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Author Topic: Smudge proposed NMR experiment replication.  (Read 103418 times)

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The 1st screenshot was taken with the other scope / probe, meaning 8pF / 10MOhm.
White is when the probe tip is not touching the coil (only the ground lead), blue is when the probe tip is connected too.
The resonance changes from about 4.5Mhz (white) to 3.3Mhz (blue).


The 2th screenshot is from my Spectrum Analyzer / Tracking Generator sweeping the same pancake coil.
Here the resonance found is around 4.45Mhz.
 
Itsu
« Last Edit: 2020-06-22, 19:41:20 by Itsu »
   

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So the self-resonance of this one coil is approximately the NMR of hydrogen in the magnetic field density of typical ceramic magnets.   All without any external capacitances.

If we assume the 115uH to be accurate then the interwinding capacitance can be estimated as ~12pF.
Of course that will change once you connect and sandwich two such coils.
   

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Right, and that change will be downwards for both inductance and interwinding capacitance, thus i can continue with a second 30 turns pancake coil.

Itsu
   

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Here I show the calculation of self resonance and self capacitance of a pancake coil (note the description of the video), but Itsu knows that anyway.
The 1 pF decoupling capacitor was a good idea.
I am somewhat puzzled by the excitor coil's axis being perpendicular to the pancake coil's axis. Can you elucidate that geometrical arrangement?

Also, in my opinion the most natural and energy preserving state for a coil is a shorted coil (conversely, for a capacitor it is an open circuit) so if you short the pancake coil and do your measurements across a loosely coupled Tx/Rx exciter/sense coil (which has a low inductance and low capacitance), then these measurements will be even more accurate.
Alternatively, a "ping" by a powerful nanopulser fed* into the exciter coil would work well, too, because the self-oscillations of a shorted pancake coil would decay for a long time after the "ping". To avoid the need for RF Tx/Rx switching you could use a separate loosely coupled "Rx/sense coil".

* In order to prevent exciter coil's self-oscillation, the exciter coil should be fed through a good series rectifying diode ( not a diode with DSR properties ! ).
A good rectifying diode will block the reverse current in the exciter coil IMMEDIATELY and will allow it to self-oscillate only for 1/2 cycle.  OTOH, DSR diodes and other crappy diodes do NOT block the reverse current immediately
   
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The 1 pF decoupling capacitor was a good idea.
I am somewhat puzzled by the excitor coil's axis being perpendicular to the pancake coil's axis. Can you elucidate that geometrical arrangement?

Thank you for the measurement education. Doing truthful and exact measurements of analog circuits is more difficult than the layman realises. I have no electronics education only mathematics, software, hardware near software and law.

The perpendicular position of the exciter coil in my video was dictated by laziness. I could just wind it over the plexiglas coil support without any additional fixtures. And because it somehow worked I left it like this.

The measurements in my video were inspired by TinselKoala und Gyulasun helping a tinkerer. I soon lost interest. I like to build things with my hands, just a hobby. And I like the fringe of all sciences out of curiosity. Normal things are so boring. But I dislike people who pretend to have built or done something extraordinary. Trying the impossible is courageous, but lying, cheating and having illusions is bad.

Greetings, Conrad
   

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I have no electronics education only mathematics, software, hardware near software and law.
What programming languages are you good at ?

The perpendicular position of the exciter coil in my video was dictated by laziness.
That is an honest answer and it explains a lot. Such geometric arrangement of the coil makes it loosely coupled to the pancake coil. That is a good thing in this case even if it is inadvertent. 

I could just wind it over the plexiglas coil support without any additional fixtures. And because it somehow worked I left it like this.
Loose magnetic coupling minimizes the influence of the exciter coil on the DUT.  To be optimal, it should be placed further away to minimize the capacitive coupling, too.

Normal things are so boring.
How true!

But I dislike people who pretend to have built or done something extraordinary. Trying the impossible is courageous, but lying, cheating and having illusions is bad.
There is an immense pull for the human mind across this demarcation line.
   
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What programming languages are you good at ?

The programming language used is a secondary consideration. If you ask a butcher "what knife do you use", he will tell you "the one required for the task". One is good in a certain software area, like database systems, networks, operating systems, event driven applications, hardware drivers, and so on. Depending on the available software tools (compilers, assemblers, integrated development systems) for a certain processor platform, you chose the programming language. For internet based applications it is often Java and JavaScript. Drivers for various hardware are nowadays written in C or C++, at my time all this was written in Assembler, because it is time critical. Often the use of a certain programming language is driven by hype, like the Ada hype or Cobol in the 70ies. I would also call Java a hype. There are many very good tools for C++ on many processor platforms.

