TESORO GOLDEN SABRE

[johnsmith77]

Have you readjusted GEB trimmer to see if there is difference?

Yes, seems GEB trimmer does not affect DISC mode at all. Not sure with silver (i have only silver chain), but at first try no difference with ferrite, foil, iron.

[ivconic]

I checked now.
I all metal mode foil accepted, iron accepted.

In disc mode, when disc min: iron rejected, (not deep as i want, but rejected), foil accepted, ferrite accepted.
When i turn disc pot more, foil rejected, iron accepted.

How it can be?

Have you readjusted GEB trimmer to see if there is difference?

[johnsmith77]

I checked now.
I all metal mode foil accepted, iron accepted. GB trim allmost at the end CCW.
Previously with a little different coil (1 turn more on Rx and 1nf plus on 0.022 oscillator capacitor C2) i managed trim GB to reject ferrite at a little ccw from middle position. This position is stated in tgsl tunning manual, if i correctly remember.

Main thing:

In disc mode, when disc min: iron rejected, (not deep as i want, but rejected), foil accepted, ferrite accepted.
When i turn disc pot more, foil rejected, iron accepted.

If discrimination rejected higher response phase metal (at this example-foil); it should reject also lower response phase metal (iron).


Am i correct?

[ivconic]

"..You can easily misadjust the TGSL. The GB trimmer can sometimes be set on the wrong side of the "quiet spot" while rejecting ferrite in the A.M. mode..."

Thats true and i experienced that many times.
But that also depends mostly on coil.
Not a big deal, as long as you can achieve null in trimmer range.
Along with achieved null (tested on ferrite) do test it also on tiny piece of Al foil.
It may happen tiny Al foil to be fully rejected (even in AM) , meaning the coil is "overnulled" a bit. Try to compensate by turning back a bit GEB trimmer.
It really doesn't matter if detector starts to make short "cracks" responses on ferrite, because it will remain calm and GEB-ed nice on real soil.
In the past i insisted on full ferrite rejection, which was mistake in a way.
Later i realized that there is no need for that.
That's why (in meantime) i replaced ferrite (as "reference" when nulling coils) with few pieces of hotrock and old Roman clay.
But apart that, best solution would be GEB preset at front panel.
So each time when start searching; operator to "pump up" the coil toward soil and manually readjust GEB.
That's how best performances will be assured each time.

[dfbowers]

Hello everybody I am the new one in this forum, but not a newbie in the electronics. So i made TGSL. This is my first homemade MD in my life. I have never had any commercial MD also before

My results: 1e coin 29cm, disc mode. Measure at home. I have Dfbowers mod in sensitivity pot.

All metal mode: tunned gb pot, so small ferrite can detect only about 3cm.

Disc mode, disc pot min; big pliers detects at 20cm. As i said 1e at this adjustement is 29cm.
If i turn disc pot more to middle or to max, detection range to iron is bigger.

What is your opinion about gb and disc adjustements?

Thank you

I just did a quick check on one of mine - TGSL Eduardo's version.. With disc set at a minimum (in disc mode), I can still detect a HUGE pair of pliers. If I turn disc up to just reject small bits of foil, the TGSL is quiet on iron as well... nothing at all..

That's the stong point of the TGSL, assuming phasing is set correctly. It should still reject fairly large pieces of iron. Discrimination is excellent!!

Try adjusting the GB to completely reject ferrite, in the A.M. mode. Then, make sure that you can still detect quarters or small silver in the disc mode. That will tell you that the GB trimmer is set correctly.

You can easily misadjust the TGSL. The GB trimmer can sometimes be set on the wrong side of the "quiet spot" while rejecting ferrite in the A.M. mode.

Hope this helps..

Don

[johnsmith77]

Hello everybody I am the new one in this forum, but not a newbie in the electronics. So i made TGSL. This is my first homemade MD in my life. I have never had any commercial MD also before

My results: 1e coin 29cm, disc mode. Measure at home. I have Dfbowers mod in sensitivity pot.

All metal mode: tunned gb pot, so small ferrite can detect only about 3cm.

