IDX-PRO+VDI

[Schatztaucher]

some pics

1. etch improvised
2. my little workplace
3. the first part of my rods, and the electronics box (complete aluminum)

[IC-77]

Greetings to all members of this popular forum, but some time I visit a forum, but only as an observer, but here and now I can officially registered here because there are still plenty of interesting topics and projects that I could maybe I can get involved, and certainly some help and learn. Especially liked the project, Mr. eduarda1979, which I have done but still does not work like it should, and I asked you for some help in particular of Mr. Edward, and all other members who are willing to help.

[simonbaker]

viewable

1. etch improvised
2. my little workplace
3. the first part of my rods, and the electronics box (complete aluminum)

Just so I can see pictures...

[Schatztaucher]

of course, sorry.....

[Wiltran]

1. etch improvised
2. my little workplace
3. the first part of my rods, and the electronics box (complete aluminum)

I'm curious as to what process you used to weld the aluminum? tig, mig, or aluminum solder?

[Schatztaucher]

tig

[dfbowers]

IDX DD coil

Just finished my 14th coil! This one is my first for the IDX. I used the same construction methods and materials as I have been using for TGSL coils, with the exception of the windings themselves. The other difference over the stock coil is that I have installed the tuning caps on a small jumper board inside the control box.

One observation: I have been unable to use this coil at higher senstivity settings, just because it is just too unstable, but runs perfect at lower sensitivity settings.. Probably due to the sensitivity mods that I have made. My two stock coils are the same way. Overall, it functions basically the same as stock coils.

One question I have that maybe someone can answer: Why are all White's coils designed with tuning caps inside the coils? Is there an underlying reason why they cannot be installed on the opposite end of the cable for DIY coils??
Don

[detecto]

Just finished my 14th coil! This one is my first for the IDX. I used the same construction methods and materials as I have been using for TGSL coils, with the exception of the windings themselves. The other difference over the stock coil is that I have installed the tuning caps on a small jumper board inside the control box.

One observation: I have been unable to use this coil at higher senstivity settings, just because it is just too unstable, but runs perfect at lower sensitivity settings.. Probably due to the sensitivity mods that I have made. My two stock coils are the same way. Overall, it functions basically the same as stock coils.

One question I have that maybe someone can answer: Why are all White's coils designed with tuning caps inside the coils? Is there an underlying reason why they cannot be installed on the opposite end of the cable for DIY coils??
Don

My opinion about cap in original coil is : They just put the cap inside of housing of coil just to prevent the data abouth inductance of coils ,to protect against copying just mu opinion. And other reason can be : all LC circut (oscilators) must have short wires with them selfs, short wires have smaller capacitance, and for LC circut always is recomended to use wire not longer than 2,5", in some cases if wires betwen L&C are too long, oscilator will not oscillate.

[satdaveuk]

Just finished my 14th coil! This one is my first for the IDX. I used the same construction methods and materials as I have been using for TGSL coils, with the exception of the windings themselves. The other difference over the stock coil is that I have installed the tuning caps on a small jumper board inside the control box.

One observation: I have been unable to use this coil at higher senstivity settings, just because it is just too unstable, but runs perfect at lower sensitivity settings.. Probably due to the sensitivity mods that I have made. My two stock coils are the same way. Overall, it functions basically the same as stock coils.

One question I have that maybe someone can answer: Why are all White's coils designed with tuning caps inside the coils? Is there an underlying reason why they cannot be installed on the opposite end of the cable for DIY coils??
Don

Hi Don
Got to hand it to you, your coil housings look like they came from a factory, very pro.
Not sure about your question of caps in the coil housings, I been mounting them in there for quite sometime so it makes more of my coils compatible, far as performance, nothing noticable for me with the TGSL setup, but of course maybe different with other circuit designs.
Will be interesting to here what Carls opinion is on the subject.

All the best

[simonbaker]

One question I have that maybe someone can answer: Why are all White's coils designed with tuning caps inside the coils? Is there an underlying reason why they cannot be installed on the opposite end of the cable for DIY coils??
Don

Don't have answer, but it can mean that cable has less current flowing with some coil driver designs... maybe cable doesn't twitch as much ...

-SB

[dfbowers]

Don't have answer, but it can mean that cable has less current flowing with some coil driver designs... maybe cable doesn't twitch as much ...

