IGSL

[porkluvr]

Ivconic, good to see you back. You have another monster growing, eh?

I have some questions, please:

1) What program did you use to draw the schematic IGSL.sch contained in IGSL.zip?

2) With the Minelab coil, I read that you changed the tuning capacitor to 330nF.
Wouldn't you also change C1 to 3.3uF as C2 becomes 330nF? Otherwise, with a 1mH coil I can't see how you would get anywhere near 9kHz output.

Thank you for another excellent project!

[porkluvr]

Here's a quick and dirty way to get some idea about what different components will do for your Disc and Gnd controls. Ltspice allows up to three nested parameter sweeps. Here I've used two. There are eleven discrimate pot positions plotted vs five ground pot positions.
Normally nested parameter sweeps might create a mass of confusing signal traces and would be useless but in this case the 11 Disc circuit traces stay in alignment during each of the five ground pot position iterations. I had wired a colpitts oscillator but differing loads presented by the phase reference circuits seems to cause jitter between different test segments. Hence, V3 used for the signal source.

I think this is useful to see the comparative ranges of the two controls and also the control linearity. I got the idea for this sweep from something SB posted in an unrelated thread, so thank you SimonBaker.

-----------------------------------

SB, you probably already know this but if you want more range on the disc control you can simply add a capacitor across U1B 6 and 7. That will leave the CCW range relatively unaffected but extend the CW range.

150p should add about 36 degrees (referenced to using 10p).
I calculated degrees using Fo=8750cps.

Adding a cap across feedback will affect the linearity of the Disc control. So what can be done about that?

In Ivconic's original circuit I believe that R75 (10k) was added for amplifier stability. R75 would not really be needed for stability if a feedback capacitor is used, but different values of R75 can be used to give different Disc pot response curves. You can get some idea of how different values of R75 (Rx in the simulation) and feedback capacitance (Cx) would affect Disc linearity with with this simulation.

You'll probably notice where I took some liberty with component values. Somebody could easily change them back if so desired OR you can easily change 'transmit' frequency (V3) . I tried to make sure all necessary third party models and symbols were included in the sim file so it should run 'right out of the box' provided you have LTspice installed on your PC.

[simonbaker]

Here's a quick and dirty way to get some idea about what different components will do for your Disc and Gnd controls. Ltspice allows up to three nested parameter sweeps. Here I've used two. There are eleven discrimate pot positions plotted vs five ground pot positions.
Normally nested parameter sweeps might create a mass of confusing signal traces and would be useless but in this case the 11 Disc circuit traces stay in alignment during each of the five ground pot position iterations. I had wired a colpitts oscillator but differing loads presented by the phase reference circuits seems to cause jitter between different test segments. Hence, V3 used for the signal source.

I think this is useful to see the comparative ranges of the two controls and also the control linearity. I got the idea for this sweep from something SB posted in an unrelated thread, so thank you SimonBaker.

-----------------------------------

SB, you probably already know this but if you want more range on the disc control you can simply add a capacitor across U1B 6 and 7. That will leave the CCW range relatively unaffected but extend the CW range.

150p should add about 36 degrees (referenced to using 10p).
I calculated degrees using Fo=8750cps.

Adding a cap across feedback will affect the linearity of the Disc control. So what can be done about that?

In Ivconic's original circuit I believe that R75 (10k) was added for amplifier stability. R75 would not really be needed for stability if a feedback capacitor is used, but different values of R75 can be used to give different Disc pot response curves. You can get some idea of how different values of R75 (Rx in the simulation) and feedback capacitance (Cx) would affect Disc linearity with with this simulation.

You'll probably notice where I took some liberty with component values. Somebody could easily change them back if so desired OR you can easily change 'transmit' frequency (V3) . I tried to make sure all necessary third party models and symbols were included in the sim file so it should run 'right out of the box' provided you have LTspice installed on your PC.

