Non motion detector

[ivconic]

Aren't T2 and F75 exactly the same machine under the hub?
Coil for one will work fine with another.
Same goes to slightly different machine F70, but the same aplies for coils.
...
And now this is just my assumption; aren't the Quest X20 and T2 are also exactly the same detector, with slightly changed upc code and on different pcb and some different components used?
Logically; Quest X20=T2=F75

[ivconic]

Just a comment on your Quest search-coil:
It is clear that the Quest design is very closely copied from the Teknetics T2 machine. This makes sense if you know about the copyright infringement lawsuit between Deteknix and First Texas Products.
So the T2 coils, and any aftermarket T2 compatible models will match the spec of the Quest. BUT ... Fisher F75/F70/Teknetics Patriot are NOT compatible, they have a conventional single-ended Transmit coil winding, not the centre-tapped type. RX coil specifications appear identical to the T2 spec.
Worth mentioning: The inductance measurements of each half of the centre-tapped winding are completely meaningless. Because there is 50% of the wire in the bundle not conducting, the wires are effectively not a tight bundle, so there is poor coupling between each one. This lowers the inductance. The total inductance figure of 695 microhenry is correct. I think the TX is constructed by winding the two halves bifilar, then joining them up so they are in series connection.

One thing that should be considered when using T2 (or F75 ) coils : they are nulled at 13 kHz, and are finely tuned, they are not good when used at 12k or 14k.
The coils used on the Tek G2/Fisher F19 / Tek Greek series etc are a semi-broadband design, certainly covering 8k to 19k, and they may be a better choice if different freq choices are wanted.

These are good observations to keep in mind. Personally, I don't care what the operating frequency will be.
Because this is an attempt to design a new non-motion detector, so it's all in the game. What is imposed as such must be respected; so be it.
The only F75 schematics and maybe a few more models from the list that are available to us; show just single-ended TX.
But these are schematic made by various enthusiasts and not original schematic that came from the manufacturer.
There's a slim chance that in that part, the TX part, they didn't draw things correctly.
Unless you have access to the factory schematic, then we can know with 100% certainty that this is so.
I had a Gold Bug Pro until recently. I swapped coils between it and Quest and both detectors worked great in those checks.
Only the pin layout on the connector is different.
I believe you are right and that not all coils on my list are absolutely identical. But it is striking that the inductances are almost the same
or at worst very similar.
Whether my non motion will run at 5, 9, 13 or 19 kHz doesn't really matter to me.
Quest X5 runs at 8kHz.
Gold Bug Pro runs at 19 kHz.
When I swap their coils; they still work great. Both Disc and GEB are accurate and in place. VDI numbers are correct.
How do you explain that (if the coils are not the same)?
But ok, let's not spread the story unnecessarily off topic; if this is a coil for Quest X5 then I don't mind my non motion running at 8kHz.

[Skippy]

Just a comment on your Quest search-coil:
It is clear that the Quest design is very closely copied from the Teknetics T2 machine. This makes sense if you know about the copyright infringement lawsuit between Deteknix and First Texas Products.
So the T2 coils, and any aftermarket T2 compatible models will match the spec of the Quest. BUT ... Fisher F75/F70/Teknetics Patriot are NOT compatible, they have a conventional single-ended Transmit coil winding, not the centre-tapped type. RX coil specifications appear identical to the T2 spec.
Worth mentioning: The inductance measurements of each half of the centre-tapped winding are completely meaningless. Because there is 50% of the wire in the bundle not conducting, the wires are effectively not a tight bundle, so there is poor coupling between each one. This lowers the inductance. The total inductance figure of 695 microhenry is correct. I think the TX is constructed by winding the two halves bifilar, then joining them up so they are in series connection.

One thing that should be considered when using T2 (or F75 ) coils : they are nulled at 13 kHz, and are finely tuned, they are not good when used at 12k or 14k.
The coils used on the Tek G2/Fisher F19 / Tek Greek series etc are a semi-broadband design, certainly covering 8k to 19k, and they may be a better choice if different freq choices are wanted.

[nejdet]

master audio solid problem.no sound.bc557 getting hot

Where is bc557?

