Tesoro Lobo news

[perdica 2]

ZOOMIX do you have disc???????????????

i think you can adjust for all-metal but how is the disk?
if you see other tesoro models on SIM the disk goes from 90 to 180 deg ref to RX signal

i have simulated disk of both lobo schematics with or without added resistors the disk goes
from -120~-100 to -20 ~ 0 deg ref to RX sig no rx cap added and no changes on pre amp
i think the GEB is fine

try R10 180k , switch 5th and 6th pin entries on LM393 ,with this changes you can get disk
from 30 to 180 deg ref to Rx signal ,no RX cap added and no changes on pre amp

[perdica 2]

picture of sim based on posted schematic
http://i45.servimg.com/u/f45/12/55/85/88/slide110.jpg

[zoomix]

Vur prédica2,

I tried to check the phase of -12 but my scope has only one entry. I think the best would be to a phase meter to control ^. I found several schema.

My knowledge of analog electronics are limited, but I try to understand. I see that you work on a simulator and thank you for your help.

The results are good. -I change the capacity for a 25nF TX and I can turn the gain up.

Another important finding was correct discrimination has always 24Nf with 470K on R10. The discriminated of ferrous as well as in an area of ​​1.5 cm was located 35 cm from the coil. This area was moving according régalge GB

Since I switched to 25nF, the area disappeared.
Ferrous metals are correctly discriminated and never rings. The legacy currencies in oxidized steel rings again showing that discrimination works well. 200K on R49, 51K between R11 and pin 7 of U4B. Iron is discriminated with the potentiometer is 30%

I also think that the GB is correct. We must find the right setting of the potentiometer on the PCB.

Can you Comfirmed your last message:

In your simulator, you advise on R10 to 180K and connect pin 5 and 6 U5B together and to ground? No capacitor on RX?

With that, I'd discrimination in a phase shift of 30 ° to 180 ° with Rx as a reference signal? is that correct?

What you call "amp" ? it's pre-amplifier consists of all OP amplifier located before the BF245?

[perdica 2]

Vur prédica2,

I tried to check the phase of -12 but my scope has only one entry. I think the best would be to a phase meter to control ^. I found several schema.

My knowledge of analog electronics are limited, but I try to understand. I see that you work on a simulator and thank you for your help.

The results are good. -I change the capacity for a 25nF TX and I can turn the gain up.

Another important finding was correct discrimination has always 24Nf with 470K on R10. The discriminated of ferrous as well as in an area of ​​1.5 cm was located 35 cm from the coil. This area was moving according régalge GB

try R10 180k and more ,no RX cap added and no changes on pre amp


try R10 180k and more ,no RX cap added and no changes on pre amp

Ferrous metals are correctly discriminated and never rings. The legacy currencies in oxidized steel rings again showing that discrimination works well. 200K on R49, 51K between R11 and pin 7 of U4B. Iron is discriminated with the potentiometer is 30%

I also think that the GB is correct. We must find the right setting of the potentiometer on the PCB.

Can you Comfirmed your last message:

In your simulator, you advise on R10 to 180K and connect pin 5 and 6 U5B together and to ground? No capacitor on RX?

With that, I'd discrimination in a phase shift of 30 ° to 180 ° with Rx as a reference signal? is that correct?

What you call "amp" ? it's pre-amplifier consists of all OP amplifier located before the BF245?

1.about U5B ,SORRY i was basing on a previos posteted schematic where pin5 was grounded,
the FOMA and W.LAHR have right conections with pin6 grounded, sorry!!
-with R10 100k on sim. when you tourning disk.pot. a some kind of jumping was apearing on phase , but with biger value of R10 (150k and more ) has a good shift of 30-180deg
2.if you see on my picture the GEB channel is is on 0 DEG reference to RX signal measured at the output of the pre-amp (pin 1 of U7A) ,and if you see when it rise,it make slite curve whitch narrow the the accept region from -80 to +90 (narrows 180 to 170 deg),thats becouse to reject ferrite and ferromagnetics materials
- the center of accept region is 0-DEG
- with 30 to 180 on disc channel i refer to that ,the center of disc channel goes from 30 to 180 ref to RX signal measured at pin 1 of U7A
3.the pre-amp i call ,everything from input ay C4 to output at (pin 1 of U7A),
-yes ref signal is measured at the input of bf245(tis75)
-RX CAP i refer to parallel cap with coil
-try to get good sine on tx ,without good sine it makes huge changes at at GEB and DISK
-W.LAHR schematic it looks best with one mistake R14 from 1k ->10k (R10 sel.)