Hi Porkluvr - that's very interesting what you did, I'll have to play with it.

No, I didn't think of that Cx cap as extending the range, although I've played with it for other reasons. But yes, it's not too hard to extend the range a little by shifting the phase of the two signals that are summed by the potentiometer. If you push it too far, you get a very small signal somewhere in the middle (due to summing), and you really want to keep it as large as possible to reduce phase noise in the sync pulse.

So that is a nice trick to keep in mind when modifing the TGSL to run at lower frequencies -- thanks!

(I'll have to see what those "pot" circuit elements are, I have seen that before. Also an unusual pot/resistor arrangement for the adder).

-SB

[ivconic]

Ivconic, good to see you back. You have another monster growing, eh?

I have some questions, please:

1) What program did you use to draw the schematic IGSL.sch contained in IGSL.zip?

2) With the Minelab coil, I read that you changed the tuning capacitor to 330nF.
Wouldn't you also change C1 to 3.3uF as C2 becomes 330nF? Otherwise, with a 1mH coil I can't see how you would get anywhere near 9kHz output.

Thank you for another excellent project!

1) http://www.expresspcb.com/expresspcbhtm/download.htm

2) You don't read carefully... I pointed that oscillator is not the same - now is quite different setup. Completely changed.

[ivconic]

Ok...here it is:

[der_fisherman]

Welcome back.

[der_fisherman]

Hi Ivconic,
your new version IGSL looks and sounds good, very good.....
Will you be offering PCBs or Kits or both, maybe via Silverdog if you yourself cannot do that, or whatever.
What I mean is, I would like to wait for your particular design, but only IF you are eventually going to sell them at some point in the not too distant future.....I was so impressed with the air test video on YouTube!!! I am sure that it will be impressive in the field as well....
Regards
Andy
PS. I know that its a bit fresh of me to ask just the question now, but please don't be offended in any way.....
PPS. Where are you on this planet, in the case of you making your own kits? Just the country will do fine.....

[simonbaker]

Here's a quick and dirty way to get some idea about what different components will do for your Disc and Gnd controls. Ltspice allows up to three nested parameter sweeps. Here I've used two. There are eleven discrimate pot positions plotted vs five ground pot positions.
Normally nested parameter sweeps might create a mass of confusing signal traces and would be useless but in this case the 11 Disc circuit traces stay in alignment during each of the five ground pot position iterations. I had wired a colpitts oscillator but differing loads presented by the phase reference circuits seems to cause jitter between different test segments. Hence, V3 used for the signal source.

I think this is useful to see the comparative ranges of the two controls and also the control linearity. I got the idea for this sweep from something SB posted in an unrelated thread, so thank you SimonBaker.

-----------------------------------

SB, you probably already know this but if you want more range on the disc control you can simply add a capacitor across U1B 6 and 7. That will leave the CCW range relatively unaffected but extend the CW range.

150p should add about 36 degrees (referenced to using 10p).
I calculated degrees using Fo=8750cps.

Adding a cap across feedback will affect the linearity of the Disc control. So what can be done about that?

In Ivconic's original circuit I believe that R75 (10k) was added for amplifier stability. R75 would not really be needed for stability if a feedback capacitor is used, but different values of R75 can be used to give different Disc pot response curves. You can get some idea of how different values of R75 (Rx in the simulation) and feedback capacitance (Cx) would affect Disc linearity with with this simulation.

You'll probably notice where I took some liberty with component values. Somebody could easily change them back if so desired OR you can easily change 'transmit' frequency (V3) . I tried to make sure all necessary third party models and symbols were included in the sim file so it should run 'right out of the box' provided you have LTspice installed on your PC.

Hi Porkluvr:

When I unzip the file into a folder, and double-click on "sweep 9K QT.asc" to run it, I get a message saying:

"Couldn't find symbol(s): potentiometer 2".

Is there something missing? It seems to run Ok anyway. (correction: the wG pot is missing. I copied the wD pot to replace it, renamed the wiper to wG, seems to work).

