Whites TDI 8uS mod?

I found and purchased a virtually new in the box through hole TDI from the original owner. After I get some hours with it under my belt and become familiar with it I would like to trick it out to an 8uS.

Does someone have the procedure for the tweak? I have looked on the net but haven't found any. I am handy with a scope, meter and iron. Reg? Tom?

/PB

Bob,

I had a through hole model TDI ( great unit but I had to sell it) and talked to Bill Crabtree from Surfscanners about modding the unit to get the delay to 8uS. This was about a year or so ago, and he told me it's not that hard to do,but the issue was finding a coil that could run at 8uS. I think at that time, there wasn't any made unless you made one yourself. Since then, I think Razorback makes or can make coils to run at that delay setting. Bill is no longer in business but frequents a few forums and is the administrator of one, so you may want to reach out to him and talk. He may still do mods on units.

Stating all that, I have no idea how to mod one, so I would have had someone like Bill who has all the equipment and knowledge, to do that. If you think you can, and can get a coil that can optimally run at that delay, I say have at it ! Would love to hear how you make out and how it ends up running.

Thanks Rover,

Yes, most Razorbacks will run at 8usec according to Jason the owner. I am waiting for him to get back to me.

I am comfortable with a scope, meter and iron. In a prev life I used to re-freq radios and pagers in a faraday cage I built.



Edited 2 time(s). Last edit at 11/06/2011 03:10PM by Pawnbroker _Bob.

Correct. The coil AND coil wire MUST have capacitance and inductance that is conducive to 8uS. Otherwise...... you will never achieve 8uS. (((And there is a big performance difference between 8.5uS vs 10uS))).

Hi Guys,

My discussion over on the Find's TDI forum addresses some of the issues of building coils for the TDI and how it relates to this 8usec issue. Keep in mind I never give away all my secrets but even I have difficulty building coils that actually work correctly at the 8 usec delay.

One real big problem is really making coils that actually work CORRECTLY at the 8 usec. It is possible to make a coil that appears to work, but, is it really working correctly? Just because it doesn't explode or melt at the end of the rod doesn't mean it is working right.

Having made dozens of coils that will work on the TDI, the magic safe delay is 10 usec and even then the coil size becomes a big issue. The bigger the coil, the harder it is to build a coil that works right at short delays. Below the magical 10 usec, the coil size becomes extremely critical as does other factors. The point being if a person does mod their detector to a shorter delay, finding the right coil becomes a problem.

I think that Tom has found this out already when he tried to get a different coil for his Eric Foster designed detector. Even Eric Foster has difficulty building a coil that works less than 10 usec and few people are better at building coils then he is.

As for Jason and his coils, well, he built his first TDI coil from wire and other components I sold him. The instructions were free. Since there are not magical designs, and the components used by Jason were about the best one can use for building a fast coil, I am fairly certain what his coils will do.

I mentioned a few things to look for on the Find's TDI forum when running at a shorter than 10 usec delay to see if the coil is functioning correctly. Something as a quick twist of one's wrist while holding the detector will also give away one of the weaknesses.

Now, with that said, the safe bet will be to use a coil smaller than the factory 12" coil. About the largest I have been able to build is one in the 8 by 11 elliptical design that doesn't display one or more of the quirks that show up. Again, just because it still makes noise doesn't mean it is working right. So, keep this in mind.

Reg

Thanks Reg,

As always, you provide valuable information for us PI users.

Part of the reason for my first post is because there is a small group that bad mouth the TDI for many reasons and some of the problems are because of coils that don't work right. Also, there are people who get inside detectors and make adjustments not knowing just what might happen.

Unlike a typical VLF where things may shift, most of the adjustments inside the TDI are extremely critical. Adjust the wrong control and there is no doubt the detector will not work as well as it did and in some cases, may not work at all. There is one and only one control that can be adjusted to change the minimum delay.

