Neat Electronic Tool From The 1930's, Lets Look Inside!
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- Опубліковано 2 жов 2024
- High tech stuff from the 30's! This neat little monitoring tool definitely needs to be brought back to life. Lets fix it together! To learn things about electronics that you won't learn anywhere else, check out my Patreon page here: / mrcarlsonslab
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To learn things about electronics that you won't learn anywhere else, check out my Patreon page here: www.patreon.com/MrCarlsonsLab
Hello Mr. Carlson. I have a suggestion for you that might make it easier for you better get an idea of what your viewers (or maybe just your Patrons) think you should do next etc. There is a free to use polling website that I have seen being used on various UA-cam channels for several years. Here is the website "www.strawpoll.me" 73 de OZ2BO. Ps. I have been putting off becoming one of your patrons for an embarrassingly long time. This has now been rectified! :-)
(I´d like to see the messy job of de-potting that transformer please;-)
If you're not already, you should be a father. You seem like you'd be a patient dad who could raise some smart kids.
I have a 180, you're a genius. Did you take the IQ tests?
Hey, i have an idea for you that's better than de-potting. If you can figure out where the capacitors are and how they are attached, you should be able to drill through them or their leads, breaking the circuit. You could get this using x-ray. I bet you have some tubes and power supplies good for that at home, right?
MrBrymstond Sure you do buddy.
DEPOT the transformer . . . please ! . . . . . . certainly a bit messy but it would certainly teach us a lot. Your running commentary during the process would be interesting, fun and educational.
I would second de-potting the transformer BUT also request, for the educational factor, to show in one video the de-potting process and then in a separate video showing for this same device, how you would go about scavenging another transformer and making it work. My reason for asking it be done for this device apart from the familiarity from having watched this video, is also because of the interesting design for the transformer they chose with the separate taps and what not which could be difficult without the proper knowledge of how to overcome those issues when grabbing a transformer that isn't necessarily set up with the same taps. Extra work, sure, but I think it'd be really worth it. The other reason I just thought about is what if the internal capacitors had actually been direct shorts to ground and fried the transformer? Then we'd really need a replacement and short of finding an exact match, we'd need to figure out how to grab something and make do with it. Ok, mini-rant done :D Thanks for all your hard work on these videos, Mr. Carlson. I truly do appreciate the time, effort, and care with which you present them to us.
GREAT suggestion/reasoning, thanks.
depotting is a standard practice on NSTs for tesla coils. Did only one and it is a mess...
I've never seen a "tar" device de-potted. I worked for a company when I was in HS that made 600KV+ x-ray machines. Sometimes a Marx Surge pulse generator module would go bad. We had to de-pot the epoxy modules using MEK to find out what went wrong.
Someone do a hashtag #depotthetranformer
A lot of this old stuff used resistor wire for the power cord. I had an old radio that had a bad AC cord, but it was resistor wire so I had to add a large wirewound resistor to the inside of the chassis. It worked just fine but that wirewound resistor got so hot that I could not use it very long. I was only 9 years old at the time so I did not know about resistors with heatsinks. I guess the purpose of the resistor wire for the AC cord was to provide 6 feet of resistor allowing it to cool. All this ancient electronics gear is so fascinating. Thank you for documenting these devices in your videos.
Yes, please De-pot the transformer. Can't wait to see what's inside there.
DE-POT! DE-POT! DE-POT! lol, seriously, I'd love to see that process, if it's safe to do so, and you're the man to give a proper demonstration.
While I have never de-potted a transformer, nor do I anticipate doing so, I would really enjoy watching the process required done.
I love how the sine wave kinda resembles a crown being rotated in 3d space. A handy quirk of the nature of sine waves and trigonometry.
I have repacked some old bakelite capacitors for a Philco radio that were filled with this tar. I used a heat gun to melt it and drip out into a tin can and then pried out the old parts and desoldered connections to terminals. Final cleanup was with lighter fluid before placing modern caps inside the old bakelite container. Using the heat gun will give you more control of the process than the oven, in case something decides to ignite.
