TESORO GOLDEN SABRE

[Max]

Hello Max.

Well.... there was, for some 40 minutes, no erratic sound, then suddenly it became erratic again , just like it was triggerd by something.
The power was the same, near the coil was nothing moving !
It is more quiet but there is still something that makes the golden, at full sens, instabel. Reducing the sens a little solves the problem...and it stays very sensible, ....

Let us know your results !

Best regards.

Ap

Hi,
yes I had tested right now... seems ok for now... are about 15minutes up and running very quiet.

I've solved before the almost (about) all of erratic bleeping changing the TL062 with a TLC2262 that's much better there and are also better than this ic but I have 2262 now. If you have still the TL062 change it for something better low noise dual op amp, TLC2262 is good for that.

About LM308 N version is ok for testing and working too but I still think, as Ivconic reported, that H-version are rock-solid for absolute stability issues.

Problem is that they aren't easy to find and cost much... so not a general solution to the problem.

About the cache-test... from your experience, do you think it could detect the jar of 220 silver coins at 60cm depth ?

Best regards,
Max

[ivconic]

!

Ap Berg, try this; Sense at 80%, Disc at 10%, Disc mode ON....Should work calm without false signals....
Thanks for tip!
Best regards!

[ApBerg]

Hello Friends.

Put a 6N8 cap after the 100K (R30,R2 comming from the switching fet
Made it very quiet, but also the sens is going back....?

If I trace the scopeprobe near the fets they give a lot extrnal noise, can this give problems for the nearby LM 358 ? Input pin 3 and 5.
Also the bandido has caps on those inputs.

Best regards.

Ap

[ivconic]

H

Yes i was thinking the same too; must be noise from switching fets!
But i am thinking must be some other way to "choke" those? To couple with some capacitor, small capacitance, just to blank "sparking"...
Not sure about values yet. Some cap on drain or source.....Any ideas?
My latest TGSL is working like hell in Disc mode. Absoulutely calm and very deep! Even i am suprised! But in All metal mode something strange is happening; when no metal in coil proximity all is calm,silence and stabille but once i cross with coin over coil, TGSL is starting singing and not stoping when coin put away!? I have to switch it off or touch coil with hand to stop it.Again it remains calm until next movement? Coil is superb...it is something again in device? But when switched in Disc mode no problem at all; it is working so good....i dont have words...
Must be those fets!? Must be some way to fix this? Coil and cable are not sensitive at all on touching,moving,"torturing"...remains calm without false signals at all....Very,very good!! 3cm coin over 40cm in the air...
Max sorry i didnt answer you; yes i think TGSL must detect jar with 220 silver coins at 60cm buried in the ground.According to results i gained so far i am 100% sure it will detect those with no effort at all...
Regards!

[Max]

Yes i was thinking the same too; must be noise from switching fets!
But i am thinking must be some other way to "choke" those? To couple with some capacitor, small capacitance, just to blank "sparking"...
Not sure about values yet. Some cap on drain or source.....Any ideas?
My latest TGSL is working like hell in Disc mode. Absoulutely calm and very deep! Even i am suprised! But in All metal mode something strange is happening; when no metal in coil proximity all is calm,silence and stabille but once i cross with coin over coil, TGSL is starting singing and not stoping when coin put away!? I have to switch it off or touch coil with hand to stop it.Again it remains calm until next movement? Coil is superb...it is something again in device? But when switched in Disc mode no problem at all; it is working so good....i dont have words...
Must be those fets!? Must be some way to fix this? Coil and cable are not sensitive at all on touching,moving,"torturing"...remains calm without false signals at all....Very,very good!! 3cm coin over 40cm in the air...
Max sorry i didnt answer you; yes i think TGSL must detect jar with 220 silver coins at 60cm buried in the ground.According to results i gained so far i am 100% sure it will detect those with no effort at all...
Regards!

Hi Ivconic,
nice to see your last is very good on depth. I noticed similar effect on mine just one time... I mean in disc mode worked very nice, then switching to all metal I get strange bleeping that confused me after nearing the target.

In my case it was due to the coil-cable wiring cause I was testing just a return-gnd wire from coil to pcb... probably some kind of twisted pair effect or similar.... then some saturation/closed-loop-signal in the circuit happened I think.

I changed the cable using separate conductors for both coils (like in the tesoro's original coil I've bought) and things become quiet in all-metal too.

I'm not sure that your problem could be there, cause you reported that moving cable give no signal... but I suggest you recheck coil wirings.

Other possible cause in the circuit:

If problem is in the circuit it could be related also to capacitors used I think... e.g. some dried electrolytic in the signal path could give such kind of problems too cause they have bigger ESR... and then losses... so when one of this charge the decay ratio could be higher than other caps. giving confusing/erratic behaviour.

That could happen with new/shelf parts too... cause electrolytics dry also if unused for some years. If you have used shelf/new parts check them with an ESR meter if you have it or just change with new ... expecially in the "bipolar" section.

Actually I got last week new from store parts with hi-ESR and had to complain with guys at store cause one expect new parts are new... not years old products they sell as "new" (never used). But they (poor of electronic concepts) don't even understand well problems related to ESR... so I've decided not buy capacitors anymore at their shop to solve my ESR issues and avoid other troubles.

Best regards,
Max

[Unregistered]

Hello

Hello,
Max.What are the number of turns for this 12OO coil?
40cm is very good depth!!!
When I nuled my 22 cm DD coil using 200mV range of my multimeter the depth is good,but no disc at all!!!I null to 0,01!
Why is this happening?
Thanks

[Unregistered]

Hi

Ivconic,
I have wind this DD 255X137 with you first data 102 TX and 108 RX!
Maybe thats why I cant get the same results , now I see you give 100 TX and 105 RX!

