IGSL

[raff33]

hi ivconic,
many thanks again
Regards

[ivconic]

Hello Ivconic!

Nice to hear from you. Very nice design. The feature that interests are the dual channels, much like the Nautilus by Tyndall.

One strong feature of the Nautilus line is one that might not be obvious right away, and I would be interested in hearing from you if you notice this same behavior.

With the Nautilus, you have two channels, one AM and the other DISC. The Nautilus has no target ID but the user can get a general indication of conductivity by listening to the intensity and timing of both signals.

For example, if the disc channel is louder and rings in about the same time as the AM channel, then it is likely a high conductor. If the AM channel is louder and rings in slightly before the DISC channel, then it is likely a low conductor.

ALSO, it is much more difficult to be fooled by large iron with this machine because the AM channel will come in "booming" and long before the DISC channel.

While the TGSL does not have any modulation to the signal intensity, you may still notice a difference in the timing of both signals, which may be useful!

Now I realize from reading your post that the IGSL is sort of a "reverse" from this, but still might be a useful feature if you can tune yours this way.

While waiting IGSL pcb to be etched; i returned to this post. Yes, dfbowers, now looking again at this Nautilus schematic; i see certain analogy even more than i realized before! Principles are different but some analogy still exist. I had on my mind Nautilus and what was done at it, but i never payed more attention on it's details.
Now i made redraw of schematic and adapted "style" to be more "readable", and here it is. Some values and some connections need to be checked, because i am not sure about those. PDF file is not readable enough to be sure in those.
Would be nice if someone can check this and correct eventual mistakes..

[ivconic]

I am not really well informed about people involved at some Nautilus works, as well as about people involved in some Tesoro works, but i see some "signature" that repeats in many older Tesoro designs.... and now; looking in this Nautilus redraw - i also see same "signature" here!?
Would be nice curiosity if someone knows more on this and let us know here...

[simonbaker]

So nice to see you back here Ivconic!
Is there an expanded Iron range on this project?? That would be sweet, especially with the idea behind the way this machine is designed to operate.
I've often wondered what it would take to alter and expand/lower the iron range on a Tesoro?? I saw once that SB had begun to experiment with that but dropped the attempt. Is it not practical on the Tesoro circuit?? or just a matter of no interest??
Or does this circuit have that ability??
Thank's again Ivconic!

I am very slow with projects but still interested in "180 deg" discrimination for TGSL; especially since newer Tesoros use 180 deg disc. By using it, you can throw away the "ALL METAL" circuit and switch completely I believe.

My mod does give 180 deg disc, but it is centered wrong! To center it correctly seemed to need an extra op amp (for 90 deg shift), and I didn't want to add parts.

However, now I look at the Silver Sabre Plus circuit and see another way to create DISC signals, so maybe I can adapt that for the 180 deg disc mod.

We should also remember that conductive iron may be be similar to, but not the same as, ferrite -- two completely different concepts and circuits needed to ground balance ferrite vs. discriminate conductive metals. Conductive iron may be a combination of both effects, and to accept conductive iron without destroying the GB probably requires increasing the DISC phase range. I assume IGSL extends the DISC range by inverting logic of one of the channels, but I have not studied it in detail.

-SB

[ivconic]

So far only Jerry and Dfbowers understands the main idea at IGSL. I am afraid that IGSL must be built to be understood completely. I do suggest it.

[simonbaker]

So far only Jerry and Dfbowers understands the main idea at IGSL. I am afraid that IGSL must be built to be understood completely. I do suggest it.

I think I understand basically -- IGSL is two TGSL side-by-side. The ferrous channel is achieved by reversing the logic at U7a (reversing input connections), causing metals below the DISC threshold (instead of above it) to make the comparator go positive. Then each channel has separate tone.

It is a nice model to add information for deciding whether to dig or not. Many thanks for PCB.

Regards,

-SB

[dfbowers]

While waiting IGSL pcb to be etched; i returned to this post. Yes, dfbowers, now looking again at this Nautilus schematic; i see certain analogy even more than i realized before! Principles are different but some analogy still exist. I had on my mind Nautilus and what was done at it, but i never payed more attention on it's details.
Now i made redraw of schematic and adapted "style" to be more "readable", and here it is. Some values and some connections need to be checked, because i am not sure about those. PDF file is not readable enough to be sure in those.
Would be nice if someone can check this and correct eventual mistakes..

