goldscan IV coil

[Ariubarzan_M]

i need Construction of the search coil goldscan IV

[Max]

coils... here's very easy recipe

i need Construction of the search coil goldscan IV

Hi,
the original coil was 436uH inductance with about 3.5ohm dc resistance.

Now you need a good inductance meter and a scope to replicate coil and setup e.g. damping in perfect way... but you can experiment too.

If you need an 8'' coil try this:

Use 0.38mm wire, 28turns will give you around 400uH, then around 2.85ohm resistance, that's not too far from expected value.

With such a simple coil, shielded with mylar stuff I got easy 1eur coin at 40cm on the air... but it's just about trivial coil... complex ones require much care and to be very careful at e.g. materials.

My advice is you'll read (if didn't already) bbsailor's article on fast monocoils... then find teflon insulated wire! Also... if have scope and inductance meter things are well more happy!

Kind regards,
Max

[Qiaozhi]

Hi,
the original coil was 436uH inductance with about 3.5ohm dc resistance.

Now you need a good inductance meter and a scope to replicate coil and setup e.g. damping in perfect way... but you can experiment too.

If you need an 8'' coil try this:

Use 0.38mm wire, 28turns will give you around 400uH, then around 2.85ohm resistance, that's not too far from expected value.

With such a simple coil, shielded with mylar stuff I got easy 1eur coin at 40cm on the air... but it's just about trivial coil... complex ones require much care and to be very careful at e.g. materials.

My advice is you'll read (if didn't already) bbsailor's article on fast monocoils... then find teflon insulated wire! Also... if have scope and inductance meter things are well more happy!

Kind regards,
Max

Using calculator:

[Max]

Using calculator:

I guess he has no Qiaozhi's calculator!

Otherwise... why ask for details... ?

Hmmm such calculator seems not like the one I have... but maybe yours is better , who knows ?

Kind regards,
Max

[Qiaozhi]

I guess he has no Qiaozhi's calculator!

Otherwise... why ask for details... ?

Hmmm such calculator seems not like the one I have... but maybe yours is better , who knows ?

Kind regards,
Max

I was just confirming that your calculation was correct.

Get your copy here -> http://www.geotech1.com/forums/showp...91&postcount=6

[Max]

I was just confirming that your calculation was correct.

Get your copy here -> http://www.geotech1.com/forums/showp...91&postcount=6

Yes , I see... the calculator is pretty accurate... I made the coil starting from 30 turns, reducing number to get desired value that time... around 400uH as described.

But... the big drawback... is that... though I got 1eur easy at 40cm I got also brick fragments at simial distance !?

That's what I hate of pulse induction MDs... they detect fired clay and similar stuff like metals!

Totally unuseful in places with lots of bricks and pottery things... MD goes crazy by itself... and opertator too...

Also... what I'm happy of digging a nail at half-a-meter in hard ground!

I think that's why I have all them (PIs) hanged on nails in my garage !?

So PIs are not serious things for my needs...

Do you know of anyone building a SERIOUS PI MD ?

Kind regards,
Max

[ivconic]

Yes , I see... the calculator is pretty accurate... I made the coil starting from 30 turns, reducing number to get desired value that time... around 400uH as described.

But... the big drawback... is that... though I got 1eur easy at 40cm I got also brick fragments at simial distance !?

That's what I hate of pulse induction MDs... they detect fired clay and similar stuff like metals!

Totally unuseful in places with lots of bricks and pottery things... MD goes crazy by itself... and opertator too...

Also... what I'm happy of digging a nail at half-a-meter in hard ground!

I think that's why I have all them (PIs) hanged on nails in my garage !?

So PIs are not serious things for my needs...

Do you know of anyone building a SERIOUS PI MD ?

Kind regards,
Max

I like this calculator!

...

"...Do you know of anyone building a SERIOUS PI MD ?...."

I will!!!
Next time i build Delta Pulse, i will print sticky label with: " SERIOUS PI MD" on it!
No..seriously...i understand your remarks Max. Also had simillar experiences with various Pi's. Yet..those do have usage in many occasions.
For example, you can take PI with your VLF on terrain and check just a few suspectable spots, on places where VLF can't be used. Usually PI's are good to check for larger metal deposits at depths where VLF cant reach, also. I do take PI with me occasionally, mostly when want to check some specific place for something larger at higher depth.

Not for everyday prospecting for sure.

[Reg]

The Goldscan 4 is very tolerant of coil inductances. I have used 300 uh coils on mine and they work fine, so one should be able to use about anything from 300 uh and up.