[perdica 2]

try R10 180k and more ,no RX cap added and no changes on pre amp

[Legaucho]

Hello all

My first try was not so bad, I will you give all informations concerning this.

I us one NEL DD Coil Sharpshooter 5.5” x 9.5”

Values:

TX: 3.2 Ohms 0.92mH

RX: 71.1 Ohms 15.52mH

Please find the PCB values and also connections switches and pots.

[smity]

Very beautiful pictures. A lot of work. Can all this (together with the "LAY") file placed in one file ("RAR")? Would have been fully completed project. Thank you.

[Legaucho]

Very beautiful pictures. A lot of work. Can all this (together with the "LAY") file placed in one file ("RAR")? Would have been fully completed project. Thank you.

Hello my fried, I do it, good luck.
All the best

[zoomix]

Hi all

I put the coils in a carrier fiberglass cast that I have.

For now, I have not yet filled with resin polyrethane

With the disc still, I always have very good result but when I swing on the coinage, it does not ring.

For proper operation, I increase the value of GB resistance but I lost 5 to 8 centimeters.

Prédica2, I did the tests you suggested but there is no obvious improvement. Discrimination is OK with R10> 180 but with cap on RX for my 2N7

Best regards...

[Legaucho]

Hello all

Some pictures of my work.

[wallker]

Legaucho, you made quite a nice detector there.
Could you do little test with a gold nugget and post results here ?
Thanks in advance.
Regards Marko.

[perdica 2]

to ZOOMIX

MAKE A NEW COIL !!!

Fo 20Kh

TX 1.3mh 10 ohm c47n (7.6 Vp-p)
RX 6.7mh 30ohm (no rx cap, there series resonance cap 22n in sch.)
NO changes on preamp

your coil produce too mach phase shift

[perdica 2]

ZOOMIX
If you want to put paralelel capacitor, it shall be 15n or 22n because the 15n with 22n(C4) makes serial 9n
and 9n with 6.3mh RX coil resonance Fo it will be 21Kh

with 22n paralel with 6.3mh resonance Fo it will be 19Kh

in sim at this way ,it has same efect as without paralel RX cap

-your RX coil as understood is 28mh and at 20Kh runing MD , with aded 2.7n it makes serial 2.4n ,resonance Fo 19.4Kh
and removing RX paralel capacitor it makes huge changes

[satdaveuk]

Here is the latest rev. 2.0 Lobo PCB and rev. 2.0 Lobo Component overlay :

Best Regards..............Eugene

Hi Eugene and everyone
Can you put on here the latest circuit diagram that goes with the lay file please, love to have a peep at it being a Tesoro fan.

Many thanks in advance to all conserned here

Regards

[amtech2005]

Hi Eugene and everyone
Can you put on here the latest circuit diagram that goes with the lay file please, love to have a peep at it being a Tesoro fan.

Many thanks in advance to all conserned here

Regards

Hello Satdaveuk . I will look for the schematic tonight . I still need to get a drill press so I can finish my Lobo circuit boards I made one month ago . Not much spare time either , so it is not procrastination !!

Best Regards.................Eugene

[amtech2005]

Hello Satdaveuk .
I will have to make a new schematic when I populate and solder the components to my lobo pcb . I still need to drill the holes first .
I can't seem to find the schematic that matches my latest pcb file . Perdica 2 and Legaucho are way ahead of me in their progress . You can study what they posted in the mean-time .

Regards..............Eugene

[Kev]

Hi Friends,
I've been looking at all the info for the Lobo trying to decide if I should risk building one, and also waiting to hear of others results. I'm hesitating taking the plunge.

One thing that puzzles me is the switch wiring, which to my mind doesn't make any sense.

