Tesoro Lobo news

[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

[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

[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.

[amtech2005]

Schematic ?

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

[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

[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

[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

[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

[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.

[Legaucho]

Hello all

Some pictures of my work.

[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]

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

[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]

My LuBa is working

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.

[perdica 2]

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