Many of the other controls require special equipment and test procedures to adjust and the settings may be within 1 mv or less. You can't make these adjustments with a simple meter but require a very decent scope or very special meters. Worse yet, certain procedures have to be followed or one can't even make the adjustment because of all the noise causing wide fluctuations.

This is why I have never posted the specific information as to how to adjust the detector to reduce the delay. Post the info and everyone becomes an expert or they think they do.

What is worse is the newer TDI's have all timing in software so there is no control that can be adjusted to change the minimum delay. You would have to write the code and reprogram the micro to do that.

Now, one person I informed of how to do the mod was determined to find the "hidden" adjustment on the newer units. Well, there is no hidden adjustment, so I strongly suspect the TDI he was playing with is not up to par today.

White's doesn't need bad mouthing because of people tinkering inside the detector and ending up having to send their detector in for repair. I suspect this has already happened but can't prove it.

Now, the SL is a completely new pc board and most of the controls have been removed, leaving only one. One guy went so far as to tinker with this control and then posted he did it and said all the control did was increase the noise. Well, he was indirectly correct because the noise will increase. However, that will also happen when you advance the operator adjustable ground balance control.

So, if we have one guy who openly admitted tinkering inside his detector, can you imagine how many do it and not say anything?

The additional point I am trying to point out is some of the complaints you read about are not really faults of the detector but of the owner and this doesn't just apply to the TDI. This is one of the big reasons manufacturers don't provide any technical information. Without it, most people with common sense will leave things alone, especially the internal controls. I know I do.

Now that most of the original TDI's are out of warranty, I have been more flexible as to whom I will send the simple instructions on how to do the 8 usec mod. I need to know who the person is and get their word they will not distribute or post the instructions on the net. White's doesn't need the hassle. Their tech is busy enough repairing older detectors on a regular basis as well as the limited failures that do occur on the new ones. The last thing he needs is to be bombarded by people tampering with a perfectly working detector and rendering it borderline useless.

Even though I tell people that the newer design can't be adjusted, people will simply try to prove me wrong. The difference is I have the necessary technical information need to know I am right in what I say.

BTW, I mentioned the guy who got inside his SL and tinkered with the one internal control. Well, think about what I mentioned and you might be able to figure out what the internal control does.

Reg

Reg,

Wondering if you have talked or communicated with Eric Foster recently, and if so, how is he doing ? I have a Goldquest SS V2 that I feel is one of his best designs, and it's one of the smoothest PI's I have ever used ( won't ever sell that unit). Doesn't have ground balance or different tones, but it is one heck of a unit.

Eric recently posted on the TDI forum and he said he was doing fine when he responded to my follow up post. In fact, he mentioned he was building a smaller work area so he can stay up on the latest ideas. I am reasonably sure that White's communicates with him also. As for me, I haven't emailed him personally for a while.

BTW, I suspect he monitors several forums so he may read this.

Reg

Reg,

Just to let you know, I have learned a lot about PI units from your posts, as well as Eric's, in addition to talking to Bill Crabtree on the phone several times.

Thanks.

John

Hi John,

Thanks for the kind words. I have always tried to provide honest and as accurate as I know to be true info to let people know how things work. Not only that, over the years I have put in hundreds of hours using my ideas and testing things with many out in the field either coin or nugget hunting.

Now, getting back to the 8 usec mod, there are certain things one can do from a technical standpoint to make the detector a little faster but most of these require knowledge of what to do and the proper equipment to assure things go as planned. In most cases, the increase is quite minimal but noticeable. There are extremely limited number of people who may be knowledgeable to do this. Unfortunately, there are also a few who claim they can but have no idea of what is really happening.

Leaving the detector alone except for the one internal adjustment does allow a person to sample early and is simple and relatively safe to do. If the coil is fast enough, all will work well with minimal problems. As the coil becomes less than fast enough it may still work reasonably well to quite well but will also display strange signals and quite often begin to detect many hotrocks previously ignored. As a general rule, as coils get larger than 11" diameter or so, the difficulty to work properly diminishes with size. Obviously, the design of the coil including the shielding, the type and size of wire and of course the coil lead all come into play. In other words, the whole coil assembly or any part of it becomes or can become part of the problem.