Nice! I'm not sure what the original source of the hand drawn schematic is. I will double check yours when I have a few hours. I have 2 other Nautilus schematics as well if you are interested. The DMCII has the features that are relevant to your post though. The DMCIIB has a signal loop balance circuit which feeds phase and amplitude back to the Rx coil for nulling in the field and has adjustable Tx power as well.

Too bad Nautilus has never come up with product to keep up with technology though. They are large and heavy but many relic hunters are willing to put up with it just for the features. I and temped to build your IGSL just for a comparison! Maybe next winters project.

Don

[Jerry]

So far only Jerry and Dfbowers understands the main idea at IGSL. I am afraid that IGSL must be built to be understood completely. I do suggest it.

I am one LM339 short of having everything for this project, so it is time to stock up on things again. Have to get enough to make minimum order.

Jerry

[satdaveuk]

circuit ref numbers

Hi im so greatful to this forum and all the input members that have donated towards it.
Would be nice if someone actually gave a circuit diagram that matches the PCB here with circuit numbers instead of part numbers.
IE: R1 instead of 100k.
It would be so much better for fault finding etc
Or maybe im behind the times.
Saying that if its not already done, i will do it when i got these projects up and running
All the best
Dave

[mikebg]

Would be nice if someone can check this and correct eventual mistakes..

Ivica, I see the following corrections:
R6 - doubled nummeration
R6 & R6 - no value
R52 - draws too many energy
R64 - too large resistance
R75 - no value
R77 - no title
R87 - better to be placed in series with collectors of Q12 &Q13 to battery voltage and collectors with large capacitance to COM.
R89 - useless resistor
C27 appears in parallel to C6
Different notation of C and R values. For example C23, C24 and C9 have value noted with letter "p", but letter "p" is omitted at value of other picofarad capacitors: C22, C25, C28, C30 and C32.
Resistor R18 is noted as 2.7, but other resistors are noted as 2M7.
SP1 - no value of resistance.

[simonbaker]

Ivica, I see the following corrections:
R6 - doubled nummeration
R6 & R6 - no value
R52 - draws too many energy
R64 - too large resistance
R75 - no value
R77 - no title
R87 - better to be placed in series with collectors of Q12 &Q13 to battery voltage and collectors with large capacitance to COM.
R89 - useless resistor
C27 appears in parallel to C6
Different notation of C and R values. For example C23, C24 and C9 have value noted with letter "p", but letter "p" is omitted at value of other picofarad capacitors: C22, C25, C28, C30 and C32.
Resistor R18 is noted as 2.7, but other resistors are noted as 2M7.
SP1 - no value of resistance.

For fun:

R89 - useless resistor

How about: short circuit protection (current limiting); startup current spike limiting; isolation of speaker spikes from rest of circuit?

R87 - better to be placed in series with collectors of Q12 &Q13 to battery voltage and collectors with large capacitance to COM.

How about: guarantees reasonably high impedance to driver circuit regardless of speaker choice?

Just speculating...

-SB

[ivconic]

Hi im so greatful to this forum and all the input members that have donated towards it.
Would be nice if someone actually gave a circuit diagram that matches the PCB here with circuit numbers instead of part numbers.
IE: R1 instead of 100k.
It would be so much better for fault finding etc
Or maybe im behind the times.
Saying that if its not already done, i will do it when i got these projects up and running
All the best
Dave

Yes, that's an constructive remark, tend to agree.

[ivconic]

Ivica, I see the following corrections:
R6 - doubled nummeration
R6 & R6 - no value
R52 - draws too many energy
R64 - too large resistance
R75 - no value
R77 - no title
R87 - better to be placed in series with collectors of Q12 &Q13 to battery voltage and collectors with large capacitance to COM.
R89 - useless resistor
C27 appears in parallel to C6
Different notation of C and R values. For example C23, C24 and C9 have value noted with letter "p", but letter "p" is omitted at value of other picofarad capacitors: C22, C25, C28, C30 and C32.
Resistor R18 is noted as 2.7, but other resistors are noted as 2M7.
SP1 - no value of resistance.

Agree. I have doubts about some values. I can not see clear some things in posted .pdf file.

[ivconic]

Ok, now let's back to IGSL. Here are the latest updates of schematic and pcb. Some mistakes are corrected....

[ivconic]

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