TESORO GOLDEN SABRE

[Max]

So you are maybe right.
Molzar have the original device maybe he can comare with handmade.
I dont own original TGS.
I can compare with TRS but wont be fare due to diferent coil size.
The thing that worry me is that Max gived over 40 cm with same coil for large coin.
And my results are poor with this last device and this larger coil.Near 30cm.
Hum....
I now its all about the coil and thuning but there is still something I miss here.
Don't wanna discus nexus here its other stuff.
How you think that RX can be optimized in this design?
Please share your ideas.

Hi,
yes the bigger the coil... and you'll get some more depth... BUT remember that big coils need big targets (so in your case big coins).

I say that cause maybe this detail was not considered in latest posts.

If you have to look for small coins I think the best of best is anything from 20cm to 27cm. In TGS I found that the optimum compromise is Ivconic's size... dear old DD 10 or 11' not more.

The coin I used for tests on big coil is big: >32mm diameter, UK half-crown of 1967...copper-nickel alloy... not anymore in production... can see one similar in picture. Mine is that way...

You have to consider that the field shape is different in large coils... then the lines density is different for a fixed amount of power at tx.

Happens, then, you need more exposed target surface to flux in larger coils to gain the response you need... and that's expecially true on small items like coins. With larger objects like a coke can the larger coils work pretty well and you get a very effective increase of range... but we are talking of small stuff here.

The other side effect is the increased ground influence on big coils... so you could end-up on soil with lowered S/N on 12' than with smaller coil say 10' or 11' range.

But the increase on large coin is not speculation... you see it both on air and into the ground... just the approach must then fit in your searching scenario... so if look for smaller stuff stay with smaller coil cause larger will give you more troubles than advantages.

As an example... I use maybe 90% times Ivconic's coil... and (maybe) 5% my larger coil on TGS...

Optimize RX ? lower noise front-end... fix instability and noise propagation on board... use different parts... put one-shot at end of audio path: that way you could increase gain and leave tx power as before... the reduced noise will increase S/N... you can run at increased gain, max sensitivity with no or minimum chatters and then get far/weak signals more easy... that could mean a gain of >5cms detection range (maybe!) on 20-25mm range coin on 10' coil.

That's not bad... that way you could break the 40cm range on 1eur with a 10' coil... but you may ask Ivconic about advantages and troubles related e.g. to the one-shot (monostable) at the end of chain... like poor pinpointing etc

Kind regards,
Max

[ivconic]

That is very usefull info.
Can you post tgsl performance on same ithems with 27 DD?

*1e coin = 32 to 36cm in air (~48cm if monostable mode available)
*cola can = 55cm in air (~ 80cm if monostable mode available)

Hard to say exact distance...i made over 30 coils so far. Not all showed the same performances (no wonder....handmade )
But all coils had performances in noted range.
What differs TGSL from other brands is noticeable depth "limits" over some distance. Quiaozhi could be right when talking about TX power. What makes TGSL exceptionally good and interesting for us here is extra sensitivity on very small coloured items in soil. I've been working with few of my handmades many months on real fields and had a lot of very nice finds. Especially on places where many other brands already "passed" and had worse results. Most of those nice finds were extra small coins and various items. Most of those were 5-6mm size. Another benefit was extra stabillity and splendid discrimination and junk rejection. That's why is so worth of making and working with.
Also that is why i do suggest smaller diammeters coils for TGSL. Smaller than 27cm. Most preferably 20-24cm diammeter.

[metaldetector107]

last TGSL

Dear Ivconic Max
i have made your last TGSL but when tested i hear i countinuse sound
also when nulling coil i hear some cracks
TX freq is 14.4khz
please help
best regards

[erolunall]

Hello
I made Goldy 3.2 from Apberg sprint draw.

Same as Metaldetector 107.

IC 4.leg Volt is 0.65 .
Tr 2907 and 2n222 Heating during work which is near 4024 .
one of friend said changing all of 2n222 and 2n2907 solving problem .

Regards
Erol

[Max]

Hello
I made Goldy 3.2 from Apberg sprint draw.

Same as Metaldetector 107.

IC 4.leg Volt is 0.65 .
Tr 2907 and 2n222 Heating during work which is near 4024 .
one of friend said changing all of 2n222 and 2n2907 solving problem .