Disc mode, disc pot min; big pliers detects at 20cm. As i said 1e at this adjustement is 29cm.
If i turn disc pot more to middle or to max, detection range to iron is bigger.

What is your opinion about gb and disc adjustements?

Thank you

[Max]

Check how you have installed Q3, the marking on the SilverDog PCB (maybe all PCBs from the same Layout file) is reversed.
Firstly I have to say that I have not had a PCB in my hands with this problem of the Q3 transistor, when I built mine, I put the transistor in backwards according to the legend (the correct way for most transistors, but maybe not all!!), but I would guess that the -6.2 volts will be completely wrong, maybe only 3 volts or so if the transistor is placed as the component placing dictates......

Measure the -6.2 volts first, I believe relative to 12 volts ground/minus.....(my PCB is not quite finished!)

If true:- If the -6.2 volts is bad, it will affect the correct operation of the following Op amps:- U1a, U6a, U4a, U7a, U7b, U8a, U12 and U5a. Probably they will just work still, but with drastically reduced gain…..it’s worth checking up on that point.

Its a simple matter to check.

Metal in the search coil area, connectors for example, will reduce the overall sensitivity, I never use more than a soldered connection with heat shrink tubing for insulation. I cannot say exactly how the connectors will affect things, but if they were added AFTER nulling, you may have found your problem already......

Not getting a good null will also affect the sensitivity, how did you actually "null" the coils? Full and exact details in short sentences.

Is your main 12 volts good? Have you checked it with a scope for noise?

I am not a TGSL or IGSL expert - yet anyway , only Ivconic is.....Simon is pretty good too, read and carry out anything they suggest....Don Bowers knows the normal TGSL well, has also written helpful documents.....coil construction for example....See TGSL part 1 and part 2.

regards

Andy

"null the coils" means you got about 0 mV signal (peak-to-peak) at RX coil in REAL conditions of working MD on the bench (sometimes the concept is quite more complex as you need nulling in average soil conditions... but with TGSL/TGS and similar is not the case)

said so you need balance TX flux and counter-flux (nulling coil) to get exactly 0 mV at RX in working conditions (read it, as if it is connected to primary amplifier etc of detector): actually Ivconic's way of doing so is looking at output of preamp during nulling phase, plus some other tricks to null the signal

Said that some people here look for small not-null value (few mV p-p) cause coils can be slightly overnulled to gain increase in stability, but, usually, you can't get much lower 1mVpp when nulling a VLF coil in any case, unless you use tricks that ar not just geometric properties and align of coil but also "dump" magnetic flux somehow in some hot spots, e.g. using tiny pieces of Aluminium foil at coil bottom and/or adding some conductive substance (e.g. graphite) to the epoxy/putty of coil to both shield from static charges the coils and absorb some magnetic flux due to small eddy currents flowing inside this stuff...

read Ivconic's posts about, it's all there

[xXx]

Hello!

Sorry for my English but I use the translator. To recommend the use of probes TESORO Firewire cable 6 / 4 works well. It selected a dozen of others have used a home-made probes at my ELDORADO.

http://imageshack.us/photo/my-images/714/15102011002.jpg/

Best regards !

[Fabian]

hello, i have problem with my TGSL. Detecting distance is very poor (15cm with 1 Euro).
Inductance are 6.5mH and 6.04mH.
I did some measuerments with oscilloscope and everything is seems OK.
Could it be the metal connector problem. It is placed in coils !


Can you help me please !?!?!

Hello Juka vk. Re-read #889 Ivconic's post, it's very explanatory. My experience says that is always about the coils. It isn't hard to achieve, but needs some practice.

I hope this can help you.

Best regards

Fabián

[der_fisherman]

My mistake, sorry.

[silverdog]

Check how you have installed Q3, the marking on the SilverDog PCB (maybe all PCBs from the same Layout file) is reversed.
Firstly I have to say that I have not had a PCB in my hands with this problem of the Q3 transistor, when I built mine, I put the transistor in backwards according to the legend (the correct way for most transistors, but maybe not all!!), but I would guess that the -6.2 volts will be completely wrong, maybe only 3 volts or so if the transistor is placed as the component placing dictates......

