SBG-PID

[scs]

Scheme from the PCB Artist program. There are no errors are. The signs number off details are different !!!

[6666]

Sacho, I am very interested in the GEB, when you tested the circuit does it balance out highly mineralised ground ? thanks.

[Andi68]

Which schematic can I now rely on, which is faultless ?

[bernte_one]

@ andi build the latest clone pi and have fun

https://www.geotech1.com/forums/show...ighlight=clone

on our soils we need permant gb autune function and some kind of crap filter


if you search in the norwegian backwoods far away from any settlement you can use a high power analog pi for meteorite hunting

[scs]

https://www.geotech1.com/forums/atta...7&d=1556082873 schematic is o. k. Ground Ballanse and Discriminator simmular in Goldscan 5.Detector is tested in normall ground.

[Carl-NC]

Always hate to see such awkward way of drawing schematics.
Purposely messed up to the level of being completely confusing.

I was going to say the same, it looks as if someone drew it just so it would fit in a minimum size square.
Thanks for the redraw.

[Andi68]

Carl, what's your opinion on this circuit?

[ivconic]

I noticed error a transistor VT9 is connected back. Please for excuse.[ATTACH]46087[/ATTACH]

Which schematic can I now rely on, which is faultless ?

Correction updated... so far this should be the one, according to all available info:

[Carl-NC]

Carl, what's your opinion on this circuit?

I find it interesting and pleasingly simple, especially for a GB-PI. If you replace U1/U6/U8 with a small micro, it gets even simpler.

[green]

Correction updated... so far this should be the one, according to all available info:

[ATTACH]46112[/ATTACH]

Shouldn't pin4 U8 be connected to pin3 U1

Does it take an EF sample?

[6666]

This would make a great Silverdog project, especially with ground balance, hint hint.

[Andi68]

Thank you, Carl and ivconic

[ivconic]

Shouldn't pin4 U8 be connected to pin3 U1

Does it take an EF sample?

Correct!
Update:

[scs]

R27=10k,R28=15k.

[Qiaozhi]

Looking at the timing components associated with the CD4538 monostables we have:
Main sample delay = 27us
Main sample pulse width = 33us
EFE sample delay (from the end of the main sample pulse) = 120us (so EFE delay is actually 27us + 33us + 120us = 180us)
EFE pulse width = 33us

At the moment I cannot see how the ground balance is supposed to work. All R19 appears to do is balance the outputs of the main and EFE channels before they enter the final integrator stage. Anyway, with a fixed main sample delay of 27us, is there really any need for GEB?

The discrimination part looks interesting. R17 appears to also balance the main and EFE channels to provide some form of conductivity discrimination, whereby the meter swings one way for low conductivity and the other for high conductivity.

The coil is shown as 20 turns with a 20cm diameter. Depending on the wire thickness, the inductance will be somewhere between 230uH and 280uH.