IGSL

[satdaveuk]

Dont take this as gospal but checking the spec sheets there is MC14066, HEF4066BP, as well as the CD4066 all run between 3-15volts im sure will do the job, Shall order 2 of each and varifi ok.

Thats when ive built it mind you

Regards

[der_fisherman]

I dont know whos in charge of updateing these files but it needs to be done because its going to catch alot of people out, was so lucky just ordered aload of stuff about 2 hours before desided to have a ponder here, and there it was, lucky for me in one sense because I would have been looking for faults like these lads, proberly spent hours on it, id be well peed off.
Trouble is I need to make orders over £100 to get good prices with no postage charge and although there was only 2 hours in it they wont budge because the order was already prosessed.
Im not pointing the finger here oviously wasnt done on purpose, infact maybe its a wake up call to check and double check component specifications are selfs in stead of takeing them as gospal.
Anyway all the best ive calmed down now lol

Take care
Regards

I agree with you completely and I feel that this is also a point which we should be also considering when picking a schematic/CAD package, where the parts list is automatically generated and everything can be covered by version numbers.......

I have talked about this before and many have commented, but we have not made any final decisions......maybe we should!!

Regards

Andy

[golfnut]

Ferrous GEB IGSL - schematic error?

All, IGSL.

My one I can get good high tone on the Non Ferrous - reject to Ferrite ie GeB is tunable and ok.


Ferrous channel always sees the ferrite - never been able to reject it.

If you look at schematic the disc channel has u7b and U7a both are non inverting inputs.
This channel is good.


The Fe block U7d and U7c have one -Inv input and one + Non Inverting input
This channel dont GEB

Is the schematic wrong ?????

Should U7d pins 10 and 11 be swapped over??

[bernte_one]

hello golfnut

i dont look at shematic but i can say that i´m able to tune geb so that ferrit is not shown
i only can say that it is easier to reject a small ferrit instead of a big one
but i think it also depends of the ferrit material

if you have problems to reject ferrit check if tx and rx a right connected try reverse one side
check if the one with shield is connected right point to pcb
igsl also works when coil is wrong connected
but first what i see when wrong connected is a higher null voltage level and more sens to small objects- and also ferrit

regards

[golfnut]

what confuses me..

The non ferrous channel works really well.


The ferrous channel I cannot get rid of any size or type of ferrite and have SOLID Iron GAIN

Why iis U7d an inverting input ???? Is it this difference that makes it an Fe channel???

Or is it an error common to all???

I have a dig on a villa on Saturday and I would like to get it all singing well

Plus I redid the preamp resistors to 330 and 15k (same gain lower noise)
I feel the range has improved - I will get some numbers.

ATTACHED ERROR PICTURE
SEE NEXT POST PIC

Steve

[golfnut]

Better Picture..

[Qiaozhi]

Also why is this an inverting input?

Because the top section is designed to reject ferrous targets, and the bottom section is designed to reject non-ferrous.

[golfnut]

1) I had my Fe channel with no rejection of ferrite...

- Field Test - It doesnt matter, ground balances ok as it is on Fe Channel


2) I have a oscillation the comes and goes - blips the Non Fe channel.

- I erected a Copper screen/fence to sheild the Rx preamp- --- This helped but not enough.

_ I wrapped copper tape aroun the 3 P1 pot wires and grounded it --- this helped when I poke finger in nearby and previously I got a blip, now quiet. Not enough..

- Added 0.1uF to + and - rail on U4 - not enough

- added 1Meg FB resistor to U4a - samll improvemnt - not enugh.

Osillation more consistent repetition rate now.


- Dabbed a cap on the -ve rail and the rate of oscillation changed ?


Tried 1000uF on the -ve rail local to U4 - Sorted.

It is much more settled now.

It does oscillate if you turn P3 up some more non Fe gain up or Iron Gain too high.

I can easily get a Uk 20p buried 15cm in wet clay soil / with small amount of grass on top.


Im doing a roman villa on Saturday with it - look a proper charlie with it oscillating away next to 40 etracs

S

[6666]

In post #1025 there is a reference to Don Bowers excellent article on phase shift
I have searched through the thread but could not find it, maybe missed it
but does anybody have a copy please , thanks
6666

[dfbowers]

In post #1025 there is a reference to Don Bowers excellent article on phase shift
I have searched through the thread but could not find it, maybe missed it
but does anybody have a copy please , thanks
6666

This one?

http://www.geotech1.com/forums/showthread.php?t=15710

Good thing Qiaozhi made it sticky!

[6666]

Hi Don

use scope on TX and RX and adjust for +/- 20 degree phase shift, as per Don Bowers excellent article.

This one about phase shift
thanks

[Vladd]

Is this similar?

http://www.youtube.com/watch?v=IuETHmjBK-Y

[golfnut]

IGSL Building

I would say dont buy an IGSL or TGSL until you have read Dons write up on this project.

Use this info to decide If this is what you want and can build.

I built mine months ago and only just got around to reading it.



Id say the nulling I did with a meter is not that good - the flaw then is poor GEB on Fe channel - on my IGSL. - Run out of adjust range -rejecting ferrite doesnt happen.



Plus the initial phase relationship of the Tx signal to the leaked Rx signal isnt within the
+/-20degree range. Need to check this around nulling time.


In use with Fe reject max, Fe sens min - I still get both tones on most Iron targets.

I can hunt with it but its not as good as it could be.


S

[simonbaker]

I would say dont buy an IGSL or TGSL until you have read Dons write up on this project.

Use this info to decide If this is what you want and can build.

I built mine months ago and only just got around to reading it.



Id say the nulling I did with a meter is not that good - the flaw then is poor GEB on Fe channel - on my IGSL. - Run out of adjust range -rejecting ferrite doesnt happen.

I have yet to see evidence that the exact null phase affects where ground balance takes place -- there is some theory to say it's possible, but all my experiments seem to indicate the peculiarities of the "null phase" are due to an additional quadrature signal, maybe capacitively coupled, coming from the cable or possibly across the shields capacitively, which should not be affected much by ground. I cannot demonstrate that the null phase affects the DISC pot or the GB pot settings noticeably.

However, with the GEB, which side of the null balance you are on may have a significant effect on the overall operation, although how big that effect is I don't know. I know the TGSL will work on both sides of the null signal; dfbowers noted trouble with pot directionality in some case, need to review that.

Plus the initial phase relationship of the Tx signal to the leaked Rx signal isnt within the
+/-20degree range. Need to check this around nulling time.

Again, I think that relationship depends highly on your cable, shields, and other tuning, at least from what I see with experiments. Although it probably does mean your MD is built somehow different from the standard one, I wouldn't conclude it means it can't work well. But we'd need to explore deeper what's going on.

Not disagreeing with your basic assessment, just want to note that I've been trying to revisit the lore surrounding nulling, particularly with regards to the TGSL, and it is an ongoing process.

Cheers,

-SB

[growdude]

Igsl coil wiring for minelab coil

Can some one give me coil wiring diagram from board to connector diagram also power switch wiring