TESORO GOLDEN SABRE

[Stefano]

The same for me. I thought that the images to take as good were the ones on the left!
Just now I realize we had the orignal TGS scope pictures sampled on a standard Tesoro setup (Tesoro coil and circuit). Very good.
But if these are the waveforms which we I can consider as reference, I can't understand why the pictures F1 and F2 show as phase difference of -20 and -30 where I expected to be +20.

[simonbaker]

[quote=Molzar;106340]

That is interesting point about parallel 10k pot on original schematic. I tend to agree.

However, the funny thing is that Molzar's original Tesoro TGS still had somewhat ugly waveform at LF353 pin 1 also, even with all the circuitry. That was surprising. http://www.geotech1.com/forums/showp...postcount=3896 (see pdf files).

Hi Simon,

If you are referring to Image 3 (LF353 pin 1) in the pdf, the picture (left) is Max's handmade (which has distortion) the graph (right) next to it is the original machine / coil (no distortion)

So the original has no distorition.

Molzar

Thanks Molzar, I completely misunderstood your presentation. Now I understand; photos on left are Max's handbuilt, graphs on right are your original TGS.

So no distortion of discrim signal at LF353 pin 1. Makes sense now. Oscillations are because our handbuilts use larger oscillation voltage (because no feedback JFet), and it causes overdriving of LF353, which makes oscillations. Original TGS has smaller TX voltage (10 v pp).

Apparently 10k pot instead of 100k pot helps some in our circuit also, good to know.

-SB

[ivconic]

.

[Molzar]

[quote=simonbaker;106338]That is interesting point about parallel 10k pot on original schematic. I tend to agree.

However, the funny thing is that Molzar's original Tesoro TGS still had somewhat ugly waveform at LF353 pin 1 also, even with all the circuitry. That was surprising. http://www.geotech1.com/forums/showp...postcount=3896 (see pdf files).

Hi Simon,

If you are referring to Image 3 (LF353 pin 1) in the pdf, the picture (left) is Max's handmade (which has distortion) the graph (right) next to it is the original machine / coil (no distortion)

So the original has no distorition.

Molzar

[simonbaker]

When disrimination pot is replaced with 10k sinus on pin1 improves.Sinus on pin1 depends from Tx sinusoide.I tried this.When you put 10k disc pot Tx signal goes weaker and it`s crack at the top disapears -sinus on pin (LF353) improves too.I think that disc. pot must be 10k -in TGS there are 100k and 10k paralel,so 10k is correct I think.

That is interesting point about parallel 10k pot on original schematic. I tend to agree.

However, the funny thing is that Molzar's original Tesoro TGS still had somewhat ugly waveform at LF353 pin 1 also, even with all the circuitry. That was surprising. http://www.geotech1.com/forums/showp...postcount=3896 (see pdf files).

But I agree 10k pot seems like it would be more consistent with original circuit. And your tests say it improves the signal so -- good observation!

I devised another circuit to get rid of the "oscillations", but I don't think it is worth trying if your oscillations are not too bad.

-SB

[Math]

great thanks for help Pompey, just ordered parts now~

[Pompey]

ok but am just beginner a &bit confused by the 0.1 onthe pcb placement are these 0.1nf =100pF, thanks

0.1 means microfarad ,so 0.1=100nf

[Math]

ok but am just beginner a &bit confused by the 0.1 onthe pcb placement are these 0.1nf =100pF, thanks

[Pompey]

hi Ivconic ive had a look &think TGSL is a great project &am going to try to build one as my first project~ i've had alook at the complete details in the projects section and just wanted to check on a couple of things before i start~

-for the capacitors they all match up with the parts list and schematic but when i looked at the placement OC theres seems to be ten 0.1 on there &only one on the schematic&parts list, also five 0.022 instead of seven on the schematic and for the RXc shown on the placement, is this just the one 0.015?

-for the resistors i havent checked with the placement OC yet but on the parts list~ R1 2k2 & R2 24K & R52 330are missing, also R4 1K & R5 330 ithink must be R56 &R55, there are 3 values for R6 im checking the first one 47K is right~ and for the amended R13 &14 values the schematic shows 4K7 but parts list has 5K1 could you let me know which to use, thanks~

Never mind part list has some mistakes -pcb is correct.Put all parts as on pcb.Schematic is also correct.

[Math]

hi Ivconic ive had a look &think TGSL is a great project &am going to try to build one as my first project~ i've had alook at the complete details in the projects section and just wanted to check on a couple of things before i start~

-for the capacitors they all match up with the parts list and schematic but when i looked at the placement OC theres seems to be ten 0.1 on there &only one on the schematic&parts list, also five 0.022 instead of seven on the schematic and for the RXc shown on the placement, is this just the one 0.015?

