Identify chemicals with radio frequencies - Nuclear Quadrupole Resonance (MRI without magnets)

[@HuygensOptics]

Nice Ben!. Suggestion: in metal detection, they use something called a double D configuration to remove pulse signals completely. Basically you have a separate transmission and reception coil and by strategically placing the reception coil, you can remove the pulse and focus on the signal. This is something you might want to try, because it allows you to remove all the filter electronics from your setup.

[@dittilio]

I assume this set-up you're describing essentially destructively interferes with the carrier signal, leaving the sample signal largely untouched so instead of filtering the noise, you can simply threshold it?

[@HuygensOptics]

@@dittilio no it's about direct cancelling the magnet field. I actually discussed the principle in a video I made some years ago: kzbin.info/www/bejne/e5TYhaafm7iaeNU (around 3.50 min)

[@Scrogan]

Ah, of course! Very neat idea. I think you’d need to tune each part separately, but at least that’s a lot easier than remaking the output coupling filter. Could even automate a scan using varactors, or those funky current-controlled inductors.

[@testboga5991]

It's called induction balance and yes, it works.

[@zombieregime]

@@HuygensOptics Oh damn! Huygens Optics stopped by! Been following your videos on the mini-monolithic telescope and those dirty lenses. Now I gotta stop by your channel and finally get around to those grinding videos Ive been sitting on watching! Love when these home science on complicated subject channels get together, it makes for an awesome community with a mix of interested amateurs fully invested in everything knowledgeable professionals have to share. And sharing the knowledge its what its all about. Thumbs up to all in the community! You're all awesome, the pros in the know, and the amateurs just looking to expand their knowledge set!😎👍

[@brunonikodemski2420]

I built my first NMR machine when I was in high school, in 1960, using the descriptions in a Scientific American magazine. I got an old radar magnet core (with wiring), which allowed a small volume to be magnetized. Winding some sensor coils around this zone, I was able to get a full inversion of several materials, using only an electrometer as a measuring devices. Totally useless to identify much of anything, but clearly showed the principle. This led my algebra/trig teacher to teach me some calculus, since he said I would need it in college. When I got to college I was at least three years ahead of anyone else in my classes, and aced them all. Ended up as an electrical engineer, and later integrated circuits designer. That's the value of real science.

[@varshneydevansh]

woah

[@baloneysaucejohnson8747]

Homeschooling dad here, you are an inspiration and a blueprint for my little boy.

[@selfawareness369]

Dude you’re my hero!

[@brunonikodemski2420]

@@baloneysaucejohnson8747 If you've got some old audio amplifier, and a tone generator, you can do all sorts of experiments in the magnetics area, resonant frequencies with a beam of aluminum, making a laser beam bounce off a speaker cone (using reflective tape or paint) onto a wall, and all sorts of "wowee" experiments for young kids. Online there are gobs of these demos, and I did some of these for my kids, for science projects. One kid got a PhD in physics, other doing tradesman work as commercial repair guy for large apartment complexes. Bot good to go in modern world.

[@johng.3740]

What do you guys put inside them highly integrated microchips....eh?

[@bigclivedotcom]

Ben. Your videos are always ludicrously good. You need to master "shorts" to seed curiosity, then pin a link to the full video at the top of the comments. (Beware - making meaningful shorts about technical subjects is hideously tricky.)

[@jonnyphenomenon]

Hi Big Clive!

[@hi-friaudioman]

Nice to see you here sir.

[@MrOlivm]

He needs a forum to have people help draft them. Mmm maybe I should support though patreon and see activity there. Does he even accept support that way?

[@jafinch78]

@@MrOlivm Yes, read through the description of this video and you'll find his patreon link. Might be elsewhere found on his channel when clicking on his name and maybe somewhere like in the about section?

[@FerociousPancake888]

Can’t only your subscribers see shorts or did they change that?

[@w2aew]

Fascinating stuff as always, Ben. And, thanks for the shout out!

[@pyromen321]

I just want to say that I really appreciate what you’re doing. Every time you upload a video it’s entirely unpredictable and absolutely fascinating.

[@robertsemmler16]

ppl who compalin about youtube premium cant appreciate this content. this is priceless.

[@circuitguy9750]

This is absolutely amazing! It's incredible to see these very complicated topics explained well and demonstrated on DIY-quality equipment.

[@fast_and_curious9144]

DIY!!

