TGSL Tuning & troubleshooting

[Stefano]

Hey Stefano..
Part 1 shows pics of your coil being constructed! Hope it's working out OK for you.
Don

Yes, I noticed. It's definitely a light and accurate coil. I'm well satisfied about it.

[dfbowers]

Wow! That's wonderful! Well done Don, thank you.

Hey Stefano..

Part 1 shows pics of your coil being constructed! Hope it's working out OK for you.

Don

[simonbaker]

I attach picture, which explains why i think connecting ground to LF353 pin 5, or pin 6 will give the same results.

Interesting question.

I tried LTSpice simulation and attached photos shows my results. They don't match yours exactly. However, I don't know if correct. Did you try with actual circuit?

I can't explain slight phase shift between the cases; maybe due to different impedance of op amp inputs???

These waveforms are of course just the "null" signal, does not show how target signal phase would be affected if at all.

-SB

P.S. I don't trust this yet because I recall trying a similar comparison for dfbowers and did not see difference between his "wet" grass version (vout3) and the TGSL standard (vout1). So I need to doublecheck.

[Stefano]

Wow! That's wonderful! Well done Don, thank you.

[dfbowers]

I think that is definitely a mistake in the illustration -- good catch! We should fix that since it seems pretty essential. As dfbowers mentioned, the alternative wiring (with no grounding of RX coil) removes the possibility of error.

This highlights how darn difficult it is in these forums to divine a clear, accurate set of instructions for building some of these projects. Reading the threads is fraught with peril -- every other post has a mistake or disagreement. It really is an experimenter's game here. But Don's and Ivconic's manuals are the gold standard for now. It is very important to put such documents in a "sticky" post, like Qiaozhi did with Ivconic's material, and then allow continual editing to fix discovered errors. That way over time the information will become more thoroughly "vetted", tested, and reliable, and you'll always know where to find the latest version.

Of course if you're willing to tinker, analyze, and ask questions, you'll eventually get there regardless.

-SB

I got her all fixed up.. Sorry about such a stupid mistake !! I just hope that I didn't screw up someones project. I fixed some other minor errors that have been bugging me too. I'll keep it a living document. Additions and corrections welcome!!



Don

[simonbaker]

Thank you for answering.

Yes, i heard it before like that; for example: md anker has sensitivity in air ~50cm, but very low in the ground.

So all these TGSL mods worth nothing when searching in ground, or just some of them?

1) Vladimir's mod:

http://www.geotech1.com/forums/attachment.php?attachmentid=12430&stc=1&d=1276182774

2) Sb and Qiaozhi mods:

http://www.geotech1.com/forums/attachment.php?attachmentid=13374&stc=1&d=1285885512

3) Dfbowers mod, when shorting R37 1k

I was going to try them, but now...

It is still an open question to me. The original TGS filter may be the best. However, remember it was designed for a concentric coil that is also smaller than what Ivconic and others have adopted for their double-D designs.

So I suspect the TGS was designed for good pinpointing and quick response and stability more than depth. Naturally, people here are curious about more depth.

The mods you mention mainly create a little slower response (except Qiaohzi's, which had a different purpose) and sometimes a little more gain, which in theory might help with depth and better tuned to larger coils -- but more delay of the beep.

I have a feeling increasing gain in the filter section does not help much, and seems to make annoying instability. But perhaps other changes we haven't thought of could help with that.

The usefulness of the mods may depend on the soil and targets you are hunting too.

So I think you still need to experiment for your own purposes. So far though, I don't think these "filter" mods have produced any radical improvement with typical ground.

Of course Ivconic's new-feature mods like IGSL (and hugo's sneaky double-tone) might improve usability a lot.

And dfbowers wet-grass connection mod may be quite useful.

No doubt we'll keep trying to outsmart physics, or make gold out of lead, as long as they keep making solder...

-SB

[satdaveuk]

Hi John
I never said once dont try mods and experimenting and far as Simon baker, Vladimiers, Qiaozhi, and DF bowriers modifications , they are the people to ask if they are saying it does the trick in real time then take there word and go for it, they are some of the best engineers on here, but as they will tell you themselfs its experiments, whats a good thing today pit falls will be found tomorow then wont be such a good idea, you just got to look at the mods that have took place since the TGSL was started and not just this one many many others on this and other forums.
And that is the reason and only reason that I dont agree with marking documents as final, just use version numbers like manufactures do, Get it all the time in my trade, you cannot order spares by just model and circuit numbers, you either use part numbers together with chassis version, if you havent got those your knackered.
A good instance of that is look at Vladimirs circuit compared to say simons, bare in mind they are both TGSL, theres lots of differences, due to the sound stage is Tesro together with other parts of his circuit the reason been he started in the very early part of the TGSL design in fact its a cross breed.
I for one will try every single mod going anyway because thats the way I am and injoy doing it with a abundance of spares at hand in the workshop, and using spare time, so its costing me peanuts, but what I do recomend for the novis is leave it a alone until they get a tip of the hat from them who knows, otherwise I see tears moaning getting repeated questions, telling us how they could have gone out and bought a ready made one blaah blaah blahh, Some kids on here have spent there savings on this project and the rest borrowed from good old dad lol.