[tiktak]

Hi,

Ivconic,
What is this second trimer in original design and how should it be adjusted?
Thanks

[Max]

Hello,
Max.What are the number of turns for this 12OO coil?
40cm is very good depth!!!
When I nuled my 22 cm DD coil using 200mV range of my multimeter the depth is good,but no disc at all!!!I null to 0,01!
Why is this happening?
Thanks

Hi,
for 12OO you can use:

WIRE 0.25mm/30AWG (0.28 with varnish)
TX turns 145
RX turns 155

but tuning is absolutely critical...so... you can get them work easy but is very difficault get maximum depth from that design on e.g. golden sabre (at least for me... at now! on bandido I get very good results with that)

for Ivconic's 255x137mm DD

WIRE 0.25mm/30AWG (0.28 with varnish)
TX turns 100
RX turns 105

Numbers can vary if you don't use right formers or wire...stay close to that or you have to find new by yourself to match inductance and resistance.

Nulling is always critical for VLF coils... some coils more than others you can use multimeter but it's very hard make repeatable results with that only.

Best regards,
Max

[Max]

Ivconic,
What is this second trimer in original design and how should it be adjusted?
Thanks

Hi,
you mean the other than ground balance one... it's for notch window amplitude regulation.

Kind regards,
Max

[ApBerg]

Silver ????

Hello Friends

Some testing: ground adjust from the Goldy(golden light) and the sens. for silver.The coil used is a 20 cm opencentre.The scope shows the transmitsignal and the goundswitching fet.The shift from the Fet is made with the gound adjust potmeter. Look at the results At the point were there is zero ground effect (?????) the sens for silver is for a small and large coins almost the same !!!
When this is al true than this means that large silver is very hard to detect.?!

Well hope I have made some mistake ...

Best regards.

Ap

[ivconic]

Yelp!


Actually, it seems very strange and very interesting!
In All Metal mode, already mentioned problem occurs ONLY WHEN
APPLY COIN TO COIL FROM GREAT DISTANCE AND CLOSE TO POINT WHERE
IS JUST ABOUT TO DETECTION OCCUR!?
But when move coin in the zone and accurate detection no problem at all.
Detector makes "beep-beep" and than stops normally like in Disc mode.
So let's repeat;
it cant stop beeping ONLY if coin is approximated to coil from zone out
of detection,slowly...first "beep" occurs and no matter if coin is
removed, beeping continues until switched OFF or I HAVE TO PUT HAND ON
COIL OR EVEN HELPS WHEN I TOUCH THOSE 3 WIRES WHICH CONNECT PCB WITH
DISC/ALL SWITCH...OR IF I RANDOMLY TOUCH SOME PART (BUT NOT EVERY) ON
PCB...IN THOSE CASES IT WILL STOP WITH BEEPING.THIS IS THE CASE ONLY IN
ALL METAL MODE, IN DISC MODE ALL IS WORKING PERFECT!
Also if i move coin from a side into "sure detection" zone, let's say
10-15cm away from coil surface (must be much louder signal than) than
device is working normal,same as in Disc mode, no beeping more when
coin is removed from zone of detection????
Today i tried somehow to dig what is all about - but no results.
Coil is prefect, no doubts in it. Cable wirements from coil to device is
also good - no mistakes, no twisted pair effect, absolutely stabile,no
false signals....nothing!
I put sort of "gnd cage" over those switching fets - still the same...
it seems fets are not problem here despite a lot of noise they producing.
I changed that 15pf, replaced...tried even without it...- same...!?
Coupled LM393 supply pins with 0.1 to gnd...- same...?
Damn!Damn!Damn! This thing is making me crazy! It is not a big deal to
have detector working perfect in Disc mode but not in All Metal mode.
I can live with this.It is working so good in Disc mode so i dont mind
about beeping in All metal mode at all. Besides i am not using All Metal
mode anyway...
But from constructors point of view this thing is interesting me much!
I just would like to understand this better.
I would like to see others opinions on this! Sean,KT315,Carl...others!
Please come here and help us to solve this thing!
What should be a problem here?
Regards!

[tiktak]

Hi,

Hi,
Max.
What you sugest to null acurate?
And how the TX and RX should be positioned when the coil is ready?
/is TX close to ground or RX should be there?/
i mean when coil is ready to go and conected to shaft

[tiktak]

Hi,

Ivconic,
How are you shore that you acive null using your method?
Because when I null with multimeter wired directly to RX and put in 200mv range I cant get detection at all ,but when play with the windings I get point where detection is good,but when measure dont show NULL?
Please advice me.
I make two coils looking for null.And now they are ready but the 22DD have good depth but no disc at all,the 255X137 bad disc only foil and no depth?
What could be my mistake?
Should I try seal next coil like you when I find the best point in all metal?
Why my disc disapiar?
THANKS

[Max]

Hi,
Max.
What you sugest to null acurate?
And how the TX and RX should be positioned when the coil is ready?
/is TX close to ground or RX should be there?/
i mean when coil is ready to go and conected to shaft

Hi,
accurate null I made just with scope and dummy load... 1k resistor and suitable capacitor to resonate at about tx frequency. I don't use multimeter for that though I've made too in past.

"/is TX close to ground or RX should be there?/"

Don't understand well ... maybe you mean which coil have to be flat on base of housing ? If so... I have just my impression to offer :

I've found that putting RX flat at base and TX bounced over is better...for me... but I've made an OO coil in which is better TX flat... so I'm too a bit confused at the moment.

Best regards,
Max