[@zombieregime]

Lab equipment costing thousands upon thousands of dollars come with precision, repeatability, accuracy, a maintenance plan, and a fancy case. No building filters, or hand tuning, just plop the sample in and hit the go button. But when you understand the mechanisms involved, it really is amazing the kinds of instruments that can be built in a garage that can return useful data! This channel is a great example of what is possible with just some know how and a bloke in his garage!

[@zombieregime]

@@josseman somethings are unavoidable, also some things are being thrown in the dumpster, or have a simple electrical fault yet being sold 'as parts', or hand me downs, or gifted, or on clearance, etc. Hell, I have a $5000 gilderfluke ride-car controller I acquired through work on theme park animatronics and stage production technology. An expensive piece of equipment doesnt necessarily mean the person who owns it bought it new, or at all. Besides, if you're crafty, you can cover a fair bit of signal inspection with a parallel port and a high sample rate soundcard, or some basic rf/sdr bits and bobs. Sure, a 'real' o-scope, even the cheapest one being sold new, would blow it out of the water. But its technically possible to cover some low hanging bases, just dont expect miracles. Its about using what you can get your hands on. What should they be doing? Judging the waveform by touching wires to their tongue?

[@Marin3r101]

@@josseman how else are you supposed to measure signals accurately? You and everyone and their mother can buy a Oscilloscope, try buying an MRI... You seem like the type of person that can't believe being driven means something."Wow I can't put my head around how you came up with this idea." Or "I don't know how YT Content creators do what they do." This channel may not go into his reasoning for tinkering but human nature is curiosity.

[@rrho6701]

@@zombieregime Imagine if a small fraction of the money that the US gifts to foreign countries, were used to set up a few hundred MakerSpace DYI labs across the country, with equipment to loan out like libraries. Where would we be?

[@ivanpopovic9503]

During my final year at the university, I was called to be a part of the team designing a real NMR. They gave me the task of designing superconducting magnet. It was very fun, 9 month project that ended with working NMR device, used by chemistry department for structural molecular analysis. It is fascinating that you made working zero field device using only the basic equipment! Great work!!!

[@en2oh]

not sure when you did that, but I was studying Chemistry in the late 1970's. Bruker was our NMR. Brings back old memories - some of which were even quite good! :)

[@Bordpie]

Back in 2012 I was visiting universities to pick which one to go to and which degree to pick. I ended up touring the physics department at The University of Sheffield (I ended up doing Mechanical Engineering there instead) and I remember them talking about a device to detect the nitrogen or high energy nitrogen bonds (can't remember exactly) in explosives in plane luggage using some technique similar to MRI. I'm guessing it's something similar to this.

[@CuriousMarc]

This is fascinating. And the DYI wizardry is even more impressive - I didn't know this was even possible! Lots of parallels with the Cesium clock principles, but using the spin of the nucleus instead of the spin of the electron. Even the multi-pulse technique seems analogous to the Ramsey effect used in the clock, where you have two equal interaction regions separated by a period of free precession. And just like you, I also get my RF magic straightened out by watching w2aew's channel!

[@batcathatsatchat]

The main similarity between the Hahn echo Ben is doing and Ramsey experiments is just that they are both pulsed experiments. Standard Ramsey is limited by T2*, the signal is dead if the space between the pulses is beyond this, whereas Hahn's echo refocuses T2*. You can combine the two, either by reading off the Ramsey signal with an echo (pi) pulse, and/or by inserting a series of pi pulses between the Ramsey pulses to extend the resolution beyound T2*. Ben mentioned T1, but more often than not, T2 (non-refocussable dephasing) is the bigger problem.

[@frogz]

you make things that people literally study a lifetime for sound easy

[@anteconfig5391]

That's a good thing. I find that things are often easier than people say they are. If this guy can make something sound easy it's probably 'cause he knows what he talkign about

[@accountdeleted3706]

If you can't explain it simply you don't understand it

[@bbk9787]

That’s because he is doing it himself and doesn’t have to wade through the constant beating around the bush colleges make you do to get simple information.

[@MR-nl8xr]

That's because humans tend to make things complicated, especially when you add money with them.

[@AlphaPhoenixChannel]

Very cool - For some reason a "low-power-pass" and "high-power-pass" filter is something I'd never even considered. Very cool results! I love that this kind of measurement is home-shop-possible if you're patient

[@uploadJ]

Its almost like he's designed a RADAR TR tube self-switching system!

[@discretegames]

This is the only channel where I like the videos before watching because I know I'd end up doing it anyway.

