Bipolar PI design

[algan]

For example, instead of a 4053, you can use some kind of integrated circuit that is a high-side MOSFET driver. Here are some sample circuits with different integrated circuits.

[ivconic]

PS2 timing is very complicated (that's why it works so well) and is performed entirely in the analog domain.
Here, things have been moved to a higher level, the timings are done digitally, which is good and guarantees greater accuracy.
Another thing, I wouldn't confuse a PS2 type detector with this bipolar PI detector, one of the last intentions on my list is "depth" with this project.
I suggest that we slow things down and don't start modifying right away, until we've made the original.
I would definitely make an original right away, but I'm waiting for Carl to sort out his work and publish the gerbers.
The only thing I would explore here, for now, is possibly replacing the 4053 with a better solution.
My main motivation here is to achieve as short a sampling time as possible with this type of TX.
In other words it means "fast" bipolar PI.
In other words it means; "depth is not important" but sensitivity to smaller objects.
I am not referring here to nuggets of gold and similar "particles" (AMX thread is dealing with such), but primarily to objects the size of a medium coin and larger.
...
Any further elaboration of the merits of this detector by me would be mere rewriting of what Carl otherwise brilliantly covers in his book.
I suggest that anyone interested should first buy the book and read it.
It would not be fair to the author to list here entire paragraphs with explanations of why what was done and how it was done.
...
I started this thread only because of a question about finding the best solution to replace the 4053 with a better solution.

[algan]

Yes, I'm also interested in this design, it would be nice if Carl posted a lay file or a Gerber file or a picture of the board, and if he doesn't, we should make it and test it, and maybe we can start with the TX first and experiment with what input signal TXN and TXP should be.
Ivconic, you're making a pulse star 2, I'd be curious if you use this model of the TX there, whether the penetration into the ground will improve and what the difference in depth will be compared to the original.

[ivconic]

In the book, Carl himself noted well that the use of the 4053 switch is "delicate" due to the high internal resistance in the "ON" state.
He further suggested mitigating that problem by using the 74HCT4053.
I still have parts of earlier debates from the AMX topic fresh in my memory and I know that such details are very important and that special attention should be paid to them.
I am 100% committed to building this detector. But I would like to improve some such "little things" in advance.
Of course, Carl himself "made it possible" by not giving the gerbers for the pcb yet. Otherwise, I would make the original version first, which is definitely recommended.


I apologize to everyone that I did not follow the numbering order of the components on the schematic according to Carl's original schematic.
I will try to correct that because it will be much easier to talk about the project further if the numbers match.
I also "broke" the quad opamp into dual and single opamps. I don't think this is a big problem.
But I will redraw the schematic and replicate the original.

UPDATE: I just corrected the enumeration and uploaded most proper drawing.

@Carl, small notice:
You have duplicated "IC8a" at Your schematic.
Not important, yet good to include it in "Errata".

[ivconic]

Ok, now that I've got everything set up, let's just focus on the TX:

[ivconic]

And this schematic above is just a "picture" too, for all those who are interested, here is the schematic file.
The software that is needed is "ExpressPCB",
(don't get confused, it's a free installation package that during installation also installs a schematic part called "ExpressSCH" in which I mostly draw schematics)
and you can download it free from here: https://www.expresspcb.com/
And here is the sch file:

[ivconic]

But it's just a picture from a book, not a "living" thing to work with. That's why I redrawn that schematic in the software in which it's easiest for me to continue working (click to enlarge):

[ivconic]

It is very difficult to find anything in the book that is not very interesting.
But I immediately decided on the Bipolar PI design as the first thing to focus on.
There are several reasons for that.
First, I like the idea of a "non-invasive" detection method because of the possibility of adapting this project for demining purposes.
Second, this approach is only the tip of the iceberg of possibilities for further development of PI detectors. That is my humble opinion, there are probably many who will disagree with me.
I have tried to participate in the AMX thread a long time ago but felt deprived of the vast knowledge that the other participants in the thread undoubtedly have.
Then I realized that I still have a lot to learn in order to be an equal interlocutor with others.
Luckily Carl's book is here, I have plenty of time to read and study. And now I'm slowly (after all, I'm quite old) starting to understand some things.
That's why I think Bipolar PI design is a good initial step and an introduction to some broader knowledge.
Carl offered very interesting solutions that "provoke" further thoughts.
There are two parts in particular that I really like. TX and audio. I wouldn't dwell on audio for now, because I think it is necessary to make it first and only then draw conclusions.
At this point I would focus on TX first.
Originally from the book Bipolar PI TX looks like this: