TESORO GOLDEN SABRE

[Wiltran]

TGSL Coil question

I got a question for Dbowers. If you are winding a TX DD coil for TGSL, and you are less than 14.5 KHZ, - say 14.420 KHZ, do you just unwind a half a turn to make the TX resonant at 14.5, and loop the extra wire back under the foil faraday shield? or do you only use complete turns even if you go over or under the 14.5 KHZ?. also I am curious to know if the Eduardo modded TGSL design is actually a real improvement over the Ivonics TGSL?
thanks.

[dfbowers]

I got a question for Dbowers. If you are winding a TX DD coil for TGSL, and you are less than 14.5 KHZ, - say 14.420 KHZ, do you just unwind a half a turn to make the TX resonant at 14.5, and loop the extra wire back under the foil faraday shield? or do you only use complete turns even if you go over or under the 14.5 KHZ?. also I am curious to know if the Eduardo modded TGSL design is actually a real improvement over the Ivonics TGSL?
thanks.

Yes, you can just take a few turns off to get the frequency correct. I usually do that before adding any shields, but adding the shields will change your freqency slightly again anyway . As long as you are close and can still get phasing correct you should be ok .
Eduardo's version is essentually the same, so no real difference besides increase DC gain on U103. At the same time, it make the TGSL more difficult to run smoothly. It does make for a hotter machine, if that's what you want. BUT.. in my opinion in the end, the ground is going to be the big limiting factor on depth. For all practical purposes, I pick stability.

Also, Eduardo's version seems to have a slightly better audio, but I only have one build of his version so far. Using headphones, I don't know if there is any advantage there. I'm interested in seeing how yours might come out!

[Wiltran]

TGSL COIL QUESTION

Thanks for the quick reply. So then its ok to take off a half turn only and loop it back following the D shape, so the pigtails will line up at the bottom of the "D". that way I can get the freq. more exact. Eduardos version is hotter? does that mean that it would find a quarter deeper in the ground?. The sound is pretty good on the TGS, and I found if I used headphones it works the best. If there isnt any substantial improvement with Eduardo version I think I might as well build latest Ivonics (version 3 I think), and maybe add the Dbowers mod to the comparator diferential. I built the TGS, and I like it except the notch feature in actual use is confusing to me. I built a 12" concentric coil, that works good, and am now building vacuum formed coil shells thanks to information you provided in your posts!

[dfbowers]

Thanks for the quick reply. So then its ok to take off a half turn only and loop it back following the D shape, so the pigtails will line up at the bottom of the "D". that way I can get the freq. more exact. Eduardos version is hotter? does that mean that it would find a quarter deeper in the ground?. The sound is pretty good on the TGS, and I found if I used headphones it works the best. If there isnt any substantial improvement with Eduardo version I think I might as well build latest Ivonics (version 3 I think), and maybe add the Dbowers mod to the comparator diferential. I built the TGS, and I like it except the notch feature in actual use is confusing to me. I built a 12" concentric coil, that works good, and am now building vacuum formed coil shells thanks to information you provided in your posts!

I would not worry about 1/2 turn at all as long as your phasing is correct. Shield and cable will change your freqency too. I notice much more change if my 15nF tuning cap is off by 500pF!

I think that you could potentially find a quarter deeper in the ground with a hotter TGSL, but then you might add a lot of unnecessary noise. I find myself backing down the senstitivity anyway just to get things running smoother. Again, the ground is the limiting factor in many cases.

I would be interested in seeing your 12" concentric if you don't mind. I have been tempted to try building one too.

If your vacuum forming doesn't come out, let me know. I may be able to send you a shell.

Don

[Wiltran]

TGSL Coil question

Ok Don, so it sounds as if I get the TX coil close, i could probably adjust better with cap.

Here are some pics of my TGSL, and my surf pi. These two mds worked out better than I expected Surf pi -11" on a nickel and better than that on the tgsl. I also built a DBP2010, which worked, but was a major disappointment. The first DD coil on the tgsl was a failure, I could get the coils to null good, but when I added the epoxy filler. the null was ruined! So I built a 12" concentric, following the coil instructions by Dave Emory. Everything was going great til I got to the bucking coil.ll I can say is if you have a way to wind the bucking coil on a spool that will slip over the receive coil, it will make your going easier. I had trouble getting a null adding and subtracting turns on the bucking coil. Finally I got the null close , and I tweeked the bucking coil so it nulled. I want to try another DD coil, cause I want to build another coil shell. Having the coil shells make the md a whole lot easier. Wil

[manurespreder]

hello there,

i am reading about coil making and there is mentioned "0.27-0.28mm with resin layer"

now i am wondering what does "resin layer" mean?
enamelled? or lacquered?

