Posted 19 November 2010 - 07:25 PM
Posted 19 November 2010 - 09:39 PM
Posted 20 November 2010 - 09:14 AM
You can read all sorts of info on the TDI/TDI pro here, http://tdi.invisionp...rum=tdi&act=idx and here, http://z7.invisionfr...dex.php?act=idx
there is a ton of how to and info here. I have a TDI and it is a great detector, and a very flexable detector. If you spend the time to learn it and use it then it will serve you well. You will have to put the time in and spend a lot of time in the field with it, but it is a good detector. I also have a GPX 4000 and they are nothing alike, except you swing them. Each has it's own place and use.
Posted 20 November 2010 - 09:26 AM
Posted 20 November 2010 - 04:27 PM
Then why don't you have one ? they are lighter than the minelabs Mike C...
Posted 20 November 2010 - 04:48 PM
Posted 20 November 2010 - 08:50 PM
Ha-Ha Rod ya I'm getting old thats why I'm using a rino now but I can still keep up with the best even with my out of date 4000 which is at the ML trama center right now- -I must admit though I did find more gold with my extreme than I have with my 4000-but that could be because there was more gold to be found then- - as far as the Tdi goes I personally know of 2 people that sold them after they seen what a ML PI could do up against their Tdi's- --I personally think that Dino as in Jurasic would suit your extreme just fine Mike C...
Mike, you need a light machine? Heard you were getting old Me I'm still young an virile and can carry around my old, out of date, gold finding GP Extreme (GPX) Even choose to keep my GPX when I "upgraded" to the 3500 a few years back Plus it would not be penny wise to buy one given the aforementioned Been thinking about a name for my old GPX...Ol' Betty...Ol' Reliable...maybe Ol' Mike C. ?
Posted 20 November 2010 - 09:02 PM
Posted 20 November 2010 - 11:44 PM
Hey Rod Rino as in Garmin-for my Ol-timers memory-Ha-Ha---Mike C...
That sucks your detector is on the blink Mike Especially right as the good weather kicks in, but I'll bet you have a back up Been thinking about a Rhino, maybe trading in my quad Its a hard call. Plenty of gold still out there, somewhere Maybe get a dozer Love the old dino detector
Posted 21 November 2010 - 06:41 AM
I suspect the two TDI owners that sold their units did so after only owning them a short while. As such, they didn't know the tricks to make the detector hum. Worse, yet, they probably found a way to really make the TDI look bad. Yes, the more expensive units can go deeper, especially on a certain size gold. To make matters worse, if a person doesn't know this or know just how the TDI works, or the best way to adjust the detector, then it is really easy to make the TDI look bad. So, it is easy to make a detector costing 3 to 4 times as much to look better.
It is easy to make the TDI easily ignore gold sitting right on the surface. It is easy to adjust the TDI so it is too noisy. It is easy to tweak one of the controls and lose over half the maximum depth on certain objects with a simple twist of a knob.
On a different note, it is easy to hunt areas with the TDI that cause other PI owners to quit. On one of my last trips to AZ I had a guy inform me he could hunt in the middle of Octave with his ML just as easy as I could with my TDI, but after less than an hour, he was done. I hunted the trashiest locations with ease and only dug a few pieces of junk. Unfortunately, I ended up with only one Barber dime and a handful of other non ferrous stuff for my efforts but it was fun.
Now, I loaned my TDI to Tony Pancake on one of my last trips down to AZ and we hunted Octave again. During that time, all he could say during the hours we spent hunting in the middle of that trash can called Octave was how great the TDI was and easy it was to tell the iron junk from good targets. BTW, his ML sat in the back of the vehicle.
What was the difference between Tony and the guys who owned a TDI for a few days? Well Tony has owned different ML's and knew the quirks of them as well as how a PI works. He knew what to expect and the basics of a PI. So, for him it was a simple fast track with a little help from me to get a good handle on the TDI and he was off hunting right in the middle of Octave amongst the cans and other junk and all the while finding even new tricks to use to eliminate digging or recognizing the junk. During those few days he used the TDI, all he could do was yell over to me letting me know what he liked about the detector and another new trick he found to use. Oh yeah, Tony was given the knowledge of a few tricks on what to expect if the TDI was adjusted a certain way.
Now, there is no doubt that the ML will go deeper, especially under the right conditions and even Tony knew that. Change conditions and locations and things can change. Besides being able to minimize digging trash in the trashy areas, it was easy to walk directly under power lines with a mono coil and not have to worry about readjusting the detector. At the end of that trip Tony was pleading with me to leave the TDI with him for a while.
Personally, I can take a TDI to a park, hunt for a couple of hours and basically dig nothing but older silver and copper coins while not digging trash of any sort. The nice part is, I don't even hear the trash signals. I can then go to a ghost town and do the same thing. Hunting meteorites is a piece of cake with a TDI and again, I can ignore much of the trash. When time and location is available, I can hunt gold, both large and small in about any area including some of the trashiest locations available, while again, not digging much if any trash.
I can target small gold or large gold, depending upon what I want to do while ignoring a lot of other things including much of the trash of the area. Unfortunately, I can't tell lead from gold, but I can tell basalt from the good stuff, which as you probably know is to be found in many gold locations including around Octave.
