Whites TDI DD coils

[lamaison33]

Hello,
I have read in various forums that the TDI with a DD coil will be able to recognize the iron compared to other materials, I would like to have some feedback and eventually what plate do you recommend?

[homefire]

Pretty much a Given on all PI machines that I've ever messed with. PI's have a thing about iron. You looking for Iron Targets or Avoid them ?

Not tried this don't have a TDI but this guy seems to have a way to loose some Iron.

https://www.youtube.com/watch?v=QHkocgr-iYk

[Qiaozhi]

Pretty much a Given on all PI machines that I've ever messed with. PI's have a thing about iron. You looking for Iron Targets or Avoid them ?

Not tried this don't have a TDI but this guy seems to have a way to loose some Iron.

https://www.youtube.com/watch?v=QHkocgr-iYk

This is a well-known "trick" with the White's TDI. It hijacks the ground balance control to create a hole in the response that the nails fall into. This is an example of conductivity discrimination, and should not be confused with ferrous/non-ferrous discrimination. Any targets with the same conductivity response will be eliminated, and iron targets that are smaller or larger than the nails used in the test will still be detected. For obvious reasons, you cannot use this technique if you need the ground balance control for what it was designed for.

[lamaison33]

and I add that the depth with this method decreases dramatically, I look for a non-ferrous ferrous discrimination, and I heard a Bulgarian boy who by putting a ML coil to the TDI managed to distinguish ferrous from non-ferrous.

[Ferric Toes]

Using DD or concentric TX/RX coils on a PI will give very good discrimination between any size ferrous targets provided you sample in the 'on' as well as the 'off' time. Works great in non-mineralised soil and dry sand, but any mineralisation or ground conductivity, such as a salt wet beach, completely messes it up. But combining a ground balancing circuit (all done in the 'off' time) with a discriminating circuit running in the 'on' time period, it may be possible.

Eric.

[lamaison33]

Thanks for the info, I'll try to put a DD coil on my TDI,to avoid a little bit of iron.
Simone

[lamaison33]

Eric, please explain this to me. But combining a ground balancing circuit (all done in the off time), it may be possible.

Thanks
Simone