Non motion detector

[gallico58]

Hi Ivconic, I always follow you, I wanted to ask you if it is possible to replace LF442 with TL082?

[ivconic]

Ok, I nicked some time to continue to work on this.
Here is the next step, for those who would like to pursue this further:

[ivconic]

Good luck in your new job. Καλη επιτυχια..!!!

In time, hopefully sooner, I will prepare a schematic with different approach.
Quest X5 coil, TX stage accordingly.
Better and more efficient negative voltage generation.
And some better audio solution.
This is still a nice diy project for hobbyists.
Mentioned drift is a problem, but not that huge and significant problem.
I spend few nice years with Cscope 1220B on the sites and fields, having lot of nice finds with it.
More frequent re-tuning (pressing a knob on 1220B) is not very big problem and can be get used on that easily.
Even the Deus in his "non-motion" mode is slightly drifting.
So, no big problem at all.

[Xtrem]

Good luck in your new job. Καλη επιτυχια..!!!

[ivconic]

I believe you have reached the top ,about the drifting, using analog circuit.
I mean about the reset circuit with the improvements of Carl, Its very stable,
the same is used in Lorenz LP5.
You could adding a buffer before this, like older models of C.Scope (2200TR)
I have tested and im using this in my VLF and PI projects.
In VLF ,i have seen ,that it is more stable , trimming the filter ,using the lowest value
for C, exact there , where the ripple start .
Sorry about my syntax, im not using translator.
[ATTACH]57427[/ATTACH]

Screw the syntax, I understand you well.
Πριν από 28 χρόνια ήξερα πολύ καλύτερα ελληνικά, αλλά δεν είχα την ευκαιρία να τα χρησιμοποιήσω, οπότε ξέχασα σχεδόν τα πάντα. Δυστυχώς, είμαστε πλέον αναγκασμένοι να χρησιμοποιήσουμε αυτή την αξιολύπητη γλώσσα για να επικοινωνήσουμε.
I temporarily stopped working on this non-motion, because I got a job that has direct connections with some solutions like on a non-motion detector.
I couldn't say anything more than this because I'm bound by a contract.
But again it is proven to me that there is some strange force that governs our lives ...
Just when I got stuck with this work here; suddenly, out of nowhere came the opportunity to work on a much more complex design that works on almost the same principle.
And I never dreamed of that.
So when I'm done with what I'm doing now; I will continue with non motion but with some, I hope much better solutions.
However, I expected greater interest and greater contribution from other members. Unfortunately I was wrong. Which greatly weakens the motivation to continue working on the forum.
Until then...

[Xtrem]

I believe you have reached the top ,about the drifting, using analog circuit.
I mean about the reset circuit with the improvements of Carl, Its very stable,
the same is used in Lorenz LP5.
You could adding a buffer before this, like older models of C.Scope (2200TR)
I have tested and im using this in my VLF and PI projects.
In VLF ,i have seen ,that it is more stable , trimming the filter ,using the lowest value
for C, exact there , where the ripple start .
Sorry about my syntax, im not using translator.

[ivconic]

hi ivica, the rereleased 1220 and 990's sold recently seem to be way better when it comes to drifting.
though, i haven't opened one so they are probably nothing like the old 1220b inside, but you never know cscope does not reinvent the wheel, they dont change designs for the sake of it, its one of the reasons i find myself going back to them, there is not another decent nonmotion machine you can buy brand new that works as well.

Yes, 1220XD looks like significantly improved one.
Problem is; those are hard to obtain here in my country.
If i had it; i would reverse it now and make files on it.

