Tesoro Lobo news

[Legaucho]

Thanks Eugene for your upload Lobo3 , I will tried later

[Qiaozhi]

Hello WM6 . I saw the red dots , someone added them on a later schematic version .
What I noticed is , on both original schematics no Cx or Rx capacitor value !! I do not know if Tesoro has capacitors in the elliptical search coil itself . Or If the Cx and Rx are mounted on the circuit board and they are unmarked and were never tested out of circuit with a capacitance meter . So these TX and Cx values can be calculated using proper inductance value of the search-coil which I think Porkluvr mentioned earlier ?
20khz is necessary to get this circuit working properly , no exceptions !!

HH................Eugene

All the Tesoro search coils I have examined only contain the windings. There are no capacitors in the search head.

[amtech2005]

Hello WM6 . I saw the red dots , someone added them on a later schematic version .
What I noticed is , on both original schematics no Cx or Rx capacitor value !! I do not know if Tesoro has capacitors in the elliptical search coil itself . Or If the Cx and Rx are mounted on the circuit board and they are unmarked and were never tested out of circuit with a capacitance meter . So these TX and Cx values can be calculated using proper inductance value of the search-coil which I think Porkluvr mentioned earlier ?
20khz is necessary to get this circuit working properly , no exceptions !!

HH................Eugene

[WM6]

Hello Legaucho and everyone . I think this project has hope now . I found a schematic from Foma [Nov .2007] using Eagle 4.16 format . It matches W. Lahrs work , I think this is the one we need to use . Because later dated schematics had changes made that were not
right !! Its that 11 degree phase shift [foot note] on 1989 schematic that puzzles me . It could be the key to perfect discrimination and sensitivity. Mr. Legaucho Check out this schematic I put in a zip folder right here . So far it looks like no errors from W. Lahrs work . If we make a circuit board it should be made from this schematic !! Also add a few extra pads for future mods or updates is always a good idea too. Thank's goes to Foma for his work.

HH............Eugene

Thanks Eugene.

Did you found some writings regarding red test point in schematic?

[amtech2005]

Hello Legaucho and everyone . I think this project has hope now . I found a schematic from Foma [Nov .2007] using Eagle 4.16 format . It matches W. Lahrs work , I think this is the one we need to use . Because later dated schematics had changes made that were not
right !! Its that 11 degree phase shift [foot note] on 1989 schematic that puzzles me . It could be the key to perfect discrimination and sensitivity. Mr. Legaucho Check out this schematic I put in a zip folder right here . So far it looks like no errors from W. Lahrs work . If we make a circuit board it should be made from this schematic !! Also add a few extra pads for future mods or updates is always a good idea too. Thank's goes to Foma for his work.

HH............Eugene

[Legaucho]

Hello Eugene and Porkluvr, thank you to you for your interest in this project and help you can give me. I am a neophyte in electronics, I study the mechanics. But I know still able to use a multi-meter, the color code of the components, I have and use also one inductance meter for my coils. I know searched equivalences for the components but I am unable to change the basis of a diagram. What made me realize, more detectors (eg Barracuda, Tesoro Golden Sabre and Eldorado, Chance, etc. ..).

[amtech2005]

This should work now , open zip file and click the right icon to read the Russian circuit analysis

HH..............Eugene

[amtech2005]

I too don't understand why somebody is stuck on 17500 and believe that 20kHz was the original freq. All other things being the same, the 2k2 frequency trimmer adjustment would need to be set very nearly to the end of travel to get 17.5kHz... all the while 20kHz would come up very near 50%.

By the way, the schematic that can be downloaded from the Russian forum has some interesting possible circuit 'tweaks' but it also has some bad mistakes. For instance the 22n capacitor shown as C35 would lower the operating frequency to around 2kHz according to LTspice.

Also the 51n and 68n capacitor values for C20 and C21 are about 1000x what they should be. The 1n capacitor (what looks like C15), should be 100p. Any one of these looks like a killer defect and I don't think that having them all together is somehow going to make things any better.

But I like those PCB layouts, especially the SMD version !! Maybe those will be more useful than the altered component values.

Hello Porkluvr . I am glad you noticed all the little glitches that are making a big mess of this project . If you open the link at the top of the page , the blue [last version] .RU schematic posted is very different .

I think the best schematic to study is the one above from 1989 with the hand written notes. So glad you joined our discussion .

Bullwinkle avatar is a great improvement compared to the guy with the spectacle !! Thank-You for your help Porkluvr .
I have one more translated Lobo document to post shortly .

Best Regards.............Thank-You

[porkluvr]

I too don't understand why somebody is stuck on 17500 and believe that 20kHz was the original freq. All other things being the same, the 2k2 frequency trimmer adjustment would need to be set very nearly to the end of travel to get 17.5kHz... all the while 20kHz would come up very near 50%.

By the way, the schematic that can be downloaded from the Russian forum has some interesting possible circuit 'tweaks' but it also has some bad mistakes. For instance the 22n capacitor shown as C35 would lower the operating frequency to around 2kHz according to LTspice.

Also the 51n and 68n capacitor values for C20 and C21 are about 1000x what they should be. The 1n capacitor (what looks like C15), should be 100p. Any one of these looks like a killer defect and I don't think that having them all together is somehow going to make things any better.

But I like those PCB layouts, especially the SMD version !! Maybe those will be more useful than the altered component values.

[Legaucho]

Many thanks Eugene for your comment and pictures. For many years I want to realize this detector, so I probably like you pictures and various diagrams. I made an montage based on the Foma diagram but did not give good results may be due to bad components or errors that I could do.

[amtech2005]

Hello Legaucho . I think this schematic has your potentiometer values you need for Russian version and or Foma version:


HH.............Eugene

[amtech2005]

Hello Legaucho .You can build this last Russian version that you found yesterday , but you will have some trouble unless you make some
corrections !!

Here also is original PCB top .

Eugene

[amtech2005]

I read through the "other" forum and the only thing that bothers me is , why do they keep basing everything on 17.5 khz ?? They say it works best , is it something to do with 50 cycle mains over-seas ? Look at schematic below : I believe this schematic version to be the most correct , this schematic version was dated months before Mr. Lahr's version and the notes clearly state for the recieve IC [LS204] that the gain was set @ 20 for 20 khz !!! And also noted was a -12 degree phase shift . These parameters are so critical at the first receive stage , if it's not right at this point will negatively effect the sensitivity and discriminatation of all the other stages . Below is the oldest schematic and board photos .

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

[amtech2005]

Hello Legaucho . Did you see on the newest version they changed to different I.Cs than the original schematic like using "NE5532's instead of lm392 and lm393 maybe higher gain and to reduce total IC operating current [load] .Still checking your pcb image and comparing differences .

HH................Eugene

[Legaucho]

Hello Eugene

Please find below the PCB like I have understand on the last modified version.
Best regards