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All Tdi's Are Not Equal


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I really hope people do not believe the TDI or SL has all the features mentioned because they don't.  First, the main difference between the TDI and SL is the noise reduction circuitry that reduces the warble, and the fact, the two have different voltage supplies.  There is also a filter speed difference between the Pro and the SL, but not with the regular TDI and SL.

Now, the Pro does have a different filter speed than the SL and that causes some of the problems that should be eliminated.   

There is no smoothing circuitry outside of the usual capacitors in this design once the GB is turned off.  In fact, there is no smoothing circuitry since the warble and typical noise and warble happens because of the extra gain in the GB channel and when the GB is turned off, the GB channel is basically dead and typical warble and noise will not exist.

A couple of years ago, a simplified version of the SL was introduced to Australia and soon after its introduction it was determined this detector had what was commonly called a "hiccup" that was aggravating enough, many people were wanting to return the detector.  I was asked by one of the people over there if I would help them find a solution, which I ultimately did.  One of the recommended solutions was to eliminate an extra filter found in both the SL and TDI versions.  Why eliminate this filter?  Simple, the filter has a very slow time constant so this filter would or could interfere with the autotune filtering causing some very weak signals to be compromised at certain sweep speeds.  In other words, the filters would buck each other at times and very weak signals suffered.  Unfortunately, eliminating this additional filter caused an increase in gain that would result in increased noise and the preset threshold setting to not be properly set.  This caused concern and the filter was left in thus causing its own problems.  

Does the SL have its own design weaknesses?  Yes, but many that caused the "hiccup"  problem in OZ are now removed on later units.  Because the problems that caused the hiccup in OZ didn't cause problems here in the US or Europe, no recall was needed.

Reg

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Well my SL does have those features because when I set the GB to 7 and turn the Gain  to 10 and if I wave a coin in front of it, the first time it will see at 15" and by the 2nd or 3rd sweep it will not signal the coin past 11 or 12 inches and when you turn the GB off it sees the coin at about 11 and a half inches and unlike the TDI Pro it suffers a depth loss unless it sees Copper,

I Appreciate what you are saying but this is what happens, and these things do not happen with the Pro, I have owned this machine for about 18 months and it has always had these features / Problems,

Sorry  But the TDI Pro has the smoothing effect when the GB is turned OFF, and you only have to watch that video to see it in action and my SL does it when the Ground balance is turned On and it has ZERO Depth Increase when the GB is turned off, Even in Air Tests or in the Ground,

Sorry Reg I respect the fact that you are a Wizard when it comes to Building and operating these machines, But please do not try and tell me what my machine is NOT doing or as you put it does not have these features, because I am here and so is the Machine and as a side Note there is another member on the forum who has seen both of my machines in Action, 

john

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Why do you sweep faster with the TDI Pro than you do with the ATX?  If you do this with the SL, it will not work the same as the Pro and I explained why.

Again, there is no smoothing feature caused by any special circuitry outside of simple capacitors that are there regardless of whether the GB is on or off that will cause any smoothing when the GB is turned off.  

So, I have no idea of what you are experiencing or why, but I can tell you with absolutely certainty, there is no special smoothing circuitry activated when the GB is turned off.  That is what I am saying and watching a video of the ATX won't change that, especially when talking about the SL.  

Feel free to make a video yourself of the SL and show what you say it is doing wrong.  That might help.

You can't sweep the SL as fast as you do with the Pro and expect it to function the same.  As I said, the SL filtering is slower and will not have the same results.  This difference in filtering is well known and was mentioned as one of the differences between the TDI and the Pro.  The TDI will not work the same as the Pro either, since it has a slower filter speed like the SL.  

Reg

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The sweep speed on the Pro is far more forgiving where as the filters on the SL slow it right down to almost half of what the pro can handle, With "The smoothing effect" for the want of a better name desensitizes the SL so when it first see's a coin at 15" it will smooth it out or Balance it out or what ever else you wish to call it and it is the same effect as what the pro does with the Ground when you turn the ground balance Off, but for some reason my SL does it when the GB is On,

and I have tried Lead, Silver Morgan Dollars modern Quarters ancient coins and the only thing that the SL will react to adding more depth with the GB Off is a 95% pure Copper coin other wise it will not see any coins past 12" where as if I turn the GB off on the Pro it will see coins at about 16 to 18 to 20 inches, I have never seen this machine behave as you have said in many of your posts, I appreciate what your saying but compared to the Pro the SL behaves as if it is wired back to front

Because with the GB on it does that smoothing thing the Pro does with the GB in the Off position and when I turn the GB off on the SL the signal is sharp but it do will not sound off past 12" on a US Quarter which is a 25% Depth loss because it will give a faint sound on a Quarter at 15 to 16 inches when the GB is On, I know the sweep speed is slow it has never been any different where as the Pro's sweep speed is similar to that of the ML Sovereign GT maybe a bit faster but the SL is half that speed, I know what I have said is a complete turn around on what should be happening apart from the sweep speed, But this machine has a mind of it's Own, I have tried do some of the things you have posted but nothing ever comes of it and like I said when the GB is off then a copper coin is the only thing that this machine works like it does when the GB is set to 7, and with the factory coils (DF) it will not see anything weighing below 0.16 to 0.17 grams, and It will not emulate the performance that you speak off, even running it at 13.8 volts

