TESORO GOLDEN SABRE

[nelson]

Thanks Max.
I know no one can belive me when i said that i can get the correct coil working, but i can tell that i have done it with correct wire, numbers of turns, correct size form, etc. and nothing. The best coil i made it has less turns and is working at 19.2 Khz.
The other coils works, but performance is bad. My 19.2 Khz coil, was very easiñy nulling the others did not.
So is the reason i think i must have a problem with the receiver part of my TGS. Yesterday i lots of time cjeking components numbers on PCB and by now i found nothing.
About coils mH, do you know if the values posted where measured by each experimenter here or where obtained from a factory sheet?
Has always, many thanks for taking the time to help me.
Best regards to all
Nelson

Hi,
change about nothing... use one of the 2 values...

This isn't your problem.

Your coil is wrong if you get such higher frequency... as I told you before... maybe it's wire... or number of turns... or you made wrong tightening of wounds... leaving turns too open etc etc.

Also varnish tickness is important cause of the surface capacitance increase or decrease you can get.

I suggest you find sure 30AWG and made it again using provided data.

The bare wire will be exactly 0.25mm not other things (the varnished wire diameter goes from 0.27 to 0.28mm).

Wire is critical if you use Ivconics numbers on turns... so stay close as possible... otherwise you'll get another wrong coil.

Then nulling is most important phase in all this stuff... and require extra care... it's not easy thing... but you can do. Don't worry.

Kind regards,
Max

[Hush]

Hi Nelson, Max, and others.

I have a big problems with TGSL too. Can't beleve the problem is with coil, just like Nelson, cose I've made 3 coils, different size,very carefuly and they works all the same-very bad.No, it can't be the coils.I think maybe those FETS BF 245 are not good for this project... somewhere Max and Porkluvr
wrote about this,but as I haven't scope, can't see whats really happening.
Ivconic's detector works from the first moment exelent, but he didn't use BF
but J107, and I think it is reason of his success (not only that, he is old fox, and he knows much about detectors).As I saw, some poeple used BF and
machine works good, but manufactures making components with some tolerances and you can't find components with same characteristics.That could be our problem, but who knows.I've made also TGS and TGSL- works the same, no differences.So, it must be some of those components on PCB
doesen't work properly.Oh, I am very tired of trying again, again and again...
Even Geo, master of detectors, have some problems with TGS, if I understend well.
Can't find those FETs, only similar I can find in market is 2N4392.Is it good enough for this project?
Ivconic, wish you to get well.
By friends, wish you all the best.

[Max]

Hi Nelson, Max, and others.

I have a big problems with TGSL too. Can't beleve the problem is with coil, just like Nelson, cose I've made 3 coils, different size,very carefuly and they works all the same-very bad.No, it can't be the coils.I think maybe those FETS BF 245 are not good for this project... somewhere Max and Porkluvr
wrote about this,but as I haven't scope, can't see whats really happening.
Ivconic's detector works from the first moment exelent, but he didn't use BF
but J107, and I think it is reason of his success (not only that, he is old fox, and he knows much about detectors).As I saw, some poeple used BF and
machine works good, but manufactures making components with some tolerances and you can't find components with same characteristics.That could be our problem, but who knows.I've made also TGS and TGSL- works the same, no differences.So, it must be some of those components on PCB
doesen't work properly.Oh, I am very tired of trying again, again and again...
Even Geo, master of detectors, have some problems with TGS, if I understend well.
Can't find those FETs, only similar I can find in market is 2N4392.Is it good enough for this project?
Ivconic, wish you to get well.
By friends, wish you all the best.

Hi,
the BF245 can be A,B or C type. Each series has slight different cutoff voltage range... and that could be your problem if devices do not switch off when they must do.

For example... the "A" version has cutoff at Vgs (max) = -2V.

Personally I've tested B and C versions on my TGS and TGSL... both types worked OK. The A version I don't remember well now... but think I've tested in some critical place there... and worked too as expected.

You can use J117 there and make your life easier or use also TIS75 if find any from old stuff... e.g. radio things or switch to some other fet model too.

