IDX-PRO+VDI

[hoadlies]

Hi

I have made a new TX and RX coils for a 27cm DD as I have wound them I have covered them in epoxy so I now have two ridged D shaped coils.

If null them and glue them together now will the null or phase be altered when I later add a space blanket shield or is the null purely a physical position thing

HI KOALA ,,GREAT QUESTION and I cannot answer myself ,But will be interested in the Answer as I am also into some more coil building ..& that topic is a vital one & I have been wondering the same thing ..

CHEERS MATE ,,BARRY..

[Koala]

Hi

I have made a new TX and RX coils for a 27cm DD as I have wound them I have covered them in epoxy so I now have two ridged D shaped coils.

If null them and glue them together now will the null or phase be altered when I later add a space blanket shield or is the null purely a physical position thing

[golfnut]

Hi Barry, for tweaking the freq - I first simulated how the phase shifters work at 6.5kHz is spice. Then put my 12kHz freq in the model and it wasnt that much different so I had confidence to ham up a test.

I made a smaller L Tx coil with 0.3mm and tuned it with the appropraiate cap to give a clean looking sinus, and it was about 12.5k this is a useful all round number - it will see this small silver and small gold but still get some depth on bronze and artifacts, all in most soils...

low freq machines up to 6k see chunky items well. Freqs over 15k tend to see small stuff well. When you get to about 18k up, they see larger coins etc not quite so well. Rules of thumb from my limited experience.


If you want a bit of both go for something in middle 12.5k was just what I had and it sees small aincient silver hammereds at 0.6gram or a lead gun powder measure or brass fitting from a black bess!.

For all boxes ticked we could try a dual freq machine!

[hoadlies]

Hi, I hope you had some fun along the way - for me half the fun is the fight to get these sometimes annoying projects to a point where they become of practical use!

There is scope within these kits to alter things to address the individuals needs - within limits.



On thing was C16. people realised in use that the PP on IDX needed to be waved over the target. The reason for having to rock it about is that unlike some smarter more coplex kit the PP on here is ac coupled through C16. So if the machine is still - as you would be excused for doing in PP - you never get a tone !!

The ac bottleneck is C16 - the best thing to try is making it a lot larger. Most people dont have a 10uF polyester!! in a smallish footprint - you could try a 22uF non polarised or something like that.

This way you get closer to the PP feel where it will ring out over a target with the subtlest of movement. You still have to move it - still ac coupled - so need movement to generate a signal..


DC coupling is the best solution for true non motion PP, but if U5 has significant dc offset - this will upset the dc conditions on U6 and you got a tone.


I found in use I get better position without PP as I use a DD I do XY sweeps and need a hole about 6" square to not chew artifacs.

I cut my PP Channel out so Rx signal isnt fed into it and no residual noise comes out of it in normal disc use. My cmos switch is hardwired into non PP mode.

Plus I wanted to "see" smaller items, so I made mine at 12.5kHz Tx and about 8/5kHz Rx.


S

HI thanks STEVE for the explanation on the PP & C16..

I guess to raise the frequency as you have done One would have to do that prior to finishing the coil closure ?? as to alter the caps in coil ????
Would it be possible for you to Expand on your method on this frequency Mod ?????in Dummy language as I am HA,Haar ..
Or have you already done that in an earlia message here ?? I have your Schematic with your PP mods shown but I am still a bit unsure ..

GOODONYA-MATE ,,BARRY..

[der_fisherman]

According to what I read, it was a walk on their OWN land!! WOW!!
Regards
Andy

[golfnut]

Hi, I hope you had some fun along the way - for me half the fun is the fight to get these sometimes annoying projects to a point where they become of practical use!

There is scope within these kits to alter things to address the individuals needs - within limits.



On thing was C16. people realised in use that the PP on IDX needed to be waved over the target. The reason for having to rock it about is that unlike some smarter more coplex kit the PP on here is ac coupled through C16. So if the machine is still - as you would be excused for doing in PP - you never get a tone !!

The ac bottleneck is C16 - the best thing to try is making it a lot larger. Most people dont have a 10uF polyester!! in a smallish footprint - you could try a 22uF non polarised or something like that.