[@truegret7778]

That's awesome. When I worked at a cargo container inspection company (using Gamma waves), we were developing device to put in all cargo containers that did a very similar technique. Broadcast, transmit (or chirp), a known spectrum, and a short time later listen to the return. With the return, we have effectively characterized that container. When we cut a small hole (1 ft sq) in the container, the return changed and we detected it. We then know there has been a container intrusion. There is more to the story of what we did after that detection ....

[@TheBackyardChemist]

Cocaine?

[@c2n10]

Gamma Wave? as in human brain waves or Gamma RAY as in ionizing radiation?

[@truegret7778]

@@c2n10 Ah, yea, good catch. This was like 15 years ago .... Gamma source. Not sure they still offer the VACIS (Vehicle and Cargo Inspection Systems - port entry, trains, mobile).

[@truegret7778]

@@TheBackyardChemist Ha ... no, more like dirty nuc bombs.

[@jafinch78]

@@truegret7778 Man, I hope they're performing more samples tested and with better accuracy so no false negatives.

[@skivvy3565]

This is the only channel that *Begins with the end results, and showing you. So you stick around due to respect and fascination* . Even all our other favorite channels like tech ingredients and practical engineering are guilty of saddening clickbait and shady tactics

[@stefanm4184]

I worked on an MRI as an intern for 4 months and never understood how the thing worked despite talking to MRI physicists almost everyday. The way you just explained T1 time and spin echo makes so much sense I can't believe how much I just learned.

[@BRUXXUS]

I never know what to expect by a new Applied Science video, but I do know I'll learned something and enjoy the heck out of it!

[@drewf64]

Wow, not only is it amazing to do NMR without a magnet, this is also one of the best explanations of NMR/MRI I've heard

[@mkimball6]

NQR is closely related to NMR, but not the same. NQR is only for quadrupolar nuclei with a decent quadrupolar moment, like 14N and 35/37Cl. NMR without a magnet is more difficult, you basically have to use hyperpolarization

[@dario2466]

Sometimes I wonder, but yes, I was born in the right time. Thanks to all those wonderful people exploring this world and sharing their insights.

[@NROHK]

Absolutely amazed at your breadth of experiments. This one was impressive!

[@dalehorton7748]

Slight error in the diagram, the last 1k resistor to ground on the transmit side actually has another diode pair after it in the practical circuit - which would be essential to not add a 1k load to the sense coil.

[@MrOlivm]

A little Diagram/Map Trap to catch the unsuspecting. Good catch!

[@Ori-lp2fm]

Perhaps you’re right if you tested it

[@dalehorton7748]

@@Ori-lp2fm Go play.

[@canonicaltom]

Good catch. For anyone who wants to see the actual diode stage in the video, go to 13:08

[@fazergazer]

Ben. Echoing Clive’s comment: Your content has always made the most ludicrously complicated subjects accessible. I’d go as far as to say your content is in the top 0.00001% of the KZbins for teaching. This is the best description of this practical and theoretical NMR yet. Especially like how you introduce progressive layers of understanding. Like the pulse inversion to rephase the precession. I was struck about how these phenomena have analogous (though not physically arising from the same cause) in optics. Like the phase-conjugate mirror used to demonstrate a laser cavity where one mirror was replaced by a highly non-ideal reflector made from a spatula. The beam automatically tracked the spatula as it was moved about the lab. Anyway, I was a structural biologist and used NMR, x-ray diffraction, and related techniques along with lab-directed evolution using GFP-based folding and solubility reporters, including the “shazam” split GFP tagging systems I developed, now used by other labs to probe the hidden life of molecules in living systems and make new biosensors. I wish your content would have been available in graduate school. cheers!

[@tessalittle6244]

i have to agree - I've been working with NMR as an analytical tool for a decade went on courses and the last part about pulse sequences and the quadruple aspect is very fascinating and has given me new inspiration to consider approaches like for in the field diagnostics

[@ryanfranz6715]

Such advanced science and engineering baked into a single half hour video, yet explained so well I think I might actually understand. I need to go on a walk now to digest all that.

[@Zorndar83]

One reasonable addition to increase the SNR a little could be using a differential amplifier and a pickup coil with two coils of opposing direction (1st ordr gradiometer), that way you could get rid of some of background noise. The passive lambda quarter trick was new to me, I typically work with SQUID detection of NMR signals. Great video!

[@GodzillaGoesGaga]

Was also wndering if a directional coupler could be used to measure the return signal ?