No much difference but you have be sure your fets suits there e.g. about the channel type and cutoff voltages etc... that's really important check and you can made with scope watching at gate signal on one channel and drain/sounce sampled signal effect on the other channel.

Design of TGS is not critical about fets... could be other and more important problems to watch at... coils seem easy but aren't for many people here... at least at first. All tesoro's require good nulled coils to works nice... otherwise you'll waste your time with average detectors (as some of them are when you buy and with e.g. original coils).

PS: 2n4392 I think could be ok there... has VGSoff max of = -5V

Kind regards,
Max

[nelson]

Ok Max. Tomorrow i ll get LM308 from a good guy that contact me.
Next time i ll try to null again my last coils.
Question: When you try to null coils at first try, do you have very poor distance detection. If this is rigth, i have notice that a 2 cms coin is detected at about 5 cms, so may be i nedd to do fine nulling to get correct deep values.
regards
Nelson

Hi,
the BF245 can be A,B or C type. Each series has slight different cutoff voltage range... and that could be your problem if devices do not switch off when they must do.

For example... the "A" version has cutoff at Vgs (max) = -2V.

Personally I've tested B and C versions on my TGS and TGSL... both types worked OK. The A version I don't remember well now... but think I've tested in some critical place there... and worked too as expected.

You can use J117 there and make your life easier or use also TIS75 if find any from old stuff... e.g. radio things or switch to some other fet model too.

No much difference but you have be sure your fets suits there e.g. about the channel type and cutoff voltages etc... that's really important check and you can made with scope watching at gate signal on one channel and drain/sounce sampled signal effect on the other channel.

Design of TGS is not critical about fets... could be other and more important problems to watch at... coils seem easy but aren't for many people here... at least at first. All tesoro's require good nulled coils to works nice... otherwise you'll waste your time with average detectors (as some of them are when you buy and with e.g. original coils).

PS: 2n4392 I think could be ok there... has VGSoff max of = -5V

Kind regards,
Max

[DIRCEU]

Hi Nelson, Max, and others.

I have a big problems with TGSL too. Can't beleve the problem is with coil, just like Nelson, cose I've made 3 coils, different size,very carefuly and they works all the same-very bad.No, it can't be the coils.I think maybe those FETS BF 245 are not good for this project... somewhere Max and Porkluvr
wrote about this,but as I haven't scope, can't see whats really happening.
Ivconic's detector works from the first moment exelent, but he didn't use BF
but J107, and I think it is reason of his success (not only that, he is old fox, and he knows much about detectors).As I saw, some poeple used BF and
machine works good, but manufactures making components with some tolerances and you can't find components with same characteristics.That could be our problem, but who knows.I've made also TGS and TGSL- works the same, no differences.So, it must be some of those components on PCB
doesen't work properly.Oh, I am very tired of trying again, again and again...
Even Geo, master of detectors, have some problems with TGS, if I understend well.
Can't find those FETs, only similar I can find in market is 2N4392.Is it good enough for this project?
Ivconic, wish you to get well.
By friends, wish you all the best.

HI HUSH

I HAVE A FEW PROBLEMS TOO. NOW I DECIDED CHANGE BF's.
RECENTLY I ADQUIRED TIS 75. I WILL POST THE RESULTS.

REGARDS

DIRCEU

[Hush]

Hello Max and Dirceu!

Max, thanks for an answer. I've found on some slovakian site BF245C isn't good for TGS so decided to change it with BF245A typ.Heh- now as I see
it is not very good solution.Haven't B typ, so I give up of BF245 at all. Can't
find TIS75, any J typ, so I'll try with 2N4392, and post results latter. Tnanks again for trying to help us!

Dirceu wish you a luck, and PLEASE send report!

Regards!

[ivconic]

Sorry for delay. Personally i havent spoted significant differences in behavior, between J107 and BF245b,c in TGS design. It is not critical there.
More critical is choice of LM308. H version showed better stabillity(metal case). Even if you put plastic LM308, will not give you uncontrolled instabillity, dont worry. Even TL081 can work there descent. I think your problems are laying somewhere else, but where? If not arround coil, than must be arround LF353 and first comparator (LM393). You should check those twice, each component.
Regards!

