TESORO GOLDEN SABRE

[metaldetector107]

RX tank

Hi friend
can i use a free square wave oscillator for LC tank matching?
best regrads

[simonbaker]

I tested to put metal out of center of coil and connect it to coil shielding. As ivconic say there are no visible effect on coil sensitivity.

That is useful to know, thank you for doing test. I was not thinking about connecting metal junk to shield, but that is another case to think about.

Regards,

-SB

[WM6]

I have wondered about metal screws and parts in coil mounting (Heathkit coil used metal screws I saw in one posting!), so certain amount of superstition as you say. I'm sure I'll continue to avoid such metal out of "habit" too.

-SB

I tested to put metal out of center of coil and connect it to coil shielding. As ivconic say there are no visible effect on coil sensitivity.

[simonbaker]

I think i already done that many times. Maybe my intentions were not same as yours but i done that for other reasons. So what happened? Nothing. Static junk nearby static coil does not affect depths neither the discrimination. In a way coil&detector are "selftuned" to present situation and only dynamic changes are affecting those. It is almost the same thing as you put steel screw on coil enclosure instead plastic one - nothing bad will happen ! Coil will continue to work accurate. Ok...in most of cases phase will be shifted a bit but not significant. It is "habit" from the past - to use plastic bar extension and plastic screws on modern machines. I am practicing the very same when manufacturing my handmades....although i cant tell exactly why am i doing that? Most probably that i adopted the same "habit" looking at originals!
Cant claim for sure for all possible models, but at TGSL and Delta Pulse plastic bar extensions and plastic screws are not important. Doesnt make a difference. Try and see.
This is very funny especially at older nonmotions, where operater can manually tune detector to present situation. So...what the heck is so obligated to use plastic there?
I might be wrong. Would like to hear other opinions...
Cheers!

Ok, you answered me well. So I have no excuse if coil no good on my workbench -- taking outside will not magically make it better. A few objects around should not make radical difference in testing coil. Of course I'll try to keep objects as far as possible. My table is card table which has metal frame and legs.

I have wondered about metal screws and parts in coil mounting (Heathkit coil used metal screws I saw in one posting!), so certain amount of superstition as you say. I'm sure I'll continue to avoid such metal out of "habit" too.

Regards,

-SB

[Max]

Dear Max
please i need a data for a DD coil about 18 or 20 cm cuz i am trying to use monitor stand as a coil housing.
so please

kind regards

My recipe was for 22cm DD coil... but I think you can try with smaller diameter and same numbers...

Try first match tx frequency... then focus on rx and phase.

Kind regards,
Max

[metaldetector107]

Coil

Dear Max
please i need a data for a DD coil about 18 or 20 cm cuz i am trying to use monitor stand as a coil housing.
so please

kind regards

[Max]

Dear Ivco Max Qiawzhe all friends

please i want to build a samll DD coil for TGSL aroun 18 t0 22cm
because i have problem with coil housing so i have a monitor stand

so please help

best regrads

Hi,
what's that ??? Fried chicken stuff and potato sticks ???

Everytime I see your posts I became hungry...

But you have to post also beverage... not complete!

About coil... I made... if remember well got good results with 120turns for both tx and rx... but you may need wind some turn more at rx... check carefully about phase is important for disc stuff to work.

Kind regards,
Max

[ivconic]

Looking at new digital machines like White's serie and simillars, those are for real pretty "open" - operater can adjust those in whatever manner. Ground balance, air balance, manual presets in all those menus. So it is really funny to insist on plastic screws and plastic bar extensions at them. Whatever the unwanted (static) distortion is present arround the coil - operater can compensate it easilly with such "open" machine. No problem at all.
That's why i said it is "habit" from the past.

[ivconic]

When coil is balanced to have residual voltage....let's say 1mV. Closing up same screw to distance when it will usually be on coil enclosure will affect residual voltage just to some 0.0x mV or even 0.xxmV - not significant.
Than closing up metal bar (instead plastic one) to same distance as it should be in final assembly, also will rise up residual voltage to some minor values.
At the end it will be so minor change in residual voltage that it is not important at all. But than we have to worry about phase shift too. Phase will be affected, of course. But also not significant. GEB trimmer at TGSL allows that range of correction to "distorted" phase again. So...
Point is that screw (static relative to coil) and metal bar (also static realative to coil) are not presenting more significant influence on phase and residual voltage, especially on second one.
Further, coils can be balanced in manner to anticipate those minor distortions in future. I will point again on splendid Payne's article reffered to this subject.

