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Re: TDI Signal Chart
Posted by: dan93
Date: June 01, 2013 08:58PM
In your post you said if you set the GB low when looking for silver coins, the signal will be weaker than it would be if the GB was set at maximum.

In a VLF machine if the ground phase reading is say 60 and you lock the ground balance to 80 will silver signal be stronger? Will you lose depth by setting higher? Just curious if this works on a VLF too.

Re: TDI Signal Chart
Posted by: Reg
Date: June 02, 2013 04:53AM
PI's and VLF's work and ground balance totally differently so I can't answer your question. I would think you should be able to test your question though by running an air test. However, because VLF's can be so much more ground sensitive, I suspect any real world gain would be offset by the ground signals.

On the TDI, offsetting the ground balance isn't that dramatic of a problem. Besides, you can ignore the offset signal if the detector is set up correctly, thus it doesn't appear to be a problem.

Sorry I can't help you with your question, but I have never analyzed the VLF with the intensity I have on the PI.

Reg

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Re: TDI Signal Chart
Posted by: akille68
Date: July 19, 2013 08:47AM
Hi Reg,
Hope to find you well. Your chart is very informative and as I told since I got my first TDI, some years ago, if you are looking for silver and copper the further you get to go with GB pot the deeper the beast goes...



Alessandro



Edited 1 time(s). Last edit at 07/19/2013 08:47AM by akille68.

Re: TDI Signal Chart
Posted by: Oregon Bob
Date: August 08, 2013 09:07PM
Thank you Reg for posting the TDI Signal Chart. I keep running into new questions that are answered by your chart. This is, by far, the most informative post I've seen about the TDI. I think everyone should study this chart. It helps in a number ways. Thanks again.



PI detectors: Whites TDI SL, Minelab GPX 5000

Re: TDI Signal Chart
Posted by: markg
Date: January 29, 2016 07:00AM
Reg, that is some amazing information.

Re: TDI Signal Chart
Posted by: mntnflyr4fun
Date: April 23, 2017 12:47PM
I must be dense. I have looked at this chart till my eyes are crossed and still can't quite wrap my head around it.

For one thing, when using the hershbach coin program, the TDI settings are low GB (1.5-2) and 10msec pulse delay, cond. switch high. This produces a low tone on coins. When I look at this chart, it seems as tho once you get belowyet the balance point of 5.5 or so the high conductors move into the high tone range and should produce a high tone, not a low tone.....yet in practice the coins produce a low tone...

I am missing something important here in the understanding of what this graph is trying to communicate, but just can't get ahold of it.

I am getting the idea that the only way to really understand this machine is to test many targets while changing the gb pot to see when where the signals change tone or balance out...

Re: TDI Signal Chart
Posted by: barbecued scallops
Date: April 23, 2017 05:29PM
Quote
mntnflyr4fun
I must be dense. I have looked at this chart till my eyes are crossed and still can't quite wrap my head around it.

For one thing, when using the hershbach coin program, the TDI settings are low GB (1.5-2) and 10msec pulse delay, cond. switch high. This produces a low tone on coins. When I look at this chart, it seems as tho once you get belowyet the balance point of 5.5 or so the high conductors move into the high tone range and should produce a high tone, not a low tone.....yet in practice the coins produce a low tone...

I am missing something important here in the understanding of what this graph is trying to communicate, but just can't get ahold of it.

I am getting the idea that the only way to really understand this machine is to test many targets while changing the gb pot to see when where the signals change tone or balance out...

Yes. Clad and silver coins will produce a low tone regardless of GEB settings. That is how you discriminate. Setting the GEB low will force iron to give a high tone. It also forces objects that are "just barely" low tones to become high tones. Some zinc pennies will go from a low to a high (yay). Then if you want to dig coins, you only dig the low tones. It's a deadly strategy at parks...go try it.

Re: TDI Signal Chart
Posted by: Reg
Date: April 23, 2017 09:29PM
Think of the 5.5 line setting as typical iron trash conductor and not for coins. Compared to trash, coins are usually not typical or even common signals in most places I have hunted.

