Tesoro Eldorado

[ivconic]

After very succesfull Golden Sabre i decided to make another Tesoro detector. This time i couldnt decide easy, Royal or Eldorado. Yet i decided to make Eldorado. Somebody posted somewhere pcb for it. I didnt liked it.
So i used Sprint Layout 4.0 (CD came from Netherland ) and draw my own pcb.It is single sided pcb. Detector is almost finished, only those 4x 2M7 resistors are missing.In next few days i will complete it and check if it is working.

[ivconic]

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[ivconic]

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[ivconic]

almost ready..

[ivconic]

I dont have 5K1 resistors so i put 4k7 instead. Also decided to put 2N3906 and 2N3904 in chopper stage. Also omitted battery test from pcb. I dont need it. Also i wonder about that capacitor; should it be 150pF??? I do have doubts about it. Than... compensation capacitor is missing on original schematic, for LM308, so i added it in case it will need it.
If you think i made mistake about something here please bee free to correct me.
Regards!

[ivconic]

Oh! Almost forgeting most important... Right now i dont have LF442 neither TL062 so i put TL072...in testing purposes only. Later i intend to buy originals and replace. Just for curiosity i am interesting what are you thinking of TL072 as replacements for LF442?

[aft_72005]

Hi Ivconic
Thank you, I get your reply
Best regards

[ivconic]

Hi Ivconic
Thank you, I get your reply
Best regards

Yes! You gave me idea to post this here.
Regards!

[aft_72005]

Hi Ivconic
You’re working very well.
I regard to your opinion, uploading eldorado project here will
Be very good help for people that decided more teaching in the matter.
Yes, you are GURU.

[ivconic]

Thanks!

Wirements....

[Unregistered]

Eldorado

Hello Ivica.

Nice work !! The eldorado is also a very good detector. As I remember it has some more sens. for smal coins than the golden.

Regards.

Ap

[aft_72005]

Hi Ivconic
Please explain about Eldorado testing.
How much detection range for 2cm dia coin in air?
Also discrimination and …..
Regards.

[ivconic]

Yes i will do that soon. Like i said it is not finished yet. Expect to finish it in a few days and than perform usuall testing. I will post results than here.
Regards!

[ivconic]

OK i was restless to see if this gonna work. So i delayed some more important things to be done first and few minuteas ago i finished with Eldorado and tested it. Not working!
It was expectable not to work at once. I expected simillar problems.It is always like this when man staring new project, never done before.
Well...after switching it ON some "dashed" tone appears. But fast "dashed".
There is no noticeable detection or any kind of reaction on metal in coil vicinity.
Voltages are 7.8V abd -6.23V on very start and in few seconds drops to 5.8v and -4.7v....!? Nothing burns, nothing hot,nothing even warm. Audio is not very loud it is medium but good audible.
When TL072 (all 3 of them) pulled out of sockets (later included, cant be seen on posted photo) voltages rises a bit. If i turn pots and loose audio than voltages rises to expectable values. But even with audio and without TL's voltages are almost normal - expectable. Since i dont have proper opamps right now i took first simillar to check. So i put 4558x3 instead TL's and situation was the same as with TL's...?!
I used TGS coil already proven as excellent. So...?
What drains voltage here!?
I am very occupied with few other designs at the same time so i cant really follow and retrace this accuratelly.But it is very possible that i made some mistake drawing pcb....or schematic is not accurate!? Which one of those!?
It will take some time me to retrace this and recheck all over again.
Meanwhile if somebody of you do that faster and spot something i missed please do post here so i can have less job.Also will help to others here.
Regards!

[Max]

OK i was restless to see if this gonna work. So i delayed some more important things to be done first and few minuteas ago i finished with Eldorado and tested it. Not working!
It was expectable not to work at once. I expected simillar problems.It is always like this when man staring new project, never done before.
Well...after switching it ON some "dashed" tone appears. But fast "dashed".
There is no noticeable detection or any kind of reaction on metal in coil vicinity.
Voltages are 7.8V abd -6.23V on very start and in few seconds drops to 5.8v and -4.7v....!? Nothing burns, nothing hot,nothing even warm. Audio is not very loud it is medium but good audible.
When TL072 (all 3 of them) pulled out of sockets (later included, cant be seen on posted photo) voltages rises a bit. If i turn pots and loose audio than voltages rises to expectable values. But even with audio and without TL's voltages are almost normal - expectable. Since i dont have proper opamps right now i took first simillar to check. So i put 4558x3 instead TL's and situation was the same as with TL's...?!
I used TGS coil already proven as excellent. So...?
What drains voltage here!?
I am very occupied with few other designs at the same time so i cant really follow and retrace this accuratelly.But it is very possible that i made some mistake drawing pcb....or schematic is not accurate!? Which one of those!?
It will take some time me to retrace this and recheck all over again.
Meanwhile if somebody of you do that faster and spot something i missed please do post here so i can have less job.Also will help to others here.
Regards!

Hi Ivconic,
I read your post... and I think I know what's happened there... the voltage converter is inefficient thing on all these Tesoro's expecially at lower frequency like in the BandidoII range (10KHz) and Eldorado... if I remember well... is one of those with weak converter power.

The fact you have first full voltage means that at startup your current drawn is less than after few seconds... and I think there's effect from some saturation of op. amp. there that make your thing waste too many energy ending with so low voltage at converter output.

I think you have to change some things:
- change the 2 resistors of 5K1 at base of transistors of converter with 1K

if not enough...

- change also the 3 TL072 with something lower current like TS27M2 or TS27L2 if you can find them ... I suggest those cause I already know you cannot find the TLC2262 things at your place: these are more easy to be found... e.g. recovering from stuff.

Let me know...

Kind regards,
Max