Let's not deviate from the topic, which is NMR.

Greetings, Conrad
   

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Let's not deviate from the topic, which is NMR.
This is not a deviation from the topic because I wrote a piece of software for NMR that interfaces with Itsu's equipment.  I would like to finish it and when I read that you can program, I thought you might be able to help me finish it.
The software would make his life easier ...and IF HE CHOOSES TO, it would allow us to do NMR experiments remotely on his equipment, such as interesting pulse sequences for spin echo experiments.  I could also give Itsu remote access to my equipment and to some of you, too.

The programming language used is a secondary consideration. If you ask a butcher "what knife do you use", he will tell you "the one required for the task".
Not in this case because, the part I already have is written in concrete language.

For internet based applications it is often Java and JavaScript.
A necessary evil

Drivers for various hardware are nowadays written in C or C++, at my time all this was written in Assembler, because it is time critical.
I think that drivers with Interrupt Service Routines should still be written in Assembler.  The interrupt mechanism is always platform specific so there is no advantage in the portability of higher-level languages. A similar case can be made for code serving other hardware peripherals such as DMA, timers, UARTs, etc...
Less demanding drivers can be written in C because nowadays compilers generate well optimized code.  C++ is OK for non-realtime drivers, too, but its exception handling scheme is generally incompatible with SEH in kernel mode. However if one knows what's going on behind the scenes and implements all the speedups offered by it, such as R-value references then the results can be acceptable.


Often the use of a certain programming language is driven by hype, like the Ada hype or Cobol in the 70ies.
I didn't know that about Cobol! I thought that in the 70s, it was all they had...

I would also call Java a hype.
Oh definitely !
In my opinion any language that doesn't compile to machine code is not worth my time.  All this hand-holding just takes away too much control from me as a programmer  >:(
« Last Edit: 2021-09-16, 15:22:00 by verpies »
   

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This is not a deviation from the topic because I wrote a piece of software for NMR that interfaces with Itsu's equipment.  I would like to finish it and when I read that you can program, I thought you might be able to help me finish it.
The software would make his life easier ...and IF HE CHOOSES TO, it would allow us to do NMR experiments remotely on his equipment, such as interesting pulse sequences for spin echo experiments.  I could also give Itsu remote access to my equipment and to some of you, too.


I agree,  we were doing some NMR on iron toroid experiments last year when interrupted by domestic problems overhere.

Does this interfacing concerns the mentioned airspy receiver (which i now have one) mentioned here:
https://www.overunityresearch.com/index.php?topic=3691.msg77379#msg77379

or is it something  different?


Itsu
   

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Does this interfacing concerns the mentioned airspy receiver (which i now have one) mentioned here:
https://www.overunityresearch.com/index.php?topic=3691.msg77379#msg77379
or is it something  different?
It is different because it involves interfacing and synchronizing your FG, SA and scope at the same time, as they all have Ethernet ports.  I could incorporate the AirSpy as the receiver, too but because it has only an USB port I'd have to find a linkable API for it.  Not some damned C# library ! @&*$#
   
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How to work with a scope from anywhere in the world:

1) Person A has a scope and a PC and Person B only has a PC.
2) Both persons download AnyDesk to their PCs https://anydesk.com/en/features/remote-support.
3) Person A connects his scope to his PC with an USB cable (the software comes with the scope) and allows Person B remote access to his PC via AnyDesk.

There are other programs for remote assistance, I just mentioned AnyDesk because it is free for personal use.

Greetings, Conrad
   

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How to work with a scope from anywhere in the world:
Yes, remote access tools for single instruments exist even for free from the OEM but they do not allow for synchronization of these instruments. Especially through the LXI Ethernet ports they require a PC in the proximity of the instruments because of the USB latency, distance and routing limitation.

This is not much different than accessing a scope via intermediary PC running windows over RDP (which is built into the OS since WinXP for free).
   
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Yes, remote access tools for single instruments exist even for free from the OEM but they do not allow for synchronization of these instruments. Especially through the LXI Ethernet ports they require a PC in the proximity of the instruments because of the USB distance and routing limitation.

Are the instruments to be synchronised connected to the same remote PC? If yes, the other person can see via AnyDesk everything that is happening on the remote PC (any instrument connected to the remote PC).

If the instruments to be synchronised are remote from each other (not connected to the same PC) it will be rather difficult.

Greetings, Conrad
   

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Are the instruments to be synchronised connected to the same remote PC?
No, an intermediate PC is not even necessary when accessing these instruments through the LXI Ethernet ports and TCP/UDP/IP.
USB is not a serious control solution.
   