-for the resistors i havent checked with the placement OC yet but on the parts list~ R1 2k2 & R2 24K & R52 330are missing, also R4 1K & R5 330 ithink must be R56 &R55, there are 3 values for R6 im checking the first one 47K is right~ and for the amended R13 &14 values the schematic shows 4K7 but parts list has 5K1 could you let me know which to use, thanks~

[Dennis the Mennis]

Coil values not right ...

I only got low distances with not so good nulled coil so far. Doubt in coil remains in your case too.
What about ferrite? Take 10cm long ferrite rod and check if it is fully rejected up to 5cm away from coil surface.. Than check with some small and thin silver coin is it accepted at the same adjustments when ferrite rod is rejected... Inform us here.
Cheers

I'm not going to say, "told you so".

Looking at the values for your coils and the tuning caps used, I have calculated your TX frequency to be 14.5KHz, which you have confirmed is correct. However, your RX circuit is tuned to 19.7KHz, which in my opinion is too high, as Tesoro circuits are usually off resonance by around 9%. In this case you should be using a calculated capacitor value of 15.5nF to tune the RX to 15.8KHz. I would suggest trying a 15nF cap instead of the 10nF and see if there is any improvement.

I wrote " 15n // 4n7 for Tx " but it had to be 22n // 4n7
> when I calculate this with the frequency 14.5 KHz I get 4.51mH for the TX coil ....

I should have been more suspicious when I removed all the dust and spider webs from that MultiMeter .

Anyway the values given by the MultiMeter are way too high .
This explains hopefully a lot .
Here another hint pointing in the same direction ...

Another thing;
am i wrong or i see TX amplitude there barely over 10vpp ( I get aprox 12v )?
That could be the cause of poor depths.
Usually amplitude is 15-16vpp at TGS/TGSL...

And here Ultimate_Haze with apperently same problem .... brother in disaster

I just got new multimeter.Its VC9805A.Think that its previous version of the one you show.Because dont have backlight.
So it shows quiet different readings.Frequency is with some old coil is 15,2 and old one shows 14,2.Also my LC meter is wrong too.It shows 6,35mH on one winding and this new multimeter shows 6,75mH.
It must be that my units are damaged somehow.
I will make new coil using this VC9805A.Hope that this will solve my problems.

I went to electronicshop and measured the coils there with LC meter the values to be sure ... much lower values
I try to calibrate the inductance part of the meter and to make sure everything is correct I will measure the inductance with frequency generator and cap again for oscillationfrequency .

I'll be back ...

regards

Dennis the Mennis

[ivconic]

Thanks U_H.

Regarding LC meter: who knows which one is more accurate? I did a test:

http://www.geotech1.com/forums/showthread.php?t=15668

We can only be approximate I think when it comes to LC measurements.

But why so important? As some other have pointed out, it should be possible to adjust capacitors slightly if coil is not exact, if clearly understand relationships. If not, that is a mystery in itself.

Look, metal detectors operate at many frequencies. It should be possible to make a TGSL that runs at other frequencies than 14.5 kHz. If not, why not? Tesoro does not always choose 14.5 kHz for their detectors, many of which have very similar circuitry.

I wish I had smart answer. For now, keep building and trying. The answer is there somewhere.

-SB

Agree.

[simonbaker]

Hi,
Simonbaker.
Sorry to hear this.Wish fast recovery.

Thanks U_H.

Regarding LC meter: who knows which one is more accurate? I did a test:

http://www.geotech1.com/forums/showthread.php?t=15668

We can only be approximate I think when it comes to LC measurements.

But why so important? As some other have pointed out, it should be possible to adjust capacitors slightly if coil is not exact, if clearly understand relationships. If not, that is a mystery in itself.

Look, metal detectors operate at many frequencies. It should be possible to make a TGSL that runs at other frequencies than 14.5 kHz. If not, why not? Tesoro does not always choose 14.5 kHz for their detectors, many of which have very similar circuitry.

I wish I had smart answer. For now, keep building and trying. The answer is there somewhere.

-SB

[Ultimate_Haze]

Have finish one new coilTX6.03mH;RX6.28mH.Some minor change.Now will try to make 6,50 for RX.
And still the coil refuse to null lower then .180/2V AC.
The thing that bugs me is that I read 15,9kHz form 2n2907 and 14,7kHz from 4024 pin1.Some changes in lf353 pin1 too but still not even similar to sinus.
Will continue to examine and will post some pictures later.

[Lambada]

Hi, sorry for my interruption, but I have a question. Does TSGL has a X/Y Chanel to attach a VDI godograph? Like http://md4u.ru/img_godo/th_godo_v204_001_l.jpg

If not, which one of tesoro's can be attached VDI meter?