This way you get closer to the PP feel where it will ring out over a target with the subtlest of movement. You still have to move it - still ac coupled - so need movement to generate a signal..


DC coupling is the best solution for true non motion PP, but if U5 has significant dc offset - this will upset the dc conditions on U6 and you got a tone.


I found in use I get better position without PP as I use a DD I do XY sweeps and need a hole about 6" square to not chew artifacs.

I cut my PP Channel out so Rx signal isnt fed into it and no residual noise comes out of it in normal disc use. My cmos switch is hardwired into non PP mode.

Plus I wanted to "see" smaller items, so I made mine at 12.5kHz Tx and about 8/5kHz Rx.


S

[hoadlies]

Well done for sticking at it.

Does it reject ferrite using the geb control?
If you bob it up and down over your earth can you get to no tone using the geb control?

HI STEVE THANKS MATE YES it doed reject ferrite with geb but with a 10k in series & then about 12-1-0clock..
Yes it rejects small clean screw at about 10-oclock ..

YES it detects non ferris & coins ..

I would like to ask you about the 1 uf cap c16??? on your earlier read mods to short it out& or remove???? using 2x pole switch ,To explain I shorted it out but then got a constant tone so I have left as is ..

WELL today I had to go to ADELAIDE 200ks Sth ,, Whilst there I picked up my order of Wire which I found nice people [suppliers to motor rewinders] 1 kilo of 0.2mm wire [Thats a dam lot of RX wire] But it cost only $33.00 Aud ..He thew-in 1/2 kilo of 0.7 mm for free[ I like him Great bloke] I offered to pay but he said have fun with-it ..
I also bought a Can of correct wire potting spray [$15.00] ISONEL-POLYESTER -INSULATION, as used by motor rewinders .. would still use initial dabs of super-glue etc etc..

I then called into my favorite electronics store for 5 metres of beldin-8723 cable..

SO mate I will build another couple coils to try-out soon ..A slightly smaller DD & DONS coplaner ..

THE air test is about 20-25cm not as good as most on here but it was the best I could get & retain the geb control ..
With the ground reject I needed to run the Geb at approx 3 oclock ????
But it detects very small objects ,But not tried it with buried coins [No time as yet].

I am very pleased to have gotten this running ,But with-out This site & advice from You & others I would have been lost ..

I need to try-out on some plastic sheet to see if my Graphite mix works on covers for concentric coil ..& try for the magic Resistance ????



Does it reject iron with the Disc control?

When set to JUST reject clean small iron does it ACCEPT all of the metals you want to find?

Do you feel you have acceptable air range to a mid size non clad coin?




If the above interrogation is all yes's - you should be home and dry, what you have done Barry, is what this forum is about.

Go and have some fun with it, with that cordless battery you will need to charge - ANNUALLY..


Post us pics of some early Aussie coinage... But dont find gold or we all will be real jealous!!


Low and slow mate, low and slow

Steve

SORRY I got your Quote mixed-up ..
BATTERY YES I have many good GEL-CELL 12 7amp hour but a bit heavy so I will try the 14.4v drill batt as seen ..

CHEERS TO ALL ,,,,,,,,,,,,,,,,BARRY..

[golfnut]

"SQUARE-CARD TEST ??? Please explain .."

Sorry didnt see this.

To get a known ohms/square value I did square cards with some copper tape connection points. These show the ohmic resistivity of your trial mix repeatably. I think 1-8kohms/square is ok.

[Silver Dollar]

Well the only gold I look for is on the beach! Those coins were found in California, I'm on the opposite coast from them.

I just finished my Hammerhead PI. I'm still messing around with coils so haven't taken it out yet. You can get a kit
from SilverDog (though I think he's fresh out just now). http://www.silverdog.co.uk/shop/inde...tegory&path=36

I also bought a Chance PI board someone had leftover from a few years back when Silverdog was selling them. That one is based
on an ATMega8 processor and does some discrimination. It hasn't arrived yet and then I'll have to obtain some parts...

It's darn cold here today and we expect more snow on Monday. It's been a snowy year with about 85" of snow
so far!