On the W.L. 6/90 schematic when S2 is in Norm/Disc and S3 is in the disc position both the 200k and 10k Ohm resistors are in parallel ...why? no-sense.
On the Foma schema it is the same only that the 200kR is 100k
Also on the Foma scheme the outer connections on S2b (SW1A Foma) are swapped, this also doesn't seem to ring true to me.

Looking at the circuit I believe that the W.L. 6/90 scheme is correct but the switch labeling is swapped, possibly transposed from the front panel label by the author.

Where it reads
Auto/All Met
Auto/Disc
Norm/Disc

I believe it could actually be
Norm/Disc
Auto/Disc
Auto/All Met

The actual routing seems to make more sense when view from this perspective.
Of course the fully wired switch can be swiveled 180 degrees to give the correct rendition on the front panel.

Problems with poor detection may actually be attributable to cap selection, part substitution, coil/front-end mismatch, etc., I notice what appears to be mica caps around some of the amps possibly the pre and disc, poor cap selection here would not allow optimum results.

I could be wrong of course.
Cheers
Kev.

[satdaveuk]

Hello Satdaveuk .
I will have to make a new schematic when I populate and solder the components to my lobo pcb . I still need to drill the holes first .
I can't seem to find the schematic that matches my latest pcb file . Perdica 2 and Legaucho are way ahead of me in their progress . You can study what they posted in the mean-time .

Regards..............Eugene

Thanks Eugene
Regards

[zoomix]

Hi all, Following the advice of prédica2, I start to have a coil of 1.3mH and the 10.9mH because the values ​​provided by Foma are not good.

I want to say that the software works fine CALCOIL to achieve a precise coil.

After assembling the LOBO with the first coil (TX and RX 28mH 2.6 mH) and made ​​functional test like the video, the tests outside in the lawn shows a serious problem of GB. A problem when the coil is in motion.

The test carried out with a new coil are similar. When the coil is moving there as interference et no sound of lobo.

(A measurement with a frequency meter shows that it is not 17.5 KHz output of 4024. This varies from 18.2Khz to 20 .. khz. )

I made the shield of the new coil as shown on the coil TGSL and I tested different values ​​of the resistors GB but it changes nothing.

I saw that foma said on the site must be made ​​by md4u 100pF on RX to find the right value set and get a bob-GB DISC and so I'll try.

I also placed a pot on the 1M resistance disc to vary from 180k to 470K for testing since changes in the GB influance dicri .

If someone could solve this problem, it makes me be a big help.

Thank you all

[porkluvr]

Zoomix can you clarify these two apparently inconsistent statements?

1) Following the advice of prédica2, I start to have a coil of 1.3mH and the 10.9mH...

2) After assembling the LOBO with the first coil (TX and RX 28mH 2.6 mH)...

What is what??

And where did you ever get the values of 28mH and 2.6mH? There has been a lot of confusion (which obviously still exists) ever since the Lobo schematic(s) became available, but what planet did you get these numbers from?

1.3mH +~11r (tx) and 10.9mH + ~51r (rx) (approximate values, this matches the data for the 5x10 coil) is almost certainly your best choice for working in the 19.5~20kHz region unless you know what you are doing and deliberately choose to deviate.

************************************************** *******

But this is all pretty much inconsequential, anyway. Let me explain.

You have made an extreme decision to attempt constructing a Lobo clone without a dual trace oscilloscope. There are so many variables that you have a very difficult task.

For instance, the adjustments on the transmitter are interactive. Both trim pots need to be tweaked in alternation until the final "best" tx setting is obtained. And then... there is the problem of aligning the rx phase to your phase detectors. Rx phase starts with the rx coil (!). But, then you have a dual preamp block with each and every component affecting rx phase. That is not an exaggeration.

Maybe somebody else will have a magic bullet and/or lots of time for you, but realistically, imho your chances are almost nil unless you can use a dual scope.

[porkluvr]

Zoomix,
Here's something that might help us help you.

Start with a good coil - obtaining a factory coil is probably expensive, so otherwise use the data listed here. Coil probably needs to be properly nulled and I have NO idea how to help you with that; maybe somebody?