[vahit05]

master audio solid problem.no sound.bc557 getting hot

[vahit05]

thank you for your support

[ivconic]

Well, you made a connection between 4066 and 412 and I think you used a double 4066 in the video, I would appreciate it if you could describe it.

Look up, post #29, i posted schematic of that.

[vahit05]

Well, you made a connection between 4066 and 412 and I think you used a double 4066 in the video, I would appreciate it if you could describe it.

[ivconic]

It is difficult to say what could be the problem. I saw your pcb and that paste you used. This paste can cause various problems.
Sorunun ne olabileceğini soylemek zor. Pcb'ni ve kullandığın macunu gordum. Bu macun ceşitli sorunlara neden olabilir.

[vahit05]

vconic m.hello.please master additions in the video,between 4066 and lf412.and the bc557 in the sound output gets hot.and there is no sound.thanks.

[Qiaozhi]

ivconic ustam.selam.lutfen videodki usta eklemeleri,4066 ile lf412 arası.birde ses cıkısındaki bc557 ısınıyor.ve ses yok.teşekkurler.

Please read the forum rules -> Basic Rules of the Forums
and make your posts in English.

[vahit05]

[ivconic]

Don't be fooled by such small dimensions of this coil!
On the Quest X5 detector it works "killer" well! And very deep!
I was so positively surprised at the first few hours of working with the X5 and that coil!
And who likes larger coils; there is a much larger selection of medium and large coils for detectors from the list, with the same specs.

[ivconic]

Coil for Quest X5, i was talking about, to be good to replace present Tesoro coil:



Looking at it's specs and also on the list of fully compatible coils that can be used; becomes obvious why I am ready to pick it for this design.
If we count all the coil models for the detectors from the list; we'll have indeed rich variety of affordable and easy obtainable coils for this detector.
But!
TX stage must be changed also!
An interesting detail is that these coils have a middle point/lead.
Which is probably connected to ground in most of the mentioned detectors.
I have never in practice tried so far to make a detector with such a TX.
And that would be very interesting for me to try.
There must be a good theory explained and elaborated behind that first.
I would combine such coil arrangement with direct square output too.
So...
Now it is the turn of real experts to appear here who know how to explain it well.
As if also to trying to design such a good TX output for this purpose.
C'mon fellas!
Don't let this forum sink into inactivity!

[ivconic]

I tried to make a video to show all the important aspects of the behavior, to see some details clearly and that there is no need for additional explanations later.
A picture (video) can always say more than words.
However, this is an international forum, we do not all speak and understand English very well, so it is always better to express things in pictures and videos.
That's why you should watch the video slowly, carefully and maybe more than once.
I don't use "monetization" on my Youtube channel, so that's not the reason why I suggest watching again!
Carl gave a good suggestion, I made those changes and it is clear that the threshold is now behaving a little better, cleaner and "linear" ... if I can say so.
But as before the changes, it "holds" for a while and then starts drifting and escalates.
But if the threshold and sense trimmers are adjusted very precisely; then it stays stable longer and does not escalate.
Adding R11 and R15 is not something that i invented, i took that from the Lobo schematic. It becomes than "very slow motion", though it is not so easy to recognize on the video.
Higher the value of R11 and R15; slower the "auto-tuning". With 10M it would be easier to see that behavior. With 4M7 even faster would be the auto -tune... etc
The PCB is now messy, wires are sticking out on all sides, and the PCB design itself is not the best. My bench is surrounded by various RF interferences ... it all contributes.
I believe that a new PCB with neater connections would be much "quieter".
But basically ... I'm afraid you wouldn't get much more, that's it. What you see - you get ...
Now I am only interested in whether it would be possible to add another level of gain or not.
But with more gain i am afraid that drifting will be even larger. And yet, maybe inventing more narrow filtering will allow more gain in channels... things to think about and consider!
I would not elaborate on this schematic further. I would rather move on to the changes I mentioned earlier.
So; coil for Quest X5 (I will publish specs later), negative voltage generation with 7660 and possibly better audio stage elaboration.
But any possible suggestions and ideas related to the current situation; is more than welcome.