As any of the coil parameters are changed such that the coil is effectively slower, then the odd signals become more obvious. A simple increase in coil size is one big factor. If things get bad enough, finally, the signals may even seem to reverse. If this happens, then one can turn off the GB and the signal one hears is more of a muted coil response. So, with the GB on, the secondary sampling used for GB becomes the dominant response, thus reversing the signal one hears.

Since it may not be obvious without serious testing that something is not right, I simply recommend people use smaller coils to try to remain in the safety zone when trying to use the shorter delay.

Now, one thing a person might try is a DD coil. Since DD coils are or can be inherently faster they will settle down faster than a typical mono and still have decent depth. Also, the DD displays a mild form of ground signal reduction, thus making such a coil more forgiving.

The only thing to keep in mind is a DD coil has a much narrower detection zone, thus the detector is more critical of the sweep speed, especially when trying to detect very small non ferrous objects.

So, there are advantages to reducing the minimum delay but there are also other issues to contend with. Unfortunately, if one doesn't know what can happen with certain size coils, then when things don't work right, the first thing to be blamed is the detector even though nothing is wrong with it. So, that is why I try to guide people on an individual basis so they don't go off half cocked and blame Whites for things beyond their control.

Reg

Correct portrayal/response of human behavioral psychology.

And to amplify: Change ONE variable at a time......... keeping all other parameters a 'constant'. It's MUCH easier to control/learn/RTZ.

Hello folks,

I am new here and my detecting experience is lmited to using a Whites GMT mostly looking for gold. I am considering buying a TDI and have found an older used one.

Is there a way of identifying esily the ones with the hole thru board that can be modified? This detector is some distance from me so I have not been able to hands-on with it yet, but it is early enough that it has a patent pending sticker on it.

Any easy ways to identify the hole thru model?

Thank you,

Greg

There are extra markings screened on the control box by the conductivity switch that indicate a NEWER one. It says something like "GEB switch must be on/off" with some arrows. The early original models DO NOT have this marking.

If you look at the picture of the TDI on the Whites site it shows an early one without the marking. (last time I checked)

The reason for the warning is because it will not operate properly with the GEB switch off while the conductivity switch is in the HIGH mode. It seems like it is working but trust me it is not. This is also true of the early model and the warning is stated in the manual.

The one I recently purchased also had a marked "draft" proof of the manual and what appears to be a handmade battery pack. I do not know if this is consistent throughout the early ones.

The first set of numbers in the serial # are supposed to indicate the date of manufacture. Starting with the year "9" and then say "123".... indicates it was built on the 123rd day of 2009 around the end of April. What I cannot remember is the production switch over date. I believe it was mid to late 2009. September/October '09 ring a bell but I cannot find my notes. Perhaps someone can chime in on that. Mine is a June '08 baby and is under #20.


/PB



Edited 1 time(s). Last edit at 11/24/2011 04:54PM by Pawnbroker _Bob.

Thanks PB for the info.

This is what I can see from the pictures:

SN: 8169-0321-001
800-0321
TDI
Patents: Patents Pending

So does that mean built in 2008 on day 169? I don't see and extra words printed around the conductivity switch refering to the GEB settings either and it is the same as the picture on the Whites site..

What do you think, does it look like an early hole through maybe?

Thanks,

Greg



Edited 1 time(s). Last edit at 11/24/2011 06:48PM by gzoro.

Mine is 8169-0321-011 I always thought mine was the 11th one built

That sounds like a thru hole to me.

My number is just like yours #15. The highest number I have heard of is 20. I am not sure about the rest of the numbering scheme. Whites may or may not have issued the number as it started its assembly or finished it. And if they started from # 1 again on a new manufacturing birth day. Right now that seem plausible to me. I am guessing that they came out in batches and there may have been only one or two batches per month. So only one or two "birth days" per month. Hopefully a few more folks chime in with some ser#'s and we can get a better idea.

