does change in Coil inductance needs changing in circuit?

[mehdi394]

Hello
I know that determining the search coil inductance is primary step for designing a Metal detector but, in PI detector(except for T/R types) we don't have any inductance balance, so If someone hypothetically wants to use a coil with higher inductance what part of the circuit should be redesigned?

I want more depth so I need bigger search coil in diameter, also more winding results into more powerful Magnetic Field,but more winding also changes the inductance of the coil.
just for experiment I want to use a bigger coil with inductance more than 600uH.
what I know :

1. damping resistor should be recalculated
2. more winding means more resistance which is results in more power to drive the coil and bigger battery.
3. by bigger coil I lose sensitivity to small nuggets or rings near the surface

please tell me which part of the circuit should be redesigned based on new inductance, and what am I missing other than points I mentioned above?
thanks

[Carl-NC]

More L likely means more parasitic C so, yes, recalculate the damping R.
This also slows down the response so you will need more sample delay.
More L means more R so for the same battery you will get less current. To get the current back up you will either need to increase the battery or increase the turn-on pulse.

[mehdi394]

thanks a lot Carl.

[mehdi394]

More L likely means more parasitic C so, yes, recalculate the damping R.
This also slows down the response so you will need more sample delay.
More L means more R so for the same battery you will get less current. To get the current back up you will either need to increase the battery or increase the turn-on pulse.

Thanks a lot Carl.