As crazy as it is this is how it behaves, even the Frequency control seems to be happier when set to the left and lord help you if you have the Delay set higher and you go to turn it down, The Howling it makes, It is easier to turn it off and turn the delay back to 10 and then turn it back On I pent about 250 to 300 hours trying to things you have said with as much success as a fart in a Hurricane. This thing behaves like no other detector I have ever used and this it my 4th or 5th PI

Sorry Reg, but this machine is possessed,

John

PS, I will make a short video and even that big Morgan won't wake up the SL with the GB off and it still gets it further with the GB on and heres the crazy part it see's a small mens 9ct ring further than it does the Morgan,

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@auminsweeper,John,as you are having major problems with the 'sl' and i think i am right in saying its under 2 years old,why dont you ship it back to James in Scotland for them to check the machine over,it has a 24 month warranty so you should still be well with the time duration for them to sort any problems out with it.

Just a suggestion of course,even a phone call to them asking for clarification about what they can do,i am aware that James only does half days of late but if anyone can sort the problem out it would be the factory.

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Well mate, it was only this past few weeks that I decided to give it a complete workout after testing the PRO and then comparing this one I started to notice all the Quirks, On small targets with the GB On it has the same sort of depth as the Pro +/- but change the settings and it all goes Pear shaped, but the crazy part thurn the GB of and test a US Quarter and an old half penny or a penny and there is a 50% boost but only on the penny no other metal will jump start it,

If I can Give whites the full SP I will see what they say,

John

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John,

You should be able to detect a Morgan dollar farther with the GB on than off.  The reason is, the GB circuitry amplifies the signal well over 30 times more in the GB channel than what is happening in the main channel so when the GB is on, the summed signal is amplified more than when the GB is off.That is why the signal is a low tone.  

If the GB channel signal is stronger than the main channel signal, you will get a low tone.  Sum the GB channel and the main channel and if the tone is low, the target will be detected deeper than if the GB is off. So, that is normal.

As to your claim of 15" on the first three passes or so, there may be some truth to this but not for 2 or 3 passes as you mentioned.  I just tried an experiment and if all is quiet and run an air test, I think I get a signal extending out to the 15" range but only on one pass. Any further passes are at the 12" range.  Wait a second or two between passes and they can hit 15" again but not for more than one pass.

I am guessing that changing and/or removing a few components plus shorting out a couple will minimize this situation, which is something I recommended some time back as part of the Aussie fix.  If you know a good technician with equipment to work on surface mount parts, then I can offer some suggestions.  I absolutely do not recommend a person work on the SL without extensive surface mount experience.  Try your test again and see if it dies at one pass.

I also think your detector is probably working ok and is not possessed.  

Reg

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Reg that's right, the first pass is soft then by the time of the second pass or the 3rd it is down to 12", and if I turn the GB ON it stays around 12 to 13 and a half inches at the most and it will not see it any further, A US 1977 Quarter is 12" to 12.5 max an English Penny is about 17.5 inches Max and the Morgan is 13,

With the GB Off the 1977 Quarter is about 11.5 inches, the Morgan Vanishes at 14" so at 13 inches the signal would be strong enough to make you stop and check it out But then thin 1868 English penny is there at 17.5 to 18 inches, and the signal does not diminish and it does not adjust it's self in the NO GB mode like the Pro does except when the GB is ON which is the reverse to the Pro, Nothing I do shows any depth advantage with the GB on or off, the Morgan is a good 5 /16ths bigger than the English Penny, Yet if I use a small mans 9ct gold ring it sees it at 16.5 to 17 inches with the GB off and where it all goes really stupid is when I turn on the GB to 7 with the CON set to Low and the Gain on 10 (as always) it then sees the Ring at 18.5 inches,, So it has the Power but that smoothing thing seems to work when it should not,

When you consider that is gives a faint signal at 18.5 inches on a Ring that weighs 4.18 grams with the standard 12" DF that is pretty amazing with the GB On and with it on it is Gaining an extra 2" inches when really it should be the other way round, but the amazing part is that it looses no depth to the pro on small things and yet I found the subway tunnel at 5 or 6 feet down,

What do you think of these figures ?  I am so confused at to why some things appear to be operating back to front, But that depth/distance is something else. when you sweep at half the speed of the Pro.

Thanks mate,,, John 

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Hard Prospector,

I use the TDI and SL but that won't stop me from pointing out their weaknesses or limitations.  I prefer people know the truth and any solution available if there is a weakness.  In fact, I want people like John to point out what they see as weaknesses.  I just want that information to be as truthful as possible.  It is when people like John point out things that cures or corrections will come to light making a better detector in the long run.  

Unfortunately, the present management at White's and I no longer have any communications and, in my opinion, there is no one at White's who knows much about the TDI series or how to make it better.  Instead, I suspect they will scrap the present design if and when they come up with another rather than listen to dummies like me.  

Reg

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