TESORO GOLDEN SABRE

[Geo]

Hi. What to say about discrimination. The disc works perfect only for gold , a little for bronze and none for Iron. Do you hear it. What to do the disc for gold and not for iron
Lets go.
I attach here some photos. 1st and second are at the out of LM393 with pot at min and max. 3td is the out at "all metal" and "disk".
Until here all are going ok but the final results are not OK
to be continues

[Geo]

I attach here other 3 photos. 1st and second are at the out "all metal" and "disk" with pot at min and max. 3td is the Tx signal (at coil) and Rx at out of LF353 pin7.
Until here all are going ok???? NO
I think that i found the problem. Rx signal must be 180degres to the Tx signal. But it has a difference other than 180. Why ????? maybe coil. I must wind a new coil.
Opinions ??????
Regards

[Max]

Hi ,
I am building a coil now from the diagrams posted here (by max i think), and to ahieve 14khz i had to wind 89 or 90 turns, (each turn removed rise the frequency about 200 hz approx). I would like to know how far away should be the RX freq ,to avoid complete resonance, to calculate how many turns i should wind-and if possible , why.
sorry if it has been posted before,i have read all posts at last once, but cant find it now amongs the 1468 posts
Will post pictures as soon as i have finished.I have found a nice coil form...Maybe this time i will finish the detector, i have built several but stopped when reaching the hardware part.
Thanks,
regards,
Fred.

Hi Fred,
89-90 is not good for 30AWG wire... to get frequency of Ivconic's TX coil (14.70 KHz).

Have you tightened the wire or are you measuring just on former without tightening ?

You need do that... using tape or a cotton cord or anything else... and very tight.... then you'll read the right frequency appears.

As example I show you frequency I get from on former (untightened wire) and same tightned wire (30AWG 100Turns 255x137mm)

on former: 16.36KHz
tightened : 14.69KHz

You can see the difference is more than 1KHz, 1.69KHz !

You have to tailoring coil for real in-housing conditions, means tight wire.

Kind regards,
Max

[Max]

I attach here other 3 photos. 1st and second are at the out "all metal" and "disk" with pot at min and max. 3td is the Tx signal (at coil) and Rx at out of LF353 pin7.
Until here all are going ok???? NO
I think that i found the problem. Rx signal must be 180degres to the Tx signal. But it has a difference other than 180. Why ????? maybe coil. I must wind a new coil.
Opinions ??????
Regards

Hi,
try to reverse RX leads (if you can... I mean if there isn't some connection inside e.g. epoxy that make this last try impossible) and test again... sometimes it works... with a bit of luck.

If not... you need a right coil there at rx... so you need a new coil.

Use Ivconic's data:

TX 100 turns
RX 105 turns
wire 30AWG (0.25 without varnish)

and take a look at my drawings on wood. This is a great coil for TGS.

Standard Tesoro coils are about 5.75mH at TX and 6.2mH at RX... but you can just forget about standard params and use Ivconic's data...for the 10'' coil. They are really accurate.

Best regards,
Max

[Fred]

Hi max,

thanks for your answer!,
Yes this frequency is with tightened wire,before it was OK with around 100turns, but as soon as i have tightened them i had to remove turns to go back to 14khz.
dimentions of the coil are the one you showed, and wire diameter is aprox. 0.30 with varnish.
Dont understand where comes the diference.Maybe i have to check the oscillator circuit if there is some wrong value capacitor.
But i dont think it is so important as long as i got the 14khz?
regards,
Fred.

[Max]

Hi max,

thanks for your answer!,
Yes this frequency is with tightened wire,before it was OK with around 100turns, but as soon as i have tightened them i had to remove turns to go back to 14khz.
dimentions of the coil are the one you showed, and wire diameter is aprox. 0.30 with varnish.
Dont understand where comes the diference.Maybe i have to check the oscillator circuit if there is some wrong value capacitor.
But i dont think it is so important as long as i got the 14khz?
regards,
Fred.

Hi Fred,
if wire diameter with varnish is 0.30mm you have not a 30AWG ... the difference came from there... your actual wire diameter (of copper) would be between 0.27mm and 0.28mm, so when you wound coils with it instead of 30AWG (0.254mm) you get differences... but then if you use larger wire you need wound more turns to get right inductance !

That thing is strange for real.

Is you wire diameter measure accurate ? Do you use a micrometer or something ?

Best regards,
Max

PS: yes... if you get 14KHz is fine at TX... but then you have to find right number for RX... to be out resonace a bit but with disc still working.

[Fred]

Well, i use a digital caliper, but you know how it is with such a small wire...
I will check better at home, but it should not be too far from that.

BUT,i measure frequency with the connecting cable , wich surely introduce some inductance also, but not that much.

I have to check this better.I thought 90 turns was not that special...

Thanks!
Fred.

[1843]

Hi Max,

Does this metal detector have a real DISC on iron?

Regards!

[Fred]

From the tests i have down with my 1st coil, discrimination on iron is excellent, i could not detect a pair of pliers at all- but a big copper(?) coin at 25cm.This with a bad (unfinished) coil.
Fred.

[1843]

Thanks fred!

If you put a gold ring beside the pliers, can it detect the gold?

[Geo]

Hi,
try to reverse RX leads (if you can... I mean if there isn't some connection inside e.g. epoxy that make this last try impossible) and test again... sometimes it works... with a bit of luck.

If not... you need a right coil there at rx... so you need a new coil.

Use Ivconic's data:

TX 100 turns
RX 105 turns
wire 30AWG (0.25 without varnish)

and take a look at my drawings on wood. This is a great coil for TGS.

Standard Tesoro coils are about 5.75mH at TX and 6.2mH at RX... but you can just forget about standard params and use Ivconic's data...for the 10'' coil. They are really accurate.

Best regards,
Max

Hi Max. I have reversed the Rx leads without results. So then i checked the rx signal with Tx and i saw a phase difference. Did you checked the phase difference of Tx and Rx winds??? Is there any difference ???
When i will find free time i will make a new coil.
When i tried to null it i saw that the phase differs from -90 to +90 degrees. Maybe it is time to look it, not only signal null but zero phase shift. VLF detectors are more sensitive to phase shift than to signal null.
Regards

[Fred]

Ha 1843, so you mean real disc .. well it works, but not so good with gold,and OK with copper.But as i told you i am not a reference here, just a newbie with bad coils...for sure others can answer you better than me.

Max,i have re-checked my wire diameter, it gives 0.29mm with varnish.
But i have found the problem:the zener diode i used was 5.6V! so i changed to a 5.1V (the lowest i have)and eliminated the 4148, and oscillator went to 16.3khz.
So now i have to rewind a new coil.
Thanks,
regards,
Fred

[Geo]

I want to wind the Rx coil with 0.2mm wire (0.22 with varnich).
Any comment ????
A friend gave me 3Kgr of wire 0.2mm so it is time to put it on the coil

[1843]

Is this IB like the sascho design(pulse IB disc)? Doesn't detect the color metals beside the ferrous metals I mean.

Regards!

[Geo]

Is this IB like the sascho design(pulse IB disc)? Doesn't detect the color metals beside the ferrous metals I mean.

Regards!

As i know this is a general problem (for all the VLF detectors)