My email if read as it was ment was directed at helping the non engineer, I have nothing to gain by it, but felt it was right to be said.

You ask have I done all those mods? My answer is a very honest no, done quite a few but not all as I thought I had, and to be honest again I didnt even know they were on here,now thats not anybodys fault except mine because I didnt practise what I preach not that I would have had time lately anyway due to work comitments.

Anyway keep the experiments going boys and girls thats how Tesla did it and many others.
I got a old 1950s book about tesler was glued to it while still at school, read from cover to cover umpteen times before going to sleep, what a man, things would have moved alot faster in this industrie and others if he was still around im sure of that.

All the best as always
Regards

[simonbaker]

I think thats a bit over the top you yourself and many others here have worked there *** off on this project, it cant be expected to be laid on a plate, the next thing they will be asking it to be built for them, this forum is a technical set up for experiments etc, anybody who didnt spot the error far as wireing inverted/non inverted on the circuit going to ground oviously hadnt done there home work previously before starting the project.
Far as reversal of wireing on the various pots..... so what, its only a matter of swaping to wires over so controls are going clockwise instead of counter clockwise, and dont say they got the wiper wrong I really cant see the big deal and if people on here are doing these projects cant sort that out then they shouldnt be attempting such projects in the first place.
My golden rule is when commencing the TGSL project use the origonal TGS circuit along side Ivionics and work between the two, then you cant go wrong.
Far as coil connections I personally found wireing up the same as Tesro do with there manufactured coils is best, I get few falses and its quiter, but of course I can only speak as I found in real use situations here in the UK.
This project was never a fool proof project for people with no engineering skills, they need at least a basic knowledge in electrical engineering and of course accurate test equipment.
Without either one or both of those things they are knackered, just wasting there money and everyone elses time.
And another golden rule is as said so many many times by Ivonics read the bl..... forums over and over again till its planted in the brain to how the TGSL ticks, all the imformation for this project is there in black and white, its no good reading bits of it, you need to read how it progressed, and may I add still is, its ongoing theres no final here and proberly still going when a lot of us are pulling daisys from below.( So dont lable anything as final)

You know simon I am a TV engineer by trade so Using test equipment and fault finding in the field of TV/Radio is like second nature , but even with those skills I had to get my brain in gear because of a doggy inductance meter duff chips and ongoing experiments, so how these lads with neither test kit and knowledge exspect to achive anything other than a non working project baffles me.
Or maybe im on a different planet or just plain old fasioned, if either please correct me and put me in my place.

Kind regards as always

I'm with you -- I like to dig deep and try to know how it ticks.

On the other hand, these threads grow longer by the day. A well-documented project will actually reduce the number of questions and is a good reference even for the experienced builders. It might also help get some people started who can contribute later.

But yeah, there is a certain charm to the raggedy frontier mentality as opposed to the nice neat kindergarten step-by-step DYI websites.

I don't fear this subject will ever get too easy.

Always appreciate your points...

-SB

[johnsmith77]

...unless your grounds are on another planet maybe. ...

I attach picture, which explains why i think connecting ground to LF353 pin 5, or pin 6 will give the same results.

[johnsmith77]

[johnsmith77]

Hi John
Take your detector out into a field for use as a metal detector which it was designed for and you will tell the difference big time, unless your grounds are on another planet maybe.
Air testing is only good for one thing only, that is the back end of your detector is basicaly functioning and your coils are basicaly working, nothing more and nothing less.
Far as this golden 30cm air testing that some people keeps harping on about, its bul**** unless you intend on detecting low flying metal objects.
Anybody on here thats built a TGSL using the coil specified by ivonics getting 30cm air test with a old english penny has done silvers mods, which are great if you want to impress friends down the pub but thats where it ends, soon as you hit on actually field tests it will go unstable and you will dropping sence to at least half way, and even then often you need to drop a tad more due to falsing, which infact takes you back to the depths you get without the mods
So at the moment in my opinion the mods that silver has done are no good in practical terms although I do admire him for time spent experimenting, BelIeve you me I have done numbrious tests with quality home brews and Tesro manufactured coils, which tells me with know shadow of doubt that Tesro had it right when they first designed TGS.
I got both mods on my machine with a 3 way double pole switch so its position 1 for the 1meg resistor accross the diode, mid position no mods at all position 3 adding supply to sense pot instead of ground, no point in switching both mods on together unless your in the middle of nowhere searching for metal ring IDs on pigions legs while there flying in mid air. The reason for fitting the switch was for exstensive tests I carried out a while back.
I dont want to burst your bubble, but I strongly suggest you go out and do proper tests before passing a opinion on your building technics unless you fancy joining the utube club which is full of machines getting air tested, which is meaningless far as im concerned.
Dont get me wrong theres alot more clever engineers far as metal detecting designs than me, but when we talk about field testing with various machines which ive done for the last 40 years with numbrious machines and format types you get to know there limitations and what to exspect out of them performance wise , far as improving depth in real time with the tgsl its not about making the circuit more sensitive its about making it more stable in real conditions , if you crack that one then everything else falls into place and you then will receive a browny point from me
All the best