-SB

Thanks guys.. I was just thinking about Ivconics post about adapting Fisher coils where we have no choice other than to install them externally. Other than the compatability issues I don't see the benefits on the surface. I just put them external because they cannot be changed later.

Us DIY hobby guys don't always "see" everything that designers intend.
Don

[Hannu]

I have Garrett ACE-series coils + extra connectors and it would be nice to know how to connect them to IDX-PRO. Anybody know how to do this?

Hannu

[Hannu]

look this one :

http://www.ebay.com/itm/Whites-6-59-...f#ht_500wt_973

[Mullihaka]

Just finished my 14th coil! This one is my first for the IDX. I used the same construction methods and materials as I have been using for TGSL coils, with the exception of the windings themselves. The other difference over the stock coil is that I have installed the tuning caps on a small jumper board inside the control box.

Hi dfbowers,

How did you null the coils i.e. did you look for a certain phase shift at some point or just minimum voltage at RX input?

I have the PCB fully populated but haven't started the coil winding yet.

All hints appreciated.

[mikebg]

I received an Email from Mr SLopov containing the following text:
" ....Have received finished pcb for IDX (I dont have enough time right now to prepare my ow .n pcb) from a close friend.
And prepared 2 coils. One DD19cm and one DD27cm.
For DD19 I read with multimeter:
TX 0.568mH 5,7 Ohms and RX 25.8mH 70 Ohms (will tell you caps that I used and freq. in my next email).
And DD27: TX 0.973mH 7,1 Ohms and RX 8,4mH 22,2 Ohms
with this one I try to replicate quicksilver coil for CZ series.
So briefly. The smaller coil is with good depth and not good SENS and GB.
The DD27 is compensated with 470n+220n+15n+15n =720n? With those caps I read 6.5kHz from TX. Havent used oscilloscope so far. Only multimeter.
For RX I soldered 22n +10n+4n7=36,7n. With this setup I can get 1€ coin for app. 30cm in house. But if I mouve coin slow then sound is none or barely noticed. Also this is with sens at 90% and treshold at 90%. And device is getting random beeps .Maybe noise interfaces.
How to tune those coils right way?
I read your posts.You are the only person who try to explain those details to public. Thanks
http://www.geotech1.com/forums/showthread.php?t=17949
So please explain this:
What is coupling coefficient and how can I manipulate it in reality?Also where to connect this 6M8 resistor? between hot leads for TX and RX?"
Here is the first of my answers relating to design and adjustment of IDX:

INDUCTION BALANCE
Induction balance is the most important thing when we try to increase sensitivity of a metal detector.
Coupling coefficient k shows what part of magnetic field generated by TX coil L1 is coupled with RX coil L2 and induces AIR signal. It is calculated by formula k=M/sqrt(L1*L2) where M is mutual inductance, L1 and L2 are self-inductances of TX and RX coil. Note that always k<1 when we have separate TX and RX coils. Only at monoicoil (the worst principle for search head) we have k=1 because M=L, L1=L and L2=L where L is self-inductance.
M and k are proportional to AIR signal existing in input of RX. The sensitivity of a metal detector depends on gain of RX preamp. To increase the gain, we need minimal AIR&GND signal because it will saturate the preamp.
Induction balance means that k or M are minimal. That makes the AIR signal minimal.
We can adjust induction balance by:
1. Loop deformation. Attached image shows a piece of wood or plastic (pos. 1) which makes deformation of both coils.
2. Aditional turn or bucking winding. Attached image shows the wire lead (pos. 2) of coil which is shifted for fine adjustment of induction balance.
3. Small shifted cores shown as pos. 3 in the image. They are placed near to sensitive area of search head and can be made of ferrite, iron and aluminium.
4. Mutual resistance pos. 4. It is formed for example ly a 4M7 potentiometer and a 4M7 resistor.
5. Mutual capacitance 5 (shown as a trim capacitor).
To adjust induction balance, we should connect an oscope 9 to output of preamp 6. An 1kOhm resistor 8 is used to avoid capacitance load of preamp. A potentiometer 7 is connected in feedback path to adjust gain of preamp near to saturation.
I will describe the procedure for induction balancing after explanation of design and and adjustment of TX and RX tanks to resonance frequencies.
Will be continued.