TESORO GOLDEN SABRE

[Max]

Hi,
Max.
Is this what you talking about?But what is this diode?
1N4148?

Hi,
your diode is reversed respect to schematic.
Use 1N4007.

Kind regards,
Max

[Max]

Hi ApBerg, thank you for replay!
As you wrote, I've connected coil on transmitter and frequency was 11.7 kHz
Then connected cap 15nF parallel with coil, like you suggest, freq drop at
8.9 kHz.All the time I heard constant tone in head phone, is it normal? When connected cap, tone was lower.
About coil: that should be double O coil like Ivconic's. Nexus made similar.
To Geo: very good idea,maybe try it later. Now seems my multimeter was right! I' try to reduce number of turns.
ApBerg,Geo,man from Mars thanks a lot!
Salute you!

Hi,
too low frequency. You have to match 14KHz on tx coil...
first 3-4 seconds battery checker makes ear you a steady tone.... then detector fade to no sound at all.
If not so there is something wrong.

Recheck coil calculation and measures.

Best regards,
Max

[tiktak]

hi

Hi,
Max.
Yes you are right its reversed!
I will try.
By the way I found my mistake.I were using 0,30 without varnish!And have make 165 turns for both coils on 19cm former!
This is too much!
In the original coil wire is 0,25 without the varnish right?
I have order small quantity of 0,25 wite without the varnish,so how many turns I have to wind on 19 cm former to make proper DD coil.And how much is this distance?I now that picture is not good and the part forming overlap area should be wider.But you understand what I ask.
Thanks

[nelson]

HI MAX.

A QUESTION, IS CORRECT TO TUNE YOUR RX COIL TO GET MAXIMUN SENSITIVITY BY TRYING A FEW CAPS ON THE RX COIL BTW BOTH LEADS AND WHAT ARE CORRECT VALUES TO TRY?

YESTERDAY I PLAYED WITH SOME CAPS VALUES AND I NOTICE THAT SENSITIVITY WAS AFECTED TO BE WORSE AND BETHER TOO.

MY TRANSMIT FREQUENCY IS 13 KHZ.

FOR MY COIL HOUSING I USED A PICE OF POLITYNE, DRAW THE COILS FORM ON IT, BURN WITH MY IRON THE FORM TO MAKE A FORM SPACE TO PLACE MY COIL AND AFTED THAT I USED POLITYNE FOAM TO SEAL IT. THE RESULT, A SOLID AND SEALED COIL THAT IF YOU WANT CAN BE PLACED ON A PLANTS PLASTIC BASE OR ALONE. SO WHEN I HAVE THE TIME I LL TAKE PICTURES OF WHAT I HAVE DONE TO LET THE FORUM KNOW.

BEST REGARDS

NELSON

Hi,
too low frequency. You have to match 14KHz on tx coil...
first 3-4 seconds battery checker makes ear you a steady tone.... then detector fade to no sound at all.
If not so there is something wrong.

Recheck coil calculation and measures.

Best regards,
Max

[Max]

HI MAX.

A QUESTION, IS CORRECT TO TUNE YOUR RX COIL TO GET MAXIMUN SENSITIVITY BY TRYING A FEW CAPS ON THE RX COIL BTW BOTH LEADS AND WHAT ARE CORRECT VALUES TO TRY?

YESTERDAY I PLAYED WITH SOME CAPS VALUES AND I NOTICE THAT SENSITIVITY WAS AFECTED TO BE WORSE AND BETHER TOO.

MY TRANSMIT FREQUENCY IS 13 KHZ.

FOR MY COIL HOUSING I USED A PICE OF POLITYNE, DRAW THE COILS FORM ON IT, BURN WITH MY IRON THE FORM TO MAKE A FORM SPACE TO PLACE MY COIL AND AFTED THAT I USED POLITYNE FOAM TO SEAL IT. THE RESULT, A SOLID AND SEALED COIL THAT IF YOU WANT CAN BE PLACED ON A PLANTS PLASTIC BASE OR ALONE. SO WHEN I HAVE THE TIME I LL TAKE PICTURES OF WHAT I HAVE DONE TO LET THE FORUM KNOW.

