TDI Ground Balance On Versus Ground Balance Off

[Jim in Idaho]

2 hours ago, Mark Gillespie said:

These test were with a nickel approaching the coil, not simulating an actual sweep, right to left.

I was listening for a slight increase in threshold.

Still, I thought it did better than this.

An 18 volt battery pack my help.

Yeah...mine is a little more sensitive. But, it depends on the battery pack voltage. With the NiMH pack in mine, at 10.7volts, I was getting about 13.75" on the nickel, but with the fully charged Li-ion at 12.6 volts, I was getting 14.5, and with the 16.8v li-ion, I was getting 16.5". All these with the 12"DF.  With that coil, the battery voltage is the difference, Mark. And, I gained about 1/2" by turning the GB on, but set at zero. By maxing the GB, I gained an additional 1/2".

Jim

[Mark Gillespie]

I'm beginning to believe there are several different production models when it comes to the TDI.  One might be obvious, the TDI Pro and the TDI SL.  But from other users I think there are manufacturing variations in the SL model.  About half the users I've conversed with state there is a huge depth advantage when turning the ground balance off, but that is not the case with mine.  Speculating, the difference could be attributed  to substituting TX components to coil specifications. 

I did some internal voltage/current experiments a few weeks ago and noticed one main thing.  I could increase the standard input voltage entering the system but never saw a significant increase to the coil TX circuit (less than .010 volt) regardless of input voltage.  I believe, in my unit, the voltage regulator might be preventing the use of increased voltage to the TX coil connection.  This would explain the constant air test distances across the different settings.

 

 

[Mark Gillespie]

On ‎5‎/‎14‎/‎2019 at 9:11 PM, Mark Gillespie said:

White's TDI SL, manufactured 2014, pulse delay 10
Air Test	Freshly Charged Battery Pack
			GB OFF		GB OFF		GB ON MINIMUM		GB ON MAXIMUM
			GAIN MAX		GAIN 8		GAIN MAX		GAIN 8
7 1/2" Dual Field Coil			11"		11"		11"		11"
Super Pulse 350			11 1/2"		11 1/2"		11 1/2"		11 1/2"
12" Dual Field Coil			13"		13"		13"		13"
To be honest I'm kind of disappointed
Very smooth threshold In ground performance may be different

Sorry for the mistake, the first post had the 7 1/2" coil only getting 7 1/2" but it's actually 11" with a nickel.

[Mark Gillespie]

 

I did another detailed test last night, using the TDI SL with the 7 ½” dual field coil with a freshly charged battery pack.

1. Ground balance on and set to 7 ½, conductive switch set to all, gain max, smooth, low volume threshold.  Results, two different tones, high tone for a nickel and low tone for a quarter.  Air test, 11” for the nickel and 9 ½” for the quarter.

 

1. Same settings but turning ground balance off, counter clock wise until it clicks off, conductive switch still set to all, one tone for both the nickel and quarter.  Air test, 11” for the nickel and 9 ½” for the quarter.

The same results were also noted using both the 12” dual field and the super pulse 350, no air test increase when switching from GB on to GB off.

It is obvious this machine is different from others whom state gaining from 1-2” additional air test distance with the ground balance off. 

The manual also states, " Turning the Ground Balance to the OFF position disables the ground balance and TDI will run as a straight PI detector. This gives a slight improvement in depth but, of course, will respond to mineralization and eliminates the ability to discern conductivities.  "

All this being said, there must be at least two variations of the SL.  You would never get White's to comment on this, for sure.

 

 

[Jim in Idaho]

Sure looks that way, Mark. John (auminesweeper), and I both have machines built fairly early, and we get very similar results. His was built in '14, and mine in '13. So it looks like yours is different, for sure. What did you have a for a batterry voltage in that test?

Jim

[Mark Gillespie]

I guess the main thing I'm trying to figure out is why my machine's performance does not increase when ground balance is turned off.  100% sure of what I'm seeing now.  I sent Carl a message but he's not replied and if anyone would know why, what, how on what I'm seeing, it might be him.

 

[auminesweeper]

1 hour ago, Jim in Idaho said:

Sure looks that way, Mark. John (auminesweeper), and I both have machines built fairly early, and we get very similar results. His was built in '14, and mine in '13. So it looks like yours is different, for sure. What did you have a for a batterry voltage in that test?

Jim

Jim, Mine was built in 2013 as well, but none the less mine did not show any depth advantage with the GB switched Off,  all I noticed was that smoothing effect that the TDI pro does with the GB off my SL did it when the GB was On which means it was trying to balance out the target. 

Well we have 3 for 3 that all show zero depth increase with the GB off, which is making me start to doubt the many posts I have read claiming that there is a depth increase with the GB Off, Yes there is with the TDI Pro but Not the SL.

[Mark Gillespie]

1 hour ago, auminesweeper said:

Jim, Mine was built in 2013 as well, but none the less mine did not show any depth advantage with the GB switched Off,  all I noticed was that smoothing effect that the TDI pro does with the GB off my SL did it when the GB was On which means it was trying to balance out the target. 

Well we have 3 for 3 that all show zero depth increase with the GB off, which is making me start to doubt the many posts I have read claiming that there is a depth increase with the GB Off, Yes there is with the TDI Pro but Not the SL.

auminesweeper

Would it be possible for you to do an air test similar to the settings I mentioned above, using a nickel and quarter?

I posted the same information on Carl's Getech site and he stated not having any idea about the GB question I posted.  Makes me wonder, if White's knew something had changed but never revealed it to the users.  Else I can't imagine Carl not having an answer but a reply, "Sorry, no idea what might be going on."  I would bet Reg would have an answer.

 

 

[Jim in Idaho]

1 hour ago, auminesweeper said:

Jim, Mine was built in 2013 as well, but none the less mine did not show any depth advantage with the GB switched Off,  all I noticed was that smoothing effect that the TDI pro does with the GB off my SL did it when the GB was On which means it was trying to balance out the target. 

Well we have 3 for 3 that all show zero dept the '13's are different somehow.h increase with the GB off, which is making me start to doubt the many posts I have read claiming that there is a depth increase with the GB Off, Yes there is with the TDI Pro but Not the SL.

Sorry, John. I thought you'd said '14. So, it's possible the '13's are different somehow.

[auminesweeper]

26 minutes ago, Mark Gillespie said:

auminesweeper

Would it be possible for you to do an air test similar to the settings I mentioned above, using a nickel and quarter?

I posted the same information on Carl's Getech site and he stated not having any idea about the GB question I posted.  Makes me wonder, if White's knew something had changed but never revealed it to the users.  Else I can't imagine Carl not having an answer but a reply, "Sorry, no idea what might be going on."  I would bet Reg would have an answer.

 

 

Sorry Mark I can't because I sold both of my TDI's just before I went in to hospital due to the surgery and recovery etc I was told that I would not be detecting any more but as I found out that is not the case, which means buying more in the future, lol.