Please de-pot the transformer.
I actually built one in the 80's from an article in Radio Electronics that detailed the construction. It used a 1" electrostatic CRT (I think a 1P21) and used 12AU7's for the input and deflection amps. I still have the schematic and the parts.
love that old caps label, It reminds me of a poster for an old circus or magic show
Also, it is amazing how far oscilloscopes advanced between the thirties and fifties. I've been learning about the early computers recently, and the rapid increase in the complexity of some of the signals that oscilloscopes were being used to look at during those years probably goes a long way to explain that.
Talking of which, It'd be great if you got hold of a COMDYNA or something for your old-time lab! The idea of hooking up an analog computer running a Rossler or Chua circuit to the X Y inputs of an old Marconi 'scope I have so that I can play with strange attractors is what's currently firing me up.
Mr. C I think you should De-Pot the that feisty Xfmr. I have seen Ford Model T Buzz box ignitions de-tarred. The guy saved and re-used the pitch. I date from the tube age so your care and attention to detail in bringing these relics back to life is great. Remember that one hand around HV is safer than 2. Don't ask me how I know...
When my father and I did restorations we would take the old caps like that beautiful Audiovox and remove the core and repot with a modern cap so the looks are preserved...
"It really doesn't have a choice when it is on this bench - it's going to work again!" - Mr. Carlson is the Chuck Norris of electronic!
Now what most of you lot don't realise is that some of us worked on that old kit when it wasn't old kit and we used the then state of the art test gear, sometimes even designing and building gear to do the job because no one had worked on the, "new gear", that, like ourselves, used to be new gear.
I was an apprentice in the days when audio amps had what looked like a couple of up turned milk bottles as push-pull output stages and we saw in the smaller and smaller glass bottle valves/tubes until along came those new fangled transistors followed by small scale integrated circuits, medioum scale ICs and Larger and even larger scale Integrated circuits.
Then those Large scale ics began to shrink and so it goes on. And no, "A Wobbulator", wasn't the generously endowed secretary of the manager.
He can cut a knife with hot transformer! 😆
De-pot the transformer
FHRsLP the Tar, tho. That's the secret ingredient in Kryptonite.
I'd like to see the transformer de-potting as well, even if it's just for the sake of having seen it once in my life, you never know when knowledge gets useful :)
Great video, as always. Thank you !
"When it's on this bench it's going to work again" I really love that positive attitude. That is the spirit! Another great video Paul. This is such a simple circuit. Was so much fun to see this old piece come back to life. Really hate it that they stuck those caps in the transformer like that. Would be nice for folks to see how it is done by a real professional. Thanks Paul for this video.
If it didn't the video wouldn't have to go up sooo..
Wonder if he can give my Dreamcast the once over, read a load of tutorials about simple fixes, done them all and it still won't read anything. Oh, well, it was dirt cheap
I want to know,
Where the heck do you find these things?
That Mini O'Scope is over 90 Years Old!
The Radio Shop 1
Don't get cocky, kid.
Man id love to find one of these little guys to add to my collection
Your lab looks like an Aladdin's Cave of test gear lol 👍🇬🇧
Again, I learned something. Amazing scope. Where on earth do you find those things? How peculiar, while watching that sine wave trace for some time it looked to me like a spinning carousel or a merry go round. (I have not been drinking)
I bet Mr Carlson is the only guy in North America that gets a weird old scope from the 1930's and says if it's got a bad crt, no big deal I have a replacement lol
I have three 913 CRTs. And a total of at least 50 other small CRTs. If you are interested, I made video demonstrating many types of small cathode ray tubes, including the 913: ua-cam.com/video/bRuqud2j_d8/v-deo.html
1 inch CRTs are quite common
i watch tons of vlogs on youtube and without doubt this mans vlogs are top notch, im fascinated with electronics and yet know nothing about it
Hhhhhhg guy dry t6666lpp000p0pp
Thanks Paul. I would like to see the process of de-potting and replacement of those caps. Cool little scope.
