AMX RX

[ivconic]

detectormods and ivconic, thank you for the valuable contributions. We are making progress.

Maybe we should start a new thread for the digital part which is really going to be the main part of the design.
"Does AMX Digital" sound OK?
There are many decisions to be taken for the digital part. My knowledge in this field is about zero, so please somebody with knowledge step in.

We need to decide between direct sampling and analog integrated amplifier and then ADC.

With The analog integrated signal, a slow 12 bit ADC might be good enough.

With direct sampling, like a preamp with a gain of 1000 input to the ADC, we should use a high Msps 24bit ADC.

In any case, the choice of MCU and ADC should be for relatively new products because it is no easy task to change the software once countless hours have been spent to get everything just right and tested and the right algorithms designed and tested and debugged.

"AMX Digital" is alright as far as I am concerned.
Yes that's most important question, which is about to decide the whole project destiny; direct sampling or analogue integrator.
In the "ideal world", (if I would be able to easily and cheaply get everything I need); I would always choose direct sampling.
But almost none of the conventional development systems have a processor with a good ADC (24bit is ideal).
So for good direct sampling, it is necessary to choose a good external ADC.
And it is... a can with many worms!
In the current conditions (this "current" has lasted decades for me);
it might be smarter to choose an option with an analog integrator that will "chew" the signal to the extent that even
a 12bit ADC is more than enough for further processing.
I say "12bit" on purpose, because the vast majority of various development systems have a processor on them, mostly with such an ADC.
And that choice will make this project a "people's" project. For every pocket, for every taste, for the vast majority of participants.
But! As in the previous case with your RX design; one should try to avoid "exotic" component values.
One Dave Johnson is enough for this life of mine!

[Tinkerer]

detectormods and ivconic, thank you for the valuable contributions. We are making progress.

Maybe we should start a new thread for the digital part which is really going to be the main part of the design.
"Does AMX Digital" sound OK?
There are many decisions to be taken for the digital part. My knowledge in this field is about zero, so please somebody with knowledge step in.

We need to decide between direct sampling and analog integrated amplifier and then ADC.

With The analog integrated signal, a slow 12 bit ADC might be good enough.

With direct sampling, like a preamp with a gain of 1000 input to the ADC, we should use a high Msps 24bit ADC.

In any case, the choice of MCU and ADC should be for relatively new products because it is no easy task to change the software once countless hours have been spent to get everything just right and tested and the right algorithms designed and tested and debugged.

[ivconic]

Do you know of any ADC with +/- 5V input that we could use?
Would it help if I redraw and simplify the RX ?

I am impressed with an obsolete one, WM8738, I have dozen modules with it and made audio links with it. Impressed with what I saw in practice. Live instrument playing over it, no latency that may be easy noticed especially in live playing.
You know; dealing with guitar preamps and effects for guitars is pretty similar as with dealing with some parts of metal detectors. And the speed and resolution of such ADC is playing crucial role in that story.
Fast guitar strings picking and no latency at all; that's what I call "The ADC"!
It is single supply, I tested it with 3.7-4.2V battery. It has I2S and that's limiting factor to use some dev boards. But many better and more powerful dev boards do have I2S.
As for the RX frontend; I planned (and obtained in local) LME49720, look its datasheet, looks also impressive and quite up to this task.
But... !!!
Than I randomly stumbled on this article and was completely shocked:

https://www.audiosciencereview.com/f...-family.10687/

[detectormods]

https://www.analog.com/media/en/tech...s/623637fb.pdf

this is in the gold monster as the adc driver, diff to single line.

I think this is the adc that that they use in the coil itself, https://www.analog.com/en/products/l...oduct-overview

[detectormods]

Do you know of any ADC with +/- 5V input that we could use?
Would it help if I redraw and simplify the RX ?

https://www.analog.com/media/en/tech...s/623637fb.pdf

this is in the gold monster as the adc driver, diff to single line.

[Tinkerer]

No, no... you are right, schematic I did is not making any sense at all.
Sorry.
I give up.
I am not in position to materialize your schematic, pity.
...
But than again; if you would be so kind as to make a video of how that circuit works, it would be very productive.

Do you know of any ADC with +/- 5V input that we could use?
Would it help if I redraw and simplify the RX ?

[ivconic]

Are you still working with 3D design and printing?

Yes, at this very moment I am adjusting sizes for XP Deus coil screw, nut and insert.


Last couple days I did several enclosures too.
You and others here can count on me to draw 3D enclosure and needed parts for this project, no problem.

[Tinkerer]

No, no... you are right, schematic I did is not making any sense at all.
Sorry.
I give up.
I am not in position to materialize your schematic, pity.
...
But than again; if you would be so kind as to make a video of how that circuit works, it would be very productive.

Are you still working with 3D design and printing?

[ivconic]

No, no... you are right, schematic I did is not making any sense at all.
Sorry.
I give up.
I am not in position to materialize your schematic, pity.
...
But than again; if you would be so kind as to make a video of how that circuit works, it would be very productive.

[ivconic]

As I said, the schematic is principal, just to see if it can be converted into a through-hole variant with slightly older components.
The ADC I had in mind is 5v. But even so; this schematic will require revisions for 5V ADC too.
That's a minor problem.
A bigger problem is component values that cannot be found.
A trivial solution is to put 3x1uF in parallel and get 3uF, for example. What about the other values?
Too many values to "trim" like that.
And most resistor values are very tricky to "make".

[Tinkerer]

What voltage signal do you intend to feed your ADC with?

