Building Wolf Treasure [Tesoro Lobo]

[mermelado]

Thank you very much Op04, this diagram did not have it, I will study it carefully, although I think I have already clarified the connections of the switches, as soon as I am sure I will publish it. I leave you a small video that demonstrates the power of the wolf. We're talking about an iron-framed workbench, a loose, unshielded coil, a power supply instead of a battery, and a room full of EMI. The result is about 30 cm for a euro coin.
Now, once I am sure that the commutations are correct and that I know how to operate the Lobo, which is not easy for me and the manual seems unclear to me, I will start working on the discrimination, since it is almost nil. The reason is simple, there is no phase variation whatsoever, neither between TX and RX, nor while the coil is attached to a metal. Clearly the problem seems to be with the coil. Unfortunately, the information I have found does not seem to match reality either. I will be commenting more things, in case they serve someone.
Greetings: Luis.


Note: After much reading, it seems that there is talk of a variation of about -12 degrees, which of course I do not have.


Here is the video: https://photos.app.goo.gl/gStRpZbsQUxxUjcB6

[mermelado]

Continuing with my tests I can already assure you Op04 that the scheme you publish is wrong. To give you an example, I will tell you that all the diagrams that I have seen as a wolf have a resistance of 5K1 between pin 7 of LF442 and pin 6 of LM358, however it does not have it, but is subjected to the switches. This could mean that they are all wrong except this one, but it also does not have the cable jumper in the switches that all the others have and that in a photo of the original Lobo PCB it is clearly seen that it must exist. I am referring specifically to the commutation that has a 10K resistance on its central pin and its 2 ends are coincidentally connected to pin 7 of LF442. So in principle I should ignore this scheme.
From my tests I think that I am already clear about the correct connection and it is in this same forum. As this matter of the switches seems to be gagged, it also presents a small error and that is that it says that it is seen from behind and this if true would work well, but the switches will be the opposite of the original Lobo. A simple solution to turn them around is to imagine that it is seen from the front, which in my opinion does not change the way it works. It should be noted what I have said before, that the lever upwards indicates connection of pins from below and vice versa. This has been taken into account in that photo, so that for example "RETUNE" which is marked above, actually joins the cables in the center with their corresponding pins below. This is useful for tracking the circuit on the PCB as various designs circulate on the network. This in my opinion is the correct connection: https://www.geotech1.com/forums/atta...1&d=1328510091

[Op04]

Wow...!! That is quite qood performance! When I'm trouble with disc I put higher input caps before 393 100pf to 220-270pf. The 393 chip must be the good one. For switching part, I only have lobo (that works) from vlaser PCB without switching part, I leave to you that switching part heheh... You have convince me to build lobo again. Thank you for keeping update your project here Mr. Luis
Regards.

[Op04]

Continuing with my tests I can already assure you Op04 that the scheme you publish is wrong. To give you an example, I will tell you that all the diagrams that I have seen as a wolf have a resistance of 5K1 between pin 7 of LF442 and pin 6 of LM358, however it does not have it, but is subjected to the switches. This could mean that they are all wrong except this one, but it also does not have the cable jumper in the switches that all the others have and that in a photo of the original Lobo PCB it is clearly seen that it must exist. I am referring specifically to the commutation that has a 10K resistance on its central pin and its 2 ends are coincidentally connected to pin 7 of LF442. So in principle I should ignore this scheme.
From my tests I think that I am already clear about the correct connection and it is in this same forum. As this matter of the switches seems to be gagged, it also presents a small error and that is that it says that it is seen from behind and this if true would work well, but the switches will be the opposite of the original Lobo. A simple solution to turn them around is to imagine that it is seen from the front, which in my opinion does not change the way it works. It should be noted what I have said before, that the lever upwards indicates connection of pins from below and vice versa. This has been taken into account in that photo, so that for example "RETUNE" which is marked above, actually joins the cables in the center with their corresponding pins below. This is useful for tracking the circuit on the PCB as various designs circulate on the network. This in my opinion is the correct connection: https://www.geotech1.com/forums/atta...1&d=1328510091

To make a conclusion for that we have to look on which PCB he ( guru Drako) use. But, thank you for clarifying. I hope when you finish with all the working part, you can publish the whole plan/sch/PCB being use. Regards

Add:
From my above statement above I was confused with eldorado which I'm going to build again, again here, before the disc part is 100pf, I sometimes change that part.

[mermelado]

Thank you for your kindness and help. For now I can tell you that if you look at the photo of the PCB I assembled, you will see that it is the Russian version that is sold on Ebay. Multiple diagrams are shown in the same sales announcement. The one in the diagram does not correspond 100% to the board, the commutations are reversed and the coil does not match reality. At least that's my conclusion. The TX coil has too many turns and in addition to giving too high an inductance, the resistance does not correspond to the logic of removing turns, but it is inverse. The next thing I will do is remove coils, the 80 they indicate is an exaggeration, other sites speak of about 60 and I, using the shape of the TGSL coil, I think it will go through 40 turns, for an approximate inductance of 2mh. If I clarify all this, I will post everything.
I honestly do not understand why they have complicated this project so much.