I can easily find a half oz nugget in the middle of a nail ladened area and not dig or even hear a signal from a nail. I can also search the same area with a little different setup and find the smaller nuggets in the few grams or less and still not hear or dig nails. Again, it is because of knowing how to adjust the detector and how it works.
I can make a Rich Hill 1/4 oz nugget depth of detection go from a few inches to as much as 2 to 3 times more depth just by knowing how to tweak the machine. Unfortunately, this is the down side that most new owners don't know or understand. BTW, this same condition exists on the SD's also.
At Model Creek, we found a bunch of nice larger nuggets many of which were a half oz or more. Now, at Model, I could hunt those same nuggets and again, ignore nails and most thicker iron junk and still detect nuggets from a few grain in size to larger than a half oz or more without making any changes to the detector.
Is the TDI perfect? Nope, in fact it is far from it. Do I have to make more adjustments to maximize the use of the TDI? Yep, but a quick twist of a knob and I know what to expect and how to pass over a nail or even a full size tin can and not hear a peep. I can get a strong signal from either with nothing more than applying a few tricks or a minor adjustment. So, I can make the TDI look like a unique PI or one that clearly doesn't go as deep as some others.
Would I trade the tricks I can do with the TDI for shear depth I might get with a different PI? Not in a million years. Today, much of the gold left is hidden in the areas where others fear to tread, simply because of all the trash. Those places are open to me and I don't have to worry about digging everything to find what little gold is left. Will I miss some? Yep, but so will those who get frustrated after digging a ton of nails and nothing else to show for it.
Part of the fun of owning the TDI is the ease of building a new coil. Find a housing that meets your needs and as long as you can count the number of turns and have basic soldering skills, and one can build their own designed coils. The beauty is, they will work even if one screws up a little. No, you may not be able to operate at the shortest delay, but close to it.
Want a 3' square coil to hunt large meteorites? How about a 2' by 5' one that you can drag behind your ATV and still work fine? Maybe you want a "Clean Sweep" type coil that is long and narrow you can use to quickly hunt a fairly large path each sweep but still be able to poke it under brush. The trick is you can build your own with relative ease once you know the basics. If you don't want to build your own, well, others are now building different sizes of coils and the price is surprisingly quite low.
Own one of the first 200 units, and it is easy to make that detector detect smaller gold. However, this trick should be left to those who know how to make the right changes.
Now, with all that said above, I don't recommend a TDI to just anyone. Many new owners will not learn all the tricks over night, in a week, or even in a month or two. However, those truly interested in wanting a specialized PI can learn enough in a day or two to do quite well, just like Tony did. The trick is to adapt to the TDI and not try to make the TDI adapt to you.
Posted 21 November 2010 - 10:43 AM
Great post! I 'm planning a trip to Gold/Lost Basin this winter/spring and my TDI will be my main detector with my GPX as a close second. I have never been there or detected the area but I do know that EMI is a big problem in the Gold Basin area. My TDI will handle the noise much better and it works great on small gold and space rocks. Now if by some near miracle I find a patch I will grab the GPX and put on a big coil and search for those big lumps, but I'm not holding my breath My TDI is much lighter and easier to get in and around brush and boulders. I really like the 8.5X11" Razorback mono coil it is just a great go to coil, but if it don't cut it there, then I have my 12" DF, a NF 14" elip as well as my 7.5" DF to cover just about any situation. What is great about the TDI I can use any coil my GPX will and a lot the GPX will not work with. I can even slap on a big old 18" and get way down there, and because the TDI will run so quiet I can here the little bumps in the threshold that could be that deep chuncky. I normally don't post my gold, I like to keep a low profile. I would like to show a few I picked up this summer/Fall, with the TDI and the 8.5x11 Razorback these were found near a High Power line high in the Rocky Moutains. The GPX just could not get these little dinks because of the EMI from the transmission line so near by. Got these at over 12,200 ft above sea level. Reg may know close to where I snagged them. but I trust him
Posted 21 November 2010 - 07:32 PM
Posted 21 November 2010 - 08:28 PM
Thanks to all for all the info im mainly a panner ive had a couple of detectors in the past 7 yrs but got discouraged and sold them this time im in for the long hall. I figure if i put fourth the effort in I will be succesfull. Also im gettin lazy dont feel like panning my back gettin sore. Good Luck To All Jason
Help I have one coming and is there any pointers or suggestions for the proper use of this machine. Thanks Jason
Posted 21 November 2010 - 09:55 PM
Hi Reg sounds like a very versatle beeper indeed and it would take some getting use to-I think you should put out a vidio showing how to properly use the TDI-I've always respected and listioned to what you had to say---Tell Tony P I said hey--- Mike C...
I second that thought, as far as I know no one is out there with a TDI video, might as well take advantage of the supply demand thing. Plus, I think probably no one else would be as qualified to host one.
Posted 22 November 2010 - 02:02 AM
Thanks for the kind words, but making a video or even making another trip to AZ isn't in the cards right now. For those of you who know me, know that almost every time I came down to AZ, I had my dad with me. He loved his nugget hunting and later, the meteorite hunting. Well, a couple of years ago, his back simply gave out and his trips were over. Today, I am struggling to get him situated in a nursing home and that has become a full time job bucking family and the system. Personally, I am totally exhausted, frustrated, and disgusted but all of that is a different story since none of it has to do with gold hunting.