[@pontifier]

I'm surprised at how approachable this seems when it's explained well. You make it look easy!

[@ericmichel3857]

For a DIY project that actually works it is very impressive! Especially with such limited equipment. I am an MRI engineer so this was right up my alley, and this was a very good layman explanation! A lot of old MR systems get scrapped all the time (even though they usually still work). For just the cost of shipping you could probably get hold of far more powerful equipment.

[@SireSquish]

This is the guy that bought an Xray tube via eBay and turned it into all kinds of DIY mastery. If he had MRI parts he'd likely build a quantum computer for shits n giggles.

[@ydogprime8389]

Hi Ben. At 13:02 when you show a picture of the transmitter isolator it looks like the second from the right diode pair are both facing the same direction.

[@simon_far]

I noticed that too, and was wondering if it didn't matter because the amplifier may have been producing enough voltage to overcome the reverse breakdown voltage of the diode. It would be interesting to know if this was a mistake, and if it may have interfered with his experiment results.

[@georgen9755]

what you mean by pair diode ????

[@lubos4639]

I admire your capability to explain things - as well as the courage to put this spectrometer together.

[@greenbumblebee9687]

Wow. The longer you have to wait for Ben's videos, the more you can be sure of something awesome is to come 👍👍

[@Jacob_graber]

The sampling technique you describe late in the video is so mind-blowingly clever, it leaves me in awe.

[@VincentGroenewold]

I worked with mass spectrometers and just because I was curious learned about how everything works, helps me a lot in these kind of things where electromagnetism is involved. Awesome video yet again!

[@nicolasbrusco1997]

Hey Ben, excellent video! I noticed at 13:08 when you showed your physical circuit that one of your diodes in the third stage is backwards! You might get better performance if you fix that I did my senior design project in college on NMR’s, we were trying to design one that could fit in a coffee cup so that ultimately you could send it down an oil well. This video was very informative, it cleared up some things that I didn’t understand even back then. Awesome work

[@compu85]

Thanks for making the exploration of this accessible for those of us not in the sciences. Super interesting!

[@elideaver]

what's with the backwards diode at 13:04? it looks like the third anti noise stage has two facing the same way

[@chemicalvamp]

You are one of my favorite teachers, always something cool on the whiteboard.

[@Solanza]

It's been about 7 weeks, but youtube finally managed to recommend a new and interesting channel. If only youtube could show me channels like this on a regular basis.

[@matthewellisor5835]

"...and just the first step of quantum mechanics." he said casually. Another excellent video! Thank you. If like to see any follow-up if you're still working on it. Any ideas why you were having so much more difficult with the paracetamol and why the measured peak did not align with the expected frequency? Perhaps another ingredient in those tablets with a very similar frequency? Again, thanks!

[@dangoldbach6570]

This is unreal. I literally was JUST looking at low cost NMR experiments and after reading the white papers for two minutes I was lost, this is literally the clearest explanation of NMR I have ever seen

[@TheHuesSciTech]

Great work! Years ago, I tried performing NQR on cuprous oxide powder using some custom PCBs, but failed to get a signal. Then my father pointed out that the cuprous oxide would need to be in very pure crystalline form rather than a fine powder; so I basically gave up at that point because recrystallising cuprous oxide seems very difficult. Fantastic to see you succeed; I may well try to resurrect my experiment using sodium nitrite!

[@jafinch78]

Maybe you can find a crystallographer (X-ray?) who can work some wonders for you or at least give you some input on how to process the material most effectively. Definitely make a video if you can showing. Will be a neat addition on YT for the World to see. I would like to see at least. This topic and microwave spectroscopy (even the synthetic chemistry) seem like have big gaps in demonstrations on KZbin.

[@hp7033]

You're lucky. The most I get out of my dad is suggested improvements to my Goulasch recipe.

[@fryode]

Stuff like this is why I have loved your channel for years, Ben. Life can be a scientific playground and you've proven that time and time again.

[@brocktechnology]

That λ/4 network is startlingly similar the guitar distortion circuits I've been studying lately. While your transmit isolation circuit is also very similar to other distortion circuits, the more stuff you learn, I find the more parallels you find. Kinda magical to see much the same circuit used by one person to make noise(pleasant rock-n-roll noise) and another person to pull a tiny signal out of the noise.

