TESORO GOLDEN SABRE

[Max]

This is an interesting question, because Tesoro coils seem to be balanced with a 15mV residual signal, and they work fine.

Hi,
? no it isn't...at least on my original 9x8''. I've measured the same way with scope+capacitor and 1Kohm resistor and read something 3.5mVpp... at 10KHz.
That's the voltage level I get from it ... of course not perfect null but not 15mVpp.

What model are you referring at? The 8'' Polo brown coil ?
Or a DD widescan (e.g. the 10'' coil)?

I've just the 9x8'' spider so could not say about others... but mine is nulled near the level I've made my smaller DD22 and 8'' opencentre (I get less than 1mVpp with those).

I think that large DDs suffer of bigger "null" voltage cause of more critical overlap respect to smaller...so maybe a 10'' from tesoro could reach 15mVpp but I'm sure that couldn't be a great coil on performance side that way...too instability.

For my curiosity I've tested till 20mVpp 22cm coils and found that , as Ivconic reported, you can use it as a 1mVpp nulled coil in the air cause no big differences there... but putting that on the ground I get an hell of noise in easy soil... and cannot figure out from where... if soil... or some metal particles in soil or foil etc ...I gave up with it after few days...cause made another properly nulled worked perfect on same soil.

I think that most depends on GEB... if you can ground-balance very well (e.g. on BandidoII with external pot) you can also use a coil with 10-15mVpp but otherwise is almost impossible using that: on TGS that has fixed preset GEB it will be totally unuseful on 90% of soils...at least for me... so solution are
- build one with less out-null voltage
- change the trimpot with a multiturn/oneturn pot on panel for GEB

All the rest will not work.

Best regards,
Max

[tiktak]

Hi

One more thing I have try testing with different ithems but its look like my device can't dicriminate rusty horseshoes and etc. only some IRON ont all!
What could be the reason for this?\

[tiktak]

hi

Hi,
Max.
Have you test your 12cm OO coil?
I ask because I make one yesterday but cant get good results!\
Less depth even compared with other coils I have made!
I dont now where realy is my probleme,but I hardly can reach 25 cm with all I have made and try so far!
Maybe my problem is that bad battery......or bad nulling...???

[Max]

"...BTW what's total weight of your detector with DD255x137 ?... I notice gel-type that battery will be under the arm...."

Yes, good question! This one ("katana") is arround 3kg's...heavy but very well balanced. It is kind of hard to work with it more than 40-50 minutes. I usually take short rest,5-10 minutes...It could be lighter a bit. I was thinking to mix this mass with something lighter and try to achive coil weight under 500gr.
I'll experiment with this further.

Hi,
nice to know your potting stuff is not conductive... I think know I understand what is it... I saw a lot of times in hi insulation transformers and the like... thing used to keep flyback secondary turns well fixed and insulated by a thick layer... that thing is very good stuff for work like coils !

About weight ... well... also mine is not so light... but now better than before...I'm around 1.65Kg at now... but considering the metal I've used (aluminium box+pole) it's not too much respect to commercial models like some fisher and also tesoro (e.g. Tejon). Unfortunately I had to use some old stuff from other (crap) detector and that added some more weight to my initial idea (1.3Kg maximum).
I recovered some weight changing the lead-acid battery for a pack of 10 NiMh of 700mAh capacity. Detector run smooth also with that... even if I think that the battery drop of NiMh is not as good as lead-acid ... you can notice that after a few hours of working the audio tone decrease in amplitude a bit respect to initial charged state... but I can live with that and prefer saving +300gr from my arm! With lead-acid battery weight was about 1.980Kg about 2Kg... that I've found heavy for me in long search.

Now I can sweep 1 hour without big problems... but then 2 hours it became a bit heavy... and after 3 is just pain on shoulder... but I also make always a rest/pause of 10 minutes after 90 min to 2 hours.

If you wanna save some weight use NiMh like I've done... you can also save money if recover 10 of them from old cellphone batteries... cause you don't need hi-capacity for TGSL... just working ones with 600-700mAh capacity are more than enough for 15-20 hours of working.

Kind regards,
Max

[ivconic]

"5...10mV", is to high! I already made simillar coils in the past. Those were times when i made Classic III. That's why am i talking about good nulling. I had a lot of problems with CL3 and bad nulled coils. A lot of false signals on any kind of soil, everywhere. Totally unuseable.Couldnt distinguish among detection and false signal at all.
Other side, yes i agree, coil can be useable even if it is not nulled to absolute zero. Up to 1mV it can be used with detector like TGS, cose TGS have very good soluted GEB&DISC stage so any eventual loss coming from coil can be easilly compensated inside apparatus. It is not special to null coils good, only need patience and good will...I already explained my method. Usually takes 20 minutes to null coil (due time needed to chill out melted plastic)...