You can also call Whites customer service with the ser # and they will verify it is an early one and tell you if there has been any repairs or issues with that machine or been reported stolen. Btw... they refer to the early ones as their "first build". They kinda 20 questioned me like who I was getting it from, where I live, what the price was, type of hunting..... but were very nice.

/PB

I happen to be playing with DD coils on the TDI. I had tried it once before with the stock Minelab Commander 11" DD but was just seeing if it added any depth or stability in bad ground. I wasn't testing for more pronounced iron identification. Since getting into it with Reg on Findmall's forum I have invested a lot of money on various DD coils. Right now I happen to have a 12x15 DD for it and the first thing I thought of was I need to get two same size coils...one in mono and one in DD to compare. So I already have a 14" round mono and have a 14" DD coming. I CAN tell you that with the 12x15" DD I have, there is quite a noticeable depth/sensitivity loss. And thus far I've not seen any thing to indicate the DD is giving more of a distinct audio of ferrous vs conductive non ferrous.

A while back when the camo F75 first came out, I was wanting to sell or trade it for a TDI. Carl of Whites contacted me with a trade offer of his personal TDI for the camo F75...said they wanted it for taking apart and testing. I jumped on it and I don't know whether that particular TDI was a prototype or what, but it was CERTAINLY more different than the hundreds of other TDIs I've been around and helped with at the Diggin in VA hunts. It had its own sound for iron and high conductive targets....very distinct and distinguishable. I've since then had 3 other TDIs, including the SL and now the Pro...and none of them sound like that one that was Carl's personal unit. I think I still have clips of it on my camera's HD that I could show the sound of it vs the Pro I have now. Whatever was done to it they need to go back to and improve on.

Hey thanks again PB.

Great info here. Thanks to everyone!

I think that I will be turning more to detecting and drywashing these days as the whole dredging debacle in CA has squashed my plans to get my 14 yr old in the water with me. Now they are working to make highbanking pretty near impossible with this water permit junk.

So at least we will have a TDI and a GMT to go out with together now. Should be fun!


Best to all and I hope you all had a good Thanksgiving!


Greg

Hi Daniel,

I think we need to hear/see that. It sounds interesting. <pun intended> =)

Yeah coils.... I am having a coil problem, again, leaky (i think). They frustrate me to no end. The coil seems to me to be the weakest link and I am not just referring to the TDI. I am not sure if it is bad manufacturing tolerances or what. So I am studying and gearing up to make my own coils. I dabble with carbon fiber in the marine industry and am thinking of hand forming a couple of super ultra lightweight carbon fiber ones for my tdi.

Regarding DD depth.... by its nature it should be quieter and heavier but a quiet coil equals less sensitivity and less sensitive equals less depth. I have understood that a DD of equal size to a mono will not get the same depth by several inches. However, the larger you go in coil size the more targets that can be acquired within the volume of the field..... But, if those targets are of different materials it can also skew the detection, ID and or mask, rendering it useless. That being said, the DD is better in trashier and noisy ground because of its narrow field.

/PB

My experences with DD coils on tje TDI have been dissapointing, Has anyone tried the Razor Back coils?

Hobo -- The RazorBacks are what I have coming. I already had their 14" mono and Jason said he was building me a 14" DD.

I do know on the GPX platform that there was a pretty significant depth difference between DD vs mono of the same size. The GPX 5000 came with the 11" DD and 11" Mono. I used the machine for relic hunting so I had the 11" DD on most of the time...the iron disc on the GPX only works with DD coils....thus was the thinking that the DDs might help with iron ID on the TDI. At any rate I just had to see what the 11" mono coil would do and when I tried it I was like WOW. No wonder most of the prospectors use mono coils!!