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No, an intermediate PC is not even necessary when accessing these instruments through the LXI Ethernet ports and TCP/UDP/IP.
USB is not a serious control solution.

For remote TCP access to more than one instrument you need a switch and a firewall. And it is questionable whether your internet provider will allow that.

Greetings, Conrad
   

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For remote TCP access to more than one instrument you need a switch and a firewall. And it is questionable whether your internet provider will allow that.
Not really, because of NAT-PNP, UPnP, IGDP and STUN, but I am sure Itsu has precise manual control over his own router with PAT/NAT and he has more than one device connected to his internal LAN, i.e. he is running them off some Ethernet switch. He's worked in the computer industry for a long time, after all.

Who in their right mind would give control of their LAN and router/gateway to the ISP, anyway?
   

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It is different because it involves interfacing and synchronizing your FG, SA and scope at the same time, as they all have Ethernet ports.  I could incorporate the AirSpy as the receiver, too but because it has only an USB port I'd have to find a linkable API for it.  Not some damned C# library ! @&*$#

OK,  but what is the benefit of being able to interfacing (synchronizing ok, i see that) to my FG, SA and scope or me being able to connect to someone else his?

Itsu
   
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itsu
please remove this post if not on topic or miss understood ...question to Verpies on this topic
are you saying persons who do not have access to equipment but do have skill set to
use such
could remotely experiment or do actual useful work for this open source community ?

that would be remarkable IMO
we have equipment sitting dormant in some places [Ernies equipment ATM as example
sorry if I misunderstood [and interruption].
   

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@ Chet
Yes, you understood correctly.

@Itsu
It would allow you to se, e.g. how differently my system behaves than yours and it would allow me the same with yours. 
It is better than making movies according to individual requests, "zoom on this portion of the signal, measure the spectrum a little later after the stimulating pulse, space these pulses a little, further, oh no, no go back you missed that spike...."
Of course, it is not possible to connect the probes remotely, so they would have to be preset by you.
« Last Edit: 2020-06-24, 11:24:28 by verpies »
   

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Right, so it would be on a one by one relation combined with a skype phone link or so to do some directly driven measurements, got it.

In my working environment i had an FTP server running using NAT, so something similar would be feasable now again.


Itsu
   

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In my working environment i had an FTP server running using NAT, so something similar would be feasable now again.
Configuring your router to automatically open random TCP ports for incoming FTP data connections in the PASV mode is much more difficult than allowing someone to communicate with your instruments using the TCP/IP protocol over their Ethernet interfaces. FTP is much more difficult to accommodate !

But the biggest advantage to you would be to automate and synchronize your local measurementsa and signal generation.  For example you could insert a Varactor diode in series with the pancake coils forming a tunable LC circuit, by driving the varactor diode with DC from the 2nd channel of your FG in a synchronized manner via a precomputed lookup table, you will be able to have its LC resonance frequency follow the frequency output of the 1st FG channel.  No OEM RAT software would be able to accomplish that...and that is just one example.

As for the remote collaboration, for example, I could remotely precompute the values in that lookup table (varactor bias V vs. Ch1.freq), while you sleep.
   

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Thanks, i see what you mean allthough we are talking about very specific equipment and procedures it could be a benefit for setting up measurement tests.


Seems that i can access OUR again normally after yesterdays lockup.


Building the 2th pancake coil but it takes severall trials to get it right with this 1mm thick wire and the present hot weather overhere does not help much.

I received the micro compass, so i hope to make some measurements with it tonight.

Regards Itsu
   

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Thanks, i see what you mean allthough we are talking about very specific equipment and procedures it could be a benefit for setting up measurement tests.
Yes but I have some of the same equipment that you have and having the source code at my disposal and proficiency to alter it at will to accommodate for the differences makes them inconsequential.

Seems that i can access OUR again normally after yesterdays lockup.
I experienced the same problem. I have narrowed it down to the presence of the percent character in messages. 
IMO this forum's code does not escape this character properly and the HTTP server treats it as some kind of attack and bans the IP of the sender.

Building the 2nd pancake coil but it takes several trials to get it right with this 1mm thick wire and the present hot weather over here does not help much.
Yes, heat is a show stopper for me, too.  That is why I pump the cold water from my pond to the radiator in my workshop. This is cheap because the pond cools off naturally at night.

I received the micro compass, so i hope to make some measurements with it tonight.
How small is it ?
   

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OK, on the above,  hopefully the forum's code can be debugged now.

The micro compass is 13mm diameter.

Itsu
   

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The micro compass is 13mm diameter.
Hmm, mine is 4mm in diameter and floats in oil.
   
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