[rolling rock]

Here is a cleanup of the original Lahr schematic that I did so long ago that I wasn't even sure it was my work when I first stumbled across it today.
Also here is the original Lahr drawing with no (no?) changes or additions,
and here is the Diablo 2 schematic. Notice the similarities?

Diablo 2 had an arrangement so the user could flick a switch and reduce the gain, so as to not overload. The RC time constants at amplifier B set up a slightly leading rx phase as gain setting was lowered. I do not know if that was accidental or deliberate.

[rolling rock]

I made a lot of mistakes building TGSL, but I think I hit all the problems, but I got bored and decided to park it for a while. For some reason I wanted to ride the Wolf, if it doesn't work, then nothing happens either, I will always learn new things and by the way then I will publish the first one I have learned, in case it works for someone. Anyway thanks so much for your sensible advice

I was leaning strongly towards the LOBO but I like to understand a circuit before I attempt to duplicate it, not after, and LOBO leaves too many questions. Golden (also Royal, Euro) Sabre or Eldorado could be my destination.

Look at my notes in the "cleanup" post above. Do those numbers attached to the second and third filters make any sense? The answer is NO. I would change the second filter high-pass section to 1.6Hz to maintain sanity, but that still leaves the 3rd filter sections looking like a notch instead of band-pass and I lose my sanity again when I try to understand that. Therefore, ()Sabre, or Eldorado is my destiny. Simple. Elegant. SANE.

Lobo defies understanding, imho.

[rolling rock]

I believe that, right or wrong, Lahr's diagram is the wellspring from which all LOBO clones springeth...

[mermelado]

I agree with you, as even the PCB I have from Russia looks very similar. I would say that the only noticeable difference, other than the 10pf capacitor between pins 1 and 2 of the first RX preamp "thing I haven't experimented with much yet", is that the Russian design has a low battery optical warning, instead acoustic and this is irrelevant to the proper functioning of the detector. The issue of filters because I do not know exactly what it refers to, I mean if it is a design error or a transcription error when copying it, or simply in the fact itself of its characteristics. In practice, this doesn't seem to give me a problem.
By the way, in this cleaning of the scheme, the commutation is still wrong, actually it is not wrong, but it is wrongly marked. The S2 "Auto / All Metal, etc." switches. They are backwards.
Greetings: Luis.

[mermelado]

I must excuse for a mistake. I said there was no lag and it's not true, I just measured wrong. There is a nice phase shift that can be adjusted at will by moving the coils closer or further away. Anyway I am building another TX coil with less inductance. I will publish the results.

[rolling rock]

I didn't think to correct the switches in the pics. That would be worthwhile but it'll have to wait.

I finally got around to running a proper AC analysis on the DC filter sections of various Tesoro detectors. Lobo has three sections, also I think Eldorado might be considered three filters? All the others have two. I know nobody asked for this but I want to take back any reservations I may have had. After seeing these I have to admire their work.

You won't have anything like this on your oscilloscope but you can clearly see the pass-bands being roughly dome shaped. Frequency is swept 0.5~50Hz.

Ooh I highly recommend LTspice for all you budding engineers and wannabes.

One last thing - I added a second 220nF capacitor the the X-Sabre at the amplifier input pins because something was probably there in the original design, otherwise the 100k resistor can be removed because it does nothing. It's in series with 100GΩ input resistance, or something like that.

Most of the Tesoro designs use a half-wave demodulator, so I think it's appropriate to count the resistor on the front side of the switch 2x. Cibola has a FW demodulator where each half gets counted half the time.

Sorry, I'm not trying to hijack this thread, it's still about Lobo (and such).

[Ruben2000]

Sorry, I'm not trying to hijack this thread, it's still about Lobo (and such).

Any information to help us build LOBO or improve it will be welcome. Thank you very much Rolling Rock

[rolling rock]

Ruben 2000, look at this picture. On these particular op-amps and comparators the -input goes to pin-2, +input goes to pin-3. It's probably OK, but you should check your PCB layout to make sure there was no mixup.



probably just a mistake on the drawing

[Ruben2000]

Ruben 2000, look at this picture. On these particular op-amps and comparators the -input goes to pin-2, +input goes to pin-3. It's probably OK, but you should check your PCB layout to make sure there was no mixup.

[ATTACH]56323[/ATTACH]

probably just a mistake on the drawing

My PCB is made according to this scheme. There are many schemes where the pins and polarity are reversed. If there is any error in the scheme please let me know. Thank you very much rolling rock !!

[Ruben2000]

Ruben 2000, look at this picture. On these particular op-amps and comparators the -input goes to pin-2, +input goes to pin-3. It's probably OK, but you should check your PCB layout to make sure there was no mixup.

[ATTACH]56323[/ATTACH]

probably just a mistake on the drawing

According to what I see, only pins 2 and 3 of U11 are inverted from the diagram you published. The rest are fine, no matter the polarity, the important thing is the uvication of the pins. In my diagram only U12A the polarity of pins 2 and 3 are reversed but that has nothing to do with it. Any detail to improve the scheme will be welcome !!!