BTW, why in the world would you use Steve H's settings? Are you trying to miss coins?

Reg

PS: "I am getting the idea that the only way to really understand this machine is to test many targets while changing the gb pot to see when where the signals change tone or balance out..."

Good thinking. That is what the chart is trying to tell you to do but not just when objects change tone but also the depth those objects can be detected when the GB is changed.



Edited 2 time(s). Last edit at 04/23/2017 09:36PM by Reg.

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Re: TDI Signal Chart
Posted by: Old California
Date: April 24, 2017 12:30AM
Thanks Mntnflyr4fun for bumping this thread, valuable information first time I seen it. The tone from the coin is not changing but what is changing is the strength of the audio signal, high conductive coins audio drop more than low conductive when going from one side of the GB to the other, both are opposite on the GB.

And thanks Reg for creating this chart, when I went over it a few minutes ago, It confirmed my results from countless hours of air testing and now I'm applying this out in the field.

What stood out are the same results I see from your chart, Low conductive don't sway to the extreme as high conductive. High conductive coins drop a lot in audio adjusting GB from far right to left, but low conductive slowly drop a little from far GB left to far GB right.

So when I'm hunting for deep park coins, Both high and low conductive using all conductive Toggle settings. My GB is set at 10, deep copper pennies and silver signals are strong, yet Nickels (low conductive) still have a strong signal without the sacrifice of loosing too much audio with nickels its still plenty strong using high GB for Nickels.

Great chart, I may copy this and laminate it for field use.

Paul



AKA..Paul (Ca)

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Re: TDI Signal Chart
Posted by: mntnflyr4fun
Date: April 24, 2017 09:01AM
Quote
Reg
Think of the 5.5 line setting as typical iron trash conductor and not for coins. Compared to trash, coins are usually not typical or even common signals in most places I have hunted.

BTW, why in the world would you use Steve H's settings? Are you trying to miss coins?

Reg

PS: "I am getting the idea that the only way to really understand this machine is to test many targets while changing the gb pot to see when where the signals change tone or balance out..."

Good thinking. That is what the chart is trying to tell you to do but not just when objects change tone but also the depth those objects can be detected when the GB is changed.

Considering that the "typical" high conductor is actually representing iron trash, then things start to make more sense. If I understand what you are telling me is that a silver coin will never cross above the low tone line, due to some design characteristics I am not quite familiar with. maybe a limited gb pot adjustment towards the left??? I appreciate your help.

Also, I am starting to understand that Steve H's. coin program, is shallow, but does a good job of eliminating iron trash and that most likely I need to move my gb to the right, potentially increasing my iron trash finds, but also dramatically increasing depth. ie. a gb of around 5.5 would still eliminate most iron trash but drastically increase depth on coins as shown by the chart.

I have a bunch of old silver coins, a few nuggets ready for some field/air testing to help me visualize what is happening and I think now I might be ready to use them. Before I got the confusion related to the chart and the high conductor line straight in my mind it didn't seem like I was ready for serious testinggg.....onward....

Thanks Reg

Re: TDI Signal Chart
Posted by: mntnflyr4fun
Date: April 24, 2017 09:17AM
Quote
Old California
Thanks Mntnflyr4fun for bumping this thread, valuable information first time I seen it. The tone from the coin is not changing but what is changing is the strength of the audio signal, high conductive coins audio drop more than low conductive when going from one side of the GB to the other, both are opposite on the GB.

And thanks Reg for creating this chart, when I went over it a few minutes ago, It confirmed my results from countless hours of air testing and now I'm applying this out in the field.

What stood out are the same results I see from your chart, Low conductive don't sway to the extreme as high conductive. High conductive coins drop a lot in audio adjusting GB from far right to left, but low conductive slowly drop a little from far GB left to far GB right.

So when I'm hunting for deep park coins, Both high and low conductive using all conductive Toggle settings. My GB is set at 10, deep copper pennies and silver signals are strong, yet Nickels (low conductive) still have a strong signal without the sacrifice of loosing too much audio with nickels its still plenty strong using high GB for Nickels.

