SOLVING the Mystery Behind a Soviet Spy Bug : A True Masterpiece of Technical Elegance!

How did a Mysterious Microwave Bugging Device operate secretly for SEVEN YEARS inside the US Ambassador's study in Moscow with NO power source? As I'm an inquisitive and practical sort of chap, I MADE one for a BBC TV series with Professor Hannah Fry to discover EXACTLY How It Works!
In this episode of Machining and Microwaves, I do a deep technical dive into precisely HOW this totally passive mechanical contrivance worked as an undetectable covert bugging device. It has no active components, no battery, no wires and needed no modifications to the building.
Is this semi-magical Great Seal Bug somehow connected with infamous Moscow Signal?
There's a sneak preview of some of the machining work, but everyone wants to know the REAL MECHANISM behind how this weird "Thing" operates. I machined a batch of replicas and carried out practical experiments to uncover the REAL way they work.
Huge thanks to Heather at the Radio Society of Great Britain for putting me in contact with BBC TV and starting this fascinating technical journey that's eaten 300+ hours of my life! rsgb.org/
Over the years, there have been lots of articles and academic papers which tried to analyse the way the "Thing" worked, but there is a lot of disinformation and obfuscation (and book sales!) involved, so the truth tends to get pushed aside in favour of a cracking yarn (and book sales). The CIA, FBI and US Naval Laboratories, as well as UK counter-intelligence specialists all had a go at analysing and reproducing the device, then improving it and making even MORE subtle and clever bugging devices, but this was probably the first.
Lev Termen, more commonly known as Leon Theremin, was the engineer behind it's creation, but I'll be covering his fascinating part of the story in a future episode. His life has even more folklore, fabrication and disinformation even than the Creation Myths of the Great Seal Bug.
So, buckle up for a deep dive into the Tech and Physics of how this magnificent piece of 1940s technology REALLY works.
Graphs and maths are made using Grant "3 Blue 1 Brown" Sanderson's Manim software running with Python 3.10 in an Anaconda environment. 3D CAD and mechanical vibration simulation using Fusion360, editing by Davinci Resolve Studio, electromagnetic simulation with OpenEMS running under GNU Octave. Microphone is a Shure SM7B driving a Zoom F3 audio recorder. Cameras are Sony alpha 7 IV, Sony ZV-1 and iPhone. Before you ask, I copied the background from Rob at VidIQ, not from Tech Ingredients. Alec's IKEA shelves are a nice tasteful brown and his lighting's better and he has great hair.
AIMEE, my artificially intelligent machining and engineering expert system is a little chastened from being roasted after getting a bit hyper-critical about how rubbish I am at everything in the RADIX 3D antenna lens video, and is trying to be more helpful. Spoiler alert: it's not going well.
Buy me a coffee? ko-fi.com/machinkingandmicrow...
Thanks to my lovely Patreon supporters, Patrons make a huge difference to improving this channel and helping me make more and better videos! / machiningandmicrowaves
Physics Girl video • How I broke a wine gla... Diana is very ill at the moment, please go support her channel, she makes brilliant videos
1840368sharanyab, CC BY-SA 4.0 creativecommons.org/licenses/..., via Wikimedia Commons
Spaso House library Official U.S, Embassy Moscow photographer Valeriy Yevseyev - U.S. Embassy Moscow Press Office, Public Domain, commons.wikimedia.org/w/index...
www.allaboutcircuits.com/text...
Boonton 160A image: www.hp.com/hpinfo/abouthp/his...
royalsocietypublishing.org/do...

[@MachiningandMicrowaves]

The recordings I made from the bug in fairly ideal circumstances in my lab and garden after SIX HOURS of setup are at kzbin.info/www/bejne/farVqoSiqd53raM For those who have asked, Pierre de Fermat wrote a note about having a wonderful proof of a thing, but the margin of the book he was defacing didn't have enough space. He wrote it in the margin of his copy of Diophantus's "Arithmetica", perhaps in 1637. There's a reference to the margin note in the 1670 edition from Fermat's son saying: "Cubum autem in duos cubos, aut quadrato quadratum et generaliter nullam in infinitum ultra quadratum potestatem in duos eiusdem nominis fas est dividere cuius rei demonstrationem mirabilem sane detexi. Hanc marginis exiguitas non caperet." which my grasp of schoolboy Latin almost renders understandable. My esteemed friend Google Translate refuses to do it on my phone, but typing it in results in: "Now it is right to divide a cube into two cubes, or a quadratoquadra, and in general no power to infinity beyond the square into two of the same name, of which fact I discovered a wonderful demonstration of course. THE SMALLNESS OF THE MARGIN WOULD NOT TAKE IT" upload.wikimedia.org/wikipedia/commons/4/47/Diophantus-II-8-Fermat.jpg page 61, just under Quaestio 8 Also, I didn't go into how the demodulation works. I need to cover that in detail another time, but it goes a little something like this: If you have a diode in its square-law region, the current is proportion to the voltage squared. If you then drive it with a mixture of a pure tone at 1 GHz and the modulated signal, then feed the output into a resistor, the voltage across that resistor is the sum of the tone and signal, all squared. The tone is just B*cos(omega*t + phi) and the modulated signal resulting from a simple audio tone is the usual AM expression A*sin(omega t)+ 0.5Am(sin(2pi(fc+fm)t+theta + sin()2pi(fc-fm)t-theta) omega is just shorthand for 2pi*fc, fc is the 1 GHz carrier frequency and fm is the audio modulation frequency. A and B are just the amplitudes and m is the modulation index (0.05 or so) Now add the two together and square the result using the diode transfer function. You get an exciting mixture of results! After a load of trigonometric identities and wrangling, there are some components with sin(2pi*fc+phase angle) plus a load of other stuff. Run the combination through a diplexer to take anything higher than 3 kHz into a dump resistor and everything below 3 kHz but above 200 Hz into an audio amplifier, and you recover the original audio signal. If there is also some phase modulation, that results in multiple additional sidebands around the 1 GHz carrier, although at a low modulation index, the result is pretty much the same as AM. At higher modulation indices, the results are more complex, with Bessel functions of different orders causing a spread of sidebands rather like in FM. However, they are mostly removed by the low pass filter, except for the low frequency parts of the higher-order sidebands. The amount of phase mod is (luckily) quite low. I hope you can see why I rather glossed over THAT lot, but it would be fun to do a ten minute vid about it at some point, to exercise my MATLAB, Manim, MathCAD and storytelling skills!

[@hadleymanmusic]

It was beepin over the AM. Turned off it was beepin. Un plugged it was still beepin. I never could figure that out except like a hendershot tank circuit. What do you think? Im a schooled electrician and that scared me like a movin planchette on a ouija board

[@MR-ub6sq]

Guess what I realized after watching this video? I realized that I didn't understand anything about it. But he has a good colored shirt!

[@MachiningandMicrowaves]

I have many different coloured shirts, there's probably some sort of coded message in the shirt I choose for each video. But I'll leave that up to the cryptographers to decipher

[@MR-ub6sq]

@@MachiningandMicrowaves I suspect the message is: The Soviet Union (bright red on your shirt) makes people see things as Black and White or at least gray. One Estonian writer called the Soviet Union the "Empire of the absurd".

