RELIC HAWK

[Ultimate_Haze]

Hi

Hi,
Fred.
Can you post latest PCB look.

[tiktak]

Hi,

Hi,
I will be glad if this happen BUT HOW YOU calculate this?
Please share your calculator

[amtech2005]

RELIC HAWK

Hello everyone , there are only a few issues left to resolve on The Relic Hawk Project . 1. the Search- Coil , and if the search-coil pre-amp or Minelabs little circuit inside the coil is required ? 2. Specialty transistors needed for the TX Oscillator circuit . And yes it is blazing Hot in my workshop "IT IS CLOSED" for the summer !!!!! . I calculate this Relic Hawk Project will be completed just before Christmas , and will be a Holiday Gift from Geotech Forum to all its Members !!!!!!!!...........Eugene

[Fred]

Yes Max!
It´s just too hot now to stay inside working on PCB´s ,better things to do when summer is here.
But it´s far from abandoned project!.
As you know i have made the double side PCB and it may work different.
The enamelled wire is still new on its shelf...

I´m sure rainy days will see the RH working
regards,
Fred.

[Max]

Since RH hit the stone here is
Old idea, but fresh for the forum, never posted before.
Fisher 1266 + Relic Hawk. Never done on pcb, never tested. Just raw concept of combining RH TX/RX circtuit with Fisher 1266 with ML RH coil type.

Hi,
RH hit the stone ??? No... I'm just doing other stuff... I gave up (for a while not forever...) with the iron detection at far distance, cause I think is too subtle problem to try to solve at now... that I'm full of other stuff to do... you know... it's also summertime!

I'd like also that someone else will finish the board to make some comparision... cause could be also a local problem at my prototype and that will make it easy find that if so...

Also, apart the iron detection at far... the detector works as expected... and is also about deep about detection... so it's only a small thing... maybe related to a schematic mistake or to something strange at ML design.

I have also to say that I'm using just homemade coils for it... I haven't original to test so...it's not easy understand if the problem if from a bad coil or some e.g. wrong capacitance value...

What's this new schematic ? Hybrid stuff ???

Kind regards,
Max

[eclipse]

Since RH hit the stone here is
Old idea, but fresh for the forum, never posted before.
Fisher 1266 + Relic Hawk. Never done on pcb, never tested. Just raw concept of combining RH TX/RX circtuit with Fisher 1266 with ML RH coil type.

[Max]

Hi Fred.
I will remember it
So i found the point that Max don't stay Calm
Regards

Hi,
I think we must leave off LRLs from this thread... just waste of time here... better if on remote sensing.

Now, I'm doing some checks on diff channels... along the signal path but measures are a bit complicated cause after dc decoupling only ac signals pass through the chain... then measuring something that vary is not so easy.

I will take measures just in points where I could get good informations to draw new plots... , not so easy.

Kind regards,
Max

[Geo]

Hi Geo,
I suggest that if you want Max to stay calm , never mention LRL´s when talking seriously
Regards,
Fred.

Hi Fred.
I will remember it
So i found the point that Max don't stay Calm
Regards

[Fred]

Max, I had the same problem with the PD when it was bad tunning. Also i had a similar problem at one LRL where the head was with ferrite.
Regards

Hi Geo,
I suggest that if you want Max to stay calm , never mention LRL´s when talking seriously
Regards,
Fred.

[Geo]

Hi,
I don't know... maybe is possible reduce the effect but I think that an iron mass at few cms from coil could give such an effect more or less.

The fact is that the signal goes down when with iron... no matter if there's the invertion or not and with other stuff like silver it goes well positive... and that's more and more confusing cause one would expect the total iron ignoring and there isn't!

Kind regards,
Max

Max, I had the same problem with the PD when it was bad tunning. Also i had a similar problem at one LRL where the head was with ferrite.
Regards

[Max]

Hi Max,

Sorry for the delayed response.
These plots look exactly as I would expect. If DISC is not working correctly, then the problem must be located further along in the DISC channel. Can you now probe the output of the first differentiating stage (as before) and let us know the results?