Regards,

-SB

[simonbaker]

Adding a cap across feedback will affect the linearity of the Disc control. So what can be done about that?

Summing two different size signals is really what affects the "linearity" of the pot I think -- the TX signal is bigger than the output of the op amp. If you can adjust the gain of the op amp to make the output signal equal to size of the TX signal, it should pan more "linearly" I think. Actually, I'll try to look at some equations to see if phase moves linearly with the pot wiper position in any case, not sure if it does theoretically.

-SB

[porkluvr]

Hi Porkluvr:

When I unzip the file into a folder, and double-click on "sweep 9K QT.asc" to run it, I get a message saying:

"Couldn't find symbol(s): potentiometer 2".
...
-SB

Sorry, my bad. I have two different potentiometer symbols and I inadvertently used both but only included one in the zip. They both work the same and point to the same model file.

One has 'o' to represent the CCW end and the other has an arrow pointing to CW.

You were correct to just make a copy of 'potentiometer' but you should refer to my screen copy image to see the correct orientation (as I understand it).

I should probably decide which symbol I like better and dump the other, but I hate making decisions. And then there's my creed; I say: "Never put off today what you can put off tomorrow".

I've added potentiometer2 and reposted the sim.

edit: Ivconic, thanks for the update. A picture is worth 1000 words... especially for somebody who can't read.

edit 2:
This simulation is actually the first time I have ever used a potentiometer with a parametric value and I have seldom used parameters in the past. It is a useful (and somewhat advanced) technique but if somebody wants to use these pot symbols without a .param statement, simply right click the pot symbol or the text field, and replace '{Wx}' with something like '.5' or '50%'. That is also how you would change the pot's value.

[ivconic]

Hi Ivconic,
your new version IGSL looks and sounds good, very good.....
Will you be offering PCBs or Kits or both, maybe via Silverdog if you yourself cannot do that, or whatever.
What I mean is, I would like to wait for your particular design, but only IF you are eventually going to sell them at some point in the not too distant future.....I was so impressed with the air test video on YouTube!!! I am sure that it will be impressive in the field as well....
Regards
Andy
PS. I know that its a bit fresh of me to ask just the question now, but please don't be offended in any way.....
PPS. Where are you on this planet, in the case of you making your own kits? Just the country will do fine.....

IGSL is worth to be made.
Last update is even better, because you don't need to make your own coil - much easier is to buy original Minelab TS1000 (or TS800... or any other Musketeer coil) and it will work just nice with.
It is good idea to offer kits to interested.... but i am not able to do that.
I live in Serbia, still out of EU. Posting and mailing abroad is still expensive and to much complicated.
Overall costs to mail one single kit would be much higher than if it was mailed from some EU country.
So...
But i do not stop anyone else to do that.
What was posted here in public - is free and available to anyone.
If Silverdog wants to make and offer IGSL kits - he is welcome.
In that case i will share latest IGSL version sooner.
For those who already made TGS/TGSL and coil for it - first IGSL is most suitable, because it will work just fine with TGS/TGSL coil.
For others, latest version is more suitable because Musketeer coils would be much better choice. Also newer Tesoro coils (for Cibola, Vaquero, Tejon...) are having pretty close inductances and resistances as Musketeer coils, and possibly will also work just fine with IGSL.
Also coils for Minelabs FT/GT 16000, 17000 and 18000 should be suitable too.
So, second IGSL version is having much brighter future than first one....

[ivconic]

The hell with "secrets"!

Here is the latest update (the one adapted for Musketeer coils...):

[der_fisherman]

Many thanks for the SIM.

[der_fisherman]

Many thanks indeed. That is really, really something.....
I am sure that I speak for many here.
best wishes
Andy

[der_fisherman]

May I ask which PCB software has the .lay extension?
Thanks in advance.
Andy
PS Will you be talking to Silverdog?