TESORO GOLDEN SABRE

[liekwang]

?Thank you I will see Qiaozhi and try later

[sukri01]

HI, Ive made TGSL complete details, but with no succes, until i change pin position of 2n2222 and 2n2907, now i got sound and detection, but as low as 5cm for a 2cm coin,
does anyone else got the same problem? my coil construction is 6.5mh and 5.95mh.. i need to make this work before i loose my mind..

[golfnut]

post 2Mbyte images of your build - in focus with good lighting and we will all take a look. S

[ivconic]

HI, Ive made TGSL complete details, but with no succes, until i change pin position of 2n2222 and 2n2907, now i got sound and detection, but as low as 5cm for a 2cm coin,
does anyone else got the same problem? my coil construction is 6.5mh and 5.95mh.. i need to make this work before i loose my mind..

Are you sure that you made good coil? Well balanced?

[paku]

Hahahaha You waste you time sukri Better Make Eldorado simple to setup the coil

[ivconic]

Hahahaha You waste you time sukri Better Make Eldorado simple to setup the coil

Same thing. Not simpler at all.

[sukri01]

hi golfnut, ivconic n paku.. i post some picture here few hours ago.. http://www.geotech1.com/forums/showt...highlight=tgsl. ill post more picture tomorrow, its gloomy in my house right now.
ive just shielded my coil and rwsult are still same.

those induction reading no good?
could u please elaborate on "well balanced coil"
ive made 4 coils for the past 2 weeks. i guess this one might be good

[sukri01]

why is it that some can null their coil to 4mv when i can't even pass 160mv? bad coil? ive made new one with 6.5mh on rx and 5.9mh for tx.. how can i achieved 4mv? been trying from yesterday.. best result is 160mv with 5 inches detection on 2cm coin..

[sukri01]

ive just had my tgsl scope..tx is 13.5 khz amp 14.8v and rx 14.28khz amp 0.6v. thia makes me more confuse..,

[golfnut]

The Tx sounds ok .
Dont know how you measured the Rx coil tuniing..

Try for a decent null, say <100mV at preamp output.

Do air test on small coin. Record results.


Now add a 2n2 to Rx capacitor - whilst watching the preamp output. - If it gets bigger add another 1n etc

If it gets smaller when adding a 2n2 then try a smaller original cap and add to that.

When peaked to large as it gets - this is the RX Co tuned to the Tx - sometimes they injection lock together.




Air testing will show any improvement.

I would then walk the Rx cap up or down ( So Rx tank is above or below the Tx its no big issue. ) so you have good air test.


Make sure the Amplitude is 200mV or less and the initial phase of the preamp out and the Tx drive is within +/-20degrees.

This will almost guarantee you will be able to reject ferrite with the GEB tuner. And be able to reject Iron using the DISC.


Take outside and soil test with buried targets.

If over bare flat dry earth you cant keep it quiet you need to pull the Rx tank a little further off - try 0.5nF

This will sacrifice a small amoount of air test but make it usable in soil.

S

[sukri01]

ok thanks.. i will try that..

[sukri01]

one more thing..i can measure rx frequency on u101 pin 7 right?

[golfnut]

No, the signal the Rx gets is the Tx frequency..........



Thr Rx tank / front end has to be tuned between 50 to 80% of the Tx freq - either above it or below it.

Otherwise if the Rx front end is tuned to the Tx freq it cant work..
S

[der_fisherman]

Frequency differences

I do believe it will work but will be unstable and not very sensitive. A lot of cheap units work in this manner I believe....Somewhere on this website is a proper explanation of the reasons it should not be used.....don't ask me where though!!!
Basically thats how a transformer works......
Regards
Andy

[paku]

I do believe it will work but will be unstable and not very sensitive. A lot of cheap units work in this manner I believe....Somewhere on this website is a proper explanation of the reasons it should not be used.....don't ask me where though!!!
Basically thats how a transformer works......
Regards
Andy

This Is The True