[@stephengfazio]

I just picked up a 2 series scope. Now seeing you use it I am even more convinced I made the right choice

[@pdrg]

Thank you, always feel a bit smarter after you release a video, even if that decays away quickly, the fact that I was able to follow along and understand in the moment is testament to the explanation :)

"always feel a bit smarter after you release a video" - I experience the exact opposite of that ;)

[@LuizEnger]

I'm in awe on how complete this video is! Congratulations and thank you for such great content!

[@jr7853]

Your new videos are the best part of my month!

[@tommihommi1]

Those new tek scopes really are a neat form factor, played with them at a trade show a while ago.

[@MachiningandMicrowaves]

Very neat. I'd probably have gone with PIN diodes and DC bias switching, but the passive approach probably gives enough signal to noise ratio at the expense of needing a bit more power. I'd also consider using either an adjustable pickup loop or a capacitive divider ahead of the receive chain to help increase the tank Q. Very cool solution though, simple and totally self-protecting.

[@uploadJ]

Carrier lifetimes at 3.6 MHz get kinda iffy for a PIN diide ... standard diodes can be used as switches too, they just require a bit more current to get a low 'ON' resistance'. In the past I've used 1N4148 diodes to switch quartz crystals in receiver and transmitter circuits using either PIN or simple 1N914/1N4148 diodes; PIN at 48 MHz 3rd overtone and simple diode at 12 MHz fundamental frequency.

[@db112nl]

I mainly come here to be humbled, this guy is doing advanced science DIY-style from his garage on a breadth of different topics. I.. installed a fan in my garage today... Amazing content, eloquently explained, even if 5% of this knowledge rubs off on me i would be greatly enriched! Thx Ben

[@Muonium1]

Good god, the absolute envy I have for an IQ this stratospherically high..... I recall becoming aware of this so called "zero field NMR" technique perhaps about 2 decades ago, when I believe at the time some kind of start up was trying to commercialize it for abandoned land mine detection. The extreme rapidity with which my total confusion set in when I attempted to understand it at a deeper level perusing the literature was truly humbling. I honestly can't claim to fully understand it now after watching the video either; the best I can hope for, like with most of your beyond-incredible and superbly pedagogically rigorous videos, is hope that a couple crumbs of knowledge might somehow accidentally rub off on me after a few more viewings. Whatever they're paying over at Verily, they probably need to double it. Really looking forward to the follow-up video to this...

[@sgravina]

This reminded me of my PhD thesis which had a chapter about NQR in Boron and Aluminum. Your explanation was very good and correct.

[@mikeselectricstuff]

If high Q is important, would Litz wire, or silver-plated wire be helpful?

[@AppliedScience]

I thought so too! As it turns out, Litz is only beneficial between 50KHz and 1.5MHz, at least according to the ref that I added to the description. The "proximity effect" eventually becomes worse than the "skin effect". I didn't know this, but thought it was weird that all of the NQR researchers used solid wire for their coils. Silver plating seems like it would help. Plain old thermal noise is also a big problem, and I saw some references using chilled (liquid nitrogen) coils.

[@gsuberland]

That parallel diode trick is jawdroppingly clever. I figured out the mechanism just a fraction of a second before you explained it and it was a real "Eureka!" moment.

[@Gh0sb0ss]

I never thought i'd see a resonance cascade, let alone create one!

[@Hyraethian]

The theory is fantastic, the diagrams presented excellently. The subject matter was tied together densely and in a cohesive manner. I had thoughts about a phenomenon like this. I had never expected to get such a thorough rundown on the actual mechanics of a system in action.

[@simoniuszalox3293]

Hi Ben! You are really trying a physicists solution for the paracetamol issue. May I -as a chemist- give you a recommandation? Your pills mainly consist of filler material and you concentration is low. You will have easy success with an extraction or by synthesizing the paracetamol from scratch. I know tweaking and optimizing is what this channel is all about, but if you want things to be done, do not hesitate to tune concentration instead of circuits. Keep on with your nice work.

[@kaezaklimber3391]

Oh my god. Its people like you who make real youtube's pratical science content advance so much. Thanks immensely, man, I cant even finish this comment of so much gratitude

[@killrb13]

RF tech is fascinating! Great video!

[@N.M.E.]

Absolutely insane build Ben! I'm always mind blown with anything RF anyways... it just seems so strange, like some kind of magic in the cursed limbo between electronics and optics

[@hammerth1421]

I didn't know NMR was possible without a strong external magnetic field. This is really cool!

