Moodz' Awesome Gold Pulse Induction Version 3 - MAGPI V3 Project

[KingJL]

First iteration of a miniature MAGPI v3 in SMD. Board is 100 mm x 50 mm.

Well I have completed (almost) an improved version/layout of the SMD version of the PCB that I plan on using as the basis of a probe. The new PCB is 31.7mm x 100mm.

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[Emersonpaz]

Hello moodz, some video of this detector?, I was curious. Regarding the LM6171 INA125P and DG411 integrated circuits, it is difficult to find here in my country, only buying on Aliexpress and hoping not to be counterfeit.

[Dean Sarelius]

Well I have completed (almost) an improved version/layout of the SMD version of the PCB that I plan on using as the basis of a probe. The new PCB is 31.7mm x 100mm.

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Hi KJ,
Really nice PCB just curious to know how many layers and the stackup..?

[KingJL]

Hi KJ,
Really nice PCB just curious to know how many layers and the stackup..?

Four... top inner layer = power plane, bottom inner layer = GND, top and bottom layers for routing & component placement.

[mickstv]

Hi Moodz,

Looks good, congrats....

So if I were to make the MAGPI V3, and head out to the Goldfields in Vic will it work straight away or are there secret settings for mineralised ground.


Also for coin hunting, say our typical coins 5c up to $2 what sort of in air depths can we expect ?


Regards
Michael

[IBGold]

Hi Ian ... The encoder direction is easy enough to fix. I put a diode in series with the power in your box ... you can remove ( not required if you are wired right ). The diode will be dropping some voltage otherwise something is wrong.
The voltage should read within %1 or so. My units do :-)
The volume setting is easy fixed in code or insert a series resistor in your audio line.
Yeh the other menu items disabled in code as not sure you would get the screen going. Easy to fix.

moodz

Hi Paul,

Which wires do I swap on the encoder and fine on the voltage thought it may be the reason as it is the same drop whether using 8.2V or 12.8 volt battery packs I will leave as is for now I will play with the volume while I wait for release of 1.2 code version.

Regards, Ian.

[IBGold]

Well I have completed (almost) an improved version/layout of the SMD version of the PCB that I plan on using as the basis of a probe. The new PCB is 31.7mm x 100mm.

Top:


Bottom:

If you are getting boards made could I put my name down for one?

Regards, Ian.

[moodz]

Hi Paul,

Which wires do I swap on the encoder and fine on the voltage thought it may be the reason as it is the same drop whether using 8.2V or 12.8 volt battery packs I will leave as is for now I will play with the volume while I wait for release of 1.2 code version.

Regards, Ian.

Reference pin 1 of the 7 pin programming header where pin 1 is closest to pin 1 of the PIC32.

Pin 3 = ground connects to "common" C of the rotary.
Pin 7 connects to channel B of the rotary.
Pin 6 connects to channel A of the rotary.

Pin 5 is SW1 switch of the rotary
SW2 of the rotary connects to C of the rotary to provide ground.

note these are Alps rotary encoders ... with ABC pins .. some encoders are laid out ACB ...

moodz.

[moodz]

Hi Moodz,

Looks good, congrats....

So if I were to make the MAGPI V3, and head out to the Goldfields in Vic will it work straight away or are there secret settings for mineralised ground.


Also for coin hunting, say our typical coins 5c up to $2 what sort of in air depths can we expect ?


Regards
Michael

Thanks Mick ... and good question.

The default timings give you "beach mode" and maximum sensitivity. The air sensitivity is comparable to a GPZ7000 .... but not as hot on iron ... ( the V3 certainly detects iron but not at the ranges of the 7K )
A 10 inch mono can make out a 0.1 gram nugget at around 4 cm ... the GPZ does about 2cm on the same target.
A 10cm x 10 cm foil target is nearly a meter depending ...

Its possible to change the timings if you dive into the code or when the LCD release comes out.

With the default beach timings a ferrite will give a HI LOW Hi tone .... whereas a metallic target will give a LOW HI LOW tone as the target crosses the coil. This will help you understand how the timings may be adjusted.

On the gold fields it becomes hard with beach timings .. on the beach I found lots of stuff.

The V3 is fairly simple and a "technology demonstrator" to show how the active damping and noise cancellation works ... future versions will no doubt be more complex and capable.

moodz

[mickstv]

Thanks Mick ... and good question.

The default timings give you "beach mode" and maximum sensitivity. The air sensitivity is comparable to a GPZ7000 .... but not as hot on iron ... ( the V3 certainly detects iron but not at the ranges of the 7K )
A 10 inch mono can make out a 0.1 gram nugget at around 4 cm ... the GPZ does about 2cm on the same target.
A 10cm x 10 cm foil target is nearly a meter depending ...