BEST REGARDS

NELSON

Hi Nelson,
13KHz is lower than original (14KHz) but if it works ok no problems.
I always test adding or sub about 500pF at a time found often that increase or decrease of few nF (4-5nF maximum) get me on the right way to get max sens from coil.

So you could test from 10nF to 20nF on GS.

I've done in bandidoII, got about 1-2 cm gain respect original value.

Few depth more, of course, but if a simple cap mod could give that, it's good.

At now have no time to test same thing on GSabre but I'll do soon.

Kind regards,
Max

[Max]

Hi,
Max.
Yes you are right its reversed!
I will try.
By the way I found my mistake.I were using 0,30 without varnish!And have make 165 turns for both coils on 19cm former!
This is too much!
In the original coil wire is 0,25 without the varnish right?
I have order small quantity of 0,25 wite without the varnish,so how many turns I have to wind on 19 cm former to make proper DD coil.And how much is this distance?I now that picture is not good and the part forming overlap area should be wider.But you understand what I ask.
Thanks

Hi tiktak,
yes 0.25 without varnish (that is some 30AWG) or also bit more is good too.
0.30 without varnish gave me same results when I changed caps but it's too tricky to be done, I think, getting right resistance and inductance required at first sight. I wasted much wire of this kind before getting right things.
Can't remember now the exact distance but think was something 12.5 or 12.7cm in the middle.

Best regards,
Max

[nelson]

Ok thanks Max.

In my case i obtened 4-5 cms more, just by adding a 15 nF cap btw the two rx leads just beside the coil. I had not made any changes on the pcb, so i think this will be the rigth way to get the best sens from the coil.
About frequency i miss that, it is 14 Khz, sorry.

Regards

Nelson

Hi Nelson,
13KHz is lower than original (14KHz) but if it works ok no problems.
I always test adding or sub about 500pF at a time found often that increase or decrease of few nF (4-5nF maximum) get me on the right way to get max sens from coil.

So you could test from 10nF to 20nF on GS.

I've done in bandidoII, got about 1-2 cm gain respect original value.

Few depth more, of course, but if a simple cap mod could give that, it's good.

At now have no time to test same thing on GSabre but I'll do soon.

Kind regards,
Max

[Hush]

Sory Qiaozhi, yelow brother, I didn't mean to hurt you. The multimeter is good, even isn't from China - joke of course. Your coil calculator seems better for this coil. I reduced turns from 117 to 98, inductance is 6.65 mH think it is good enough for rx coil, freq rise at 13.6 kHz. Now winding tx coil, suppose about 95 windings to get 6 mH, then shielding, nulling, when finish I'll post report. But that sound... appearing when connect tx coil and disappear when disconnect coil. Never mind, when connect rx coil, will try again.
Wish you all the best.

[Qiaozhi]

Sory Qiaozhi, yelow brother, I didn't mean to hurt you. The multimeter is good, even isn't from China - joke of course. Your coil calculator seems better for this coil. I reduced turns from 117 to 98, inductance is 6.65 mH think it is good enough for rx coil, freq rise at 13.6 kHz. Now winding tx coil, suppose about 95 windings to get 6 mH, then shielding, nulling, when finish I'll post report. But that sound... appearing when connect tx coil and disappear when disconnect coil. Never mind, when connect rx coil, will try again.
Wish you all the best.

Good to hear you are making progress. Please let us know when you have success.

[Max]

Using my own calculator (see attached) I used 127mm inside radius, 0.27mm wire thickness and 117 turns. This gives an inductance of 8.98mH, which is closer to your measured result. How accurate is the value of the inner radius? This is a sensitive parameter, and only a few millimetres can change the inductance significantly. The calculator also shows a coil thickness of 5.62mm, whereas you have 5mm. Since the calculations assume a square cross-section to the coil, your's may be elongated.
Hope this helps.

By the way, Chinese multimeters can also be good.

Hi,
Yes that's true.
Is a matter of looking before buy...
I mean sometimes there are bad quality devices and also parts coming from there...and other country also... but I've found many useful things, stuff , tools, meters etc that are almost the same (in some cases even better) than hi-branded products... that at the end are about always made in China at now.

All big companies make there their products and then sell here with enormous bargains !

