TESORO GOLDEN SABRE

[waltr]

Ferrite is removed, but the sense of silver metal decreases, why??
The silver sense is high if the ferrite is also sensed

Somewhere on this forum is info about adjustment of GB and silver detection.
If the GB adjustment is turned TOO FAR it reduces the sensitivity to Silver.
I did see this when setting up GB on the TGSL I built.
The GB adjustment is very, very touchy. If response to silver decreases then GB turned too much, turn it back barely a hair.

The TGSL calls for a single turn trim pot for GB adjust. If I rebuild it this will be replaced with a multi-turn trim pot to make GB adjustment a bit easier.

You can also play with the coil null/phase adjustment some more. Make a very tiny tweak of the coils then back to GB adjust with ferrite and silver.
If it gets worse then tweak coils in opposite direction and readjust GB with ferrite and silver.

Last step for GB adjustment check is out on real earth.

[mostafalesnar91]

Ok, I will solve the problem myself

[mostafalesnar91]

Ferrite is removed, but the sense of silver metal decreases, why??
The silver sense is high if the ferrite is also sensed

[mostafalesnar91]

It is important that the rx amplitude is set to what number??
Because I set it on any number, the results are similar! Good sense of removing the ferrite and almost good disc mode!!

[mostafalesnar91]

multi turn potentiometer or multi turn trimmer? what you want?

trimmer

[kt315]

multi turn potentiometer or multi turn trimmer? what you want?

[mostafalesnar91]

you do the target move UNRIGHT because along the intersection
while you have to move the target ACROSS -
do right video with right moving.

Ok, now don't upset yourself, I will post another video after I pour the resin!!
I can use this multi turn for gb to remove ferrite precisely

[kt315]

you do the target move UNRIGHT because along the intersection
while you have to move the target ACROSS -
do right video with right moving.

[mostafalesnar91]

in this video,disc mode does not work and ferrite is not removed!!
but my TGSL has a good sense!!especially for the silver ring!!https://youtube.com/shorts/4sEdWDF-sg4?feature=share

[mostafalesnar91]

What number should I set the rx amplitude to for disc mode to work properly 1.2 or 2.2 or 3.2 or any other number or it's not a fixed value at all and it's different for each loop My scope settings are 20us_5V_100mV .

[mostafalesnar91]

Commens on the RX coil resonance and phase shift.

The RX coil along with the Cap, C6, on the RX coil need to resonate at ~16kHz for all the functions, GB & Disc, to work correctly.
There is NO GOOD way to determine is this is correct.
If C6 and/or coil inductance is off then the TGSL will not work properly.

I have added another cap across C6 to increase the capacitance and reduce the resonant frequency to try tuning the RX circuit. I have had luck with this to get it working.
Simply adding a cap will work if C6's value is too low but not if too high (caps in parallel add).
If adding say a 1nF cap makes it worse then C6 needs to be replaced with a smaller value. Then add caps to obtain correct phase, nul, GB and Disc.

The first build of the TGSL and coil took me months to get it to work properly. Once I had the proper values in the TX & RX Circuits the second and third coils (DD & Concentric) builds were not hard and worked well.

Disk mode doesn't work and I can't remove the ferrite by moving the rx on the tx, I can only remove the ferrite by turning the gb

[waltr]

Commens on the RX coil resonance and phase shift.

The RX coil along with the Cap, C6, on the RX coil need to resonate at ~16kHz for all the functions, GB & Disc, to work correctly.
There is NO GOOD way to determine is this is correct.
If C6 and/or coil inductance is off then the TGSL will not work properly.

I have added another cap across C6 to increase the capacitance and reduce the resonant frequency to try tuning the RX circuit. I have had luck with this to get it working.
Simply adding a cap will work if C6's value is too low but not if too high (caps in parallel add).
If adding say a 1nF cap makes it worse then C6 needs to be replaced with a smaller value. Then add caps to obtain correct phase, nul, GB and Disc.

The first build of the TGSL and coil took me months to get it to work properly. Once I had the proper values in the TX & RX Circuits the second and third coils (DD & Concentric) builds were not hard and worked well.

[mostafalesnar91]

You still need the scope to "see" what's going on. Yes, it's possible to build a metal detector without one as long as everything works as expected, you don't make any mistakes, and none of the components are faulty. But Murphy is always present and waiting to screw things up. On the rare occasions, when I decide to build a balanced coil, I always use the scope to initially do the nulling. After that I use a ferrite target to set the GB with the pot in its middle position. This is not rocket science. It just takes a patience and a lot of fiddling around.

Well, now tell me what is your method for nulling the loop with the scope

[kt315]

Output of the preamp. See pages 140 and 141 of ITMD.

my thread. no offset, nothing of offset. nulling in nule. i write that because there is NO phase shift. not exist.
just as en example.

[Qiaozhi]

I will test this method of removing the ferrite today. When I do this, the coin should be sensed above 30 cm. If it doesn't, it means that all this time has been wasted, because on the first day when I joined this site, you said that it should be for The nulling must be scoped so that you can adjust the phase difference, but now I see that all my coils are automatically adjusted to 20 degrees and there was no need for a scope.

You still need the scope to "see" what's going on. Yes, it's possible to build a metal detector without one as long as everything works as expected, you don't make any mistakes, and none of the components are faulty. But Murphy is always present and waiting to screw things up. On the rare occasions, when I decide to build a balanced coil, I always use the scope to initially do the nulling. After that I use a ferrite target to set the GB with the pot in its middle position. This is not rocket science. It just takes a patience and a lot of fiddling around.