The capacitor manufacturer Aerovax is still around and making capacitors! No longer in Brooklyn though. I think you should call them and ask for your money back on the leaky capacitor. Only 80 years old and it already worn out.
With the neat graphics on it this might have been one of those times that hollowing it out and hiding a modern cap inside would have been worthwhile.
molson12oz, so... will you replace this capacitor with an identical new one for free, or not? What's the warranty policy dictated by that fancy ISO 9001:something of yours?
:P
molson12oz, yeah, sorry for not being actually funny; it's just that the ISO process certification stuff seems so out-of-place under this video, and reads as if copied from a press release.
Props for being in the industry for nearly a century, though - that's genuinely cool and good to see. Even if your capacitors are lousy ;)
It must be a miracle or a public relations coup d'etat for Aerovox to be so big in their field and yet make crappy caps.Hmmm-I'll stick with the ISO certification of quality-that's not a silly Gov label- it's an industry standard constantly improved and yes- it must be maintained.
But-once a company has earned it due to their insistence on quality it is a GREAT ad footnote.
molson12oz, previously you turned your "satire filter" OFF.
I can only assume it also works as a "satire detector", in which case I'd recommend keeping it permanently ON - because it should have been bloody obvious that my comment was tongue in cheek. Nobody expects a big electrolytic capacitor to keep working for 80 years. Plus, I absolutely love its looks; the labeling is so stylish and classy.
Anyway, I still love you, even if both your capacitors and your sense of humor are lousy :)
PS. I already know what ISO 9001 is, although I appreciate the attempt to educate me. I never claimed it's just a government label.
I’d like to see you de-pot the transformer. In my work I sometimes have to de-pot our HV DC-DC converters for failure analysis. That’s a lot of fun - trying to find where the potting ends and the circuit begins. I’d also like to see your sand-blaster in action, to be honest. I’d like to have one of those myself.
"It really doesn't have a choice when it's on this bench. It's going to work again!" Love it, Mr. Carlson! You're making me want to tackle a project or two! Oh, and yes, I'd like to see you depot the transformer. I might learn something in the process!
Very well done, nice piece of history. Yes love your videos and teaching.
I found your channel today. I am impressed by the work you do, it is very interesting! 👍
That is amazing! Love that little scope!
It certainly will make a neat video!
not to mention very interesting to watch.
Many thanks for your informative vids.
Show both de-potting and replacement. There is value to both. You might have an antique piece that you want to look original or you might have something that you just want it to work correctly.
Excellent video as always! I personally think depotting the transformer would be an excellent video, however it may be a nice idea to also find a matching one for the device, as this process seems really interesting also and would be useful to someone like me who's never done it before, without ordering an exact replacement!
Cool channel its interesting and informative, thanks.
Ooooh, this is a treat. I love these vintage teardowns. I was just finishing a long day of work when I saw this go up, and now I'm watching before bed. Absolutely turned my day around! Thanks, Mr Carlson!
Please do open up the transformer, as I always find it interesting to see what is inside.
Looking at all the comments, you don't need mine. Yes please de-pot the transformer.One other thing, I have found audio transformers in the 30's radio with potted caps in the box. I also asked "Why!"Thanks for the videos. Carl
Nice one! Yeah, I vote for de-pot and reading the other comments I doubt you'll be able to escape that fate. :)
Your videos just fly by because they are so interesting and informative, you Sir are a wonderful teacher and I love the way you bring your professionalism to are screens. Another great video I just can;t speak highly enough of you and your channel........Thank you!
Aerovox is still around. We forget how much manufacturing happened in the USA - Brooklyn no less.
I think the best educational benefit would be realized by de-potting the xformer, and replacing the defective capacitors - with externally mounted replacements. Then, I think there would be value in replacing it with another different xformer, with the explanation of how to make it work in the application. Additionally, it would be good to add a fuse to the device. There must not have been a great deal of concern in the 1930s with safety. The fuse is a glaring omission.