So, doing much specifically outside of posting on a few sites or a trip or two to the mountains when weather permits, or maybe a simple trip to a park for a quick hunt is out. I do use the posting on a few sites as a means of a form of release.
Over the years I enjoyed my trips to AZ where many were to field test a different detector. That is where I met some of you who read or also post on some of the forums. Over the years I have enjoyed discussing various metal detectors and the tricks that can be done with different models. Personally, I have enjoyed almost every detector I used because each and every one has some trick or benefit that makes it special.
Well, most of those days are gone now and it seems it is almost impossible to have a decent discussion about a detector without some criticism if it isn't a certain model of PI. That has gotten so old and discussions so bitter that I have been called a hater of a certain brand. To that I say bullshiit. I just won't bow to any model or brand and that includes the TDI.
To be honest, this is one of the few sites I will post on any more because a person can post the truth or say something decent about a different detector and not be called a certain brand hater. It is too bad some people can't realize that the tool we use to hunt nuggets is just that a tool to be enjoyed. Personally, I enjoy trying to help those who hunt for gold regardless of what detector they use. If I can help a guy learn his detector better and help him with tricks so he has a better chance of finding gold, I am happy.
Better yet, I have found gold with a lot of different detectors and to be honest, I don't have a bad word to say about any of them since they served me well. To be honest, I still have a lot of those detectors including my GB 2 or have recently picked up a used VLF such as a GM 4 so I can try it to see what advantages or disadvantages I can find when using it.
Like so many others out there, I can't afford or even justify spending more for a detector that I did for my used truck. Maybe if I lived in the gold producing area I would have a different opinion, but I don't. So, like so many others I buy or use what I feel works best for me. This has lead to friendships turning sour to the point they will never be repaired.
Hunting for gold is fun, but what is frustrating is watching the bickering going on even today on forums over detectors or issues relating to detectors. Why? I know the frustrations of trying to develop a new design and what takes so long. Heck, back several years ago I had to learn a lot about PI's simply because I needed a very light weight unit for my dad to use because of his back. So, I ended up building a low powered ground balancing PI that really worked quite well. For a detector that weighed less than 3 1/2 lbs it really was quite a little detector. Also, that little detector added a couple more years to my dad's ability to nugget hunt. So, the design had special meaning to me.
Thanks to guys like John Blennert who was nice enough to send me a couple of his "invisible" nuggets, I learned just why small gold isn't easily found with a PI and what had to be done to detect it well. I ended up modifying a PI detector that could do what other PI's couldn't do and that was to detect much of this "invisible" gold. To be honest, I was quite pleased and proud if you want to know the truth. Unfortunately, a few others mocked the fact I could detect gold others couldn't find with their detector and soon was informed I was a hater of a certain brand of PI. To that I say, bullsh*t, and it is one of the reasons I really don't have a lot of desire to post much anymore.
Personally, I think there are a lot of people who lurk simply because they don't own the latest and greatest and don't want to be insulted or humiliated which does happen on some of the other forums. This forum and and on Bill Southern's forum are two where people can ask a question without the discussion ultimately ending up as a bitching match.
For those interested or even curious, I understand Dave Emery's position and his desire to build a discriminating PI even though he put me in a spot or two in the past. I understand the frustrations and limitations of different PI's or even VLF's for that matter. To be honest, I have very few detectors that haven't been modified one way or another. I understand the frustrations and design quirks Bugwhiskers is going through with his design of the QED.
For those interested, yes, the QED exists and will work quite well once it is released. Yes, I get tired of Doug making an issue of this detector, but that is his thing, just like his criticism of a certain brand of PI. Guys like Doug who point out limitations or quirks of a particular detector and boy do they get slammed. Why?
The sad part is every detector has a weakness and if a person knows that weakness, then the owner is far better off knowing about it and how to overcome it if it is possible. Yes, the TDI has its weaknesses. Like other PI's, there is what is commonly called a "hole" in the detection of certain nuggets. Nuggets that mimic the ground signal can be ignored quite well or have a obvious reduction in detection depth depending upon how the detector is adjusted.
Doug pointed out this condition on a particular detector and again he got slammed. Why? Don't people want to know why their detector may not work as they expect under certain conditions.
Now, I feel I should point out why some gold may not be detected that well and how to minimize this condition for the TDI owners. If I don't bring this situation forward, then they will stumble into it some time in the future and be totally frustrated, but worse yet, not know why or how to overcome the situation. So, for those interested, yes, the TDI isn't perfect.
This same weakness if you want to call it that allows me to go to a local park, set the detector up to ignore zinc pennies and simply find clad dimes and larger, or older silver or wheatback coins. It also allows me to ignore or minimize signals from nails or even tin cans for that matter.
Now, for the TDI and using it to hunt gold at Rich Hill, I have to be careful because a certain size nugget within a grain or two can be almost ignored. Increase the size a few grains and that nugget will be detected several inches deeper. Tweak the ground balance control (GB) and one can do the same as changing the size a little, thus one can double the depth of detection of that certain size piece of gold.
Wander to a different location and the situation can change so dramatically that one wouldn't even know this condition exists. Actually, what changes is the gold and its characteristics. Yes, it does make a huge difference on PI's and this difference can affect VLF's some also.