Regards
Erol

Hi,
I think you mean the voltage converter ... the ones that give you the negative supply.

OK, there at output you must have something -6.2V if all ok... with components on board, means ic in sockets.

If have much less voltage or positive the negative voltage isn't enough to properly run TGS in working conditions... so something e.g. saturate and you hear steady sound always.

Check transistors, check if you e.g. put one instead of the other... if e.g. swapped the pnp with npn kind and similar mistakes...

Kind regards,
Max

[ivconic]

Hello
I made Goldy 3.2 from Apberg sprint draw.

Same as Metaldetector 107.

IC 4.leg Volt is 0.65 .
Tr 2907 and 2n222 Heating during work which is near 4024 .
one of friend said changing all of 2n222 and 2n2907 solving problem .

Regards
Erol

Most probably you will have only to change those transistors with another pair. I suggest you BC557 and BC547 there. If this dont solve the problem than you must do detailed analyse and post more informations here..

[ivconic]

Dear Ivconic Max
i have made your last TGSL but when tested i hear i countinuse sound
also when nulling coil i hear some cracks
TX freq is 14.4khz
please help
best regards

Possible bad diode at transient outputs on 4024. Check and replace those 3 x 1N4148 at pins 5. , 6. and 9. on 4024...

[metaldetector107]

last TGSL

Dear Ivconic
i changed the diodes only the sound became lower but still sounds continuesly

please help

[Ultimate_Haze]

hi

to Ivconic
*1e coin = 32 to 36cm in air (~48cm if monostable mode available)
*cola can = 55cm in air (~ 80cm if monostable mode available)

Thanks!That is realy good results.But is this clear detection with slow motion on target?Or just bearly hearble signal?


to Max,
This excplain things.Because I have noticable increase of sens. for larger ithems compared with 27cmDD.But in same time I still have troubles when test with my large coin.Which is 4cm d, thick brass coin.
p.s.can you clear some space in your PMbox?

[ApBerg]

Hello Erol,

Check the EBC from the 2n2907 and 2n2222 if you are using Plastic versions the e/c can be roteted.
Succes.

Ap

[metaldetector107]

last TGSL

Dear Ivconic
i changed the diodes only the sound became lower but still sounds continuesly

please help

[ivconic]

to Ivconic
*1e coin = 32 to 36cm in air (~48cm if monostable mode available)
*cola can = 55cm in air (~ 80cm if monostable mode available)

Thanks!That is realy good results.But is this clear detection with slow motion on target?Or just bearly hearble signal?


to Max,
This excplain things.Because I have noticable increase of sens. for larger ithems compared with 27cmDD.But in same time I still have troubles when test with my large coin.Which is 4cm d, thick brass coin.
p.s.can you clear some space in your PMbox?

It is end of detection. So audio is weak,logically.

[ivconic]

Dear Ivconic
i changed the diodes only the sound became lower but still sounds continuesly

please help

Measure voltages on ic's supply pins. For example; what are voltages on pins 4. and 8. on LF353,LM358 and LM393 ?
You must have 7.9 - 8 volts on pins 8. and -6.2 volts on pins 4.
Multimeter black probe on pcb gnd and red probe on pins, when measuring.
If you dont have minus voltage on pins 4. than chopper is not working. Replace transistors there.
Dont ask so simple questions any more. First measure and than provide here more informations. Nobody can help you to solve problem if you dont provide more informations. Use multimeter, measure and post here results.

[metaldetector107]

last TGSL

Dear Ivco
thanks i have measured v- and v+ for all LM358 LM393 LF353 all
as you mentioned are correct v- is 5.81 and v+7.9 accept
the first LM358 near by source volt its v+ is 12v but its directly connected to source volt???
freq is 14.4 nice sinewave
please help

[ivconic]

Dear Ivco
thanks i have measured v- and v+ for all LM358 LM393 LF353 all
as you mentioned are correct v- is 5.81 and v+7.9 accept
the first LM358 near by source volt its v+ is 12v but its directly connected to source volt???
freq is 14.4 nice sinewave
please help

Ok. Last LM358 is tied directly to battery - it is ok, dont worry.
Minus voltage is not ideal. Something maybe drains to much current there, but what?
Looks like you experimented to much in the nearest past and burned something else there?
Can you measure power consumption and post here? Connect ampere meter in serie with detector and battery and measure, than post here.