[simonbaker]

hello there,

i am reading about coil making and there is mentioned "0.27-0.28mm with resin layer"

now i am wondering what does "resin layer" mean?
enamelled? or lacquered?

Can you point us to the reference? It sounds like a description of enameled wire, or even the process of gluing/binding a wound coil by coating with some kind of glue/resin during winding. Where did you see it?

-SB

Update: I think I know what you are referring to. I'm pretty sure it just means ordinary enameled magnet wire, or similar.

[manurespreder]

thank you for you thoughts i was reading tgsl Making coil.pdf

[manurespreder]

i don't know.. i am dumb or what i can't find any cu enamelled wire within 0.27-0.28 on ebay only one i found is 0.3 is it possible that there is nothing such like 0.27 - 0.28?

[simonbaker]

i don't know.. i am dumb or what i can't find any cu enamelled wire within 0.27-0.28 on ebay only one i found is 0.3 is it possible that there is nothing such like 0.27 - 0.28?

I think .3 mm should work fine. You might look for 29 gauge wire too, maybe not common though. 28 or 30 gauge might work too, that's what I often use.

-SB

[habitbraker]

hello!
After reading hundreds of posts here, I finally lighted up my first TGSL and its working pretty good.
Disc is perfect and I can totally reject ferrite stick.
Its all on the bench for now and i dont have coil enclosure. I am planing to use vacuumforming method to form the enclosures. I already purchashed 1.5mil plastic sheets.

My coils have classic dimensions - d=25cm, described in "ivconic coil making PDF"
Tx=6mH, Rx=6.5mH. Wounded with 0.28mm wire. Spacers = 5mm

My air distances for now are about 25cm with Latvian coin and thick silver ring in disc mode. I am using dfbowers threshold mod, because with ordinary threshold control I could put it on max sensivity and still dot get chatters or false signals. I dont have eiro, so I cant compare with others here, but I will get one. I can put sensivity so high that coin is detected 30 cm far but then I can detect my hand - no good

I am using tl071 instead of LM308. TX Frequency is 14.1khz voltage is about 17Vpp. I am using external pot for GND bal.
Actually disc is more sensitive than all metal mode. (about 3cm more) I dont know why

First I tried nulling with unshielded coils and I could get about 20mVpp meassuring at U101 pin 7. Then I shielded it with adhesive Al tape and after that, my min null became about 1.5Vpp.
Sensivity isnt much reduced, but I think that large null is because Al tape is pretty thick and very conductive. I tried several methods of nulling, but finally I just adjusted coil so that it almost mach waveforms shown in pdf called TGS_Compare1. After that Its working pretty good.

It just my first one and my future plans are:
1. Building another TGSL or more. I have one Silverdog PCB half assembled...
2. Try LM308. I have ordered a few..
3. Wind different coils. Now I have one coil with spacers of 2.5mm drying. Will post results.
4. Try to find different shielding method.
5. Build a coil enclosure using vacuum forming. Never done it before.
6. Test it on real conditions in real soil
7. Add volume control
8. Read another 1000 posts posted in geotech Now I started to read TGSL tining&troubleshooting - I simply love that tread - so much info!!

All I want is to get famous 30-35cm.

oK . Pretty long text I have made
One question: Is this normal that waving ferrite rod together with coin I dont get response? Isnt that mean that in soil I will not get response for that coin? Single coin is detected....

Later I will post some pics

[habitbraker]

My coil winder. counter was specially made for this purpose - with -1 option and sound indication. Using PIC. It counts only up to 255 - enough for TGSL. if enyone interested I coud give shematic and source code


Shield spacers and one shielded coil. In my oppinion too thick so its no good for nulling


My setup One of plastic sheets I mentioned

[simonbaker]

hello!
After reading hundreds of posts here, I finally lighted up my first TGSL and its working pretty good.
Disc is perfect and I can totally reject ferrite stick.
Its all on the bench for now and i dont have coil enclosure. I am planing to use vacuumforming method to form the enclosures. I already purchashed 1.5mil plastic sheets.