For those of you who use a PI, did you ever wonder why some gold gives a high tone and other gold responds with a low tone? Did you ever wonder why the tone can differ? Better yet, what happens to the gold that falls in the range where the tone of that gold just changes from one tone to the other?
Here is where it gets better. Ever wonder why it seems that one coil seems to work better than another? Is there really that much difference and if so, why? There are reasons for the differences and no, one coil doesn't have more magic than another.
Getting back to the TDI, one will not find dramatic differences between coil brands that are basically the same size. So, if you are looking for that "magic" coil, dream on. The TDI brings reality back to coil use and what to expect. Will one appear to work better than another? Yep, that can happen but in many cases, a simple adjustment can turn the tables and the opposite coil will now appear to work better. The trick is to know why and how to best set up the detector even for the coil used.
Here are the facts about coils. First, most manufacturers try to build a coil to certain specs, which means they use certain number of turns of wire for a given size coil to obtain a certain inductance. As a general rule for the TDI, that inductance is 300 uh, which just happens to be the same as another major brand of PI. BTW, that has been Eric Foster's preferred inductance for many years before other brands even existed. So, no, it isn't something copied, except maybe by other manufacturers.
Usually, the wire size is consistent so coils made by different brands also will have the same current during operation. This can change from a TDI coil to one of the third party coils made for a different PI. The third party coils can and will draw more current. Actual measured current has changed maybe 15% on the average. So, more current should give more depth right? Maybe. If it did, how much might one see as an increase? Well, as a simple rule of thumb, if you double the current you might see an inch or more depth on a coin size object. Change the current 15% and one might be able to measure the difference using special test equipment. To be honest, far more depth is gained or lost because of noise and noise related adjustments. So, building a coil that tries to minimize noise and one may gain more than trying to increase the current.
However, increasing the current can and will cause a shorter run time on a set of batteries. Also, increasing the current generally means increasing the wire size. This will also increase the weight of the coil.
Now, getting back to coils and noise, different types of coils have different noise characteristics. If we keep the coil size and type the same, then shielding becomes the key factor.
So, as one can tell, there are a lot of factors as to why one detector or even a different coil can appear better than another. All the screaming and yelling or criticism or simply plain bad mouthing isn't going to change the results. What can change the results is knowing what can cause problems and how to minimize those problems.
Posted 22 November 2010 - 03:57 AM
I do find as much or more because I hunt slower!
Thanks for posting, let the bashers bash, they will any way.
Posted 22 November 2010 - 07:39 AM
I was wondering. Do many people use the "hip-mount" feature of the TDI? I use it that way all the time, and it helps a great deal by taking the weight of the control box off of the rod.
I would think that other types of detectors could be used in this manner also?
I hope the issues you have will all work out quickly and smoothly.
Thanks again for sharing your knowledge.
Patrick in Havasu.....
Posted 22 November 2010 - 08:31 AM
Thanks for the great reply about your fantastic find. I suspect you were pleased when you found the ring but extremely pleased once you found out how much it was worth. It is this type of information that motivates people and keeps them going when they get discouraged. It also lets people know the LST can be used for other purposes besides nugget hunting.
BTW, I field tested the LST for Lost Treasure when it came out. In fact, my dad even found a nice small nugget with it the first time he had it in his hands. One other note I should mention is I couldn't do as well with the TDI by any means. The TDI does very well at finding silver coins when hunting parks etc, but the LST discrimination feature will beat that of the TDI when finding low conductive thin rings. The TDI disc feature works well on some ferrous junk when in the low conductor mode, but not so well on the thin junk such as bottle caps and pieces of tin cans. On this stuff, it takes other tricks to help minimize digging of this junk.
Now, one trick I found out that worked on my LST was to operate in the Alkali mode. This allows for a wider ground balance (GB) range which does something unique and that is, it allows the GB to disc out very small ferrous junk. Yep, take a boot tack and pass over it a few times and the signal from the tack fades. Pass over a small piece of gold and the signal doesn't fade.
One down side of the Alkali mode is the LST will quickly tune out the stony meteorites such as those at Gold Basin. So, if a guy is going to try to hunt them with this detector, make sure to use the normal GB mode.
Now, since I wrote that info into my LST report, I ran into another LST that didn't fast track nearly as well as my unit when switched from normal GB to Alkali or as fast as my unit did. So, each LST should be tested to make sure this feature works for them.
For what it is worth, I found my last decent size nugget (over a half oz) with a VLF and not my TDI. I purchased a GM-4 some time back and it didn't work quite right. After owning it for a while I took it apart I found a simple grounding lug had come loose. So, after reconnecting it, the GM-4 began to work just great and was a whole lot quieter. Well, I decided to try the unit in an area known to produce very small nuggets to make sure it really was working correctly. Instead of finding a small piece of gold, I got this strong response just a few minutes after starting that didn't iron stutter. To my surprise it turned out to be a unique piece of gold wrapped around some reddish colored quartz. The almost crystalline structure on part of this nugget makes this nugget quite unique and quite beautiful once it was cleaned up. Unfortunately, I haven't been able to capture its beauty with a decent pic yet.