Nice job Paul. I would say, go for the de-potting. It's always nice to see someone turn something dirty into a gem :) I AM curious though to see what sort of instrument you'll turn this little thing into...
Yeah, I think de-potting the transformer will make for an interesting video. I'm curious to see just how ugly it gets. :)
Great video Paul as always. I would love to see the transformer de-potted to see if the caps can be replaced. If it ends up that its not possible to rrplace the caps then you can still replace the transformer and add the caps externally. It would be nice to see the case refurbished. Even if you are going to use it its still nice to see equipment looking its best.
Read my comment up thread, Gary, that black finish is, "Black Crackle", and modern versions of it are available, but back in the day we could make our own. I also give hints as to how cabinets and front panels could be made like new without even doing a tear down and rebuild.
Definitely do a transformer depot....... Really enjoy your stuff.
I would love to see a video about depotting a transformer, maybe combine it with a video depotting old tar caps to place a modern cap inside (for full restoration)? Personally I agree with repurposing old electronics and don't make them dust gatherers but only using the guts from a 80+ years old device does kinda hurt my soul. Would rather see a device in worse condition get that treatment than this, but hey, that is my opinion. Thanks Paul for yet another neat video!
Potting the line bypass caps, line cord connections and other components into the transformer "can" was not uncommon in the 20s-early 30s. Many manufacturers potted numerous component combinations into cans with leads extending out to ease in final assembly and save chassis space. Atwater Kent and Majestic come to mind.
Remember, electronics was relatively new at the time. The short life of the "modern" wax/paper caps likely wasn't well known then. I believe the thought was to seal them from moisture to help prolong their life. They were likely good beyond the expected life of the unit, but not much beyond that. The practice seems to have stopped by about 1935.
The caps are likely just below the surface of the potting compound. I've had good luck removing just enough of the pitch to remove the capacitors from the circuit. A hair dryer or heat gun works well.
I used to enjoy the challenge. Today, like you, not so much. Good luck and thanks for all of the great videos.
I could have put money on everyone saying de-pot :D
Steve Brace you'd have lo$t it.
ElectroBOOM line cord. Never mind the signal generator, hook up a mic & go to the nearest occupied frequency and holler "AUDIO"...
Damn you Mr. Carlson, I had things to do today. Now I have no choice but to watch this video. No choice!
LOL, I can relate. When I first found Mr. Carlsons channel, I totally went down the You Tube rabbit hole. Now, when a new vid posts, I HAVE to watch it.
"When its on this bench it is going to work again", Awesome
I wish I had a bench like that.
"These nice little vents are great for letting the smoke out" (2:33). Awesome 2.
It's like a Mr. Rogers version of AVE
I note there is no lables on the switches of the capacitor tester...i guess in those days you just had to learn what they do ☺
More like in those days the engineers weren't too sure themselves. Half the stuff no one had thought of a name for it yet anyways.
they still don't. they still measure capacitors in the amount of volts per second it can randomly hold. with no mention of important stuff such as the atomic number of the materials, their area, and distance to one another. as ac and radio and light and the behaviour of capacitors are all the same thing, those aspects are far more important if we ever want to get ion drive spaceships than how many farad they just so happen to randomly hold 'it does something! let's call it a product and ship it!'
As long as it does something I'm in.
Mr. Carlson, I'm voting for a depotting video. Thanx for the vid!!!
Hello mr carlson❤💚Happy Holidays to you family and friends🎄lov your videos🦋
Depot it my friend great video.
For the love of God, DO NOT De-pot the transformer!!! Heh, someone had to say it.
I would love to see that depot transformer
Wonderful bit of vintage gear! I would have liked you to remove the capacitor contents from the Aerovox can and re-stuff it with the new capacitor. I think it's important to keep as much visual history of this kind of 1930s equipment so that when someone takes it apart in 50 years time they can see the kind of capacitor that was used back in the day. Leave a note in there too to show what's been done. It actually makes a good debate as to what responsibilities, if any, as restorers we actually have.
