IDX-PRO+VDI

[Wiltran]

I made my IDX as the scheme in the attachment with some differences.
TX generator and the sound made by PIC16F675 running at 3,58 MHz, but also a difference in the supply side.

Ok thanks Holyuser. But that is completely different than the Eduardo version I built. By the way, where do you connect the VDI?

[holyuser]

But that is completely different than the Eduardo version I built. By the way, where do you connect the VDI?

But, despite some differences, the core of the scheme is completely the same, the input amplifier, a phase shift circuit, sync detectors, channel amplifiers (filters) all the same and this is important.
If possible, find the standard White's coil for 6,59 KHz and try. I doubt that the problem is there.
I connected my VDI as follows: X input - to pin 8 of U3, Y input - to pin 7 of U3 (LMC6484), battery and power is clear, I guess. These are indications of the PDF scheme I applied.

[Wiltran]

But, despite some differences, the core of the scheme is completely the same, the input amplifier, a phase shift circuit, sync detectors, channel amplifiers (filters) all the same and this is important.
If possible, find the standard White's coil for 6,59 KHz and try. I doubt that the problem is there.
I connected my VDI as follows: X input - to pin 8 of U3, Y input - to pin 7 of U3 (LMC6484), battery and power is clear, I guess. These are indications of the PDF scheme I applied.

yes that's how I have it connected, with the exception my U3 is a LF347. Would that make a difference?

[holyuser]

yes that's how I have it connected, with the exception my U3 is a LF347. Would that make a difference?

Using the LM347 instead LMTS6484, I think, is not critical.
More importantly, what coil is connected? The parameters of the coil determine the angle of phase shift that VDI used as support for the measurements.

[Wiltran]

Using the LM347 instead LMTS6484, I think, is not critical.
More importantly, what coil is connected? The parameters of the coil determine the angle of phase shift that VDI used as support for the measurements.

I built the coil with eduardos specs TX .7MM 35T .587MH 1 MFD cap inside coil,
RX .15MM 270T 35.6 MH .0033 cap inside coil. Discrimination seems good. alum foil and steel completely rejected. US quarter at about 12" detect distance. most of the chattering can be eliminated by reducing threshold. But adjusting 10k VR3, and 5k pot on VDI board seems to have no effect on zeroing foil. Steel reads about 45 and everything else reads about 70-80. Maybe VDI wont work with homebuilt coil unless its fully nulled.

[Wiltran]

Using the LM347 instead LMTS6484, I think, is not critical.
More importantly, what coil is connected? The parameters of the coil determine the angle of phase shift that VDI used as support for the measurements.

Do I understand correctly that the PIC program in VDI is tailored to a certain brand of coil? IF so it means that I would have to get the exact phase angle in my homemade coil to match.

[holyuser]

Steel reads about 45 and everything else reads about 70-80.

It seems likely that if the receiving coil are reversed terminals.

Do I understand correctly that the PIC program in VDI is tailored to a certain brand of coil? IF so it means that I would have to get the exact phase angle in my homemade coil to match.

The VDI program calculates the phase angle between supporting the X axis signal and a RX signal vector. It is essential phase ratios in the whole scheme and the coil, to be close to the original IDX.

[Wiltran]

IDX & VDI

Anybody else having success or problems with Eduardo IDX with connected VDI using DD coils?

[ivconic]

Anybody else having success or problems with Eduardo IDX with connected VDI using DD coils?

What's a big deal?
I made it and connected it to IGSL, it is working pretty accurate.
It is not more nor less accurate than White's Spectrum VDI (i had few and i can only compare to it).
Shorter: it is enough accurate and usable.
I don't think it is especially suitable only for specific type of coil.
It can be calibrated and adapted for most of hand made we have here on forum.
I still think that "Achtung Minen" is something we don't need and therefore i will not include it in my detectors, until is changed to something more proper.
Trick is in LCD character codes, if table inside PIC was changed or messed up; than certain routine calls check and returns message using LCD character set, stops further program flow and repeats blinking of that message.
It can be hacked, but i will not do that for public, because "author" is already member here.
It is up to him to decide about that message.
Other reason not to include VDI in IGSL is power drain.
IGSL is already "good customer" relating to power drain, adding VDI will rise power consumption over 100mA - which certainly i don't want, nor need.
But for "lighter" projects with less power drain ; VDI can be pretty sweet addition and i do recommend it.
So, there are no problems related to any type of coil. Phase is phase, no matter what coil you will use.
That's my few words about it.