[@ivanpopovic9503]

It is possible, but only in solids. :)

[@Muonium1]

there is even such a thing a zero or near zero field MRI. The images are surprisingly usable and comparable at least to the first generation of MRI machine image quality in the early 80s.

[@ivanpopovic9503]

@@Muonium1 As I understand (and here to be honest I'm an electrical engineer and not physicist) You are talking abour near zero field MRI, that is using Earth magnetic fileds? I heard abouth something like that few years ago from a friend who works as a physical chemist and they are using it to immage small lab animals. Quadruple resonance does not need any external field so it is called zero field resonance, and as I remember it is possible only in solids since in fluids the quadruple moment averages out. Again maybe I'm wrong, I have only the basic knowledge in nuclear resonance, my field of expertise is EE. :)

[@Muonium1]

@@ivanpopovic9503 yes see the video here "Portable MRI developed at Los Alamos "

[@helicrashpro]

Ben, I've watched your channel for years along with many other science focused channels and I can say confidently that to me you are the most impressive person on youtube. I suppose it's a little like beauty is in the eye of the beholder and your channel to me is the most beautiful orchestration of science hands down.

[@jonnyphenomenon]

I was TOTALLY going to say something about how would an alien know what our units of time were, but you beat me to it.

[@Muonium1]

We told them what units to use so the Voyager golden record could be decoded correctly. They have to use the hyperfine transition of neutral atomic hydrogen, which we tell them one cycle of which corresponds to 0.7 billionths of one of our "seconds".

[@stuartclark7488]

First lecture on NMR during my undergraduate my lecturer said "I will explain NMR in this lecture and I can guarantee that you will understand it while in this lecture. However, once you walk out of this lecture you will have forgotten everything." There is also the NMR precession dance... which helps students to remember. I now work in a field completely unrelated to NMR (photonics and metrology) but it all came flooding back. Great video and fantastic explanations as always.

[@wrekced]

This part that is open at one freq. and closed at another, reminds me of a book I got from a library in the early '90's about "Pulse Forming Networks". It showed how to design pfn's using coaxial cables and/or passive componnents. I don't remember who wrote it. It had all the formulae you would need to design pfn's.

[@thewhitefalcon8539]

I heard the Combine use an unusual one with a veeery long rise time.

[@reisleon]

I'm always amazed by your knowledge, how fascinating your videos are. Your capacity to not only reproduce an experiment but truly understanding and explaining every detail to the root of each single principle with an amazing amount of information. I'm almost jealous, in positive way, of the exceptional capacity you have to fully understand and share everything about everything you do. Your channel by itself could restore entire filds of science after an apocalypse.

[@yuvalcohen71]

I noticed that one of the diodes on the transmission side filter is reversed (both point in the same direction). I am wondering if this is intentional and if so, why. Otherwise, great video. Thanks

[@AppliedScience]

Hah! I'm surprised it works. I'll have to go see tomorrow if it's just a strange lighting effect on video. Certainly looks wrong.

[@yuvalcohen71]

@UCeAfLSBX2qycMZDr4siuuAQ 13:03

[@simon_far]

@@AppliedScience Hey, I noticed the same thing. I wonder if the voltage the amplifier is transmitting may be above the reverse breakdown voltage of the diodes you used, making the flipped ones act as zener diodes. This may be why the setup still worked even with this mistake. I'd love to know if this was just a strange lighting effect though, or if not, if correcting it may improve your experiment results. Love your videos!

[@mgdurandolo]

Your presentations of these complex topics are getting better and better.

[@simon_far]

For the isolator for the transmit side of the circuit (the pairs of crossed diodes in series) I can see that at 13:05 it looks like one of the pairs of diodes is not crossed but are both facing the same direction. I suppose that the amplifier may be producing a high enough voltage to overcome the diode's reverse breakdown voltage, making it act as a Zener diode, but I was just wondering if that was a mistake or if I am seeing it incorrectly. I love this kind of video though and have learned a lot by watching them!

[@veganath]

Yes I noticed that also, he physical has 1 more set[4x] of diodes than on the schematic[3x]. Yes I was wondering the same questions

[@pboston6RR]

WOW! That was a exceptionally lucid explanation and at the very end you referred to the Zeeman effect. I discussed that with my high school chemistry students in the late 1960s and haven’t thought much about it since. Now I realize that those 16 and 17 year olds were being exposed to the future. I learned all that stuff thru the National Science Foundation program associated with The American University in Washington DC. I took the courses because it wa fun to learn stuff just for the fun of learning new things. I took my university level chemistry back to a Beltsville, MD high school and did my studying by sharing what I was taught with my students. Repeating the presentations five times each day was great reinforcement and showed that my understanding needed work if the students were not eager to get the next installment. Many thanks go NSF ant their program to teach science by offering teachers free night school courses at an excellent university as an incentive to further share cutting edge chemistry. Thanks NSF.