The inversion with the large iron is quite simple to explain. Ferrous items cause the amplitude to decrease, but there is a limit on how much it can decrease. As the target gets closer to the coil, the signal will be inverted and start to increase. You should be able to confirm that the same thing happens with the TGSL.

Hi,
I will try... will test using same distances and report here.

Kind regards,
Max

[Qiaozhi]

Hi Qiaozhi and all,
here some plots made with data collected for different targets.

First some values...

At 220nF - 1M6 joint at input of disc channel... just after the sampling gate and low pass I have a 0.22V level above the GND level.
Consider that GND is at about 5V over the negative rail... so the level at input is something 5.22V.

Now... I tryed retrieving from there the voltage variations... but was impossible task... too small variations and too offset to do it well... so I read them after the integrator.

At pin1 of U4 (integrator , disc channel) I have +3.5V above GND when no metal near coil. Coil was nulled at 15mVpp before tests.

All metals considered give positive response BUT iron that gives negative.
The values are respect the steady 3.5V so positive values for gold, silver etc... and negative (meaning less than 3.5V there respect GND) for iron... just when nearing iron very much you'll get invertion and rise variation, but always negative value.

So, consider I've reported in plots just variations respect to the steady state of no metal near. Also consider you'll see points with straight joints + poly interpolation I've added there to get better the picture.

Do you think something is wrong with them ?

Kind regards,
Max

Hi Max,

Sorry for the delayed response.
These plots look exactly as I would expect. If DISC is not working correctly, then the problem must be located further along in the DISC channel. Can you now probe the output of the first differentiating stage (as before) and let us know the results?

The inversion with the large iron is quite simple to explain. Ferrous items cause the amplitude to decrease, but there is a limit on how much it can decrease. As the target gets closer to the coil, the signal will be inverted and start to increase. You should be able to confirm that the same thing happens with the TGSL.

[Max]

Hi Max,
Nice work with the plots,
The invertion with the hammer is precisely what i was talking about some days ago.
I thought it was possible to cancel it by coil configuration?
I don´t understand why you cannot find a way to make coils without this invertion.
I didn´t make progress on my RH, i still have a few things i must do while weather allow it
Regards,
Fred.

Hi,
I don't know... maybe is possible reduce the effect but I think that an iron mass at few cms from coil could give such an effect more or less.

The fact is that the signal goes down when with iron... no matter if there's the invertion or not and with other stuff like silver it goes well positive... and that's more and more confusing cause one would expect the total iron ignoring and there isn't!

Kind regards,
Max

[Fred]

Do you think something is wrong with them ?
Kind regards,
Max

Hi Max,
Nice work with the plots,
The invertion with the hammer is precisely what i was talking about some days ago.
I thought it was possible to cancel it by coil configuration?
I don´t understand why you cannot find a way to make coils without this invertion.
I didn´t make progress on my RH, i still have a few things i must do while weather allow it
Regards,
Fred.

[Max]

seems nice....

Hi Qiaozhi and all,
here some plots made with data collected for different targets.

First some values...

At 220nF - 1M6 joint at input of disc channel... just after the sampling gate and low pass I have a 0.22V level above the GND level.
Consider that GND is at about 5V over the negative rail... so the level at input is something 5.22V.

Now... I tryed retrieving from there the voltage variations... but was impossible task... too small variations and too offset to do it well... so I read them after the integrator.

At pin1 of U4 (integrator , disc channel) I have +3.5V above GND when no metal near coil. Coil was nulled at 15mVpp before tests.

All metals considered give positive response BUT iron that gives negative.
The values are respect the steady 3.5V so positive values for gold, silver etc... and negative (meaning less than 3.5V there respect GND) for iron... just when nearing iron very much you'll get invertion and rise variation, but always negative value.

So, consider I've reported in plots just variations respect to the steady state of no metal near. Also consider you'll see points with straight joints + poly interpolation I've added there to get better the picture.

Do you think something is wrong with them ?

Kind regards,
Max