Thank you for answering.

Yes, i heard it before like that; for example: md anker has sensitivity in air ~50cm, but very low in the ground.

So all these TGSL mods worth nothing when searching in ground, or just some of them?

1) Vladimir's mod:
http://www.geotech1.com/forums/attac...1&d=1276182774

2) Sb and Qiaozhi mods:
http://www.geotech1.com/forums/attac...1&d=1285885512

3) Dfbowers mod, when shorting R37 1k

I was going to try them, but now...

[satdaveuk]

Ok, i made only one coil and it works 30cm in the air. So i mean, if we correct mistakes, we achieve it at once, not as seventh coil making time.
Less trouble for future. If mistake left, it can be repeated in future projects.
Everybody make mistakes, even asses.

Furthermore i thought more and got decision: LF353 pin 6, or pin 5 is grounded there will be no difference. I bet. There is no mistake and both manuals correct at this point

Hi John
Take your detector out into a field for use as a metal detector which it was designed for and you will tell the difference big time, unless your grounds are on another planet maybe.
Air testing is only good for one thing only, that is the back end of your detector is basicaly functioning and your coils are basicaly working, nothing more and nothing less.
Far as this golden 30cm air testing that some people keeps harping on about, its bul**** unless you intend on detecting low flying metal objects.
Anybody on here thats built a TGSL using the coil specified by ivonics getting 30cm air test with a old english penny has done silvers mods, which are great if you want to impress friends down the pub but thats where it ends, soon as you hit on actually field tests it will go unstable and you will dropping sence to at least half way, and even then often you need to drop a tad more due to falsing, which infact takes you back to the depths you get without the mods
So at the moment in my opinion the mods that silver has done are no good in practical terms although I do admire him for time spent experimenting, BelIeve you me I have done numbrious tests with quality home brews and Tesro manufactured coils, which tells me with know shadow of doubt that Tesro had it right when they first designed TGS.
I got both mods on my machine with a 3 way double pole switch so its position 1 for the 1meg resistor accross the diode, mid position no mods at all position 3 adding supply to sense pot instead of ground, no point in switching both mods on together unless your in the middle of nowhere searching for metal ring IDs on pigions legs while there flying in mid air. The reason for fitting the switch was for exstensive tests I carried out a while back.
I dont want to burst your bubble, but I strongly suggest you go out and do proper tests before passing a opinion on your building technics unless you fancy joining the utube club which is full of machines getting air tested, which is meaningless far as im concerned.
Dont get me wrong theres alot more clever engineers far as metal detecting designs than me, but when we talk about field testing with various machines which ive done for the last 40 years with numbrious machines and format types you get to know there limitations and what to exspect out of them performance wise , far as improving depth in real time with the tgsl its not about making the circuit more sensitive its about making it more stable in real conditions , if you crack that one then everything else falls into place and you then will receive a browny point from me
All the best

[johnsmith77]

I think thats a bit over the top you yourself and many others here have worked there *** off on this project, it cant be expected to be laid on a plate, the next thing they will be asking it to be built for them, this forum is a technical set up for experiments etc, anybody who didnt spot the error far as wireing inverted/non inverted on the circuit going to ground oviously hadnt done there home work previously before starting the project.
Far as reversal of wireing on the various pots..... so what, its only a matter of swaping to wires over so controls are going clockwise instead of counter clockwise, and dont say they got the wiper wrong I really cant see the big deal and if people on here are doing these projects cant sort that out then they shouldnt be attempting such projects in the first place.
My golden rule is when commencing the TGSL project use the origonal TGS circuit along side Ivionics and work between the two, then you cant go wrong.
Far as coil connections I personally found wireing up the same as Tesro do with there manufactured coils is best, I get few falses and its quiter, but of course I can only speak as I found in real use situations here in the UK.
This project was never a fool proof project for people with no engineering skills, they need at least a basic knowledge in electrical engineering and of course accurate test equipment.
Without either one or both of those things they are knackered, just wasting there money and everyone elses time.
And another golden rule is as said so many many times by Ivonics read the bl..... forums over and over again till its planted in the brain to how the TGSL ticks, all the imformation for this project is there in black and white, its no good reading bits of it, you need to read how it progressed, and may I add still is, its ongoing theres no final here and proberly still going when a lot of us are pulling daisys from below.( So dont lable anything as final)

