IGSL

[ivconic]

Ivconic, your MD looks professional! BTW do you bend your own aluminum pipe? I tried to bend alu. pipe with bad results!

No i am not..
Huge issue! Chronic issue!
I manage to obtain shaft or two... from time to time..

[Wiltran]

IGSL

Ivconic, your MD looks professional! BTW do you bend your own aluminum pipe? I tried to bend alu. pipe with bad results!

[ivconic]

Ivconic nice work .

Grt Nakky

Thanks Nakky!
Look Selim's work! I like it!
Very good work Selim!

[der_fisherman]

Thanks for thorough comment Qiaozhi.

I do not understand what is main goal of solving disputed connection/orientation DD coil windings dilemma?

- to get better possible sensitivity?
- to get ideal phase shift?
- both of them?

Knowing answer, test (what we get by changing) cannot be a big problem.

I did answer, but not with your text, sorry.
The wet grass fix.

[selim]

igsl finish

[der_fisherman]

Wet grass fix.

[nakky]

Ivconic nice work .

Grt Nakky

[WM6]

You would need to change the number of turns on the coil in order to make this useful for analyzing the field around a metal detector coil. Unfortunately, with the current design, it would need a different measurement coil for each TX frequency. For example, using a 1" (25.4mm) circular coil to measure the 14kHz TX signal from a TGSL would require 35 turns (assuming the same top value of 1uT, and an output voltage of 500uV).
In order to use the same coil for all tests, you would need a microcontroller to scale the results correctly according to frequency and magnetic field intensity.

Thanks for thorough comment Qiaozhi.

I do not understand what is main goal of solving disputed connection/orientation DD coil windings dilemma?

- to get better possible sensitivity?
- to get ideal phase shift?
- both of them?

Knowing answer, test (what we get by changing) cannot be a big problem.

[Qiaozhi]

Andy, Here is the post where the grounding discussion was going on last summer. see post #372 http://www.geotech1.com/forums/showt...=16122&page=15

Plus, I made 2 videos in an experiment where I made two coils, One with the coils connected to the shield inside the coil shells and one with the shields and ground wires connected only to ground on the PCB.

Plus see these two videos The first is the "wet grass" configuration:

http://www.youtube.com/user/dobybowers?feature=mhee#p/u/5/7UBOca3btMw

http://www.youtube.com/user/dobybowe.../6/XhRboS639no

You commented earlier that the "wet grass" problem may be isolated to the use of a USB cable. I suspect this is true; as a commercial Tesoro (Bandido) works absolutely fine. However, occasionally you will find a faulty Tesoro coil that is intermittemt in wet grass. This is caused by a bad shield connection in the coil housing.

[ivconic]

Details.....

[ivconic]

"...Once I have my electronics built and I can start on the coil nulling, maybe I will understand better......"

True!

[der_fisherman]

Andy, Here is the post where the grounding discussion was going on last summer. see post #372 http://www.geotech1.com/forums/showt...=16122&page=15

Plus, I made 2 videos in an experiment where I made two coils, One with the coils connected to the shield inside the coil shells and one with the shields and ground wires connected only to ground on the PCB.

Plus see these two videos The first is the "wet grass" configuration:

http://www.youtube.com/user/dobybowers?feature=mhee#p/u/5/7UBOca3btMw

http://www.youtube.com/user/dobybowe.../6/XhRboS639no

Hi Don,

thanks for the tip and the reading, but I am even more confused now about null, discrimination and GEB, it all seems to hang with the nulling, and as I haven't yet even received my kit yet from SilverDog, it is of course not yet built!!! So a lot of the terminology was over my head.

I do have a dual beam scope, meters and also an impedance meter for both C and L......I think I have everything needed, except the "understanding".....

So many differences of opinion from learned intelligent colleagues here.....thanks to you all.

Is there a clear, cut and dried setup for an IGSL double D coil?

Is there one for a TGSL that also applies to IGSL?

I have not as yet found one that agrees with you, but I am still reading.....

It would appear that the differences of opinion also result in different setups and different performances!! (SOOOO TRUE)

Once I have my electronics built and I can start on the coil nulling, maybe I will understand better......

If you have any further tips, please drop me a line as I feel I need help big time, thanks. Nothing is too tiny, everything happily accepted.

Regards

Andy

[ivconic]

BTW...

[ivconic]

Small addition, maybe will help somehow:
Musketeer TS1000 coil is shielded with some material, most probably graphite spray, and further connected to TX shield (part of TX coaxial).
RX coil is not connected to coil shield nor anything else in coil , but is leaded via separated coaxial to pcb and is connected to pcb gnd (at Musketeer).
So TX leads are "carrying" ground and shielding.
OK.
At IGSL i had doubts and choices, how to properly connect RX leads.
So i connected them just on RX pins on pcb, without additional connection to pcb gnd. Checked behavior and seems it is working fine.
Next; i connected additionally one RX input to pcb gnd - again seems to work fine.
Whole testing was done in workshop, on a bench.
Later, with second setup i went outdoor and tested behavior on real soil.
If Senses turned to maximum than few and rare pikes occurs. But really rare, not often and not so disturbing.
Not even close so disturbing as on videos from post above.
Also noticed that pikes can occur only when coil is fast risen from soil, otherwise don't.
But when Senses (both) lowered to "6" or "7" than no pikes at all.
Depths are pretty good even when both Senses stays at that position.
For example; i have buried 2cm coin at one place, at 24cm depth.
It is very easy detected even when coil is some 10cm over the soil surface.
No doubts, higher pitch indicate "colored" target.
Next check i will do; is with first setup (RX leads are no way connected to pcb gnd) on real soil at same place with coin.
Last days i had other things to do, so i will check that very soon.

So.. will see.

Back to "ninja mode"!

[dfbowers]

What I was referring to about the inner and outer windings "opposing each other" is described here by Aziz (the "field-master") http://www.geotech1.com/forums/showthread.php?t=13858 (the link that dfbowers timely-ly dug up). This is an effect found with wide flat spiral coils but not with conventional "bundled" coils like we usually make them. The end result is that the wide spiral coil doesn't have as strong (or deep) a magnetic field.

The diagrams from the fieldmaster are not available, nothing there except a 404 message!! Totally useless.....sorry.

That grounding of one RX lead in the search head has always perplexed me but it seems to work in practice, although dfbowers seems to have settled on an ungrounded design which he likes better. I had a concern with the ungrounded design that some static electricity could blow out the LF353 inputs -- but someone said they were protected somehow from that by design.

Don grounds his coil shielding, but only on the supply ground, not on an input to the circuitry......perhaps Don could jump in and explain far better, Don?

regards

Andy

PS. Making the flat coils is difficult, scrapped two already......we will see what No. 3 is like tomorrow.....

Andy, Here is the post where the grounding discussion was going on last summer. see post #372 http://www.geotech1.com/forums/showt...=16122&page=15

Plus, I made 2 videos in an experiment where I made two coils, One with the coils connected to the shield inside the coil shells and one with the shields and ground wires connected only to ground on the PCB.

Plus see these two videos The first is the "wet grass" configuration:

http://www.youtube.com/user/dobybowers?feature=mhee#p/u/5/7UBOca3btMw

http://www.youtube.com/user/dobybowers?feature=mhee#p/u/6/XhRboS639no