But Quiaozhi confused me with previous claim...!? Wait for his reply on this...

[Geo]

Maybe i have not right. I just learn.........
But if the null is not absolut "zero" why to detect at more distance on air and not in the ground??? Phase shift...... maybe but it will work as Ground balance or as a little discriminator (why to lose the depth)???
At the other side i can't make the absolut null. I play with all the D coil or with one turn or i wind 2... 8 small turns in the coil with positive or negative direction..... but i always have 5.... 10 mv output to the scope.
I don't say that i am the right and you the wrong.... but as you now making a lot of coils, you can make a coil without good null (don't glue it good) and try it to the field so to be a good experience for all of us.
Regards

[ivconic]

This is an interesting question, because Tesoro coils seem to be balanced with a 15mV residual signal, and they work fine.

Now, this is strange? Also could be very interesting! Could be solution to my last problem i havent solved; mentioned ocassionall bleeps. Although those are very,very rare with my latest coils...Maybe Tesoro need coil not nulled absolute to zero? Is it possible?
Also other explanation is possible; coil which gave you 15mV might be old,many times used and a bit damaged, unballanced due pass of time,moisture and relative movements so far....Could this be a case?
I need to be perfectly sure about that! Can you measure another Tesoro coil?

[ivconic]

Now litle things for Ivconic.

When i tried to null a coil with oscilloscope and without resistor for load i had bigger indicator and some times i had selfoscillations (when the coil was very tight tune), so the results was bad. For me the best null with scope is to use one resistor parallel with coil (1..2k) and a resistor 5...10K in series with coil and scope. But... but ...but......... For me the problem is other. As i wrote before time sometimes i found that the best position for max sensitivity is a little open to the coil after a very good null. So if for example i have at the null a voltage of 5mv then the position that i have 10... 15mv was the best. I want to tell me your experience about this. Ivica or Max do you have tried the sensitivity of TGS with the coil not fine null? and if yes what do you saw.
Best Regards

Geo, i beleive that you are wrong. Yes, you will gain more depths on that way...BUT ONLY IN THE AIR! Remember that. Later when you take it outdoor it will produce to many false signals...it wont be possible to work with. Actually it is not nulled at all. It is a way off good balance and phase is to much shifted. I guess you have good oscilloscope. Try to follow phase shifts with that coil and you'll see. For example take a piece of clay and look for phase shifting on oscilloscope.
For example, Minelab Sovereign GT is pretty average when testing in the air. Many handmades can easilly beat it in the air. But....when you put it on the soil it is "devil". Goes very deep! On the other side same handmades cant detect items even to 1/3 of GT's depth...Why is that so? Think about it...

[ivconic]

Respecting induced voltages;
I have Troy Shadow X3 concentric coplanar coil here with me, also 20cm Fisher coil (came with 1266) also concentric coplanar...So, just to be sure how to null properly, i put those two on tests. As oscilator i used the one from Classic III and after that repeated with this one from TGSL.
On both original coils i measured 0.000mV. Of course tested all possible combinations coil to oscillator. Although my oscilloscope is old and obsolete, i also measured with it...same..zero induction. So, this is not about multimeter accuracy or osciloscope accuracy at all. Respecting this i decided to try to null my coils as close as possible to zero induction. At the very beggining i beleived it is impossible. But thanks to Max's suggestion to put capacitor parallel to RX, finally i founded proper way how to null those to zero.
As i posted above (although very confusing) first perform nulling without capacitor, just to close it enough not to induce much of voltage...as less as possible. In my case it was arround 0.009mV. Than add capacitor to raise a bit voltage, usually to 0.012 to 0.015mV. Than very carefully squeeze short parts of one of the coils and glue that spot with melted plastic.Holded until chill good (due relative movements). Usually when i hold it to chill, it reads 0.000mV. But than when i release it it raise a bit...to 0.001mV. So again, very,very carefully i press some of coils softly to make it to read 0.000mV, and again glue that spot with melted plastic. When chilled again release and wait minute or two to see if it will raise or not. Usually it takes 2 or 3 backs to achieve absolute zero (again, if multimeter is accurate...?)...When it is finished, than i fill it up with mentioned 2 component pitch and let to dry for some hours...And that is all...
I can accept that multimeter is not absolute accurate, but this is as closest as possible (in my conditions) method to null coil so far.