This whole circuit is designed to work with +3.3V and GND and 1,65V Reference, so that it can be input directly into a 3.3V ADC.

It is designed to extract the REACTIVE signal only, DURING the 500V to 1000V Flyback.

What is it for? To measure the losses of energy caused by the absorption by the ground and the targets.
Why do we want to quantify these losses? With the CCPI, these losses need to be compensated.

[ivconic]

I drew the schematic in principle.
Only now that I have placed each component one by one on the schematic by myself; I see how many components there are with precise values.
Very unusual and very hard to find.
Some values are impossible to find...at least in non SMD packages.
A large number of non-polarized capacitors have a "tremendous" value, and I must admit that I have not had the opportunity
to see such value in real life until now. 3uF...1.8uF...2.5uF... in common 5mm raster.
I fence myself off; I still don't know what the situation is with those values when it comes to SMD components.
Because I don't work with SMD, I did a little something, it's not worth mentioning.
I have to contradict myself again from previous posts; not only can't find the opamps from the schematic;
also it is impossible to find most of the passive components as well.
There are too many arguments against it... I'm very sorry about that.
But this approach is very far from "diy" and "hobby".
And I guarantee that the vast majority of forum members will not be able to do this.
I'm sure that hardly a few members will be in a position to reproduce all this to the end.
This is what I have repeatedly warned about in previous topics.
Tony, I'm very sorry, your work and effort is obvious, but this is a very "specific" assembly with many unusual and non-standard moments.
Here is my reproduction, I chose some components quite randomly. Purely to remain only as concept.
I took a 10v power supply just as an example, and divided it in the same way, the reference is the virtual ground,
and the real physical ground is connected to the minus.
Same as your schematic; just with a different logic when observing.

[Tinkerer]

DG419LEDQ - SOP8, OK, I can solder that. Present on Aliexpress,
AD8031AR - SOP8, OK, I can solder that. Present on Aliexpress,
ADA4807 - MSOP8, NOPE I can't solder that. Present on Aliexpress,
...
Problem.
Headache.

...

The icing on the cake... I keep looking at the wrong schematic! I should have been looking at "RX_REACTIVE_FILTER_DIFFERENTIAL_01-27-2023 - Schematic.pdf"
Now.. double headache!


Given that now the Chinese are celebrating their new year and a series of other holidays and will not work
for a total of 43 days !!! (if I'm not mistaken) ... and considering how late the shipments from there usually are...
and considering that I'm not able to solder some components...
People, don't wait for me, because you will be waiting for a long time.
And the one who was waiting for Godot waited less.
You work if you have the conditions and I will just follow what you write.
Unfortunately... it is what it is.
If I redo the whole schematic with the components I have, which are mostly through-hole and outdated, they don't even have those specifications...
it won't work at all. What a waste of time it would be.

When designing "state of the art" innovative products, it is recommended to accept the advice of the manufacturer "not recommended for new designs".
However, when I do quick mockups, I often use some 30, 40 years old parts that I still have in the "old parts box". Through holes that I can stick into the old breadboard.
I do not expect to achieve performance to beat the best in the world. I do it to test principles. To learn, to understand how the circuit works.
Like your LT1037 opamp, yes I still have some in the box. I remember when I bought them. So much better than the NE 5534. Same with the old switches, was it 4066?
4016 and 4017? (you can use them, just watch out for the drive voltage and PSU)
If you understand the principles of the functions, you can make it work. A bit slower, a bit noisier but in principle it works.
If I want to run a Flyback of 1000V, I need to be careful with the layout, the cable and all the little details. Really study the datasheets. But if you want to use a Mosfet rated for 400V you still need to read the datasheets, and change things accordingly.
Downgrading is relatively easy.
Improve over the best in the world does take a bit more effort, but it has been done since the very existence of humankind.

[ivconic]

DG419LEDQ - SOP8, OK, I can solder that. Present on Aliexpress,
AD8031AR - SOP8, OK, I can solder that. Present on Aliexpress,
ADA4807 - MSOP8, NOPE I can't solder that. Present on Aliexpress,
...
Problem.
Headache.

...

The icing on the cake... I keep looking at the wrong schematic! I should have been looking at "RX_REACTIVE_FILTER_DIFFERENTIAL_01-27-2023 - Schematic.pdf"
Now.. double headache!


Given that now the Chinese are celebrating their new year and a series of other holidays and will not work
for a total of 43 days !!! (if I'm not mistaken) ... and considering how late the shipments from there usually are...
and considering that I'm not able to solder some components...
People, don't wait for me, because you will be waiting for a long time.
And the one who was waiting for Godot waited less.
You work if you have the conditions and I will just follow what you write.
Unfortunately... it is what it is.
If I redo the whole schematic with the components I have, which are mostly through-hole and outdated, they don't even have those specifications...
it won't work at all. What a waste of time it would be.

[ivconic]

AMX_RX_PREAMP_01-27-2023 - Schematic.pdf

Here is a tentative preamp. I did some real testing with this and a real CCPI TX, using an 8" DD coil.

ivconic, if you want to use the 037 opamp, take advantage of the opamp offset correction. I am interested to see what delay you can achieve with this opamp. Probably you need to reduce the gain in the first opamp and add gain later.

Roger that. I was just about to comment that you lost me with those components already.
Ok, more/less it is doable.
I am only not able to obtain the particular switch, DG419.
And AD8031... dunno what I can do about it too.
ADA4807 too...
Not possible to obtain those in local shops.
Come to think... I can only obtain passive components from the RX schematic!