Daniel; How do you like the 14 mono on the TDI?............................... Hobo

This topic is funny to follow. Since DanielTN called me a liar and then ran around different forums telling everyone I didn't and don't use my detectors or hunt with them and I only experimented with them, and I really don't know what I am talking about, I sort of lost interest giving him any more info. The funny part is I sold a 2 lb coffee can full of silver coins a while back I found over the years, I must have found them while experimenting right? Then again, maybe I just might have found a few things since I have actively hunted with detectors far longer than danny boy has been alive.

Lobo, I think you mentioned you have been hunting since the 70's. I got you beat by more than 10 years. Since you made your public remark, well, don't ask.

As for DD coils, been there done that and when you know what you are doing, they do have the potential to let you know some iron very distinctively, regardless of what was said earlier by the legend.

Since you guys are getting valuable info from Daniel, well I leave you to learn from him. After all, according to him, I don't actually use my detectors in the field. Gee, I wonder who really did the testing when I wrote all those field tests for LT or found all the nuggets in my 21 years of actively vacationing in AZ nugget hunting?

Good luck and have fun and I am out of here.

Reg

PS: I forgot to add that I learned a lot since building my first DD coil and, fortunately, much of that was never posted on any forum. So, if you are having Jason build your DD, well he is getting his info from the Geotech forum. I guided him when he built his first mono coils, but no more.



Edited 1 time(s). Last edit at 11/26/2011 12:34PM by Reg.

Well Reg I never called you a liar. I'm the one who offered you an all expense paid trip to Tennessee to show everyone on film what your 18+ paragraph ramblings could do. You are always the first to say that nobody else knows what they are doing except you....you did it in the post you just did. But you never responded to my invitation via PM that I sent. So when things escalated on the forum, I publicly extended the invitation and posted some pictures of display cases jammed full of Civil War relics found with the TDI and GPX from Georgia, Tennessee, and Virginia. I'm not an expert and never once have said that I was but I have found some tricks and techniques that flat find relics. That post was conveniently deleted by your buddy's Reg. Offer still stands to come down and prove these facts/rambling on video. Anybody can claim anything....proof is what I like seeing. I can make the claim that I'm getting 30" of depth on a silver half dime in red dirt but until I show proof of me doing it, its all just a bogus claim. I guess I could start doing your tactic and make the claims but when nobody else in the world can duplicate it and calls you on it, I could say its because everyone else is ignorant, and I'm the only one that knows how to do it. Then I could do like you and take my ball back home, go inside and suck a pacifier because the other kids were mean. Don't be a grown up baby man....just post some proof that you actually hunt. Preferably videos as you might be an arm chair purchaser and just buy everything. At least most of my finds in the last couple years with the TDI and GPX have been dug on film giving folks a listen to the signal before being dug then showing it as its dug til its out. That's a lot better than 20 paragraphs talking about a bucket test garden. Eric Foster posts like two or three sentences at most and says more than any 20+ paragraph rambling by Reg.

Daniel,

Relax, you have inspired me to quit posting technical info or even offering it to those who write me, so please don't. Thanks, I can use the rest and I will leave that expertise to you since you claim knowing so much more on other posts than on your last one. No more ramblings people and thank Danny boy for that.

I will keep this short and wish everyone a Merry Christmas. Ho ho ho

Reg

ROUND TEN! <bell rings>

With all due respect guys.... would you please have a little consideration for the rest of us who are trying to learn about detectors in these forums. These demeaning rantings really ruin what is supposed to be a fun hobby for most of us and I am sure it dissuades others and potential noob's from engaging in the forums and sharing.

Please.... Start your own topic under the "Personal Attack" section and go for it. I will read and enjoy it, when I want to. It is really unfair for us to have to filter through various topic content here and on other forums to avoid the stone throwing. The ranting also generally kills the topic that some were trying to learn from.

Lets keep the topic on topic.



Edited 3 time(s). Last edit at 11/26/2011 05:07PM by Pawnbroker _Bob.

Don't worry bob, I am not posting any more.

Reg

Wow that's alot of mini balls! What are the round eagle disks?

Thanks,

Greg