You know simon I am a TV engineer by trade so Using test equipment and fault finding in the field of TV/Radio is like second nature , but even with those skills I had to get my brain in gear because of a doggy inductance meter duff chips and ongoing experiments, so how these lads with neither test kit and knowledge exspect to achive anything other than a non working project baffles me.
Or maybe im on a different planet or just plain old fasioned, if either please correct me and put me in my place.

Kind regards as always

Ok, i made only one coil and it works 30cm in the air. So i mean, if we correct mistakes, we achieve it at once, not as seventh coil making time.
Less trouble for future. If mistake left, it can be repeated in future projects.
Everybody make mistakes, even asses.

Furthermore i thought more and got decision: LF353 pin 6, or pin 5 is grounded there will be no difference. I bet. There is no mistake and both manuals correct at this point

[satdaveuk]

I think that is definitely a mistake in the illustration -- good catch! We should fix that since it seems pretty essential. As dfbowers mentioned, the alternative wiring (with no grounding of RX coil) removes the possibility of error.

This highlights how darn difficult it is in these forums to divine a clear, accurate set of instructions for building some of these projects. Reading the threads is fraught with peril -- every other post has a mistake or disagreement. It really is an experimenter's game here. But Don's and Ivconic's manuals are the gold standard for now. It is very important to put such documents in a "sticky" post, like Qiaozhi did with Ivconic's material, and then allow continual editing to fix discovered errors. That way over time the information will become more thoroughly "vetted", tested, and reliable, and you'll always know where to find the latest version.

Of course if you're willing to tinker, analyze, and ask questions, you'll eventually get there regardless.

-SB

I think thats a bit over the top you yourself and many others here have worked there *** off on this project, it cant be expected to be laid on a plate, the next thing they will be asking it to be built for them, this forum is a technical set up for experiments etc, anybody who didnt spot the error far as wireing inverted/non inverted on the circuit going to ground oviously hadnt done there home work previously before starting the project.
Far as reversal of wireing on the various pots..... so what, its only a matter of swaping to wires over so controls are going clockwise instead of counter clockwise, and dont say they got the wiper wrong I really cant see the big deal and if people on here are doing these projects cant sort that out then they shouldnt be attempting such projects in the first place.
My golden rule is when commencing the TGSL project use the origonal TGS circuit along side Ivionics and work between the two, then you cant go wrong.
Far as coil connections I personally found wireing up the same as Tesro do with there manufactured coils is best, I get few falses and its quiter, but of course I can only speak as I found in real use situations here in the UK.
This project was never a fool proof project for people with no engineering skills, they need at least a basic knowledge in electrical engineering and of course accurate test equipment.
Without either one or both of those things they are knackered, just wasting there money and everyone elses time.
And another golden rule is as said so many many times by Ivonics read the bl..... forums over and over again till its planted in the brain to how the TGSL ticks, all the imformation for this project is there in black and white, its no good reading bits of it, you need to read how it progressed, and may I add still is, its ongoing theres no final here and proberly still going when a lot of us are pulling daisys from below.( So dont lable anything as final)

You know simon I am a TV engineer by trade so Using test equipment and fault finding in the field of TV/Radio is like second nature , but even with those skills I had to get my brain in gear because of a doggy inductance meter duff chips and ongoing experiments, so how these lads with neither test kit and knowledge exspect to achive anything other than a non working project baffles me.
Or maybe im on a different planet or just plain old fasioned, if either please correct me and put me in my place.

Kind regards as always

[johnsmith77]

Hi johnsmith77:

LF353 pin 7 is not a good reference for phase. Can you do same pics but referenced to TX signal?

Sometimes a 90 deg shift means wrong capacitor somewhere -- uF instead of pF -- for example.

But first let's compare waveforms referenced to TX signal.

Regards,

-SB

I solved it. I know why?

It depends on cable connection mode.

Connection "for wet grass" according to ussuall cable connection to coil, changes signal polarity on Tr4, Tr5, drains. Also it changes phase shift by 90 degrees.

Do you agree?

I am interested how is going coil nulling if someone is trying null, having standart cable connection on his TGSL and that someone compares his oscilograms to oscilograms of "wet grass" connection. The second person should think he made coil wrong, then he make another hoping then he will get oscilograms as got the first person, then again again and big trouble.
He can faill

Maybye it was disscused in forum before, but i could not find?

Thanks