One should keep in mind that the TDI is not for everyone and it does take
time to learn. One can't expect to go out in their back yard, spend an hour
or two and know how to work it. It simply doesn't work that way. There is a
learning curve that has to be overcome, plus a person should learn just what
each control is doing and why it is adjusted. This isn't hard, but does take
time to do. Without such knowledge it is very difficult to know just what to
do if things are not going as planned.
One more note, I need to check just how the elliptical coil works in all
modes and under all conditions. I suspect the elliptical coil will react a
little differently and may alter just how the signals sound. The only way I
will know for sure is to try it when mine gets here.
The TDI works great for coins. I have
personally found over 100 older coins with mine in a park in town that has
been beat to death by other detector owners. The discrimination works
extremely well once you know how to set it up. In fact, I normally will not
dig any trash at all during my coin hunting outings. BTW, set the detector
up for coins and then hunt the Rich Hill area for gold bigger 1/4 oz or
bigger and you can ignore, yes, ignore all iron including tin cans.
Actually, I am not sure just how small of gold it will find while doing
that, but I do know that 1/4 oz nuggets and larger will be detected. I have
personally walked through the trashiest part of the ghost town Octave and
picked out several non ferrous items including one old coin while basically
recognizing and/or ignoring the iron junk including the cans and pieces of
cans. Large cans do require the coil be raised to fully test the disc
feature, but generally, most of the junk is simply ignored and produces no
Then, if you want to hunt small gold, you can set the detector to ignore
most ferrous junk and hunt away. Much of the ferrous junk will again be
ignored. Small pieces of cans will be detected, but using a couple of tricks
and one can determine that type of junk with very high reliablility so one
can just about walk by most of that junk also.
Then of course, the TDI can be set to hunt
all sizes gold at the same time and still able to recognize much of the iron
junk. So, in simple terms, the TDI works
great for nuggets and really does well for relics. Now, that combination is
hard to beat when you think that the TDI
doesn't suffer from electrical noise anywhere like some other PI's do.
You mentioned one should buy a ML, well that is fine, they do work well in
most places. Try working under power lines and you may have a problem. There
are also places where the emi noises makes things extremely difficult to
So far, I have not had any of those problems with the
TDI. The design is such that it minimizes
such problems. Yes, the TDI does have less
overall sensitivity and as such the reduced sensitivity allows it to be used
Oh yeah, I do have an SD, but considering the TDI
weighs far less, gets about the same depth on smaller gold, the type we find
here in the US, plus allows me to ignore most ferrous junk, I prefer to use
Now, I doubt you have used one, but that is fine. There are a lot of people
who will not want to use one let alone own one. However, before condemning a
detector, you really should spend some time with it and find out what it can
do. No, it will not compete directly with the 4500, but it holds its own
against some of the other models. Now, anyone who tries to compare the $1500
TDI to a $5000 GPX is not even using common
The trick to using the TDI is knowing how to
set it up. It does have some features that allow for a wide range of
different hunting conditions, so it can be set up to look bad if one wants
to try hard enough. BTW, with a tweak or two that takes less than 5 minutes
to do and that includes taking the unit apart and the original 200
TDI's built can be adjusted to detect gold
too difficult for even the higher priced 4500's to detect. I know this is
true because I have done it.
As I said, the TDI is extremely versatile
and can be adjusted to do a lot of different things, some of which conflict
with nugget hunting. As an example, a good PI will also detect small foil
just like it is a nugget. Now, that can be a problem when coin hunting, so
with a simple adjustment, the foil can be ignored. Make this same adjustment
when nugget hunting and yes, you will ignore small gold too. Fortunately,
the TDI was built to be used by someone with
a little common sense and as such, such people won't make the wrong
adjustments when gold hunting.
The common sense is required and some knowledge of the controls are required
to take advantage of the abilities of the TDI
to be able to recognize most ferrous junk. So, it does take a while to fully
learn the detector so you can appreciate just what the detector can do.
So, the TDI is far more versatile than a
basic PI, but it is not for everyone. Common sense, a little patience and
the willingness to learn are the requirements to maximize the features of
the TDI. Obviously, there are people who
want more of a turn on and go detector and could care less about the ability
to discriminate junk or think they will miss something.
Keep in mind, there is nothing out there that acts the same or uses the same
techniques so it is something new to learn. The TDI
has the ability to distinguish ferrous junk even when using a mono coil as
well as the DD type.
Just my two cents on the issue.
This post was re-published with permission of the author. The
original post was on the Arizona Outback forum
Updated TDI review information:
I probably shouldn't have mentioned the 5 minute adjustment because it is an
internal adjustment that should only be done by someone completely familiar
with the design. There are a lot of internal adjustments and only the one
that adjusts the minimum delay will help. Adjusting any of the others will
most likely cause the detector to fail to work, so no one should attempt
this except an authorized repair shop or Whites themselves.
I would expect it would be extremely expensive to have the detector
recalibrated, or even repaired if something were done incorrectly. So, it is
not something that should be tried.
As such, I am sorry I even mentioned it and that paragraph probably should
So, you might pass this info to the guy who asked the question and explain
to him it is something that will probably be done after the warranty is over
and can only be done on one of the first units designed. Later versions
using a different internal pc board don't even have the control, so it can't
be done anyway. Once again, it is not something a person should try by
It's recommend people visit the Whites TDI Tech forum for more TDI
information. Here is a link to that forum;