My coils have classic dimensions - d=25cm, described in "ivconic coil making PDF"
Tx=6mH, Rx=6.5mH. Wounded with 0.28mm wire. Spacers = 5mm

My air distances for now are about 25cm with Latvian coin and thick silver ring in disc mode. I am using dfbowers threshold mod, because with ordinary threshold control I could put it on max sensivity and still dot get chatters or false signals. I dont have eiro, so I cant compare with others here, but I will get one. I can put sensivity so high that coin is detected 30 cm far but then I can detect my hand - no good

I am using tl071 instead of LM308. TX Frequency is 14.1khz voltage is about 17Vpp. I am using external pot for GND bal.
Actually disc is more sensitive than all metal mode. (about 3cm more) I dont know why

First I tried nulling with unshielded coils and I could get about 20mVpp meassuring at U101 pin 7. Then I shielded it with adhesive Al tape and after that, my min null became about 1.5Vpp.
Sensivity isnt much reduced, but I think that large null is because Al tape is pretty thick and very conductive. I tried several methods of nulling, but finally I just adjusted coil so that it almost mach waveforms shown in pdf called TGS_Compare1. After that Its working pretty good.

It just my first one and my future plans are:
1. Building another TGSL or more. I have one Silverdog PCB half assembled...
2. Try LM308. I have ordered a few..
3. Wind different coils. Now I have one coil with spacers of 2.5mm drying. Will post results.
4. Try to find different shielding method.
5. Build a coil enclosure using vacuum forming. Never done it before.
6. Test it on real conditions in real soil
7. Add volume control
8. Read another 1000 posts posted in geotech Now I started to read TGSL tining&troubleshooting - I simply love that tread - so much info!!

All I want is to get famous 30-35cm.

oK . Pretty long text I have made
One question: Is this normal that waving ferrite rod together with coin I dont get response? Isnt that mean that in soil I will not get response for that coin? Single coin is detected....

Later I will post some pics

I say: good work! All your specs sound normal for a TGSL, including the large null with a shield -- very similar to TGSL from dfbowers that I use for comparison.

My coils are usually 28 to 30 cm diameter, but now I am beginning to think that 25 cm is maybe a better choice for some reason. I'll have to drill some new holes and try one that size.

Not sure about the ferrite and coin together, someone else can test sooner than me. It may depend on size of ferrite too. Also, remember the ferrite in ground is spread wider than the coin and that probably makes a big difference.

Regards,

-SB

[dfbowers]

I tried the ferrite plus coin test. It appears as though the ferrite masks the coin somewhat, but that was with a U.S. nickel and quarter. Maybe it also depends on where you have everything set. I don't believe that's a condition that you would encounter in the field though.. Maybe a coin next to a hot rock or nail that you have discriminated out.

I have tried a similar experiment in the past where I cover a coin with a clay brick. A detector cannot typically detect the coin under a single brick but if you pulled a brick out of an entire sidewalk and put the coin under a brick in the sidewalk and replaced the brick it would detect it OK..

Also, I have found little difference between the LM308 and TL071's. By picking through a handful of LM308s I see some suttle differences but that's about it.

As far as Eduardo's version goes, audio is improved with external speaker for sure but the advantage is not that great if headphones are used. I have also been contemplating replacing the 1m Ohm resistors in the DC stages with the original 460k Ohm resistors. Too noisy in actual use and sensitivity cannot be reduced enough! The doubled gain increased sensitivity but also increases noise as well. I like running a quiet detector just under where the sensitivity control causes instability but am having trouble with this version.

[habitbraker]

thanks for response!
I guess you are right about lm308. But I will try it anyway when I receive it.
If you say that your tgsl also dont detect coin with ferrite then I guess its ok too.

TRIED that coil with thichness of 2.5mil and didnt saw differences. Inductances/dimensions was the same so I guess I need to chang those parameters to see differences.


Eduardos PCB not finished yet so cant tell my exp.

I put everything in the box today and attached actual cable (1m instead of 20cm).
All is ok but I got one problem: when i touch the boxes conductive areas I got falses. I got plastic box which have inside (and few areas of outside) sprayred with Kontakt EMI http:http://www.gemalta.com/aerosol-emi-35-200ml.html
Is this normal? touching non-conductive areas and cable, even a coil (not overlap area) is ok with no beeps...

i got few questions:
I have read about null phase and if I understand correctly - if I can ground balance, i got phase right.
But also heard that better is phase of 20 deg. So question is : 20deg leading (+) TX or lagging(-) tx?

Is it ok that my response of silver ring depend on how I have ground balanced? i discovered that I got about 30 deg turning angle on my gnd bal. pot. where I can balance out ferrite. When I gnd balance on one end of those 30deg I got no response for silver. All other metals ok. But when I gnd balance on other end of those 30deg i got silver response..
I hope you understand.