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Posted the following on a particular site and almost immediately picked up ridicule for adjusting the TDI in the manner stated. I'm a very open person and can take constructive criticism if need be.

After several hours hunting with the TDI SL I finally found the perfect settings for this particular site. This place is littered with the waste bi-product of burnt coal over many years. Much of the waste is small in size, ranging from BB to marble size and the smaller pieces easily attract to a magnet. In addition to that, the area is littered with nails ranging from 1 to 4" in length and some up to 4" deep. These nails, especially the larger ones give a good audio, especially with a ground balance of 8-9. After a suggestion from Reg, I began adjusting the GB to 4-5 and if the signal became inconsistent then the target was most like a nail. After a lengthy amount of hunting I decided to run the machine at gain max, pulse 10 and GB of exactly 5. Surprisingly the false signals all but stopped and I started finding old copper pennies some being wheat pennies in an area where I had gridded off and cleaned out of all good targets. Amazingly, I still can't believe I had missed that many targets with my other machines.

Now my next plan is to locate, what I believe to be good non-ferrous targets with the SL and mark each location. Then use my regular VLF machine and see if I can detect each target and note the audio responses given. Many things to consider in this journey, very excited to say the least.

Well it seems some people on other sites think it is a sin to adjust the TDI the way I did in the following statement. I want to add one thing; the ground I hunt is very unique. All I'm stating below is what I observed and found to be true at this site on this day. I'm very well aware the best settings would be GB 8 and pulse 10, but the ground does not allow the best settings to be used to produce what I'm looking for. Coins mixed in with heavy coal waste made of iron, BB size to marble size to be exact.

Well, went back to the same site where I posted, "perfect settings for this site" and hunted a small area not more that 60' from the prior hunt. Used the same settings "GB 5, pulse 10 and gain max" and off I went. After a short while I noticed a lot of clipped or inconsistent audio reports. Decided at that point to reduce gain to 7 and continued. Hunted a few more feet, still clipped audio, strange, so I stopped to analyze the area a little more closely, sweep in one direction and get a some what good audio, but the return sweep was either silent or chatter. Suspecting something was the cause I stopped and increased the pulse delay up a tad, nothing changed. Continued to increase the pulse until I reached 17 and suddenly the audio came through as a loud, almost overload low tone. Thinking it might be a nail; I dug and out came a copper penny at less than 4" deep. Now to say the least, I was excited and puzzled.

Decided to start over where I started hunting and experiment using a pulse rate of 17. A few moments later came the same type of loud low tone. Thinking there is no way I missed that one my first pass I changed the pulse to 10 and the signal all but disappeared. Increased the pulse to 20 this time and spent over 5 minutes rotating around this target checking from every possible angle to see what might be causing the anomaly, switched the conductivity switch to all and still a consistent low tone with nothing else mixed in. Now one must keep in mind I'm using the stock 12" and at times it is very difficult to exactly pinpoint where the target actually is. Changed the pulse to 10 and the low tone practically disappeared. Now I was wishing I had brought my Deus to recheck some of these inconsistent signals, maybe next time. Well anyway I dug a nice plug and out came a wheat penny at less than 5" deep. I was very excited to recover something from an area that quit producing years ago.

Continued hunting with settings of pulse 20, GB 5 and gain at 7, and found many more coins dated in the early 60's all within a 3' path some 60' long. Already planning what I'll do my next hunt.

What I learned from this hunt:

Regardless of what some may say, don't assume you have the best settings for any site especially the sites where coal waste has been discarded for many years.

I'm suspecting the partial or complete cause of the anomalies is the small BB size waste particles from the coal fired furnaces that will easily attract to a magnet. In fact dropping a strong magnet into the same hole where a coin was revealed exactly that.

I'm relativity sure I need a mono coil, but undecided as to what I'll get.

More reports to come.

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 You should expect a stern warning and perhaps some disciplinary action from he owner/ moderator of this forum. These actions may be avoided if you promise to return your TDI to the settings used by the "experts" and tamper proof the controls with super glue.

   EE GADS! If the danged thing works by holding the coil in your hand and dragging the control box on the ground THAN DO IT! Experimenting with a detector and sharing your discoveries and opinions seems to always be welcomed and appreciated here. 

What type of operation occurred where you are detecting?

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Indeed, experiment, try new things - most importantly, do what makes detecting fun for you! Thanks for the detailed post Mark. I think anyone tackling coin detecting with a PI and having any success is doing great. It is not considered a "normal" use of a PI but the TDI due to its manual adjustments can work some magic.

Steve's Guide to White's TDI Coin Settings

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On 6/25/2015 at 6:44 AM, klunker said:

 You should expect a stern warning and perhaps some disciplinary action from he owner/ moderator of this forum. These actions may be avoided if you promise to return your TDI to the settings used by the "experts" and tamper proof the controls with super glue.