[@MachiningandMicrowaves]

@@MR-ub6sq I think my dogs see it all as grey.

[@maxtroy]

I didn’t even know something like this was possible without active circuitry. A purely mechanical microphone with no on board power source that can “transmit” wirelessly is just mind blowing. The ingenuity is incredible

[@MachiningandMicrowaves]

You can of course use reflections from central heating ducts, metal radiators and filing cabinets, but this was the first publicly-divulged case of a cavity resonator microphone

[@budgiefriend]

@Chris Lund What ???

[@UNcommonSenseAUS]

It's how rfid tags work...

[@MachiningandMicrowaves]

@@UNcommonSenseAUS Passive RFID tags use a slightly more subtle approach, using rectification like the later EASYCHAIR MkII devices but then using load-pull techniques in the near field rather than changing the resonance and re-radiating a back-scattered far-field. RFID tags are immersed in the reactive near field of an inductor driven by an exciting oscillator, where they can then change the loading on the oscillator. That is detected as changes in the amplitude and phase of the exciter, rather than collected by a separate receiver. The tag stores the rectified energy and activates a chip, which then changes the loading on the receive coil in the tag. As it is in the reactive near-field, the exciter "feels" a changing load. The changes are made very rapidly, so the data rate can be high, but very little power is required. Other tag types such as those used on toll roads use active transmitters to gain much larger range.

[@spikes1529]

in clearance areas, your not allowed to bring radios or anything as if you talked even with a radio off could push sound agianst the speaker and transmit it electroniclly.... spy stuff is crazy....

[@SamwiseOutdoors]

"64 teeth per banana" is the most accurate description of what life is like in an Imperial system that I've ever heard.

[@xenoxaos1]

Please see Banana for Scale.

[@SamwiseOutdoors]

@@xenoxaos1 That's a left-handed banana, my calibrations will be off.

[@MachiningandMicrowaves]

CEE Kurtis is the custodian of the International Standard Banana. Handedness in banana standards is always a problem. Chirality sux.

[@SeanBZA]

@@MachiningandMicrowaves Not to mention which banana you use. The yellow comes in a few varieties, and by me there is a purple one, the Natal wild Banana, which is totally different to the others, and also has seeds in it, unlike the yellow sports.

[@hobbified]

Luckily there is nowhere in the world that uses the Imperial system for anything other than pints of beer, and occasionally milk. (If you think the US does, then ask yourself: why would the US adopt a system of weights and measures proclaimed by George IV, son of the much-detested George III, in the 1820s, 50 years after the Declaration of Independence, and in the shadow of the war of 1812? If you said "they wouldn't", you're on the right track.)

[@dakel20]

Can never get over how much an absolute genius Theremin was. Been interested in the Thing for years, and absolutely delighted by these videos.

[@MachiningandMicrowaves]

His life story is pretty amazing, the lad met Lenin, knew Einstein and Charlie Chaplin, was (probably) into money-laundering to fund espionage ops in the Americas, appeared at Carnegie Hall, was thrown into a gulag, became a celebrity again and joined the communist party after the Berlin Wall came down "because Lenin asked me to". They don't make folks like that very regularly.

[@Sedgewise47]

@@friedrichhayek4862 😔Sadly, genius and morals are not necessarily correlated…

[@klin1klinom]

@@friedrichhayek4862 Just because you don't like his alignment, doesn't make him evil.

[@brainletmong6302]

@@klin1klinom unfortunately because they're commies, it kinda does

[@bwoo6223]

​@@friedrichhayek4862 are you saying Theremin is evil?

[@tylerduncan5908]

This is my first time watching one of your videos and the amount of references and jokes you manage to fit in while still being entertaining and informative is absolutely insane. Good job. You got a new subscription.

[@Taskarnin]

I suspect he has the dad superpowers.

[@ferrumignis]

I suspect the pressure equalising hole would have been even more important for atmospheric pressure changes that could otherwise cause a significant shift in resonant frequency, or even cause the diaphragm to push up against the centre pillar in the resonator and stop any modulation. In fact just getting the resonator assembled might be impossible without damaging the diaphragm from overpressure.

[@MachiningandMicrowaves]

Excellent point. Although the threads are rather leaky, I suspect they would have used wax or something as a thread lock and that might have sealed the thing too well.

[@lordchickenhawk]

@@MachiningandMicrowaves On drilling such a hole using a tiny spade bit, I hand made a 0.3 mm drill (for use in brass) out of a wire "hair" from a stainless steel wire hand brush. It was surprisingly effective and easy to pull off with only the hand tools in my back shed and a magnifying glass.

[@MachiningandMicrowaves]

@@lordchickenhawk Excellent! I've certainly made tiny spade drills from carbon steel wire, but only for plates 1-2 mm thick. Huge respect to the folks who did that 40x diameter hole

[@lordchickenhawk]

@@MachiningandMicrowaves As you say... it's always that ratio that is the impressive bit!

[@railgap]

In his book Spycatcher, Peter Wright described how fragile the diaphragm was - it could barely be handled at all with tweezers!

[@YorkshirePirate]

I passed my foundation ham exam today, but I was NOT ready for the intensity of science about to be dropped on me in this video. I feel thoroughly inadequate, but I shall keep endeavouring to understand everything after your introduction.

[@MachiningandMicrowaves]

I doubt that more than a few percent of hams would follow it all, I'm working in such a tiny niche area of radio. I do more mainstream things as well, like using moonbounce and Auroral reflection on 2 metres, plus meteorscatter, but those are probably very niche areas to most hams. I also mess about on 136 and 472 kHz, red light comms and most bands from 1.3 GHz and up, plus 1.8 MHz QRP CW and digital modes. Working the USA from the UK with five watts or less on 1.8 MHz is a hugely enjoyable challenge. The glory of the hobby is that there is a vast amount of different fields of endeavour that you can play with, and a near-infinite amount of detail that you can investigate if you like that sort of thing, or just get one any use radio if you don't want to do deep dives. One of my friends decided to check the doppler shift on the QO100 geostationary satellite to monitor how it was saying on station out in the geo belt. I like using aircraft scatter to bounce my 10 GHz signals over the North Sea into mainland Europe. I think less than 0.1% of UK hams do this stuff that I find fascinating. They probably have similar niche interests that I know nothing about. The hobby has been fantastic for me since I made my first radio back on 1969

[@educatedmanholecoverbyrich8890]

@@MachiningandMicrowaves I'm right with you, though the lower (super DC), leaves me wondering who you have to email to gain a contact. I'm 23 -3cms this way via QO100 too. All good fun. Tony G6YPK

[@MachiningandMicrowaves]

@@educatedmanholecoverbyrich8890 There are very active groups.io forums like rsgb lf group that show what activity is going on

[@edgeeffect]

Having chopped up a great many microwave ovens, I can definitely assert that resonant cavities are nothing but plain and simple black magic! This series is rather fascinating... my understanding is still only growing with the tiniest of baby steps. But your delivery is keeping me intrigued.