[Qiaozhi]

Now litle things for Ivconic.
When i tried to null a coil with oscilloscope and without resistor for load i had bigger indicator and some times i had selfoscillations (when the coil was very tight tune), so the results was bad. For me the best null with scope is to use one resistor parallel with coil (1..2k) and a resistor 5...10K in series with coil and scope. But... but ...but......... For me the problem is other. As i wrote before time sometimes i found that the best position for max sensitivity is a little open to the coil after a very good null. So if for example i have at the null a voltage of 5mv then the position that i have 10... 15mv was the best. I want to tell me your experience about this. Ivica or Max do you have tried the sensitivity of TGS with the coil not fine null? and if yes what do you saw.
Best Regards

This is an interesting question, because Tesoro coils seem to be balanced with a 15mV residual signal, and they work fine.

[Geo]

Now litle things for Ivconic.
When i tried to null a coil with oscilloscope and without resistor for load i had bigger indicator and some times i had selfoscillations (when the coil was very tight tune), so the results was bad. For me the best null with scope is to use one resistor parallel with coil (1..2k) and a resistor 5...10K in series with coil and scope. But... but ...but......... For me the problem is other. As i wrote before time sometimes i found that the best position for max sensitivity is a little open to the coil after a very good null. So if for example i have at the null a voltage of 5mv then the position that i have 10... 15mv was the best. I want to tell me your experience about this. Ivica or Max do you have tried the sensitivity of TGS with the coil not fine null? and if yes what do you saw.
Best Regards

[Geo]

Hi Max. Now it is not my good time. I don't know why but i can't make good pcbs. I have 4 UV but i dont remember the power. The UV are inside a scanner so there are very near to the pcb. This is the reason that i use it for 8 sec not minutes. Now about soda solution i use the same with you 7...8 gr for 1 liter water. Today i used water with TUBOFLO but the same problems. The same with the spray. I believe that the photosensitive pcbs are not good, the same for the spray, because i use this method at least 20 years. Tommorow if i will have time i will try with paper and Iron. But i dont know what paper to use. I have not PnP paper. Many people use white paper from magazines. but where to find a white paper...... all are full.
Never mind........ i told that it is my good day (a lot of days are not my good)
My Regards

[ivconic]

"...BTW what's total weight of your detector with DD255x137 ?... I notice gel-type that battery will be under the arm...."

Yes, good question! This one ("katana") is arround 3kg's...heavy but very well balanced. It is kind of hard to work with it more than 40-50 minutes. I usually take short rest,5-10 minutes...It could be lighter a bit. I was thinking to mix this mass with something lighter and try to achive coil weight under 500gr.
I'll experiment with this further.

[ivconic]

No Max, this never used on cars or simillar. I dont know proper name for it.Sort of pitch,resin..? Oh, yes i know; look at some old TV set,flyback transformer and cascade are filled with it, same material. Doesnt shrink a bit. Remains same volume when dry.That's why am i delited with this. No metal particles inside, pure non-conductive material.
Other; yes perform nulling on both ways and please inform us here about diffeences...
Regards!

[Max]

Those are 2 coils i made yesterday and today.Drying yet. It will need few more
hours to get dried and stiff.Also there is a mass which used to fill up coil
housings. Sort of 2 component pitch. When dried, it is hard and fast as steel.
Best so far. Cold drying no relative movements. Larger coil is 800gr and smaller
680gr. A bit heavy but almost unbreakable. I can hit it with hammer very
hard - not even a small scar...Superb!
And photo of my (my personal-not for sale) TGSL, which i am using now.
The one who collected those 254 coins in no time. Real killer! Coinkiller!
I didnt payed much of attention on appearance, it is a bit brute but real
machine!
Others i made for sale are looking much better,nice outfit...Havent neither one
right not to take photo. I'll do that next time when finished...

Hi Ivconic,
the mass you talk about is something like used in repair for cars... I mean something 2 components (filler+primer) car filler/putty ?

I've tested it to add weight to a coil 2 or 3 years ago... and it's really hard stuff... you can e.g. sand (seems metal after dry ! it's a rock).

I think most of these are poliurethane compounds... that are heavy about as epoxy and also hard... but they, big masses, shrink a bit.

I know there are epoxy based fillers (2 components) that are "loaded" with other kind of plastic (sometimes fibers) and other stuff.

My thought about them is about added stuff... I mean there are some for e.g. home improvement/repair that have aluminium grains inside... other (like car products or insulanting materials for e.g. water) loaded with metal oxides... : if so could be a real problem having that just over the coil !

Many car type have just plastic fibers inside... so are good for the purpose... one have to test making hardening some in an e.g. 5cm diameter bottle cap ... then trying to detect it with MD before using.

I've made some try and detected 1 kind of home-improvement epoxy adesive (maybe... cause is silvery looking... there is aluminium inside).

BTW what's total weight of your detector with DD255x137 ?... I notice gel-type that battery will be under the arm.

Best regards,
Max