P.S.
Ooops, i reversed X and Y positions on photo. I just saw that mistake... Should be opposite.

[ivconic]

...

[ivconic]

Anybody else having success or problems with Eduardo IDX with connected VDI using DD coils?

On second thought.... any eventual problems can be related more to detector than to coil.
Because i made 44 CL3's so far and gained some experiences with it.
It is pretty tough to adjust it right so to be stable and immune (speaking on Disc&Geb circuitry).
Air depths are great, but behavior in soil sometimes can be quite different story.
You will need to put extra effort to make it right.
It is not that easy as maybe seems.
(i bet guys from White's are laughing now)

[ivconic]

Eduardo, this MD is awesome! great depth, good stability, and has very sharp discrimination. On your next revision you might add two pads on the board to hook X&Y for VDI. Just to be sure, do you hook X&Y on VDI board to U3 pins 7&8? This was hard for me to build because the board was very compact and densely populated. Also the receive coil was hard to wind with such fine wire! That being said, it is a fine project , but not for a beginner. I can get different readings for different metals on VDI, but I cant seem to get it to zero on foil. Can you or anyone explain adjustment procedure on 10k VR3 on board, and 5K pot on VDI board? thank you.

Why would you want to "zero" it on foil?!?
Al foils should be indicated in range +5 to +25 (approximative, can't exactly recall how it was at Spectrum..), depends on size and width?
Isn't that right?
At VDI+IGSL; Al foils (and thin silver) are nicely indicated in that range, irons in minus range, good coins between 55 and 75 etc..etc...
Pure ground, hotrocks, minerals and ferrite are indicated in range -5 to +5, also approximative (or max and min ends of ranges if signal is very strong).
Aren't those proper ranges?
I think those are, because correlating with common logic.
...

If you look posted photos:
+62 is nice,fat, 3cm diamm Cu/Ag coin.
-49 is large pliers,
-6 is medium sized nail,
-33 is large rusty nail,
+49 is 2cm bronze coin,
...

I experimented with menu adjustments.
Right now i can't recall most proper adjustments i achieved.

[Wiltran]

It's good to see you got it going, Ivconic, and to see it works with IGSL! Which 2 pins on LF347 did you connect it to? and it looks like you had to change VDI settings delay ETC to get it to work. After you change the settings does it get saved in the PIC chip for default startup? thanks for the reply.

[ivconic]

It's good to see you got it going, Ivconic, and to see it works with IGSL! Which 2 pins on LF347 did you connect it to? and it looks like you had to change VDI settings delay ETC to get it to work. After you change the settings does it get saved in the PIC chip for default startup? thanks for the reply.

As you see on posted photo; pin 14. of upper LF347 and pin 1. of LF347 bellow.
Yes i experimented with VDI settings, but like i said: i can't remember.
It was few weeks ago and after i made it to work right - i reassembled it and put it away.
Damn... i needed that LCD for something else... those components - never enough!
Yes, PIC do "remember" all the settings, which is very nice!

[Wiltran]

IDX DD COIL

I am trying to fine tune the homemade DD coils, and I am finding something strange! In the TGSL, the TX coil you would come up with about 14.6 KHZ. For RX coil you would come up with about 16.2 KHZ 14.6 divided by 16.2 = .9 ratio.

If you input data into a LCR calculator for IDX with DD coil you get 6.5 KHZ for TX coil. Ok, but when you input data for RX coil you get 14.6 KHZ! a ratio of .445! Should'nt the receive coil be 7.22 KHZ?

TX coil .587 MH, 1MF.
RX coil 35.6 MH .0033 MF