[@CT-qx8nl]

I love how you put your words together. I feel the same exact way you do but would never dream of being able to put it into words the way you have. I love it

[@rayoflight62]

What I believe, all the engineering regarding radiofrequency is taught backward, bot in schools and some Universities. They show a resonating cavity, a waveguide or a magnetron, and try to explain how they work by mentioning electric and magnetic fields plus some random formula. All the students feel confused, and sometimes inadequate. The only way to learn the "magic" of RF is first grab the math of fields, then the Maxwell equations, and learn how to write the right equation for the device you have, or want to design. It may take six months of learning in the worst case, but after designing the right magnetron, or the proper resonating cavity will be no more difficult than writing down your weekly shopping list. To learn correctly you cannot avoid following the right sequence; whoever propose an easy method, where you start from what is most interesting, will be wasting your time...

[@MachiningandMicrowaves]

I dream of Gyrotrons. Gyroklystrons even. Those are beyond amazing, with a magnetron just to create a source of electrons. Tens of kilowatts of mmWave power, just from electron gyration in a magnetic field. Marvellous

[@MachiningandMicrowaves]

Most of what is taught in universities is not very connected with the real business of devices. I was asked to act as an industry appraiser in the accreditation of a new Uni course in my professional area (cybersecurity). The course was ten years out of date and was designed to be easy to teach and assess, rather than giving the students a grounding in the real world. I was going to show the analytic solution for the capacitance of a small disk close to a large membrane, but it's furiously complex. All of the examples I recall doing when I studied electronics and physics were for ideal situations with lots of symmetries.

[@oasntet]

@@MachiningandMicrowaves I learned way, way more about the physics of RF devices and propagation from getting my ham radio license than I ever did in school. Much faster, too. Applied information is way easier to absorb and synthesize than abstract information. This device is pure genius. How fast we went from the discovery of radio to what is essentially a remote-modulated radio transmitter. Even the technicians operating the listening station had to have a strong grasp of the theory.

[@nicku1]

I read about it in a book by Peter Wright a good 30 years ago. There was also a description of another high tech magic - locating Russian spies by identifying them by overloading the hetordinates in their receivers with the signal transmitted from counterintelligence cars from the street. If this overload created a dip in the frequency suspected to be spy transmission, agents had confirmation that someone in the building was listening to spy transmissions. It did not require any mechanical operations, however, it was purely electronic manipulation.

[@MachiningandMicrowaves]

I rather cheekily call him Peter Wrong, but his ghost-writer did an excellent job with a difficult subject. Rather a lot of twaddle and bunkum in the book, but since then a HUGE amount of detail has emerged about all sorts of TSCM and technical ops. I'll certainly be making some videos about the ones involving machining and, er, microwaves. I might need to be a bit flexible about what constitutes "microwaves" if I can get hold of a working IBM Selectric typewriter to try making a GUNMAN project device and supporting infrastructure! next spy device on my list is an EASYCHAIR Mk 2 I think

[@ColinDyckes]

I'd never heard of this 'passive' bug but what an ingenious device and perfect explanation of the LC operation!

[@RSGill1903]

Thank you SO much for these eye-opening videos. I did not know of this until you brought it to my attention. I find the ingenuity behind such simple yet effective devices amazing.

[@MachiningandMicrowaves]

There are SO many more of these amazing spying devices, I'm going to have a look at some of them later this year. None of this would have happened without Heather from the Radio Society of Great Britain, who put me in contact with the BBC TV team making the Secret Genius of Modern Life series. It's been an amazing journey of discovery

[@Logarithm906]

the fact that i understood a fraction of that is a testament to how well you've broken up the complexity of it into nice digestible chunks.

[@drewcagno]

I understood exactly 0% of what you were talking about, but it's really interesting that you understand it. Lol. Hope you're having a fantastic Easter.

[@michaelbauers8800]

As I have some very slight knowledge of some of these topics, I slightly understood this. Fascinating. You deserve a lot of views for trying to explain something very technical with enough detail that the interested person with a bit of physics/electronics knowledge can follow it.

[@MachiningandMicrowaves]

I get a lot of folks moaning that I use too many words, well they can go watch Shorts. I like words! It's been a fascinating journey through history and tech and science

[@jjoonathan7178]

I've always wanted to deep dive the Great Seal Bug but never got around to it, thanks for the explainer! Also -- I think I see a familiar directional bridge on the shelf behind you!

[@MachiningandMicrowaves]

Oh yes, a very nice and useful bridge it is too!

[@SteveCalamia]

This level of technical elegance is oft overlooked in modern times and is absolutely necessary for the next stages in computing. Thank you for sharing this extremely interesting and scientifically _sound_ knowledge!

[@TheAlchaemist]

You are giving a whole new meaning to "Cavity research".

[@johannes9760]

Thank you for sharing this. I like the level of thoroughness you go on your videos. Never heard this type of bug before. You made my Sunday

[@nosenseofhumor1]

The Fermat margin joke really got me lol, good one

[@Yora21]

And also Blues Brothers.

[@UrsaMajorPrime]

I was hoping I'd get to make this comment 😢

[@bobhuffman7412]

I almost spit out my tea when I heard the margin joke.

[@williamjones5367]

Ahh man, ive really been enjoying these videos. you write them very well, and i love the little hints to other scientific quirks (like not fitting your proof in the margin, absolute gold!)

[@bschneidez]

"I have a wonderful mathematical proof of that but these margins are too small to contain it." I'm dying. Haven't thought about that in sooo long

[@brutester]

About the 1ghz transmitter - there is a mechanical device called frequency multiplier. It is very bulky, but that allows to have a simple carrier like 125 Mhz that after a couple of multiplications gets to 1 GHz. On the other side you can have mechanical frequency dividers. That way you solve the electronics problem.

[@billyk4711]

A *mechanical* device operating at 1 GHz!? or even 125 MHz? Not likely...

[@jwc4520]

Thank you ! While I knew the basic principles behind the great seal bug, seeing you construct one, brings it all together. Trig and waveforms , headaches of my youth. Only time in my life that the same problem was presented 3 times and I failed to solve it all three times, embarrassed I was but did answer the rest of the exam correctly. Sometimes a concept just fails to gel. Look forward to watching more of your videos. They tickle the dormant Grey cells , as ancient connections that laid unused, reconnect . Take care.

[@haph2087]

"I have a wonderful mathematical proof for that, but this margin is too narrow to contain it" Ahh, yes, a quality reference sir. You are a man of taste.

[@jonnyreverb]

Wow... A passive bug powered like an RF inventory control device in 1945... If they'd pattened it, they could be rich.

[@BerlietGBC]

Such excellent work, the hours in research you have done along with the machining and I bet chasing down dead ends, keep up the fascinating work

[@MachiningandMicrowaves]

I wish I had more time to do this type of investigation, but Real Life and the Day Job conspire to eat up my waking hours.

[@einsteinx2]

I just found this video in my feed and am blown away by the quality of the information and presentation. Immediate subscribe! Looking forward to watching your other videos, you deserve way more subscribers!

