GoldScan IV

[zzy]

Hi Max
I have made GoldScan IV,Not finished.Do you know what is the "L4" "470K" mean?


I uses a 100uH replace it ,I think this causes a lot of noise.

[kt315]

oops! digits taken from original one.

[zzy]

oops! digits taken from original one.

HI kt315
Do you know the value of "L4"? 470uH?

[Max]

Hi Max
I have made GoldScan IV,Not finished.Do you know what is the "L4" "470K" mean?
[ATTACH]5837[/ATTACH]

I uses a 100uH replace it ,I think this causes a lot of noise.

Hi,
in original schematic by Alexis it's 473K, I've used 47mH there (47000uH) and works good.

It's not so important unless you put there something that will create too much interferences like a little speaker could do.

Kind regards,
Max

[zzy]

Hi Max,
Thanks you reply,I have another stupid question:
How to use are "HOLD" and "RESET" switch?
GoldScan IV is a motion or no-motion machine?

[Max]

Hi Max,
Thanks you reply,I have another stupid question:
How to use are "HOLD" and "RESET" switch?
GoldScan IV is a motion or no-motion machine?

Hi,
you have full non-motion if no feedback active (SAT), you have to tune frequency for a very low freq beating note... depending on your preferences... anything from 1Hz to 2-4-5Hz or more (threshold)... then nearing any metal the frequency will increase depending on size and distance. For far stuff you'll get just double or more the freq beat but when near more and more the VCO will give you an higher pitch tone.

The reset button is there to reset when e.g. you near a very big piece of iron... then capacitors cannot discharge in few time: you press it and that's enough to get threshold again like you set it at first.

The HOLD... well... let me remember... I don't use it so frequently... if I remember well it's kind of auto tune, you lock it and device will self retune to a preset value in very few time: 15mV at output if remember well... so you can use as kind of SAT control (self adjusting threashold) or if you prefer..call it motion mode. I remember that Reg put somewhere a modification with another SAT stuff... employing just a couple of resistors but now forgot where it was ...which thread I mean.

Remember: disc doesn't work like you probably expected... do not trust it on real stuff, dig everything.

The part I like is about soil mineralization controls... that's important feature for a PI. The GS4 was developed with australian soils in mind!

PS: unfortunately like other sensitive PIs it suffer much of bricks and pottery detection... really worse attitude!

Kind regards,
Max

[gef12]

Hi
With ref to the GS4 did you guys make ur own PCB or procure it from somewheres ... if so can you advise please
Seems like a good project ..
thanks

[zzy]

Hi,
you have full non-motion if no feedback active (SAT), you have to tune frequency for a very low freq beating note... depending on your preferences... anything from 1Hz to 2-4-5Hz or more (threshold)... then nearing any metal the frequency will increase depending on size and distance. For far stuff you'll get just double or more the freq beat but when near more and more the VCO will give you an higher pitch tone.

The reset button is there to reset when e.g. you near a very big piece of iron... then capacitors cannot discharge in few time: you press it and that's enough to get threshold again like you set it at first.

The HOLD... well... let me remember... I don't use it so frequently... if I remember well it's kind of auto tune, you lock it and device will self retune to a preset value in very few time: 15mV at output if remember well... so you can use as kind of SAT control (self adjusting threashold) or if you prefer..call it motion mode. I remember that Reg put somewhere a modification with another SAT stuff... employing just a couple of resistors but now forgot where it was ...which thread I mean.

Remember: disc doesn't work like you probably expected... do not trust it on real stuff, dig everything.

The part I like is about soil mineralization controls... that's important feature for a PI. The GS4 was developed with australian soils in mind!

PS: unfortunately like other sensitive PIs it suffer much of bricks and pottery detection... really worse attitude!

Kind regards,
Max

Hi Max,
Good explanation.Strangely,My test shows GS4 is a motion machine,the detection is poor.I don't konw where is the problems.

[zzy]

Hi
With ref to the GS4 did you guys make ur own PCB or procure it from somewheres ... if so can you advise please
Seems like a good project ..
thanks

Hi
Max give me the SCH and PCB,this machine is not easy to make.Too many small resistance on the bottom PCB.

[Max]

Hi Max,
Good explanation.Strangely,My test shows GS4 is a motion machine,the detection is poor.I don't konw where is the problems.

Hi,
no... you probably have something in schematic that's different from what I have. Maybe the SAT mod I talk to you... look for resistance 470K or something near the 470nF caps at middle. I remember Reg put a switch to enable that feature or not... probably you haven't any switch there... let me look at Vladimir stuff again... I remember just the Alexis' one... then I will answer better about this.

Now about performance... it's a great MD! Very impressive performance on air, well balanced also, can detect coins at very deep simply using 8'' coils. Much more depth with larger coils on big stuff... meters!
Problems then is not performance on air... but on soil: real soil contains often magnetic stuff... crystals... and not a problem when they are random oriented in the space (the magnetic moment I mean)... but fired stuff... like fired bricks or ceramics has them all aligned and it's kind of detecting a magnet: bricks and pottery make GS4 crazy very easy and from far distances...give same audio response of e.g. coins or anything else.

Kind regards,
Max

[Max]

Ok... I found it:

look at there... this is Vladimir's mod, in original Reg's SAT mod both resistance were 470K and there was a double-switch to enable or disable them from signal path.

Look... if you remove resistors you'll get non-motion, like original design in Alexis' schematic; if you leave them there you get a fast SAT behaviour... so motion kind.

Kind regards,
Max

[zzy]

Hi Max,
Just like you said,i remove the two resistors. GS4 becomes a non-motion machine.Very thankful!
And i find that when a metal object near the coil, the beating frequency will decrease, when more near the coil a little,the beating frequency increases rapidly,and then turn very sharp tone,when i remove the metal, the sharp tone will delay about 15 second to the original beating frequency.


I test it in all metal mode. Detection is poor, I use a 20cm diameter coil,
20 euro cent is at 10cm.

[zzy]

sorry

It 's very unstable.

[zzy]

Hi Max,
Just like you said,i remove the two resistors. GS4 becomes a non-motion machine.Very thankful!
And i find that when a metal object near the coil, the beating frequency will decrease, when more near the coil a little,the beating frequency increases rapidly,and then turn very sharp tone,when i remove the metal, the sharp tone will delay about 15 second to the original beating frequency.


I test it in all metal mode. Detection is poor, I use a 20cm diameter coil,
20 euro cent is at 10cm.

Hi Max,

Sorry my bad observe.The fact is this:
I remove the two resistors. GS4 becomes a non-motion machine,
but it's beating frequency increases gradually.Only you push the "Reset" button,the beat'll stop 3 second. Then it's beating frequency increases gradually.

[Max]

Hi Max,

Sorry my bad observe.The fact is this:
I remove the two resistors. GS4 becomes a non-motion machine,
but it's beating frequency increases gradually.Only you push the "Reset" button,the beat'll stop 3 second. Then it's beating frequency increases gradually.

Hi,
you probably have some mistake there... check very carefully... cause device is hell sensitive, you can belive me...I've made it long time ago... you can get 1eur at 30cm pretty easy with a 20cm coil , without any effort at all I mean.

Actually device can be tuned so sensitive that you'll never belive till you see that but that requires much efforts expecially on coils.

If you saturate the integrators it will require much time to recover threshold... but in these cases you'll use the reset to make things go quickly.

What about coil you use ? Inductance ? Resistance ?

Kind regards,
Max