[Hush]

O.K. I'll check it.
Thank you very much.
Regards!

[junko]

I am a totally newbye in metaldetecting.
I read everything you write.A lot of thank at all the contributor.
I have mounted the golden sabre with PCB, I found a missing diode in pcb layout near to IC7 lm 308.
I have mounted all standard component eccept
Tis75---Bf245a
Lf442---Tl082
Coil DD255
Tx 5mH 24 OHM 100 turn awg 30
RX 5.5mH 25 OHM 110 turn awg30
Retuned TX +1000pf for obtain 15.1Khz to 14.6 Khz
Now i have a lot of problem with inteconnection cable.
I have put a capacitor for tuning rx in the search coil 15nF, i must connect another capacitor in the pcb side 1000pf for decrease a cable jittering.
I thinks my cable it's no good ( usb cable). I will try another solution.
Have you suggestions ?
I will try to rewind one new coil tx 110 rx 120.
For now poor result 18 cm 1 euro coil.
Sorry for my english .
Thank
Best Regards
Junko

[ivconic]

I am not sure that you can use USB cable there. Better find some more proper cable. Dont put capacitors in search head.Leave those on pcb.
Here on these pages you can find proper coil wirements, producing no falses at all. And of course, ballancing is crucial.
Regards

[junko]

When you said detect a coin at 28cm or more you listen a big sound or only a Tik?
sorry for the stupid question.
I am a beginner i don't have a metaldetector for reference.
bye
Junko

[Max]

When you said detect a coin at 28cm or more you listen a big sound or only a Tik?
sorry for the stupid question.
I am a beginner i don't have a metaldetector for reference.
bye
Junko

Hi,
if you use the 1Mohm mod at comparator you have a big sound even at maximum depth.... but stability issue is important if you use it.

If you don't use that mod you'll have just weak sound a big depth,

BTW 18cm for 1eur is not good on TGS... you can do much better!

So... if circuit is ok... coils are wrong. Do not put capacitors there... as Ivconic told you... use them on PCB only... no need of them on coil housing...no need to change anything.
Also frequency matching is OK with provided data... be sure of your wire is 30AWG and not anything else; made same formers etc.

Kind regards,
Max

[junko]

Hi Max and Ivconic
I have the standard gold sabre I suppose the 1M ohm is in right
position.
(this night i check this )
I have mod the 33k to 2k2 with good result in audio.
Have you read the mistake that i found missing 1n4148 near ic7 ?
For me it caused a lot of instability .
I have see a lot of picture of mounted pcb without this 1n4148.
In the next day I will try to fine tune this good detector.
A lot of thanks
Bye
Junko

[zzy]

vpp

Hi Ivconic,I had build the TGS,but I have a question,please help me.
when nulling, i use osciloscope connect to the RX coil,I only got 40MV VPP.
can't get more lower. as you said you get 0.08-0.015V,is that voltage are VPP?
I detect 10eur-cents from 17cm in all metal, on air. It's very poor.
my DD coil,23.5cm form,TX 110 turns,RX 118 turns.frequency 14.3KHZ.
and almost can't detect gold.
Ivconic, what sounds did you hear when power on?
I don't know where the errors in.
Regards and thanks for your support.

[ivconic]

Hi Ivconic,I had build the TGS,but I have a question,please help me.
when nulling, i use osciloscope connect to the RX coil,I only got 40MV VPP.
can't get more lower. as you said you get 0.08-0.015V,is that voltage are VPP?
I detect 10eur-cents from 17cm in all metal, on air. It's very poor.
my DD coil,23.5cm form,TX 110 turns,RX 118 turns.frequency 14.3KHZ.
and almost can't detect gold.
Ivconic, what sounds did you hear when power on?
I don't know where the errors in.
Regards and thanks for your support.

No i balanced coils using multimeter in 200mV range, and it showing usually 0.08-0.015V when coils are nulled...
Later i used osciloscope to check phase shift. Since my scope is old,obsolete i cant see accuratelly vpp. You can see some photos of that scope in previous pages.
Your coil must be not balanced well.Try again.