Now, draw or copy and edit a partial schematic showing the tx tank circuit, tx section and the component values you have installed. Show the RX coil value, coupling components, and rx block component values you have used. It would also be helpful if you were to show values of discriminate and GEB components and related components.

Post the partial schematic here in this thread. Don't send it to photo bucket or whatever, post it here.

Don't tell us what you didn't do, show us what you did do.

Maybe there's hope. Try it.

edit:
I apologize that my posts proably suggest that I have not read your problem from the start, and I have not. Reading about problems like yours just about makes me want to cry and I want to get IN and get OUT.

[zoomix]

Hello polkruv,

I actually have a problem with the coils and it does not benefit the development of the lobo.

I have an original and SEF coil for tecknetics T2 (14kHz). I searched the web connectivity but I have not found. I made measurements on the connector but we must know whether he did it not integrated component in the coil .. (or other capacity). if anyone has any info on the connections of the coils could be used as ca.

On my diagram is not very complicated, all components are in the exact recommended value on the schematic of FOMA. and my PCBs from the site of REDRAM

The only difference is the value of capabilities that are tailored to my coils.

To answer your question, following the patterns of FOMA
(TX = 65 rounds of 0.28mm 1.33mH and RX 170 rounds of 0.22mm = 10.97 mH)

I measured 2.6 mH TX / RX 11ohms and 28.2 mH / 50 ohms.

I'll post the diagram connector coils and T2 readings tonight.

Maybe she could be compatible with the lobo. Legaucho said it worked okay, but he did not pursue testing ground ...

thank you for your help

[porkluvr]

Zoomix, have you not even tried to determine why your L numbers and FOMA's L numbers are so different?

You should to understand that when the Lobo schematic first became available here, The coil parameters listed for Lobo in "Coil Data" were 100% backwards. I myself was duped into trying to simulate and verify a Lobo clone in LTspice, using the incorrect coil information. It finally dawned on me what I was doing was absurd but it took my twice contacting Admin before anything got changed on the web page, and 2~3 years had elapsed.

I think the Russians figured out quickly that our Coil data was wrong and started early on using 1.33mH for tx and ~11mH for rx, but their schematic notes would be in Russian (spank you very much). Also some posters here (not necessarily Russian) insisted on posting major modifications - of course most of those modifications came without any explanation, English, or otherwise. Really not much help, imho only adding to confusion. That's only my perspective, and my memory is not perfect.

So anyway some of those notes on Foma's drawing may be incorrect and I admit that I had a hand in that because I tried to interpret Foma's meaning - ummh, but I know absolutely no Russian, and I have not physically tested anything, but I made notes on his drawings and reposted them. Anyway, I have tried to correct known errors that I myself contributed, but I'm not perfect.

There may be some mistakes on the formulas for the coils on "Foma's" drawings. Possibly my bad, or possibly I only copied already incorrect information, I don't know.

But, instead of you running out and buying a coil from some other manufacturer, you could try to experiment with coil geometries and modifying number of turns until you get something close to the Lobo target values. I'd probably like to do that myself just to try and make real some contribution here, but I have one or two pressing projects already, and very little physical energy to tackle anything.

I have attempted several times to make my own PCB layout (but adapted to my own power supply needs) but always got either frustrated, or sidetracked, or thought better of it because of all the CONFUSION surrounding this little beastie.

[zoltan]

Hi for everybody!
I write from Hungary.

II built it LOBO
LOBO works.

I cannot portray it correctly Ground balence.
Somebody can prepare a short video the correct one tuning.

Thank you

[Qiaozhi]

Hi for everybody!
I write from Hungary.

II built it LOBO
LOBO works.

I cannot portray it correctly Ground balence.
Somebody can prepare a short video the correct one tuning.

Thank you

Zoltan - I had to remove your first post where you attempted to add an image. The image was added as an enormous amount of text that caused the page to load very very slowly, and nothing but many pages of text was displayed.

Please make attachments using the Manage Attachments button further down the page. You have to make at least one post before you can add attachments anyway, and you should now be able to do that. Also, please make careful note of the recommended image sizes.