impedence and inductive balance are a few of the important factors in designing coils.

Good question

What would be nice is to have a quick connect at the end of the cable, so all you would be changing is the coil. They probably don't make them that way due to stress on the cable at the coil connection, but it seems like a screw on connection would be pretty stable to me.

It would be too risky to have a coil connector on the top of the coil. Intrusion of moisture/dirt/salt water..........etc..............

NASA-Tom Wrote:
-------------------------------------------------------
> It would be too risky to have a coil connector on
> the top of the coil. Intrusion of
> moisture/dirt/salt
> water..........etc..............

I overlooked contaminant intrusion. Thanks Tom.