Measure the -6.2 volts first, I believe relative to 12 volts ground/minus.....(my PCB is not quite finished!)

If true:- If the -6.2 volts is bad, it will affect the correct operation of the following Op amps:- U1a, U6a, U4a, U7a, U7b, U8a, U12 and U5a. Probably they will just work still, but with drastically reduced gain…..it’s worth checking up on that point.

Its a simple matter to check.

Metal in the search coil area, connectors for example, will reduce the overall sensitivity, I never use more than a soldered connection with heat shrink tubing for insulation. I cannot say exactly how the connectors will affect things, but if they were added AFTER nulling, you may have found your problem already......

Not getting a good null will also affect the sensitivity, how did you actually "null" the coils? Full and exact details in short sentences.

Is your main 12 volts good? Have you checked it with a scope for noise?

I am not a TGSL or IGSL expert - yet anyway , only Ivconic is.....Simon is pretty good too, read and carry out anything they suggest....Don Bowers knows the normal TGSL well, has also written helpful documents.....coil construction for example....See TGSL part 1 and part 2.

regards

Andy

der_fisherman is talking about the IGSL-TGSL pcb not the TGSL or TGSL-EDU pcb

I placed my Q3 on the IGSL-TGSL pcb as per the legend and all seems ok, I believe it is correct

[der_fisherman]

Bad search Distance - possible reasons Q3 wrongly placed

hello, i have problem with my TGSL. Detecting distance is very poor (15cm with 1 Euro).
Inductance are 6.5mH and 6.04mH.
I did some measuerments with oscilloscope and everything is seems OK.
Could it be the metal connector problem. It is placed in coils !

Can you help me please !?!?!

Check how you have installed Q3, the marking on the SilverDog PCB (maybe all PCBs from the same Layout file) is reversed.
Firstly I have to say that I have not had a PCB in my hands with this problem of the Q3 transistor, when I built mine, I put the transistor in backwards according to the legend (the correct way for most transistors, but maybe not all!!), but I would guess that the -6.2 volts will be completely wrong, maybe only 3 volts or so if the transistor is placed as the component placing dictates......

Measure the -6.2 volts first, I believe relative to 12 volts ground/minus.....(my PCB is not quite finished!)

If true:- If the -6.2 volts is bad, it will affect the correct operation of the following Op amps:- U1a, U6a, U4a, U7a, U7b, U8a, U12 and U5a. Probably they will just work still, but with drastically reduced gain…..it’s worth checking up on that point.

Its a simple matter to check.

Metal in the search coil area, connectors for example, will reduce the overall sensitivity, I never use more than a soldered connection with heat shrink tubing for insulation. I cannot say exactly how the connectors will affect things, but if they were added AFTER nulling, you may have found your problem already......

Not getting a good null will also affect the sensitivity, how did you actually "null" the coils? Full and exact details in short sentences.

Is your main 12 volts good? Have you checked it with a scope for noise?

I am not a TGSL or IGSL expert - yet anyway , only Ivconic is.....Simon is pretty good too, read and carry out anything they suggest....Don Bowers knows the normal TGSL well, has also written helpful documents.....coil construction for example....See TGSL part 1 and part 2.

regards

Andy

[eduardo1979]

My TGSL. http://www.youtube.com/watch?v=KE2REksFOX8

[simonbaker]

hello, i have problem with my TGSL. Detecting distance is very poor (15cm with 1 Euro).
Inductance are 6.5mH and 6.04mH.
I did some measuerments with oscilloscope and everything is seems OK.
Could it be the metal connector problem. It is placed in coils !


Can you help me please !?!?!

Where did you test depth? Take it outside very far from electrical interference, and double-check first.

-SB

[juka vk]

TGSL problem

hello, i have problem with my TGSL. Detecting distance is very poor (15cm with 1 Euro).
Inductance are 6.5mH and 6.04mH.
I did some measuerments with oscilloscope and everything is seems OK.
Could it be the metal connector problem. It is placed in coils !


Can you help me please !?!?!