[@MachiningandMicrowaves]

I feel hugely blessed to have ANY subscribers! I started this channel as a way to recover from the grief when my wife of 37 years died of cancer, and I was astounded when the first hundred subs arrived, then I put out a couple of videos that were sort-of OK and BOOOOM, it took off. This is only the third or fourth one where I've appeared on camera, so I'm still hopeless at being the "talent" as well as the camera op and sound engineer and coffee-brewer and editor and colourist and scriptwriter and researcher and roving reporter, not to mention electronic engineer, machinist, CAD operator, programmer, animator and Physics researcher. There's no time to sleep, but I'm having SO much fun. Just wish I could get on to a weekly cycle. Ideally I want to do a 24 minute vid every second week and a 10 minute one on the other weeks, publishing at a consistent time, but I have to fight my self-defeating ADD and crushing shyness all the time. I'm giving a lecture in the USA next weekend and haven't written it yet. No sleep for me tonight!

[@desyo256]

I have no understanding in the field, but it's amazing, a sophisticated tool for Russian espionage from 1945 is still an enigma and a creditor after 78 years.

[@MachiningandMicrowaves]

The FBI, CIA, Naval Laboratory and British intelligence folks knew how it worked soon after they received the bug, but it remained shrouded in secrecy and misinformation until the 2017 freedom of information release of all of the papers. A lot of internet sources are based on earlier articles that suggest some highly theoretical operating modes. I would say to all of them, just make some units and try them. That gets rid of speculation, when you have a real device, you see for yourself how it behaves

[@DanielGBenesScienceShows]

I absolutely love this series!! With all of the incredible intentional engineering and design it took to make The Thing work, it makes me wonder how many random metal doo-dads in my house are accidentally a perfect audio/RF resonator, such as the Coke can I set on top of my vintage Disney lunchbox, along with a few wood screws and penny. I’ll guess I’ll never know. 😅

[@MachiningandMicrowaves]

Almost everything, and not just metal things, dielectrics can also do this (a little)

[@geraldito7777]

jajaja...i was thinking something similar. and i dont think the emiter about this interesting video needs a power supply. just another metal with the same frecuenci in a electronic mesh.

[@DanielGBenesScienceShows]

@@MachiningandMicrowaves There’s a fine line between physics and magic!

[@riaanferreira2130]

Where has this channel been all my life. This was fantastic content, keep up the good work.

[@yuglesstube]

The theory underpinning this device is just remarkable. A superb explanation. Such ingenuity boggles the mind.

[@silverXnoise]

I’d never associated the term “condenser” in relation to mics with the old term for capacitors, that’s a real paradigm shift. Loving this series.

[@InssiAjaton]

My teacher liked the term "condenser", or Kondensator. He mentioned it was the German name and was only replaced with "capacitance" and "capacitor", because Germany lost in the WW2. In fact, we still had two choices for our text book, which in my case ended up to be "Fields and Waves in Modern Radio" by Ramo and Whinnery (???). Some students picked the German language alternative. Then, in the final tests, there was a funny incidence. The professor had followed the Ramo & Whinnery book wave sketches, which we dutifully copied from the blackboard. This one smart student caused the professor to complain that while that student's result was O.K, there was something odd about his sketch. The student replied "Yes, sir Professor, you drew the blackboard presentation in American standard 3-D orientation. I used the European standard perspective". Evidently he was the only one in the group (including the professor) who had completely mastered the idea. I was lucky to be in his 3-student team in our lab exercises.

[@MachiningandMicrowaves]

Very cool!

[@chrissmith2114]

Some microphones work purely on the condenser principle, where the movement of a thin plate in response to sound alters the impedence of the microphone, as explained in video.

[@MachiningandMicrowaves]

@@chrissmith2114 Theremin would have been well aware of developments in condenser microphones, although he left the US just before the cavity RF condenser microphone patent was published. Condenser mics using DC bias with a series high value resistor to give audio voltage out as a result of the charge between the plates averaging out as a constant number of coulombs, and when the membrane moves in, the capacitance to the backplate increases a tiny amount and as charge is capacitance times voltage, if the capacitance rises, the voltage falls. On average the capacitance and voltage stay constant over a second or so. The Bug design is pretty much a direct lift from the US patents that Termen spent much time reading. It's pretty certain that he was working for the NKVD while in the US. Fascinating story, there's an interesting take from some Russian authors, with a title like "Russia's Edison" that adds a lit to the story, although there are layers upon layers of disinformation

[@yonkeuulen8380]

In Russian it is the same word - "конденсатор".

[@TheActionBastard]

64 teeth per banana. That is the correct conversion, sir. Very good. I see you have used our banana units before... (please save me from this dystopian imperial measurement hell)

[@aleisterlavey9716]

One has to admire the elegance of the device.

[@natalie5947]

Great explanation of how everything worked. I've always had some level of wonder for how the device actually worked and this was enlightening.

[@JackieBaisa]

As a professional tech writer, I have to agree with you at 26:10. Too few of us around, and developers don't know how to write...

[@MachiningandMicrowaves]

The suffering I go through with "documentation" written by surly coders who hate the job and do it terribly is just immense. I remember how well written the vast documentation store was that came with our big IBM systems. The thing I'm wrestling with at present runs mostly on Windows cloud servers, but was written by Linux techs whose idea of an example of usage of an obscure and poorly structured API function is to paste in a shell fragment, with the underlying surliness of a teenager aske to tidy their room but believe they are some sort of God-like Genius and think documentation is for simps. Yeah, those are what we call "Vulnerability Generators" in the cybersecurity world. Lovely. Documentation written by folks who can't write, don't want to write, and directed by management to spend as little time on it as possible. Great if you are looking for a way to sneak into a system. I think I am suffering from burnout and getting cynical in my dotage.

[@JackieBaisa]

@@MachiningandMicrowaves Truly don't blame you. I'm one writer for an org of 250, so as you can imagine, most people are doing their own "documentation" and there is just no quality control. And if you survey developers on their #1 pain point of their job? "Crappy documentation" is what they say. How ironic!

[@1978garfield]

I am blown away. I have wondered how that bug worked for years. Speaking of years about 25 years ago I got an Associates degree in electronics technology. Had youtube existed back then and I had seen your video then I would have understood hat you were talking about. As it is now I got the basic brushstrokes of what was going on and found them fascinating. Liked and subscribed. Will be checking out your older vids and waiting for new ones.

[@MachiningandMicrowaves]

I wish I had time to make more vids. Real Life keeps intruding. I have some more detailed testing of this Bug to film, then later this year I'll be looking at one or two of the other spying devices that used a slightly different method of operating, but still without any power supply needed. First though, I have a backlog of machining and testing of antenna feeds and all sorts of mechanical contrivances to get made for microwave filters and antennas and moonbounce systems

[@elkeospert9188]