So, as both of us have pointed out, there is still a need for a good VLF. For me the trick is to hunt slowly, smoothly, and be persistent regardless of the detector used. The other point to be noted is VLF owners can still find valuable objects with them. Again, the trick is to know the detector and how best to adjust it.
Thanks again for sharing the info on the ring.
Posted 22 November 2010 - 09:40 AM
I can't tell you how many people use the hip mount feature. I know I don't. Years ago, I used to chest mount different detectors but always got tangled up in the cords, just like I did when I tried a different PI, so I abandoned the chest or hip mount feature. All I can say is chest or hip mounting is a personal choice. Some people like it and others don't. I am one of those that don't like it.
The weight of a detector and its negative effects, especially on my dad, is one of the key reasons I built the light weight low powered PI. Then I built very light coils using two part foam instead of epoxy and finally I came up with a bungee setup to suspend what little weight there was making even the low powered unit almost weightless.
To get the balance right and the suspension such that it didn't cause stress regardless of how the detector was positioned, I bought a bunch of different diameter bungee cords and experimented until I found the right combination. Once I was done, the detector would simply suspend if let go and was almost weightless even when hunting a wall. The smaller cord made stretching the cord extremely easy so there was almost no strain no matter what I did with the detector. This feature made detecting a whole lot easier for my dad even though the detector was light weight to begin with.
Today, I could use 4 AA size Li Ion batteries to power that low powered PI, so you can see even the weight of the batteries wouldn't much of a problem. Back then I found some small light weight Li Ion batteries and made my own battery setup. I could hunt a day without changing or having to charge the batteries.
Now, here is something few people know about. One of the features I built into one of my low powered PI's was a quick unique way of testing to see if an unknown target was ferrous junk or non ferrous. This worked mainly on small gold less than a 1/4 oz or so and worked well down to less than a half a gram or so. Smaller than that would be a very small signal so it was simply worth it to dig those targets. Since most nuggets found fall in the size range from a quarter oz or less, I seldom dug any junk.
Unfortunately, that simple feature didn't transition to the TDI but it did lead to expansion of ideas that, when using test equipment for evaluations rather than circuitry, I can tell ferrous from non ferrous for all sizes of gold or any iron type junk. So, this feature could add something even more accurate than what the TDI has now.
All that has to be done now is to finish the design and build the add on feature. The sad part is I have lost interest or desire to finish that project. Since I highly doubt I will be doing much extensive nugget hunting, I just can't get motivated. So, now the bitchers and naysayers have one more person to bs about, me. Personally, I can see no reason I would ever build such a feature for those kind of people and if built, somehow it would end up in their hands also. So, I will let someone else do it. Personally, I have nothing to prove and don't care if people believe me or not.
One more little note a lot of people do not know, before the TDI officially existed, there was no single tone mode. In fact, the TDI almost came out without it. Then the single tone mode was added to a GS 5 and viola, what a difference. The ability to take a PI to a park and dig older deeper silver coins missed by the best of VLF's was and still is fun. The ability to target low conductor or high conductor metals and ignore the other adds a whole new dimension to that detector. Now, back when that feature was initially added, there was one and only one detector with it, mine. At times I wonder that if I had not pushed the idea what it would be like to have the only detector to have that unique feature.
Maybe because of the fact of how it came into existence, I am partial to the single tone mode.
Posted 22 November 2010 - 10:10 AM
Posted 22 November 2010 - 10:49 AM
Very informative posts, Reg. In the not too distant future I hope to round up funds for a more modern gold detector than my old original Lobo recently rescued from the closet. And learn to run it well. A TDI is on my short list.
Posted 22 November 2010 - 11:18 AM
The original Lobo wasn't a bad detector in its day and with a few mods worked extremely well. Just ask Tony Pancake. He still has one of my original lobo's that has seen a lot of hard use.
Do you live near Peeple's Valley? If so, let me know. Tony still has one of my Lobo's and you are welcome to try it and compare it to yours. I think you will find the disc feature to be far superior on mine and also find the detector to be quieter as well as more sensitive.
The original Lobo had a disc feature that didn't work that well. The reason is the idea behind its design. Instead of making the design to work best in discriminating out gold so it could be determined, the idea was to provide a design that sort of disc out other items and if it didn't sound off, dig it. The basic concept was sort of backwards from most discriminators.
Now, on my old Lobo there were dramatic changes to the disc feature that made it match or beat anything out there at the time I made the changes. Also, the gold/iron separation was far better.
The other one I have here at my house was overcompensated in the all metal mode and needs to be tuned down. On the other side of the coin, the mods to the disc feature worked very well and made it quite a decent coin machine even when using the small elliptical DD coil, which was my preferred coil.
One big difference on my Lobo is the ground balance (GB) has to be right or very close for the best results. If it is off the wrong way, you can get strange moaning responses from some hotrocks. If that happens just tweak the ground balance until they just stop. You will find this will occur when the GB is slightly positive.
Posted 22 November 2010 - 11:26 AM
That is quite a collection of goodies your wife accumulated. Looks like she has how to use the Lobo down very well. Tell her to keep up the good work.
Posted 22 November 2010 - 05:00 PM
That's a great haul. Not only one, but two "brass" knuckles.