[golfnut]

Well done for sticking at it.

Does it reject ferrite using the geb control?
If you bob it up and down over your earth can you get to no tone using the geb control?



Does it reject iron with the Disc control?

When set to JUST reject clean small iron does it ACCEPT all of the metals you want to find?

Do you feel you have acceptable air range to a mid size non clad coin?




If the above interrogation is all yes's - you should be home and dry, what you have done Barry, is what this forum is about.

Go and have some fun with it, with that cordless battery you will need to charge - ANNUALLY..


Post us pics of some early Aussie coinage... But dont find gold or we all will be real jealous!!


Low and slow mate, low and slow

Steve

[hoadlies]

WOW

HI S/D ,Thanks for your help Mate ,Well this is my 1st attempt so its not perfect etc etc,,, But I have learned much from You guys who have more expertese ..& it is much appreciated ..

WOW Paint tins of Gold coins ,,, Would not be my luck though.. I would dig-up paintins full of S&%#t Ha,haar..GOOD ON THEM.. just the same .maybe I should WALK-THE-DOG ,HA.Haar..

I guess you could find tins of gold coins with the cheapest detector also [big target]..

OK as we have some Gold areas in OZ I would like to build a PI-- ''later'',,, after getting some better coils for this current build..
Question What PI would you recommend [That I can get a board for ??????]
Do you go gold detecting ?????..

Are you still in Icy weather over in your area ??? HERE the weather has cooled down ,so its nice working out in my shed with 25c conditions..

ALL THE BEST ,,MATE,,,,,,,,,,,BARRY..

[Silver Dollar]

Looks good! One of the drawbacks to fiberglass is the weight.
The coil housing is the toughest to make light and strong without extra weight....
Good luck using it.

I saw on the news last night a couple was out walking their dog
and they found 8 paint cans filled with gold coins from the 1800's. The face value
of the coins was around $20000 but most were in perfect condition so they estimate
their worth at $20 000 000!!!

[hoadlies]

[/ATTACH]

HI ALL ,,& MANY THANKS To those who helped me ,including ,EDUARDO ,who srarted this IDX thread ,STEVE,DON,KOALA ,Silver-Dollar ,,ETC ETC ..GREAT STUFF BY ALL..

THIS is my fist ''AUSSIE-ROUGH'' DIY detector & it works!! Not sure how good as yet not time to test yet but it seems Ok outside of the Shed ..

MY Fibre-glass Shell with the coils & bottom attatched is Quite heavy !!
My next coil will be lighter as I have now 0.2mm wire for RX ,where as this coil RX is from 0.32mm ..

The pole-wand was a quick 1/2 hour job an old Mop handle with a wooden piece to attatch to shell ;With Toilet Bolt .HA,Haaar..,alluminium arm rest pop rivetted etc etc..

A couple pics above of my next coil shell ,1 of the coil I dismantled for the shell is 9.1/2'' & making a bottom for another 8'' ..

CHEERS TO ALL ,,,,,,,,,,BARRY..

[Koala]

The shield does not increase the air test.

Space blanket graphite or no shield makes no difference in air test depth.

Using a thick foil will affect the depth.


In the real word a good shield is very important as the detector will be beeping (falsing) all the time. Tuning your coil to maximum depth is not the be all end all the coil has to run stable.

[hoadlies]

In my first DD coil I use foil tape, I get ~30cm on 1Euro. Now i build second coil, if i use a graphite and X mix, then i can get better sens (it can see deeper)?

HI VALTERS,, As this is my 1st coil I cannot say if graphite is more senitive or not ,Maybe STEVE ,or others can tell you ..
Tonight I potted the coil so I will be able to test it ''ON=-GROUND'' AIR test is not really that great ,but the best I can Achieve.. ,But GEB is OK at just over 12.oclock ..& Disc can reject small iron ..

I used 0.34 wire for the RX & reading was close to 34mh, with my inductance multimeter???
The next coil I will use 0.2 wire..for RX & for TX I used 0.68mm & got .34=35 mh???..

CHEERS ,,,,,,,,,,,BARRY..