[@jonanderson5137]

Radio wave propagation is black magic.

[@WowUrFcknHxC]

Nope it's definitely light magic 😬🤭.

[@shouldb.studying4670]

@@WowUrFcknHxC that illicited an actual groan 🤣

[@Thefreakyfreek]

Agreed

[@timnizle1]

😂

[@7prudent]

It is science...

[@muhammadshahzaib3813]

What i learned in this video is you can bend water with comb. Nice video as always. Thanks for your time. Much appreciated.

[@williammorris1763]

I swear you have the most esoteric topics year after year. Keep it up! 🙂

[@mobilemarshall]

I have been curious about what a mini home made MRI machine would entail, so this was an especially interesting video. Never heard about this before.

[@ENDESGA]

I've been learning quaternions and how they work in quantum physics, and this really all makes sense now! Quaternion flipping makes it do into the inverse space and back, so it requires two flips to go back to the original state. I wonder if I can simulate what you talked about with quaternions...

[@jbray250]

This is legitimately one of the coolest videos that I've seen, absolutely awesome

[@ButterBallTheOpossum]

You really are a next level dude.

[@Srfingfreak]

We need to make sure this channel is backed up and available for all humanity forever

[@Kai-ml2iu]

Cool video! The problem of high power transmit pulses coming right back at the VNA is a common problem in the industry. Both radar and telecomunication equipment have to deal with it whenever they want to use the same antenna for Rx and Tx. In the GHz range and above, fully passive devices (so-called "circulators") can be built to seperate the waves depending on the direction they are coming from. In your application, they would not be feasible, unfortunately. However, analog telephones use an opamp circuit replicating that behavior at much lower frequencies. Maybe you would have to use discrete transistors due to the frequency and power requirements, but ultimately it could eliminate the need of replacing the VNA protection circuit each time. The LC tank and matching cap would still need to be tuned, obviously.

[@chrisfuller1268]

Amazing!! This is the only video which clearly explains NMR and I have been looking for a clear explanation for years.

[@4DRC_]

You should make a little board of just the anti parallel diodes and place it right before the LNA so you have one last crowbar to save you if you have the wrong filter on.

[@gnfrank]

This is brilliantly creative. Such a wonderful design. And so well explained. I’ve watched it twice and replayed sections over and over to make sure I understood it. Left me astounded at how well it’s done. Superb.

[@GermanMythbuster]

❤❤ *OMG, Ben has made a Video, let me put my life on hold I have to watch this NOW!* ❤❤

[@paulfrindle7144]

For the first time I truly understand nuclear resonance - as the lining up decays after the forming pulse. Your gyroscope precession analogy is perfect. Amazing - thank you :-)

[@ThisTrenton]

Awesome video and always great explanations! If you take suggestions for future videos I would love to see a deep dive on Near-Mid Inferred Spectroscopy of dissolved liquids. It's used in water quality analysis and also in farming for dissolved nutrient analysis and the whole idea is really cool. Haven't seen anything on how to use a measurement like that to quantify concentration in solution so maybe that would be something to think about.

[@mr1enrollment]

with application to hydroponics and the nutrient concentrations

[@MickHealey]

Incredible. Your depth of knowledge is astounding on so many different topics. For me, this one is up there with your digitising the SEM.

[@user-sb3wh3dd4v]

Always fascinating and informative! Thanks!

[@tolkienfan1972]

I get excited when I see that an Applied Science video has been posted. It did NOT disappoint! Thank you!

[@manupatet]

Just repeating these experiments I would consider a personal achivement. Phenomenal content

[@James-yp5dn]

Dude is crazy smart 🤓

[@MrSomethingdark]

This is one of those videos that just stuns you with what it is. This, my good sir is what YT is all about!!!

[@Scrogan]

Huh, that looks rather different to EFNMR spectroscopy, where I think the characteristic output frequency is dependant on your magnetic field strength. Also I’d have expected litz wire to be better for high Q due to the skin effect, compared to that thick enamel wire. Oh and the second two diodes in your anti-noise amp filter look like they’re both the same way around.