[sinclairuser]

Good!
Cscope 1220B is probably the best non-motion i had and worked with so far.
But it suffers from the drifts also. Needs frequent retuning.
And it's schematic is not clear enough to be 100% sure and replicate it.
I had two 1220B so far and yet i didn't trece them out.
Here I am trying to make something new, to exercise, learn something and kill a time.

hi ivica, the rereleased 1220 and 990's sold recently seem to be way better when it comes to drifting.
though, i haven't opened one so they are probably nothing like the old 1220b inside, but you never know cscope does not reinvent the wheel, they dont change designs for the sake of it, its one of the reasons i find myself going back to them, there is not another decent nonmotion machine you can buy brand new that works as well.

[ivconic]

ivconic , nice work , very helpfull
see please at this link at post 8
https://www.geotech1.com/forums/show...220B-Schematic
why do not you mention about this detector? it has a center tabered coil too, and the transmitter
are not very different.

Good!
Cscope 1220B is probably the best non-motion i had and worked with so far.
But it suffers from the drifts also. Needs frequent retuning.
And it's schematic is not clear enough to be 100% sure and replicate it.
I had two 1220B so far and yet i didn't trece them out.
Here I am trying to make something new, to exercise, learn something and kill a time.

[Xtrem]

ivconic , nice work , very helpfull
see please at this link at post 8
https://www.geotech1.com/forums/show...220B-Schematic
why do not you mention about this detector? it has a center tabered coil too, and the transmitter
are not very different.

[Op04]

Don't remember where I got this

[Skippy]

Maybe this 'X5' Quest coil is a different design?
The T2 coil has an RX inductance of 7.0 mH, not the 11mH your Quest coil has. The earlier Deteknix/Quest machines were T2-compatible, but newer ones?
I have never seen a good T2 schematic, so I have no idea how the TX was driven. But as just posted by OP04, the Makro Racer, maybe others, used centre-tapped TX, and their schematics have been posted on here.
The F75 has been documented, I can find the schematic if needed. I recall that the double-tuned circuit originates in the Troy 5, but it's a Fisher design, and was carried over to the F75.
I can't remember what the spec of the Tek Delta/Fisher F5/F19 etc coils is, they are posted on here somewhere.

[Op04]

I remember nokt macro also use center tap coil

[ivconic]

No....
T2 and F75 are different, and one of the significant differences is the coil. Fisher wanted the option of concentric search-coils ( it was a park-detecting variant of the T2) , and the centre-tapped arrangement of the T2 makes concentric's hard/expensive to manufacture. So a single-ended TX was used, with a double-tuned arrangement ( two L's, two C's ) in the drive circuit, giving about 60% more TX amplitude, making up for some of the voltage loss caused by the move from differential drive. The RX gain was also increased, so there was the same total gain as the T2.
I'm not familiar with Quest's full product range so I don't know all the possible coil specifications.

That is also good information, thank you!
Check out the highlighted parts of your post.
That is exactly the direction in which I would like this discussion to turn!
Given that I have this coil, and in case of T2 you mentioned ... is the inductance at the ends of it 11mH, in the center-tapped arrangement or is it 2x11mH?
If the inductance is 11mH at the ends then my Quest coil might work as a "center-tapped".
In that case I would like to see some good solution for TX output.
But more important than that is to discuss the pros and cons of both methods for TX.
Here's why I'm asking.
A good part of the drift problem that can be seen in my videos, I believe, is first of all related to TX.
...
I took larger Nel Tornado... or something like that, can't remember the label on it, coil, made preciselly for T2 and rearranged pins at the connector and connected to Quest X5.
It works quite alright!

[Skippy]

No....
T2 and F75 are different, and one of the significant differences is the coil. Fisher wanted the option of concentric search-coils ( it was a park-detecting variant of the T2) , and the centre-tapped arrangement of the T2 makes concentric's hard/expensive to manufacture. So a single-ended TX was used, with a double-tuned arrangement ( two L's, two C's ) in the drive circuit, giving about 60% more TX amplitude, making up for some of the voltage loss caused by the move from differential drive. The RX gain was also increased, so there was the same total gain as the T2.

I'm not familiar with Quest's full product range so I don't know all the possible coil specifications.