Great chart, I may copy this and laminate it for field use.

Paul

Paul, thank you for chiming in. Between your comments and Reg's clarification, the light came on (I think)). If I understand correctly your deep park coin settings get the old coins but also must have you digging some iron trash based on what I now think I understand.

I was going the opposite direction with the Hershback settings, eliminating most iron, but also limiting my depth terribly but having the machine run quiet by setting cond. sw. to high. By using the "all" setting instead of "high" it sounds like you are then using the audio to help you sift out some of the park iron....that sound right?

My Hershbach settings (GB 1.5-2) were also responsible for some awfully quiet hunts I have had in a park I knew had lots of iron junk as well as old and new coins. Running your settings makes much more sense to me now.


Thanks for your help
Kerry

Re: TDI Signal Chart
Posted by: mntnflyr4fun
Date: April 24, 2017 09:37AM
I am also wondering if I should be increasing my pulse delay above 10 or would that introduce even more iron to deal with?

Re: TDI Signal Chart
Posted by: Reg
Date: April 24, 2017 05:25PM
Changing the delay will alter all other settings, meaning what happens at 10usec in terms of tones and sensitivity of most different objects will change at a later delay. For a novice, this can confuse things. The upside of a later delay is it will allow one to see silver and copper coins better below certain trash.

Reg

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Re: TDI Signal Chart
Posted by: J.D
Date: April 25, 2017 12:11PM
Thanks Reg for posting this ...in my honest opinion with many many years of metal detecting experience ...I think using the tdi in the park is really not a practical way to go at all ...there are many better choices than the tdi am I wrong (please feel free to correct me)..I know that this the tdi classroom but please one needs to understand that trash tolerance will be really tested when using the tdi in a trash infested park and just wondering if you yourself use this method....Although once again I thank you for putting up the graph for us to see and I really appreciate your effort...I just feel with the minelabs and the deus,s and nokta,s and all the other superb detectors made for park hunting are very good at discriminating these days and when compared to them why would one even bother to use the tdi for this purpose I feel that that it would be way too impractical and too complex with way way too many setting variables for such use.i hope I have not offended in any way as this is in no way my intention ..its just my 2 cents worth ..... once again I thank you Reg definitely great reading.....Thank you sir



Edited 1 time(s). Last edit at 04/25/2017 12:12PM by J.D.

Re: TDI Signal Chart
Posted by: roadapple
Date: April 25, 2017 01:43PM
JD,

I'm certainly not Reg, however those of us that have the TDI and multiple detectors ( inclusive of those named ... minelab... etc ) know the limited capabilities of the VLF detectors. The TDI is in a league of its own with pulse induction capabilities unique to that of other PI detectors. Secrets to success, is to bring out the TDI's abilities through various unconventional adjustments , which in some cases, can completely silence and ignore certain metals while enabling other metals to be detectable. All is achieved at much greater depths within conditions of mineralization in which VLF detectors fall short.

There seems to be an endless combination of adjustments with the TDI for various conditions ...... and that's what makes it fun ! The TDI can turn once declared stagnant ground into productive target rich ground. Just my two cents worth on the subject.

Quote
J.D
Thanks Reg for posting this ...in my honest opinion with many many years of metal detecting experience ...I think using the tdi in the park is really not a practical way to go at all ...there are many better choices than the tdi am I wrong (please feel free to correct me)..I know that this the tdi classroom but please one needs to understand that trash tolerance will be really tested when using the tdi in a trash infested park and just wondering if you yourself use this method....Although once again I thank you for putting up the graph for us to see and I really appreciate your effort...I just feel with the minelabs and the deus,s and nokta,s and all the other superb detectors made for park hunting are very good at discriminating these days and when compared to them why would one even bother to use the tdi for this purpose I feel that that it would be way too impractical and too complex with way way too many setting variables for such use.i hope I have not offended in any way as this is in no way my intention ..its just my 2 cents worth ..... once again I thank you Reg definitely great reading.....Thank you sir


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