Tesoro Aztec

[ivconic]

I used search option to find similar thread.. seems not existing.
Sorry if i post this despite existing one (which i can not find now).

Tesoro Aztec is real nonmotion discriminating detector!
I made it and it is working from a start.. no problems.

[ivconic]

Silverdog gave me idea to "put some fresh air" in this one...
Aztec is not so serious to be made as main working machine.. but it is excellent to be made as pinpointer! More than good!
Tough to find better design for such matters.
It is working.
I had problems to find 307 opamp.. i also had problems to find two CA3130 so i used one CA3240..
Besides that; everything seems right and schematic seems accurate..

[ivconic]

Don't laugh to much on this pcb!
It is over sized and ugly... i know!
I am posting it here just in illustrative purposes..
There is no voltage regulator in original design, don't be confused with the one i put on pcb.
Actually i never put it on real pcb, just used wire jumper across in and out.
Aztec is very interesting in behavior.
Must be made to see my point.
Non motion, discriminative (excellent disc and geb), sensitive.. !

[ivconic]

What's so special about 307 opamp?
I don't have experiences with it, impossible for me to find it.
Any substitutions?
Because... i put LM308 and have feeling that it was not good move!
CA3240 seems doing job just fine instead two CA3130.
On same place LF412 can be used..i presume.

[ivconic]

Possible problem in a way how switches are presented on schematic.
It didn't worked until i made fast "triggering" by "closing" one of the switches for a moment.
Second one was already jumped with jumper..
I planed to leave it in "Disc" position all the time, so i put wire jumper on one side and left the other "opened".
Than, as i said, i needed to trigger the second one, and that's how is starting to work just nice..

[ivconic]

Coil... same as for TGSL or IGSL first version...

[ivconic]

Aha, one more thing!
Fet based amplitude control is excluded from my pcb... as usual..

[silverdog]

Aztec

more great work !!

not sure about this as a pinpointer though - its the coil that troubles me, I think a pinpointer with a ferrite rod coil, so you can probe in the loose soil is best.

Not sure how we can make a TGSL coil small enough ?
Can the TX,RX be overlapped on a ferrite rod ?
Would the Rx requirements be too many turns ?

[ivconic]

more great work !!

not sure about this as a pinpointer though - its the coil that troubles me, I think a pinpointer with a ferrite rod coil, so you can probe in the loose soil is best.

Not sure how we can make a TGSL coil small enough ?
Can the TX,RX be overlapped on a ferrite rod ?
Would the Rx requirements be too many turns ?

Yes, those are good questions.

I never tried to make TGSL coil such small... can't tell.
Maybe 8-10 cm diameter coil will be fine?
It is possible to make such coil.

But than, nulling such coil will cause a headache!
...
Maybe we should try to make it on ferrite rod?

Sheesh, how to null such coil???

[porkluvr]

Ivconic, LM307 is run-of-the mill, unity gain stable opamp. Same as 301, but with added 30pf internal compensation.

It was magic back when opamps were new but there is nothing special about it.

Use 741 or other 1Mhz BW opamp and you should have no problem.

[Gwil]

LM308

Please note that the LM308 op amp is not internally compensated, and needs an external capacitor for stability - see data sheet for details.

Gwil

[ivconic]

Ivconic, LM307 is run-of-the mill, unity gain stable opamp. Same as 301, but with added 30pf internal compensation.

It was magic back when opamps were new but there is nothing special about it.

Use 741 or other 1Mhz BW opamp and you should have no problem.

Thanks Porkluvr!

[ivconic]

Please note that the LM308 op amp is not internally compensated, and needs an external capacitor for stability - see data sheet for details.

Gwil

That is true. Thanks!

[bernte_one]

hello ivconic

i see 3 points were i can connect the switch (normal / disc mode)
can you mark the points where the switch has to be switched on for disc mode

i think all 3 has to jumped on by switch in same time for disc?
when all points are switched off (not connected by switch) the normal mode is on?

you write also that there is no need for voltage regulator? ok then i save this part and drive it direct from 12v accu pack


thanks for sharing your ideas with us

[bernte_one]

start next weekend
after remove these nice shortings in the upper traces