[ivconic]

I think i already done that many times. Maybe my intentions were not same as yours but i done that for other reasons. So what happened? Nothing. Static junk nearby static coil does not affect depths neither the discrimination. In a way coil&detector are "selftuned" to present situation and only dynamic changes are affecting those. It is almost the same thing as you put steel screw on coil enclosure instead plastic one - nothing bad will happen ! Coil will continue to work accurate. Ok...in most of cases phase will be shifted a bit but not significant. It is "habit" from the past - to use plastic bar extension and plastic screws on modern machines. I am practicing the very same when manufacturing my handmades....although i cant tell exactly why am i doing that? Most probably that i adopted the same "habit" looking at originals!
Cant claim for sure for all possible models, but at TGSL and Delta Pulse plastic bar extensions and plastic screws are not important. Doesnt make a difference. Try and see.
This is very funny especially at older nonmotions, where operater can manually tune detector to present situation. So...what the heck is so obligated to use plastic there?
I might be wrong. Would like to hear other opinions...
Cheers!

[simonbaker]

For simillar reason i put plastic table in my workshop. Huge plastic table...no crews no nails in it. That table is serving me to test coils and to balance also new coils. Table is 80cm high - enough to void steel from concrete in floor.
So... especially prepared conditions for dealing with coils.
Other thing... junk near coil and both static - doesn't make much sence to me! More real situation is junk nearby coin, both static and coil movable over them...

Ok, you answered my question in a way. My purpose was: I wanted to prove how important it is to create such a special place to test coils, not question of junk when hunting.

I have no space, so I was hoping maybe nearby junk not so important when testing coils, but only test with real excellent TGSL would prove it true or false.

I guess you have decided it is important to make special area, but if you get a chance to test it by putting some junk near coil and waving coin, I would be interested.

Regards,

-SB

[Darko]

Dear Ivco Max Qiawzhe all friends

please i want to build a samll DD coil for TGSL aroun 18 t0 22cm
because i have problem with coil housing so i have a monitor stand

so please help

best regrads

Maybe this will help: http://www.geotech1.com/forums/showp...1&postcount=68

Regards,
Darko

[metaldetector107]

20cm coil

Dear Ivco Max Qiawzhe all friends

please i want to build a samll DD coil for TGSL aroun 18 t0 22cm
because i have problem with coil housing so i have a monitor stand

so please help

best regrads

[ivconic]

For simillar reason i put plastic table in my workshop. Huge plastic table...no crews no nails in it. That table is serving me to test coils and to balance also new coils. Table is 80cm high - enough to void steel from concrete in floor.
So... especially prepared conditions for dealing with coils.
Other thing... junk near coil and both static - doesn't make much sence to me! More real situation is junk nearby coin, both static and coil movable over them...

[simonbaker]

Hi,
when stuff are close could be a problem... but just in very trashy sites you have such cross between e.g. coins and old rusty nails etc...

Civil war scenario... many fields are this way.

In that cases I suggest you try with Lobo w/concentric coil or other MD cause TGS/TGSL with DD is general purpose stuff... can't do anything good.

If things are apart and distant a few... is not big issue. Device works as good as without iron near. As explained.

It's common drawback of such designs have finite recovery... and thus missing stuff when iron near... but some are better than others.

If you consider also that TGS was designed for nugget hunting... you can figure out why cannot be compared to "trash" digesting machines...

Kind regards,
Max

Thanks all for answers.

I'm thinking about special case on workbench, not practical detecting in field -- very different.

On workbench, junk and coil both stationary, only target moves. In field, target and junk both move relative to coil.

I am wondering if stationary junk on workbench "deadens" or shifts phase response of coils to a moving target.

I mean really testing it with a homemade TGSL -- coil on table, move coin above it. Then add junk on table, again move coin above coil. Any difference in depth or discrimination??? I don't have a "great TGSL" (30+ cm depth) to test with.

This is helpful to know... is it possible to determine good coil on workbench, or must every coil be taken outside to test if good???

Regards,

-SB