Very informative posts, Reg. In the not too distant future I hope to round up funds for a more modern gold detector than my old original Lobo recently rescued from the closet. And learn to run it well. A TDI is on my short list.
Posted 22 November 2010 - 06:15 PM
Posted 22 November 2010 - 09:46 PM
There are a couple of key issues that need to be addressed when using the TDI and why a person should use the single tone feature. To begin with, one extremely important issue was mentioned before and that is to know the characteristics of the gold in the area you are hunting. Yes, it makes a huge difference on all detectors but with the TDI it gives the opportunity of the operator to maximize the possibility of finding a nice nugget.
So, to better understand what I am saying, it is important to know that one can have two nuggets both 1/2 oz and have one respond as a low conductor and one sound off as a high conductor. The way the TDI should be adjusted depends heavily on knowing which is the most likely and why.
So, lets talk about the gold first. Gold is gold is gold right? Wrong, pure gold is best described as a high conductor and will respond dramatically than another identical size nugget that has other alloy metals such as silver, copper, or some other metal. Take a pure nugget and melt it down and then add a little of the other metals, even one more conductive such as silver that the combination changes conductivity dramatically. A nice pure nugget that is highly conductive can suddenly become a poor conductor that is more difficult to detect deep or because of the setup. Now, is this my idea and my opinion? Nope, in fact a certain lab builds test alloys that are calibrated and even have their specs posted for the world to see. Here is a link to that site for those interested.
Now, if you look at the chart, it probably won't mean much but look at the conductivity column and note that pure gold is 77 but the next step down is down to 16. So, what does this mean? Well, at a conductivity of 77, the gold responds as a very good conductor but alloy the gold with silver and it can easily drop dramatically. Note that a 75 25 ratio with silver, that 77 drops to 16. In simple terms, the high conductor suddenly becomes one of the lousier conductors and this makes the gold react totally different on a detector. On a VLF with target ID, this could mean two identical sized nuggets that have the ratios mentioned above could read on something like a dime to a quarter when pure but when at a poor conductor conductivity may read as a nickel.
On a PI, this can mean the gold can or may respond as a strong low tone on the TDI for the pure gold to a strong high tone on the alloyed nugget. Change the alloy and that same nugget can respond anywhere in between. BTW, this condition doesn't just happen on the TDI but on all detectors including other PI's. It is most obvious on the SD versions for those interested.
So, what does this really mean? Well, how the low tone and high tone are developed is determined by the signals as they relate to the ground balance (GB) control setting. If the detector is properly ground balanced and there happens to be a piece of gold that mimics the ground signal, that signal from the particular gold can be minimized just like the ground signal. So, at just the exact right nugget, the signal from that nugget can drop to nothing or almost nothing. In other words, on a nugget that may be detected a foot or more under certain conditions may drop to only a few inches of depth. Change the nugget by a few grains and the depth of detection jumps significantly. Alter the GB adjustment just a little and the same thing happens. Now, as I mentioned before, this condition isn't unique to the TDI. In fact, I first noticed it on my dad's SD2100. At the time, I wasn't sure what was happening or why, but I knew it existed because my low powered PI clearly would detect a particular nugget almost three times as deep as the SD.
Now, if we combine this high conductor/low conductor knowledge to the single tone feature and what happens is we can select to detect high conductor objects separately or switch to low conductor objects while ignoring the other that is not selected. Combine this ability with the fact we can change how certain conductors react and we can now sort of pick and chose those targets we want to detect and the ones we want to ignore.
As a good example, lets say we are in an area where all gold of any size reacts as a low conductor. This happens more than people realize. Anyway, knowing that even 1 oz nuggets will respond as a low conductor, then selecting that mode and then adjusting the GB so that nails now respond as a high conductor, then when the detector is switched to the low conductor mode, all gold within the logical range will sound off loud and clear while nails and other typical thicker ferrous junk will generate a high conductor signal and as such will be ignored.
Enter an area where gold larger than a 1/4 oz responds as a high conductor and a person can again, adjust the detector such that nails now respond as a low conductor and now a person can hunt the larger gold in really trashy areas and simply ignore the junk.
One quick note on ignoring this junk thing and that is, if the coil is too close to the junk, it can react with an overload response that generally sounds simply like a strong good signal. However, raising the coil and checking again will quickly tell the operator if this is the case or the target really is a good target. By raising the coil sufficiently, the overload signal will suddenly cease and the object disappear. A good target signal will simply fade smoothly under the same conditions.
Ok, so now we know that gold can change signals just because of the gold purity. Well, change the surface characteristics or general characteristics in structure and the same nugget effective response can change dramatically. The important thing to remember is the gold from one area may respond totally different than that from another.
So, once a person gets a handle on the fact the target can respond differently simply because of the conductivity of that target, then it becomes important to fully understand just how the GB control can affect the depth of detection of that object. As an example, take a nugget that generates a high tone at normal GB. What happens as we advance or reduce the GB control. Do things change? Yep and if a person wants to get the most out of their TDI, they will know how the things will change.
I learned if I tell people just what to expect, they will not test it for themselves, so I prefer to let people determine their own destiny. I will say that what happens will happen on other detectors also but may change characteristics because of the design. In the case of the TDI, simple testing will give a guy some idea of what to expect.