"weleda hat recht. der beitrag ist alles andere als objektiv. herr aust stellt das mittel nicht lege artis her. es muss zunächst stundenlang verrieben werden" Dr.. Aust macht das vollkommen richtig. Verrieben werden in der Homöopathie nur Substanzen, die weder in Wasser noch in Alkohol löslich sind. Kochsalz ist aber wasserlöslich.... "frau grams geht nie darauf ein, wieso die fürsorgliche mutter beim kranken kind mit dem falschen mittel keinen erfolg hat. " Die Krankheiten die Mütter bei Kindern homöopathisch "behandeln" sind üblicherweise Krankheiten die in den allermeisten Fällen von alleine heilen. Es gibt da einen natürlichen Krankheitsverlauf der meist so aussieht dass sich der Zustand des Kindes zunächst zunehmend verschlechtert und danach wieder zunehmend verbessert. Je nachdem in welcher Phase man mit der homöopathischen Behandlung beginnt verschlechtert sich der Zustand anfangs noch weiter (was Homöopathen dann als angeblich erwünschte "Anfangsverschlimmerung" bezeichnen oder sich alternativ damit herausreden, dass das falsche Mittel gewählt wurde) und sobald die Phase der Besserung erreicht ist reden sich Homöopathen ein, dass sie nun das "passende" Mittel gefunden hätten. Dabei haben die verabreichten Mittel den Krankheitsverlauf gar nicht beeinflußt. Das ist wie Regentänze aufzuführen damit es regnet. Regnet es nach dem Regentanz nicht dann war es eben der falsche/unpassende Regentanz. Und regnet es nach dem Regentanz dann hat der Regentanz natürlich gewirkt. Ist ja klar..... "außerdem fragen sich skeptiker nicht, wie die mittel ausgezeichnet wirken können, wenn dem tier das mittel heimlich gegeben wird, gar einem ganzen kuhstall. außerdem wirken die mittel auch bei pflanzen, patienten im koma und bei skeptikern" Und Homöopathiefans fragen sich nicht wie man mit Pflanzen, Tieren oder Patienten im Koma eigentlich das von Hahnemann zwingend vorgeschriebene ausführliche Anamnesegespräch führen soll um das "passende" Mittel zu bestimmen. Und wo bleibt den der viel genannte "ganzheitliche Ansatz" bei dem jeder ganz individuell für ihn passende homöopathische Mittel bekommt wenn man einen ganzen "Kuhstall" mit dem gleichen Mittel behandelt? ".- ob besagte gynäkologin nur einen schmalspur-kurs besucht hat, können wir nicht sagen. freilich ist eine gescheite diagnostik wesentlich." Eine gute Diagnostik ist natürlich wesentlich - nur findet die in der homöopathischen Lehre nicht statt. Die Homöopathie interessiert sich nicht für die Ursachen von Krankheiten - die "Therapie" erfolgt aussschließlich auf Basis von Symptomen und deren Begleitumstände. Wodurch diese Symptome verursacht wurden ist für die homöopathische Behandlung belanglos und Hahnemann hat sogar davor gewarnt seine Zeit damit zu verschwenden nach solchen Ursachen zu suchen - zu seiner Zeit durchaus verständlich da man viel zu wenig wußte um realistischerweise durch Ursachen der meisten Krankheiten überhaupt zu finden. "- eine berliner krankenkasse hatte angegeben, wieviel sie für homöopathie ausgibt. ca. 1%. also ein winziger bruchteil der kosten für allopathika. so was unterschlägt der beitrag natürlich, die "prophezeiung" der weleda bestätigend. :)" Die Gelder die für "fliegende Teppiche" ausgegeben werden sind auch geradezu winzig im Vergleich zu den Geldern die für Flugzeuge von Airbus oder Boeing ausgegeben werden. Ob das daran liegen könnte dass es mit den Flugfähigkeiten fliegender Teppiche nicht weit her ist?

[@frankgerlach2519]

The brilliance is in the simplicity of the device. It is so simple to not degrade for hundreds of years. It could still operate, had the Americans not been electronically vigilant. Maybe this type of device still operates in the embassies of, say, Nigeria ?

[@devinmccloud]

Brilliant description! If you read Teslas papers, you will see his circuits were tuned to resonance, just like tuning forks. He actually shows how the ground works as the tines of the tuning fork!

[@ghostindamachine]

This is super good stuff :) What a high quality production. Super in-depth engineering, RF, a lathe, making things. Excellent!

[@MachiningandMicrowaves]

I am trying to improve my skills, I'm working hard on getting animation overlays out of OpenEMS/Paraview 3D field dumps on to video of real objects with a moving camera position. I messed up the audio at one point because I only have one working ear, so didn't know the right channel had disappeared, so headphone users got vertigo! I need to work on my color-grading skills, lighting and macro stacking, and get better at writing tight scripts and making better designs and doing more effective research. Right now I'm in the USA at a microwave radio conference talking to immensely bright engineers, academics and makers, so I have even MORE ideas to add to my growing list of upcoming productions. Thanks so much for watching and commenting, it really inspires me to improve

[@mortyrickerson6322]

Extremely thorough! Very informative, thank you for sharing your knowledge friend

[@MachiningandMicrowaves]

I'm having SO much fun making these videos, even though I'm rubbish at it!

[@mortyrickerson6322]

@@MachiningandMicrowaves not rubbish at all youre definitely a crown jewel in the youtube community. I can not thank you enough for all the work you put in to these informational videos!

[@vladshmit]

You mentioned Physics Girl, it’s very sad what has happened to her 😢

[@MachiningandMicrowaves]

Very grim, poor lass. I put a note in the description suggesting folks visit her channel

[@markot9902]

This is ingenious! No circuitry, no electricity but it still works? WOW!

[@satchell78]

Really enjoying this series. Cool stuff

[@blakOrkk]

Ah yes, I understand these words. What they mean in this arrangement per se, no idea. :D

[@MachiningandMicrowaves]

My mother says that all the time when she's talking to me. So do my Chihuahuas. Although they only understand important words like "walk" and "dinner" and "snacks"

[@BitwiseMobile]

I was in the Navy and attended advanced first term avionics classes which go into advanced topics like RADAR and Microwaves. Klystrons, magnetrons, and waveguides were always kind of magical. They either worked or they didn't. It's not like we were going to troubleshoot the Klystron down to the component level if the unit is bad. We would, of course, determine if the unit really is bad or if one of the inputs were bad, but things like that are remove and replace. I worked AIMD and things like that pretty much immediately went to depot and probably eventually back to the manufacturer. We never saw them at the intermediate level. As far as RF is concerned, I have great respect for RF engineers and technicians. That stuff is just plain magic. I worked on SONAR gear and everything was in a nice low energy spectrum (audio), so I never had to deal with RF :D

[@hansjohannsen6722]

This device is spectacular. Thanks for sharing

[@AhmedAdly11]

Strangley the video bored me half to death, so I watched it again and loved it.

[@Chris_Grossman]

I guessed it worked by slope amplitude modulation from the first episode. Your explanation is excellent. I have a working Boonton 160A Q-meter.

[@MachiningandMicrowaves]

I'v seen a 260-A but never seen a 160A in the flesh, excellent!

[@uploadJ]

I picked up a used model 260A Q-meter some years back ... fantastic tool for coil characterizing ...

[@DirtyPlumbus]

When can we buy your replicas? Lol Fantastic work, fascinating subject.

[@MachiningandMicrowaves]

I'm thinking seriously about making a limited edition run with gold plating, in a presentation case, but maybe a watch-glass window in place of the membrane. Gift for the geek with everything

[@WollasKing]

Very interesting. To make sure I understand, it means that someone was nearby the ambassador's study to pick up the amplified signal by the bug. Thanks.