   EE GADS! If the danged thing works by holding the coil in your hand and dragging the control box on the ground THAN DO IT! Experimenting with a detector and sharing your discoveries and opinions seems to always be welcomed and appreciated here. 

What type of operation occurred where you are detecting?

This is an old school yard.  The schools in my area burn coal for heat.  They take the waste from the furnace and spread in the school yard.  The majority of this bi-product easily attracts to a magnet.  All this happened many years ago, now the EPA requires waste be taken to the land fill.

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Some people might think what is happening is not explainable but there really is a simple explanation.  What is interesting is the reason these same coins were not found with the best of VLF's is the same basic reason and that is masking of a target by another target.  Unfortunately, trying to explain it could easily take a book or at least a chapter of information. 

Now, with that said, my response will be shortened considerably from what is really needed, but I will try to supply the gist of what happens and why. 

Turn the delay to 10 usec and use the All mode and you will hear both high tones and low tones over the ground Mark is hunting.  I know, Mark sent me a sample of the "dirt" for me to test.  So, why did advancing the delay suddenly cause the low tone "good" targets to be heard?  Again, the answer is simple, the high tone signals diminished sufficiently such that they were no longer a problem once the delay was advanced.

When you ground balance the detector, you end up with the ground signal balanced out.  All targets that are high tones have a target characteristic shorter than the ground signal.  

By target characteristic I mean if the intensity of the target is the same as that of the ground, then the signal would decay faster and would disappear before the ground signal because of the delay settings.  Increasing the intensity of the target signal causes the balance point to also be increased

Ever go over a camp fire place location and notice the ground signal increases?  Now, some of you may think you are detecting the old pieces of burnt wood, but that is not the case.  You are detecting the ground minerals that have transitioned because of the heat from the fire.  Because the intensity of the ground signal has increased, then a simple small advance of the ground balance control will cause this increased ground intensity signal to be balanced out.  Normally, a weak gold signal will not balance out this way.

Getting back to the ground where Mark is hunting, changing the delay and not the ground balance has a similar effect.  Advancing the delay can cause weak high tone target responses to diminish.  If such high tone targets diminish sufficiently, then deeper good low tone targets will become he dominate signal and will be heard. 

If the high tone signals are small weak targets then even raising the coil rather than scraping the ground can cause such high tone signals to diminish sufficiently that they are no longer a problem then either.  Since coin size objects will normally be detected deeper by using a larger coil, then the use of a larger coil plus raising the coil some may not require advancing the delay.  Fortunately, copper and silver coins have a very long time constant, that advancing the delay cause very little depth loss.  So, often it is advisable to advance the delay also.

So, a simple response to Mark's problem would be to advance the delay sufficiently.  Then use a larger coil to reduce small signal responses, and finally, raise the coil a little. 

So, how much should you advance the delay?  Well, that takes practice but a simple turn of the delay control and listening to the high tone signals will help.  Advance the delay sufficiently that the weak high tone responses diminish if possible or at least are reduced noticeably. 

In summary I have mentioned advancing the GB when checking ground hot spots, advancing the delay when eliminating weak high tone signals, using a larger coil to reduce weak high tone signals, and finally raising the coil a little. 

In Mark's case, advancing the GB is probably not advisable. Instead, selecting High conductor and reducing the GB while increasing the delay will most likely be the best solutions.  Add using a larger coil plus raising the coil while hunting just may help also. 

Steve is absolutely correct, experiment, try different settings of the controls, but more importantly, learn just what each coil does or is supposed to do.  The controls are on the detector to be used.  The key is to know when and why a control should be moved. 


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Reg has been So Patient Ever since the SL came out Answering questions, When it comes to the SL despite my findings I still Ask Reg, If you find something that works for you That's Great, and what ever others say, Reg is Still The Best Man For the Job,

I think it's great how you have got Coins popping out of the Ground, Keep up the Good work, I would like to know why your VLF never saw Them.

Thanks for Your Post

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Amazing and very clear answer Reg.  Thanks so much.  I'm convinced I need a mono coil in place of the stock 12".  Had something very interesting happen or yet discovered about the TDI that I might share when I prove it to be fact.  Well Reg most likely already knows.

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  • 1 month later...

Only this morning I read one of Steve's articles when he was at Moore Ck. and how he adjusted a machine to suit a different patch of ground on tailing heaps.  

Delete the slagging you copped from the chatterati.  They've got little else with which to amuse themselves.  Besides if they were any good at all at this business they'd be out on their boat with a beautiful woman drinking expensive champagne that they bought with all the gold they found with the TDI that hadn't been adjusted.


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  • 2 weeks later...

They Can't I got the Boat and took the Girls, lol

Seriously I am fooling with my SL and because it is a Manual type machine makes it harder when starting out with it but once you get to grips with it starts to make sense, sometimes it seems like the more I learn the Less I know and the key to using it is NOT to over think It.


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