Now, I have mentioned using the single tone mode before and the fact I can target certain objects or types of gold using this technique. Why use the single tone mode when using the All mode will let me detect all objects? Well, listen carefully to the noise base in the All mode and then in the single tone mode and one will quickly figure out the noise level can diminish by a half or more. This allows for an increase in the sensitivity adjustment and still have less of a signal loss. Minimize the noise and the depth can change very significantly. To get an idea of how critical this is, I have conducted tests in the past and on something the size signal signature of a nickel can vary in depth of detection of up to 4" or more quite easily, but at the extreme, I have noticed up to an 8" depth difference.
Now, add the noise factor to the potential depth loss caused by the GB action and one can easily cause a TDI to really look bad if it is adjusted incorrectly for the conditions.
Could the TDI be refined dramatically? Yep, but be prepared to pay a whole lot more for that same machine. In other words, the TDI costs less but comes with less features. On a very expensive vehicle, you can adjust the air conditioning for a certain temperature for the passenger or separately for the driver. On a car costing half as much, you get to manually close vents to accomplish the same thing. On detectors, similar situations exist, where the operator has to make the adjustments. That is what is necessary on the TDI.
This brings up something people complain about a lot when using a PI and that is the ground signal problem and the need to use a DD coil. Also, how necessary the automatic ground balance feature is. Well, the TDI doesn't have the dramatic sensitivity capability and this feature alters just what is important and what is not.
In simple terms, is auto ground balance needed here in the US? Nope, at least not in any of the areas I have hunted and that covers a very wide range of conditions. Even in OZ where the ground is so dramatically different than over here, the TDI does very well without the need of an auto ground balance feature. So, over here it is a piece of cake, simply set and forget if using the All mode in most cases.
To be honest, I have hunted in areas where others complained how bad the ground was only to find I could turn the ground balance off and hunt with ease with the TDI. So, yes, there are locations were no ground balance is necessary. BTW, with the GB turned off and minimal noise the TDI depth of detection increases to quite close to much more expensive detectors. If external noise becomes a problem, then the TDI may even become the deeper of the two detectors.
In other areas, a person can adjust the GB through the entire range and not have any major problem with false ground signals. Finally, there are isolated areas where the GB is actually quite critical. So, each area can and should be tested accordingly. It is extremely difficult to get owners to do this, but once they do and realize they can alter the adjustments dramatically, the enlightened owners will then begin to full appreciate just what the detector can do.
As for the controls on the TDI, well they are simple to adjust once a person full understands what can and will happen. Fail to take time to learn just what the controls can do and a person might as well pick a different detector because they never will be happy. The critical controls are few in number which is nice. What really needs to be learned is just what to expect when each is adjusted and why.
Posted 23 November 2010 - 09:58 AM
Where can I buy your book? If you don't have one you should. You obviously have a lot of knowledge to share.
Posted 23 November 2010 - 03:40 PM
Looks good Rod.
This is one of the best TDI threads ever. I've added some of it to the main website if anyone objects I'll remove it, would be a shame though. This is info all TDI owners need to see
Reg, CH please have a look http://www.arizonagoldprospectors.com/
Posted 23 November 2010 - 03:57 PM
One item that is probably there that , we would particularly like to recover is the lower half of a Spanish American War Veterans Metal, my wife found the upper portion years ago, the lower portion has the serial # and then we would know exactly who it was given too! That would be so cool and we have a guy that can restore it and maybe we could find the guys family and return it on the aniversity or Veterans day. I love these kind of historical mysterys and we can turn FrogMick loose on it and he will ferret it out with the tenaciusis of a bull dog. Meanwhile gota get one of those TDI,s, there will be one on Craigs list.
The pressure is on ye Reg!
Posted 23 November 2010 - 08:18 PM
One thing I need to clarify about hunting in a trash loaded area is the TDI is like all other detectors in the fact it can't "see through" the trash. So, if there is a gold nugget under a can, the can will mask it. Now, nails don't prove to be quite as much of a problem depending upon just where the GB is set. However, if a nugget is deep and buried directly below a large nail, then most likely that nugget will never be seen either.
So, what actually occurs is the stronger of the two signals, (low conductor or high conductor) will dominate. If a person has selected low conductor but a high conductor signal is the stronger of the signal then the high conductor will be the one to generate a response. However, since the detector is in the low conductor mode, the high conductor signal is muted and this shutoff occurs after the determination as to which is the stronger of the two. So, only the high signal remains but that signal is muted, so no signal at all will be heard.
The way the signal is manipulated by iron makes a big difference also. The natural tendency is for all magnetic signals to try to concentrate in ferrous objects while non ferrous metals have a tendency to display a very weak diamagnetic action. So, the iron basically steals some of the detectable signal from other areas which can affect the detection of objects, especially if they are deep.
As for trying to remove iron junk, one of the good things about Octave is the area is quite barren, thus it is easy to remove much of the junk simply by running a large magnet over the area. Personally, I prefer to use one of the devices normally used to remove nails from areas after a house is roofed. Here is a link to basically what I am talking about.
Some of the units pictured are quite expensive but others can be purchased for about $40 or so (on sale). At least, that is what I paid for mine at Harbor Freight. Here is a link to one I have.
I ended up putting larger wheels on the unit and then had to modify it to lower the body again. The larger wheels make it easier to roll around in rough areas.