[@MachiningandMicrowaves]

The receive station and recorders would be in a building over the street that was shielded from the transmitter building. Not sure of the details but I'd guess the transmitter was 140 metres away and the receiver a little closer. The operation would have been quite a team effort

[@tolkienfan1972]

I've been waiting for this. Now I realize I'm going to need to listen a few times to get to grips with the dense material! Good stuffs

[@MachiningandMicrowaves]

There are "only" five thousand words in there. Many are duplicates, but there are SO many sentences. Those are the real menace, sentences. 158 words per minute on average. That's faster than my mother could take shorthand, she says, but she's found the "play speed" option to slow me down if I get too fast for her ears. Hi mom!

[@whatelseison8970]

Wouldn't a negative inductance be equivalent to reciprocal capacitance? I think the seldom-used term for that (when applied to a capacitor) is elastance.

[@MachiningandMicrowaves]

Elastance is definitely the word. I asked Google and got spammed by this pathetically-useless answer from Quora's rubbish AI bot: SAGE: An AI bot writing "helpful" answers What is the inverse of inductance? The inverse of inductance is called "admittance", which is measured in siemens (S). It is a measure of the ease with which an alternating current can flow through a circuit. The reciprocal of inductance is called capacitance, which is measured in farads (F). Spoken with all the authority of an opinionated and cocksure teenager who once read an incorrect Wikipedia page and mis-remembered it. Great. Not "helpful", just completely and disastrously wrong. However, the humans on Quora are also mostly wrong, so it'll fit in just fine!

[@rainbain5474]

This seems like one of the strange devices my CTO would build. Dude has the most fascinating devices.

[@boowiebear]

Wow. Fascinating. Simple device yet wickedly complicated.

[@jmpeax3596]

05:40 ah Fermat's margin-al excuse

[@MachiningandMicrowaves]

Well spotted!

[@float32]

I always assumed there was a diode, acting as a frequency doubler to the incoming signal, with that doubled frequency modulated with the mic, and then retransmitted. This is much more elegant, and I assume, more efficient?

[@MachiningandMicrowaves]

Horribly inefficient, but SO elegant! I'll be doing a deep dive on the Easy Chair Mk2 which DOES use a diode

[@SeanBZA]

@@MachiningandMicrowaves Yes, and a good demo of slope demodulation to recover an FM signal with basically an AM receiver. Horrid noise immunity, and very poor performance, but it can be very effective.

[@fotografm]

@@MachiningandMicrowaves but if you include a frequency multiplier it is easier to detect using a bug sniffer looking for harmonics !

[@theradiorover]

Fascinating Neil. I am only now realising how many hundreds of hours of work you put into this. I guess you didn't sleep much! When are we getting the "What's on Neil's shelves video"? Cheers, Fraser MM0EFI

[@irkedoff]

I like the new format. I'm always happy to see a new video.

[@Sgt_Bill_T_Co]

I read Spycatcher and was also suspicious of the great seal bug, but your excellent description fits with my knowledge of microwaves.

[@fladder1]

"terrestrial globularity deniers"😂😂

[@SeanBZA]

Transmitter likely was actually US made, from Lend Lease, and the receiver was probably made that way as well, using cavity filters made from brass, who probably were chosen so they would roughly track the cavity temperature wise, so were probably kept in a nice heated room to mimic the office temperature. Tuning likely was very critical, and used multi element Yagi antennas aimed at the room in question, with probably a tiny feed to the receiver, making stability less critical, as they probably used another LO to mix with the received filtered signal, probably via a multistage cavity filter, to get the LO for the receiver. Stable LO at low frequency using a crystal oven was probably enough and low noise. Then mix, run through a few crystal filters, and you have a reasonably stable system, depending likely on US made acorn tubes for RADAR, stripped from imported equipment, and US made test gear to go with it. The high RF signal for excitation probably was close to a TV transmitter harmonic, deliberately transmitted to cover the bug signal, but far enough that they could tune it out with filters in the receive chain, hoping to have the US think it was just a spurious emission from a badly made transmitter.

[@MachiningandMicrowaves]

They certainly used TV signals to make the later systems like GUNMAN, but I doubt that was part of this design, they were just banking on nobody noticing. With a homodyne reciever, any issues of stability or frequency changes are eliminated, although of course you have to re-phase everything if you change frequency much. With enough signal, direct conversion to AF works OK, although I found with a lot of tweaking that I could also get it to work with AM on my Russian Malahit SDR. It's not actually slope detection of course, as the TX frequency is constant, but the amplitude and phase change with modulation. I tried to pull out the phase mod in FM mode, but couldn't get it to detect anything. I think a homodyne with a baseband filter would pull out the first order Bessel function sidebands along with the simple multiplication product that makes DSB AM. One day I should make a larger unit with a more controllable diaphragm and proper anechoic chamber to see what actually comes out when it's fed with a coax probe

[@andrewbaluk1663]

soviet union was developing magnetron devices in the late 1930s and would have had access to klystron tube tech post 1945, also had indigenous vacuum tube manufacture pre-war, so i dont see why they would need to go scavenge for bits since they were quite capable of producing anything they needed.

[@SeanBZA]

@@andrewbaluk1663 True, but if they could buy cheaper than make it would be done, plus also the knowledge that they were spying on the US, with US made equipment, as well.

[@cdorcey1735]

I once attended a lecture about this device, and the speaker had a replica with components in a fitted velvet case. After the presentation, a few of us lingered for continued conversation with the speaker. While he was distracted by someone else's questions, I gently fitted the antenna into the cavity, just to check the fit. At that very moment, he turned around, pointed at me, and said softly but not gently "You're on the air." And I almost wet my pants in embarrassment. R.I.P. C.G.

[@1dgram]

Finally, the video I have been waiting for!

[@donbeckham]

One thing I have always admired about the Brits is their incredible wit and sharp tongue. I enjoy learning how you are so capable. Is it from life experiences (auditory), school, or simply being well read? Maybe you can help me understand by explaining how you came up with the phrase "not enough room in the margin". I completely understand it and through research, I have an idea of where it came from. But, I am curious how it was seeded in your mind. Was is something you heard from others or something else?

[@MachiningandMicrowaves]

Pierre de Fermat wrote it in a book margin in 1637 saying he had a marvellous proof tgat there are no solutions to x^n+ y^n= z^n where x z y and n are integers for and n greater than two. A chemistry teacher told me about it when I was 12

[@MachiningandMicrowaves]

Same chem teacher told me a mnemonic for the elements in the periodic table. He said "I'm going to tell you something you'll never forget". He was right

[@donbeckham]

@@MachiningandMicrowaves That's pretty much what ChatGPT-4 told me. You were lucky to have teachers like that. For kids today.... It's a wonderful time to be alive!! ME: If I were giving a presentation on a topic and I said, "I have a mathematical proof on the subject but the margin is too narrow to contain it.", what would I mean? GPT-4: If you were giving a presentation on a topic and mentioned, "I have a mathematical proof on the subject, but this margin is too narrow to contain it," you would be alluding to a famous historical quote attributed to the French mathematician Pierre de Fermat. In the 17th century, Fermat wrote in the margin of his copy of the book "Arithmetica" that he had discovered a truly remarkable proof for his Last Theorem, but the margin was too narrow to contain it. In the context of your presentation, you would be making a lighthearted or humorous reference to Fermat's quote. You would imply that you have a convincing argument or proof for your topic but, for some reason (such as limited space or time), you cannot present it in full detail at the moment. This statement might be used to create interest or intrigue in your audience or to emphasize the complexity of the subject.