Now, as for detecting the red brick, that can be taken care of with a few mods to the detector. Also, simply advancing the ground balance should minimize signals from the red bricks. You might try it and see.

Reg

[Max]

I like this calculator!

...

"...Do you know of anyone building a SERIOUS PI MD ?...."

I will!!!
Next time i build Delta Pulse, i will print sticky label with: " SERIOUS PI MD" on it!
No..seriously...i understand your remarks Max. Also had simillar experiences with various Pi's. Yet..those do have usage in many occasions.
For example, you can take PI with your VLF on terrain and check just a few suspectable spots, on places where VLF can't be used. Usually PI's are good to check for larger metal deposits at depths where VLF cant reach, also. I do take PI with me occasionally, mostly when want to check some specific place for something larger at higher depth.

Not for everyday prospecting for sure.

Hi,
yes, I wasn't referring to "depth" PI... like DeltaPulse ...but things used with small coils for coins, rings etc that stuff, in my search conditions in most places, are totally useless... that's why I told they aren't serious stuff....

No way I will dig other bricks by them...

About depth PI I agree they are useful; also small coil equipped are good e.g. at beach-search, no dubt... problem is inland conditions... really worse for them.

Kind regards,
Max

[Max]

The Goldscan 4 is very tolerant of coil inductances. I have used 300 uh coils on mine and they work fine, so one should be able to use about anything from 300 uh and up.

Now, as for detecting the red brick, that can be taken care of with a few mods to the detector. Also, simply advancing the ground balance should minimize signals from the red bricks. You might try it and see.

Reg

Hi Reg,
yes works for very small pieces but I have large ones too so have to use VLF there. I tested many PIs not only homemade GS4 there and found are not good for that search conditions... field is infested of pottery and fired bricks... no way for PI when coil is near soil.

I tested also double pulsed version of GS4 I made... same stuff... magnetic dipoles "move" and are detected just like metallic target... the result is that the MD detect easy small coins in the 40cm range (buried) with 8'' coil but also small fired ceramic... then I dig holes and found brick fragments! Crazy work!

After dug 35-40 of them I gave up... used VLF and problems disappeared... though cannot find such deep stuff... as before.

Kind regards,
Max

[ivconic]

Hi,
yes, I wasn't referring to "depth" PI... like DeltaPulse ...but things used with small coils for coins, rings etc that stuff, in my search conditions in most places, are totally useless... that's why I told they aren't serious stuff....

No way I will dig other bricks by them...

About depth PI I agree they are useful; also small coil equipped are good e.g. at beach-search, no dubt... problem is inland conditions... really worse for them.

Kind regards,
Max

Totally agree. Does not make much sense to go coinshooting with PI and small coil. Why doing such thing? We already have very good VLF's for such thing..and deep enough too.

[Aziz]

Hi Max,

...
But... the big drawback... is that... though I got 1eur easy at 40cm I got also brick fragments at simial distance !?
...
Totally unuseful in places with lots of bricks and pottery things... MD goes crazy by itself... and opertator too...

some of the bricks contain iron oxide pigments. The red/brown is typically Fe2O3 (hematite) and the black one is typically Fe3O4 (magnetite). Maybe this causes the false signals.

Aziz

[Max]

Hi Max,



some of the bricks contain iron oxide pigments. The red/brown is typically Fe2O3 (hematite) and the black one is typically Fe3O4 (magnetite). Maybe this causes the false signals.

Aziz

Hi Aziz,
some are pigments but on pottery not bricks. Bricks are made of fired clay containing good amount of Fe2O3/Fe3O4 and other stuff like these... so no way... the oxides are included in the fired stuff, and you can always detect them, unfortunately.

It's a big drawback of PI designs for inland use... at least my experience.

Kind regards,
Max

[Roughwater]

PI with small coil

Totally agree. Does not make much sense to go coinshooting with PI and small coil. Why doing such thing? We already have very good VLF's for such thing..and deep enough too.

Max,

When I detected at Rye Patch resevoir in Nevada in 2005 my favorite coil became a 9" mono behind my GP3500. I had started out with a much larger coil for the first 3 days and had only found 1 small nugget. However, after changing to the 9" mono my luck quickly changed. It was small enough to get between many of the thicker plants, was less noisy than larger coil and I wasn't trying to dig up mineralization. The smaller coil still had good depth and great sensitivity to small nuggets. The 4th day I found 5 nuggets with that little mono, the largest being over 1 ounce. One other thing, this was really my first week of detecting with a PI detector. But my point is there is definitely a place and time for small coils on a PI.

Terry