IDX-PRO+VDI

[Davor]

when waving pliers at it....

The Disc/GEB detector signals are opposite is polarity - one up, one down. ?
Is this correct?

Yes. IDX and TGSL are single quadrant detectors, and they trigger only for both I (GEB) and Q (Disc) channels going positive (in this particular case, and that particular spot it must be both negative, the inverting gain stages take care of that). If you reverse inputs of the lowest comparator, you'll get a Fe discriminating rig.

[golfnut]

pic

pic

[golfnut]

Signals from DET

Looking at my IDx - it works well... -




when waving pliers at it....

The Disc/GEB detector signals are opposite is polarity - one up, one down. ?
Is this correct?


If these signals are going into a common comparator for triggering - both sigs have to 'trip' above threshold (both sig paths are AND - ed together) then the sig polarities should match - so seems wrong?

Steve

[Schatztaucher]

sorry, of course. I went there just for the principle of the right connection ....

[Davor]

... and in a process you'll get an all-metal indication. Kinda two flies with one blow. Good thinking.

[golfnut]

Geb level

With my recent enlightenment - finally understanding operation of things like IDX IGSL.

I know that keeping the Geb Ch putput nulled to min is really important.


I have a couple of old miniature meters - I want to rig one to the geb output - So I can visually track whats happenning and tweak it down to min - I think this will remove some ambiguity and quickly sets machine up for some hardcore search action..

I may need to buffer the GEB Ch - pick off sig where VDI normally does

S

[LAX]

Thanks a lot.
I've thinked this as well, but I wasn't sure.


Lax

[eduardo1979]

2 Tones

That is correct.

[verotopasera]

This scheme is correct. The former does not. Look at the pin 5 of the CD4024.

eduardo1979 Place the file here (lay)

[eduardo1979]

This scheme is correct. The former does not. Look at the pin 5 of the CD4024.

[Schatztaucher]

perhaps this can help

[LAX]

Hi all,
Can anybody help me how do I connect my IDX pro to Eduardo's 2 tone board ( all from Silverdog).
As you can see I'm not a pro

Lax

[golfnut]

I built one of these last night.


My disc appeared backwards - all really odd.

Tx to Rx phase was about 150 deg - tried the old 'swap the Rx coil wires over' trick and it all came in.


Nice to have a PP - not played with these before, glad to see it works on the 27cm DD.

As it is it doesnot see small items like small balls of solder, maybe lead shot - which may be a blessing after grubbing thru a palm of soil for an atom of iron with a PI!

Im running at 7.8kHz (I targeted 8k) to help find smaller items.


I only have about 20T (0.3mm) on Tx coil and 6v peak to peak
and about 200T on Rx (0.2mm)

Crisp Disc, can see difference between rusty iron and steel, Silver booms in fortunately right round to far end. Small roman bronze approx 50 % travel.


Need to finish this for a farm permission in a couple of weeks.

S

[maxfly]

Thanks for help

I appreciate all the replies with my issues,

Regards,
Max

[maxfly]

Hi Golfnut,
Thanks for heads up about frequency.
That has solved most problems. Legend!
I set it up at 6.5khz with 90deg phase angle but found that I couldn't adjust gb anymore so have settled somewhere aroun 7.6khz with 120deg phase. Scope looks heaps cleaner at 6.5khz, maybe I'm missing something in the setup procedure or can adjust a component to bring g. Into range?
I too have notice dicrepencies with schematic.
Eduardo has suggested to remove vr3 pot and use 1k res. Not sure what it does either.
Vr2 is gone but what was its purpose?
Anyway I'm getting about 35 cm on a large nickel coin in air at the moment so not terrible.

Max