[@donbeckham]

@@MachiningandMicrowaves A 118 word mnemonic, that you will never forget?? you have my attention!! Do share!! :D

[@MachiningandMicrowaves]

The pronunciation of the three I can always recall are: Scanty Vancra Manfee Connie Cousin. Nam Galsipsclar. Libeb Ker Nof knee, although in my head it has the correctly-capitalised element symbols. He did have one for the second row of the transition metals, it went something like Why Zero Noble Mothers Teach Rude Ruth . Somehow I can remember the groups accurately. I can't remember the Actinides, but I remember it was mildly obscene, and therefore of consuming interest to a 12 year old

[@peterfitzpatrick7032]

God, I hate those tiny splinters when machining brass, they get everywhere... 🙄 Heres hoping Diane is getting better... 🙏 😎👍☘️🍺

[@benmcreynolds8581]

I learned about this AMAZING STORY from the show "Dark Matter's Twisted but True" I loved that show. This story Facinated me and you covered it so in-depth. Really glad I found your channel.

[@rjordans]

That was a great explanation, thanks!

[@hobbified]

Ah! From the time I first heard of this thing I understood the concept of backscatter and the concept of "sound can change the properties of an RF circuit" but nobody ever explained how the thing *worked* beyond that. I figured it would have to be FM (but how exactly?) or PM (but wouldn't the effect be ridiculously small when you're talking about μm of movement against cm of wavelength?). The reality is that the soundwave is doing "FM" on the resonator frequency and then the probe is acting like a *slope detector* (sans the actual rectification part, which happens elsewhere) so that what comes out is AM. In normal application, slope detectors are just about the dumbest way of demodulating FM, but sometimes "dumb" is absolutely beautiful.

[@MachiningandMicrowaves]

The movement of the membrane is around 10 nanometres on a gap of 25 micrometres, so about 0.04%, but at 1 GHz, that amount of change would affect the phase of the retransmitted signal slightly, but I couldn't detect any PM. That could just be the capture effect of the strong illuminating signal, which I could null out to -75 dB after many hours, but may have still been much stronger than the reradiated signal. One day I might set up a more robust experiment.

[@williamnot8934]

BS

[@MachiningandMicrowaves]

@@williamnot8934 "Back Scatter", I assume!!!

[@williamnot8934]

@@MachiningandMicrowaves Shovel,Rubber Boots and Wheelbarrow BS

[@MachiningandMicrowaves]

@@williamnot8934 Ah, THAT variety. Super

[@TheClumsyFairy]

I have to say I really love these types of video.. I love your shop work too, a mix of this and the shop stuff, but minus the AI GF Secretary thing would be amazing.. I should say I've missed a lot of stuff in the last 6 months or so, I got put off by the pretend AI woman thing.. I'm not saying any of this because I feel that my opinion matters in any way, or indeed is a reflection of your audiance, but I kinda think saying "Well done", and "I like this" is more productive. Thank you for keeping up your efforts, and adapting, to find the balance between what is pleasurable for you to make, and what's pleasurable for the wider world.

[@MachiningandMicrowaves]

AIMEE did get a bit out of hand, but that's my personal demons fighting to make themselves heard. As a narrative device, taking the role of the all-seeing, all-knowing Narrator in classical Greek plays, AIMEE gives me a way to defuse the potential for sounding smug, but also saves me from re-recording on-camera video segments. I recorded a section of this one that I spent hours on, but mispronounced some words. By then I'd moved all of the camera gear and changed lenses etc, and it was 4.30 AM and I was tired, so I just wrote a TTS script and had AIMEE scold me for saying something silly. In the end, I ditched the whole segment though! I've lost a 10 minute piece to camera about the 150 picometre Van de Waals diameter of Nitrogen molecules and their mean free path and mean spacing, with lots of science about the interaction between the membrane and the molecules in the air. I can't find the audio, video or even the text files, yet I can remember clearly doing the initial rough edit of that segment. I might find it again and put it out on Machining and Microwaves Plus if it looks interesting enough to resurrect.

[@garci66]

amazing video. Just popped up in my feed. Knew about the device but the level of detail provided is great!

[@MachiningandMicrowaves]

I had to miss out a lot, but there will be at least one more tech video in this series, perhaps two, plus one on the detailed machining and metrology and another on the results of my researches into where Theremin took his influences from, and what he was REALLY up to in the USA in the 20s and 30s. I never realised that after contact with the West eased , he got back in contact with his US wife Lavinia and I think he even suggested remarriage. What a lad...

[@synco1985]

I have discovered your channel last week with this video. I am in love with it, the way you talk and explain and work are awesome, Thank you for creating this content! keep up good work, sadly I have few friends that could understand the explanation behind this device. Again, thank you for all your hard work!

[@MachiningandMicrowaves]

Thanks Mihai, I wish I had more time to make videos. It's really nice when people watch them and comment. I would make them anyway even if nobody watched, because I'm a storyteller and just love tale-telling. I hope I can improve and make better videos as I learn more about lighting, cameras, editing, scripting and visual effects

[@synco1985]

@@MachiningandMicrowaves You are a really good story teller. And I love the jokes, especially de one imperial/metric and the comparisons and analogies. :D

[@TyPoProteus]

The youtube algorithm brought me here and I couldn't be more pleased! I love your style and can't wait to go back and watch all your other videos :).

[@MachiningandMicrowaves]

Yay! Thank you!

[@ptonpc]

Fascinating as always. Thanks :D

[@MachiningandMicrowaves]

My pleasure!

[@zebo-the-fat]

Very nice, keep up the good work!

[@trollforge]

Good one Neil, even though the maths were way beyond my pay grade... I for one would certainly be interested in a show or 6 on what tools were actually used to create the original, and how they were used.

[@Hermiel]

Understood not a word. Enjoyed every minute.

[@Raintiger88]

Finally someone explains this in a language I can understand! Thank you!

[@MachiningandMicrowaves]

I tried hard not to dumb it down but still make it accessible. I'm still a rank beginner at this KZbin nonsense!

[@thomasrussell4674]

Brilliant video man!! I always wondered how they just about exactly did the trick and I had a pretty decent/correct idea of the principles, but the actual device was much more deceptively simple and elegant than I had thought.

[@MachiningandMicrowaves]

A classic bit of design for sure. There's so much incorrect information out there, it's just amazing.