Its possible to change the timings if you dive into the code or when the LCD release comes out.

With the default beach timings a ferrite will give a HI LOW Hi tone .... whereas a metallic target will give a LOW HI LOW tone as the target crosses the coil. This will help you understand how the timings may be adjusted.

On the gold fields it becomes hard with beach timings .. on the beach I found lots of stuff.

The V3 is fairly simple and a "technology demonstrator" to show how the active damping and noise cancellation works ... future versions will no doubt be more complex and capable.

moodz

Thanks Moodz....

All the best with it...

[Dean Sarelius]

Hi Dean,
If you are using a 11.1V battery it would read within +/-1% of 11.1 volts typically.

I have several units and they are all OK.

R4 and R9 value text is vertical sorry about that.

Is you simulation having trouble at this voltage ?

moodz

Hi Moodz,
My understanding is that if I were to use an 11.1V battery the top of the A-D converter value would be say 3.3V.
Therefore in order to set the values of the resistors as an example 10K at the top and 4.2K at the bottom, ie (4.2/14.2) x 11.1 = 3.28V so R9 should be 4.2K instead of 1K...?

[moodz]

Hi Moodz,
My understanding is that if I were to use an 11.1V battery the top of the A-D converter value would be say 3.3V.
Therefore in order to set the values of the resistors as an example 10K at the top and 4.2K at the bottom, ie (4.2/14.2) x 11.1 = 3.28V so R9 should be 4.2K instead of 1K...?

Hi Dean

If you are talking about the 11.1 volt LIPO pack ... fully charged the voltage is higher than 11.1 volts should be 12.6 volts.

.. the values of 1K and 10K are convenient and the rest is handled in the software.
The two resistors proved a 1/11 divider of the input voltage. So the maximum voltage this circuit can read with the ADC at full scale ( ie 3.3 volts input ) is 3.3 x 11 = 36.6 volts.
The V3 circuit will withstand about 18 volts for short periods without blowing up and so 36.6 is about twice this rating and a good rule of thumb.
It also happens that linear regulators and quite a few switch modes chips can take up to 35 volts input so again it is very useful.

There is no need to read the battery voltage beyond 0.1 volt resolution.

If it was a commercial product my code would read the battery voltage and if the customer applied too much voltage my code would store this in flash so if a warranty was claimed then this would be pointed out to the customer. ( been there and done that ).

moodz

[Dean Sarelius]

Hi Dean

If you are talking about the 11.1 volt LIPO pack ... fully charged the voltage is higher than 11.1 volts should be 12.6 volts.

.. the values of 1K and 10K are convenient and the rest is handled in the software.
The two resistors proved a 1/11 divider of the input voltage. So the maximum voltage this circuit can read with the ADC at full scale ( ie 3.3 volts input ) is 3.3 x 11 = 36.6 volts.
The V3 circuit will withstand about 18 volts for short periods without blowing up and so 36.6 is about twice this rating and a good rule of thumb.
It also happens that linear regulators and quite a few switch modes chips can take up to 35 volts input so again it is very useful.

There is no need to read the battery voltage beyond 0.1 volt resolution.

If it was a commercial product my code would read the battery voltage and if the customer applied too much voltage my code would store this in flash so if a warranty was claimed then this would be pointed out to the customer. ( been there and done that ).

moodz

OK this makes sense to me now, of course I can always refer back to your code and this will help me to understand the setup..cheers

[Dean Sarelius]

Four... top inner layer = power plane, bottom inner layer = GND, top and bottom layers for routing & component placement.

Thanks KJ cheers

[Dean Sarelius]

Thanks Mick ... and good question.

The default timings give you "beach mode" and maximum sensitivity. The air sensitivity is comparable to a GPZ7000 .... but not as hot on iron ... ( the V3 certainly detects iron but not at the ranges of the 7K )
A 10 inch mono can make out a 0.1 gram nugget at around 4 cm ... the GPZ does about 2cm on the same target.
A 10cm x 10 cm foil target is nearly a meter depending ...

Its possible to change the timings if you dive into the code or when the LCD release comes out.

With the default beach timings a ferrite will give a HI LOW Hi tone .... whereas a metallic target will give a LOW HI LOW tone as the target crosses the coil. This will help you understand how the timings may be adjusted.

On the gold fields it becomes hard with beach timings .. on the beach I found lots of stuff.

The V3 is fairly simple and a "technology demonstrator" to show how the active damping and noise cancellation works ... future versions will no doubt be more complex and capable.

moodz

Hi Moodz,
My understanding is that the V4 will provide discrimination while the V5 will be a bipolar design.
Comparing the bipolar option to the V3 mono-polar pulse what if any will be the advantages in your opinion..?