[@bradarmstrong1656]

I found @warecreepers comment about "litz wire...high Q" to be interesting so I asked ChatGPT the following question and got the following agreeable result: me: explain the RF nature of Litz wire used in a coil inductor for high Q at 3.6 ghz ChatGPT: Litz wire is a type of wire that is made up of multiple strands of insulated wire that are twisted together. It is often used in the construction of high-frequency inductors and transformers, as it has a number of advantages over traditional wire constructions at radio frequencies (RF) such as 3.6 GHz. The main advantage of Litz wire is that it reduces the skin effect, which is the tendency of high-frequency currents to flow primarily on the surface of a conductor. This effect is caused by the fact that the resistance of a conductor increases as the frequency of the current increases. By using multiple strands of wire in a Litz construction, the skin effect is reduced, and the current is distributed more evenly across the entire cross-section of the wire. This leads to a reduction in the AC resistance of the wire, which in turn leads to a higher Q factor in the coil inductor. A higher Q factor means that the coil inductor is more efficient at storing energy in the magnetic field, which is important for high-frequency applications such as RF communication systems. Another advantage of Litz wire is its flexibility and ability to handle high current density. This makes it ideal for high-frequency applications, where the current density can be very high. It also allows for a more compact design, which is often a requirement in high-frequency applications. In summary, Litz wire is a type of wire that is made up of multiple strands of insulated wire that are twisted together. It is often used in the construction of high-frequency inductors and transformers because it reduces the skin effect and leads to a higher Q factor in the coil inductor at RF frequencies such as 3.6 GHz, also it has a better current density handling, flexibility and it allows for a more compact design.

[@MrFraneque]

I must say that again. You are the neighbour I always dreamed to have. Thumbs up always, following and supporting since the beginning. Ben, your master videos are inspiring. I LOVE them all. Keep on going!

[@jafinch78]

Speechless! Absolutely total awesomeness. This along with microwave spectroscopy... and maybe a few other spectroscopic techniques when the thought comes to mind, make me wonder really why aren't those methods more well disclosed, taught and used? Neat winter season of experiments on YT. I'm having Les' Lab like thoughts with you demonstrating and teaching a wider range of lab or shop homebrew potentially useful tools; that at the least are awesome to watch you use, better comprehend the system and be aware of the usefulness. I'm also having thoughts of auto tuning those caps with a feedback loop from the NanoVNA I guess firmware... though there are a few apps that can be used to glean the data for a spectroscopy as well as automating some more processes to get more a sweep to characterize unknowns I guess. Probably can use some computational chemistry apps as well to correlate. I suppose my thoughts are turning into some Rube Goldberg molecular energy level states super sweep spectroscopy machine... ideally using the least destructive if not non-destructive methods.

[@ardenthebibliophile]

They are known, and taught if you know where to go. It's not more widely used as it's limitations make it applicable for niche scenarios only

[@dans5595]

that was fun! i took a course in magnetic resonance in graduate school nearly 40 years ago, and never used it in my professional life. your video brought it all back. you might try, in a future video, to cast the pulse sequences in terms of rotating frame diagrams. they make it much easier to understand. i hope you further develop the instrument to do pulse sequences. i'll be looking forward to it.

[@tufan__1048]

citizen scientist at his best.

[@tufan__1048]

Hi Ben.,did you recognize the scam here?

[@Timothy_Osman]

You're a legend man I remember someone mentioning this in the last year of attending uni in 2008 ish and they were promoting it as the future of spectroscopy for airport screening services

[@Gaark]

Never fail to melt my brain man, the stuff you get up to is fascinating

[@kevinmarr7094]

Great explanation of the classical and quantum physics covering how to drive and receive the signals. Using the gyroscope to show precession made it easy to understand.

[@mikeselectricstuff]

13:02 one of the diode pairs isn't reversed...

[@richardjones38]

What you're able to make garage is amazing. It would not surprise me if one day I browse KZbin and you've actually come up with a DIY MRI machine!

[@KosHMaraS.]

Amazing! You the best. I was afraid even trying to search "How to DIY spectometer" - thought it's super mega magically difficult to build. Appears that I was wrong, because some people are gifted teachers and easy explainers.

[@aurtisanminer2827]

This is super neat! You actually get a higher Q antenna with thinner wire. It decreases operable bandwidth but the tx/rx signal at the proper frequency is stronger.

I have such high expectations for this channel (way above anything else) and I keep being positively surprised.