The only big difference sometimes is only the price !
Found great things that cost 1/10 or also 1/20 of BRANDED ones and work/are the same!

Kind regards,
Max

[tiktak]

Hi,

Hi,
Max.
Have you tryed to replace TL062 with LF353?And if so what are the results?
Thanks

[Max]

Hi,
Max.
Have you tryed to replace TL062 with LF353?And if so what are the results?
Thanks

Hi,
no I use TLC2262 instead of TL062. More stable.

Best regards,
Max

[nelson]

Hi Max.

Can you help me with this:

1.- I made the coil you did (22 cms), and i obtained almost the same results has you (inductance, resistance and nulling).

2.- I got a few more cms by just adding a 10nF cap on rx coil leads.

3.- Now i m still having unstable sound that seems that the problem comes from the TX stage, cause when i put my hand or a coin very close to the wires that comes from the pcb, the detector sounds. Seems to me that i need to shield somethinf.
My RX anf TX leads that comes from the pcb to the chasis connector are 30AWG, same has used for the coil construction. These wires are about 3 to 5 cms long. So i was thinking on using shielded cable to run RF from tx and rx leads.

Any ideas Max?

Ohh i forgot, max detection on air for a 1 cm coin is just 22 cms, no more than that.

Regards
Nelson

[Max]

Hi Max.

Can you help me with this:

1.- I made the coil you did (22 cms), and i obtained almost the same results has you (inductance, resistance and nulling).

2.- I got a few more cms by just adding a 10nF cap on rx coil leads.

3.- Now i m still having unstable sound that seems that the problem comes from the TX stage, cause when i put my hand or a coin very close to the wires that comes from the pcb, the detector sounds. Seems to me that i need to shield somethinf.
My RX anf TX leads that comes from the pcb to the chasis connector are 30AWG, same has used for the coil construction. These wires are about 3 to 5 cms long. So i was thinking on using shielded cable to run RF from tx and rx leads.

Any ideas Max?

Ohh i forgot, max detection on air for a 1 cm coin is just 22 cms, no more than that.

Regards
Nelson

Hi Nelson,
you can use a cat5 stp cable (the one used in ethernet works, flexible) to make internal connection from board to the panel connector. Other shielded cables are fine too... e.g. two pieces of RG-58 and the like or also some quality audio cables.
For coil cable you must use a shielded cable with at least 1 shield and two wires inside. You can use also e.g. 120cm of cat5 stp flexible. Only things needed are a good shield and low capacitance per lenght.

Is normal that when you touch leads unshielded you increase capacitance and so variation is seen by detector as a signal... you imbalance input stage that way. If use shielded cables the effect is reduced to minumum.

Another important thing is that cables must stay wounded e.g. on coil pole... expecially true for the lower end of them that goes to coil housing.

You have to avoid that cable moves during sweeping or you'll have a false signal from that movement relative to the coil.

Keep in mind that this is not a minelab/coiltek coil... where preamp is inside the potting at coil dish (but also minelab suggest to keep it fixed for similar reasons related to tx field radiation from cable). In our GSabre we have preamp on control unit... so also coil cable is "sensitive" to metal... not only the tx wire floating problem like in others...that's the clear reason of keeping it fixed to the pole.

Also in Tesoro' manuals there are instructions for that, in the assembly of detector part is explained how to wound coil cable to the lower end of pole.

1cm diameter 22cm depth ? I got about that too, maybe few more...
can't remember now.
Anyway, my reference is always 1eur coin... got something 27cm for that.

A better coil for detecting 1cm coin at good depth is maybe 25cm DD.
Think it could detect coin at 28-30 that way.

Think that I can reach BandidoII performance with some cap mod. and a bit of luck, have to find time!

Best regards,
Max

[tiktak]

Hi

A better coil for detecting 1cm coin at good depth is maybe 25cm DD.
Think it could detect coin at 28-30 that way.

Hi,
Max.
What you sugest?I just bought coil housing and ined diameter is 25cm!!
So will be glad to test this.But how much turns should be wounded for TX and RX?
I will have this 0,25 without the varnish wire in monday and will go buy some other multimeter that have 2v range and will try to make another coil.
Thanks