Now, in areas where I have used this, I have never removed all the junk but usually it was good enough for what I was doing at the time.
Getting back to the signals and how they react to ferrous junk, the theory is basically the same as that of a magnetometer which means iron will concentrate magnetic signals. On a magnetometer, the increase of the magnetic field is then detected, thus indicating a field disturbance which can only happen because of ferrous materials in the area.
Now, changing the subject to writing a book or carrying a recorder, well that is not in the cards at the present time. Right now, I used forums like this one as a means of escape from the truly frustrating issues I am dealing with. It is sort of my my way of leaving the issues behind for a while that are causing my gray hair to fall out. As such I don't know when the inspiration or desire will hit. For me, recorders don't work, been there tried that.
Now another problem with writing a book is having to start somewhere and stop somewhere. Worse yet, there has to be some rhyme or reason to the information between those two points. Now, writing about issues or a specific situation is limited and can be broken up easily. Even then, the simple things can get complicated.but there is always an end.
As a good example, I recommend people practice with the single tone mode. What I also need to say is a person should expect what should happen and when you do, how best to deal with it. To be more specific, lets say you want to use the low conductor mode in hopes of snagging a small piece of gold. Well, to minimize the detection of nails, we need to set the disc feature or better stated, the GB at the point where nails generate a high conductor tone. So, this means setting the GB above 5 and more likely at 6 or 7 to be safe.
Now, if there are no nails to contend with, then the GB setting can be used for other purposes such as increasing signal strength from a target as well as reducing the noise base.
Now to fully understand why the noise level (base) changes, we need to know just what the GB control is doing electrically and that is changing the gain of the GB amplifier. Increase the GB control and the gain of the GB amplifier is increased. The increase gain results in increasing all signal levels, especially the noise level, and this occurs more obviously towards the upper end of the GB pot.
Next we need to realize that the GB circuitry was primarily designed to ground balance out the ground signal. Thus usually occurs at a setting of about 9 on the GB control. This will hold true almost anywhere in the world. In other words, the setting won't change much even though the signal strength of the ground minerals changes.
Now, the ground conditions do change dramatically with the ground in OZ multiple times stronger than that found here in the US. Is this my opinion? Nope, actual measurements have been taken to substantiate this fact by Eric Foster using specialized equipment. Even though the strength of the signal changes, the characteristics of the ground signal are such they don't change the GB setting that much if any at all.
Now, given the above information, then a general setting of about 9 on the GB should work for most locations, providing the detector is properly calibrated. So, if we deviate from the 9 setting, we should see an increase in the ground response. In areas where the ground signal is weak, the response at a GB setting of 4 may be so slight that it is almost impossible to detect. However, in other areas where the ground signal is extremely strong, then at the GB setting of 4 just may see a noticeable ground signal reaction if the coil is bobbed up and down.
So, if a person wants to use the GB disc feature and need to set the GB at 4, then common sense 101 says, don't bob the coil any more than necessary and preferably not at all. At the same time, that common sense factor should also be used to understand that if we pass over a rock while the GB is way off, we could get a noticeable reaction. Why? Simple, the rock has a totally different makeup than that of the ground, so basically, passing over a rock that is embedded in the ground will appear to the detector more like a void or a hole in the ground structure, and a hole acts much like bobbing the coil up and away from the ground as it passes over the center of the rock but sort of like bobbing that same coil back towards the ground when leaving the surface of the rock.
One more thing on this subject and that is in some areas such as dry washes, there can be a layer or a stripe of black sand that may or may not be noticeable. Adjust the GB way off and pass across a stripe of this black sand and suddenly there is a response. If this happens, then we are detecting the black sand right? Nope, but most people will not believe that. That black sand does two things, concentrates the signal and creates a totally different response much like the rock hole concept. So, we don't detect the black sand after all, but the fact the ground signal changed as a result of the presence of the black sand. Go over black sand by itself and providing the coil isn't right on top of the sand, you should not get a peep of a beep from the black sand if it is magnetite.
So, the disc feature isn't all peaches and cream and it has its limitations. BTW, this rock thing and how it can change the ground signal is even more critical to a VLF when trying to use any form of discrimination. In fact, it can cause something as large as a half oz nugget to be ignored if in the disc mode even when it sets right at the surface but next to the rock. To the disc circuitry, the rock is a void and sees it as a sudden step in the ground signal. This can easily result in the disc circuitry of a VLF also resulting in the rejection of a good target if a good target is indicated at the same time as the void step. Can this condition be minimized? Yep, but I will let people think about that one. Here is a dead giveaway hint, try to avoid the sudden step type signal. You can do this to speed bumps or a road to take the sudden jar out of hitting one when driving if there is enough room. No, going around the speed bump isn't the answer.
Ok, enough speed bumps and other odd things, as you should be learning by now, there is there is much more to maximizing the success than one might think. BTW, see how easy it was to begin at one specific issue as I did several paragraphs before, but then I had to wander all over the place to better understand even the basics of that one issue. Now, try writing a book under those conditions.
One more note, if you go back and print out all my posts in just this thread, then add a few pictures to highlight the issues I was discussing, there would be enough material for a small book and we haven't even started yet. So, consider this my first mini book free of charge.
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