IGSL

[sini]

Hi,
TX coil resistance is 3,7 ohm. Capacitor is 330 nF (I do not know type, there is written EL 1228 ). Inductance of TX coil is about 1 mH, cable is PROEL HIGH QUALITY MULTIPAIR AUDIO CABLE INDIVIDUALLY JACKETED-CMT2.
Is resitance of Tx coil big ( low Q ) ? What type capacitor should I use ? I can buy only MKS type ( metallized polyester ) or MKP ( metallized polypropylene ).
Sini

[Davor]

TX coil resistance is 3,7 ohm.

This is the culprit.
OK, it is not that bad, it only puts lower harmonic attenuation into perspective. My coil is about 1m4 and about half resistance.
Your capacitor is fine and your cable is fine.
Going for higher Q comes with a price of a heavy coil, so the ultimate goal would be having a lighter coil with lower Q, but superb signal nevertheless.

[lordtoske]

Pozdrav .hteo bi da te pitam u vezi ove dve seme. Jer zelim da napravim detektor.primetiosam da nisu iste .kojabolja da je napravim.hvala

[Qiaozhi]

Pozdrav .hteo bi da te pitam u vezi ove dve seme. Jer zelim da napravim detektor.primetiosam da nisu iste .kojabolja da je napravim.hvala

Please read the forum rules -> Basic Rules of the Forums
and make your posts in English.

[Davor]

kojabolja da je napravim.hvala

(which one is better for me to make)
In case you already have a TGSL coil, go for TGSL variant.
In case you have a Musketeer coil, or you don't have a coil at all, go for a Musketeer variant. Even if you change your mind, you can adopt TGSL coil for a Musketeer device with replacing only a few components.

[lordtoske]

I need help. I looked at all the seed IDSL musketeer. Does anyone can give me a good hay, stanpanu position with image tracing, and who wound up to be a probe. In short components, and other things that can make a detector. thanks for the help.

[Davor]

You may seek Petravka for PCB-s. I did not see him around for a long time now, but if you can reach him it will be nice, as his boards are very professional

[sini]

Hi,

I have one silly question. How to set up ground balance on the field ? If I set up ground balance by ferrite rod, then detector is sensitive to soil. Should I set up GB by coil pumping ? Please, can you describe me IGSL GB procedure on the field.
Thanks

[Davor]

Yes, bobbing (pumping action) is the way to fine tune GB in the field.
GB in IGSL assumes you are detecting on terrains that are not too mineralised, and having GB as all metal reference works well. If you try some difficult terrains, or sea water, you'll find it very difficult to properly balance, and when you do, you'll notice that rusty nails start responding in most bizarre ways, all due to the all metal reference being off. It is a common problem with most VLF-s. It can be fixed with IGSL with some tweaking that I did not attempt yet, and I'll let you know how to do it once it works for me.

[sini]

Thanks for answering,
I think that soil in my area is mineralised ( may be because of using fertilizers in the past ) and every 30 cm is some nail,screw... Situation in forest is much more better.
Robert

[Davor]

Today I finally paid visit to my shack to tidy it a bit and make an inventory. I only did a few small things to my IGSL so I'll shortly report it here. Nothing cardinal.
I replaced LM833 with NJM2068, without touching the topology. Results ... somewhat cleaner sound and a centimetre or so more distance to target. I did not expect any difference, so this is something unexpected.
I also replaced those back to back electrolytes with non-polars. I heard about gains in depth/distance, and I may confirm it is so. I used 10uF non-polars, but I did not notice any slowing. I suspected it to be so, and now I have a confirmation.

I was playing with some new front end topology that may be used with just about any coil (not only FKK with centre tap) that utilises near resonance and flattens a phase response by low impedance loading. It is nothing spectacular, only I was not up to it today and it will have to wait. Spice is very happy about it. If it works as it seem to be, we all will have a very cheap improvement of our VLFs at hand.

[acikaa87x]

hi there can anyone help me how to make Musketeer coil for IGSL???? thanks

[satdaveuk]

Im all ears but not holding my breath

[Davor]

You can check the pics here: http://www.geotech1.com/forums/showt...824#post131824
Such coils need a proper shell, and shielding, but they all start as simple coils. When you get the desired number of turns check the inductance. It should be a little less than the goal value, as by wrapping them more tightly the inductance will rise. It is not too critical though.
Tx coil resistance is critical because of its influence on Q factor, but the Rx coil's resistance is of somewhat less importance.
Nulling the coil is a bit more interesting.

[der_fisherman]

Hi Davor,
I've been away from the forum for sometime, so my apologies if this question has already been answered.
When I was here before, you were making good changes and additions to the circuitry, it appears from this recent post that that is still the case. So my question is simply, have you or someone else compiled a list of all the changes and placed it somewhere online? Which ones are needed? etc....
I have an IGSL that was made with the original circuit and values, that simply is so unstable that it is unuseable....I would like to try and get it working as I hope it should.....
Many thanks in advance for all of your time, trouble and expertise. I am sure I am not alone here either.
Andy