[@thomasrussell4674]

@@MachiningandMicrowaves well you've really demystified it in one way, but in another I'm only left with a deeper sense of awe at the elegance and simplicity of the design. So much so that even a cursory direct viewing of the object itself (not the seal but the inner workings) is not even obvious enough to immediately raise clear suspicion to an untrained eye, like say your average embassy removalist or cleaner, it could be mistaken for some hanging or balance device related to the ostensible gift. I'm really intrigued by the writing on the back of the item, can you make it out? I remembered reading about this roughly 30 years ago in an old spy book when I was less than 10yo and being fascinated, remembering it very clearly ever since and so always happy to learn more whenever the subject came up. Your re-creation is impressive but so is the follow through, such as your animation of waves propagating down a street, really well done. I'm no radio whiz just your average KZbin viewer, but really impressed and appreciative of all your explanatory efforts. See, not having any expertise I had always imagined some passive device might have been like a little crystal radio set, I definitely expected perhaps a coil and a diode, never in my life would I have guessed something so arcane to the untrained eye, so while I admire your ingenuity in recreating it, what you've really successfully communicated is grounds for me to be impressed with the Russian originators, knowing all the practical, material and technological limitations the whole world faced at the time, let alone the Soviet union with shortages as they were, even (as you pointed out) limiting what was likely available for the two items of powered equipment between which the great seal formed the graceful nexus.

[@thomasrussell4674]

Oh sorry I see now it says "Property of division of security department of state" I was watching on a small screen-in-screen before I didn't realise it was easily legible.

[@MachiningandMicrowaves]

Yes, they stuck that on the back cover. The original has gone missing and there are no available images of the main elements of interest around the bronze ring attachment of the membrane and the precise slot layout on top of the resonator

[@mrmagoo.3678]

Sneaky and Absolute Genius, the Inventor of this Device is a True Spy Mastermind!..Madness.

[@colinwilson210]

I always wondered what magickery made this work, thanks for the explanation !

[@rpitt6267]

As someone with more technical ability than many and the frustration of NOT always being able to share my knowledge with those who dont quite drok what i am saying..... My hat is off to you good sir! Excellent discussion and clarity! To be truthful i have wondered about the engineering of these devices for some time, i now understand them! Cheers!

[@tinetannies4637]

What a fascinating video, thanks!

[@jarrodvsinclair]

The fact they did this before computers and with almost no 1ghz radio in existence is amazing. i really hope the engineer that built it has notes somewhere out there

[@MachiningandMicrowaves]

See my previous video for the background, Termen/Theremin was in the US in the late 20s to late 30s and has some patents to his name, but was of course working in a sharashka after being interned on his return to Russia. I guess that somewhere in a hallowed corner of the KGB archives, there's a well-preserved and revered file of NKVD papers with all of the juicy details carefully recorded.

[@PatrikFormanek1]

Incredible performance of the engineer. We don't know exactly what impact this inclusion had. But it may have prevented a nuclear war during the Cold War.

[@chriscampbell2235]

Very interesting breakdown - and truly genius design!

[@skipperriddles3839]

Great video, you made it very easy to hear, which made my understanding much more solid. Wondering if you find working on a lathe as relaxing as i do.

[@MachiningandMicrowaves]

I'm always stressing about chasing micrometres or ten-thousandths when I'm using a metal lathe. My wood lathe is much more relaxing!

[@FredPilcher]

Absolutely brilliant! :And superbly presented. D

[@MrHolozip]

What a wonderful video - I've been waiting for this for a while! Is a high-frequency modern-day equivalent of this possible? I'm sure we could make something much much smaller these days...

[@MachiningandMicrowaves]

The developments during the mid-1950s were even more amazing. With MEMS microphones, you can make really tiny devices, but energy-harvesting and supercapacitors are still bulky. I'll have a go at some of the other early systems later this year, I've got most of the components for an EASY CHAIR Mk 2, but ideally I'd want to make a reproduction of the transmitter using period-correct thermionic devices. I have some early 1960s transistors that are very nearly correct, and one subscriber has a resin-cast device block so it would be fun to get some detailed X-ray micrographs of that and make a faithful reproduction that actually works.

[@billsemenoff]

The cavity acting as a variable capacitor seems straightforward enough, but the point about the antenna re-reflecting is pretty mind-blowing considering they didn't have visualization software. Wonder what ever happened to those engineers... probably defected to the USA!

[@MachiningandMicrowaves]

All matched antennas re-radiate half of the incident energy, and unmatched ones re-radiate almost all of it. The cavity is slightly more than just a capacitor, it's a weakly-coupled high-Q resonant cavity. Termen continued working in Moscow until he retired, although he visited the US again in 1991. There's an excellent documentary about his life. en.wikipedia.org/wiki/Theremin:_An_Electronic_Odyssey and Glinsky's book Theremin: Ether Music and Espionage is also good. I've seen it suggested that he corresponded with, and even wondered about getting back together with his American wife, who he'd had to leave behind after his rather, er, "hurried" exit from the US in 1938. He'd spent ten years in the USA in the 20s and 30s. There's no record of anyone else involved in the construction, but any clockmaker could have made the metalwork and the rest of the equipment is fairly straightforward. Easy for me to say with 20/20 hindsight of course. Making that connection between Termen's knowledge of radio frequencies from his instruments and his researches at the US Patent Office on microphone technology, it's easy to suggest where he made the connections between the various technologies, but having the spark of genius to be the FIRST to do it is what makes the difference. A bit like running the four-minute mile or climbing Everest.

[@alistercarmichael4990]

Tremendous. What a dive into the world of passive RF. Absolutely still with you though my field lines and circuits is a little rusty. My mind boggles at how tight the design was at the limit of available equipment. Just how far we have not come in all this time. Well, with what we know. Who believes the narrative on the telly after watching this ? Great work. A credit to society for producing content like this.

[@vlaskz]

I really need a Crossover between this and Technology Connections channels. Also even the background seems to fit perfectly.

[@MachiningandMicrowaves]

I had a Kallax and I nicked the idea from VidIQ and three or four other channels before I even knew about Alec's channel. He has better hair and nicer LED lights.

[@vlaskz]

@@MachiningandMicrowaves so I don’t have to lose all my hope, right? Alec is just as awesome as you!

[@vlaskz]

@@MachiningandMicrowaves I’ll ask the same for him. He deserves to know my opinion about all the sinergy you could together.

[@MachiningandMicrowaves]

@@vlaskz Heh heh, Alec is WAAAAY out of my league, he's a Proper KZbinr!

[@stevehill4615]

Thanks for the video, I'd heard/seen the story of the American Seal incident and always been interested in how the Soviet bug had worked.

[@rickeymh]

That was a brilliant invention. As an EE, the concept was easy to understand, but admittingly I got lost in some of the details. Still, it was a great story. Thank you!

[@MachiningandMicrowaves]

Real Soon Now, I'll do a detailed deep dive about the way it works right down at the molecular level, noise, acoustics and the intricate maths. Should be huge fun

[@daveevans1236]

A true masterpiece of explanation (I think) but entertaining and fascinating explanation.

[@jamest.5001]

I had a really good teacher in the second grade, she told us about this and Apollo program and lots more not typical for second graders, I was always ready for these stories! Sometimes it was book reading, they do not have teachers like this anymore, that was nearly 40 years ago! 😮

[@marcopruscini1603]

Superinteresting stuff. For me, as an average not physican it is really hardcore to understand the most but he explains it good. 👍

[@jozsefizsak]

That's pretty exciting stuff!

[@davidfarrant6591]

Absolutely fascinating stuff. Very advanced for its time. Now I need a large coffee!

[@77thTrombone]

Why YT tossed this video my way, I hoped it would be about this device. What a piece of engineering it is!

[@jeffryblackmon4846]

Thanks for an interesting half hour of viewing.