It would be pretty simple to find out if it was restored... you do NOT have to recreate the mistakes of the past to make it "real." A note would suffice.
I absolutely agree that the components need updating but if the equipment is of historical interest then leaving in place the old isolated component just to show exactly what was used originally surely gives the best of both worlds? Is the debate not more about whether a piece of equipment is historically 'worthy' of maintaining visual originality?
Exactly. The authenticity of historic equipment is destroyed by fitting modern components that are visible. At least the original component should be left so a future restorer can do it properly.
Thank you for getting right to it. So many UA-camrs think everyone wants to hear them ramble for five minutes about nothing related to the actual subject.
Man, I'm hoping the day comes when I can say: "It doesn't have a choice, once it gets on this bench it WILL work again!" and it actually happens! I've learned a lot from you, but I feel it will still be a while yet. Cheers for the videos, Mr. C.
De-Pot for sure, love to see the presumably messy and nasty process that's going to be )
I'd enjoy watching you mess with de-potting the xfmr. :)
I noticed you pointing to some ground connections inside the unit, but the power cord only had two connections. How was the unit grounded if not via the outlet? What was the benefit? Sorry for being so ignorant!
DEPOT the transformer if it is at all reasonable, please. I enjoyed seeing the 913 tube again. It's been a really long time. I worked in the production of 6326/6198 vidicon tubes in the 1950's and we would sometimes change the coating from photoelectric to phosphorescent. This produced a 1" picture tube with amazing clarity. Very useful for "in house" test equipment similar to the one in you excellent video. Some of us adapted it for monitoring our "home made" cameras.
You can still get the wrinkle coat finish.
I'd like to see you de-pot the transformer please.
Love to see a de-potting of the transformer. I have read about it but never done one. As to the black wrinkle paint i have been there but for the twin camshaft cover on my aging Italian performance spec car. The paint was flaking off looking terrible. Removed the large alloy lump and used an alloy-friendly paint-stripper then put it through the dishwasher to totally de-oil it although it came anodized a kind of black. . The special black wrinkle paint needed a hot pre-baked part to some 200degress C so into the kitchen oven went the cover. I pulled it out an hour latter, sprayed on the paint and carefully built up the layers to cover the metal but not too thick. Then by magic it did the wrinkle thing all over. Finally, to harden it i had to return it to the kitchen oven for another hour at around 100 degress C....After that i just left it cool. Later i set a flycutter in my mill and cut just enough off the top to reveal the logo etc in shinny alloy. Back in the engine bay it looked fantastic. WARNING: using the dishwasher was OK. The stink in the kitchen was terrible and the next time i cooked a roast meal.... BLERK! it tasted of paint! (Note you can only get away with this if you are single)...
LOL, great info Pete!
If it is unknown whether the transformer caps are present or not, would the capacitor tester be able to tell the difference between the caps being good vs the caps not being present? Both situations would present and open circuit in the DC.
LOL - Watching this and you talked about how none of the switches were labeled and then went and tested the capacitor using your own device where nothing is labeled. Some things don't change in 90 years.
LOL, Yes. My reason is, I'm too busy designing new equipment and circuits, rather than take the time for myself.
So essentially it's just a primitive version of a modern oscilloscope in XY mode?
Why would they bother having any type of horizontal sweep without a trigger circuit?
Show a video of depotting of the transformer 👍
more oscilloscope videos please, they are amazing
I'm always impressed of what kind of test gear your own from that Era. To me it looks also like some old science fiction movie equipment maybe from War of the Worlds ;) Thank you Paul for sharing this, otherwise I would never see such beauties!
Wait. Some of that stuff I used when it was considered state-of-the art.
Of course, this isn't one of them...
How has this channel not got more subs? So much knowledge and wisdom, excellent teacher 👍
Looking at the schematic, wouldn't the cap tester be fooled by the primary of the transformer which is parallel to the caps? ;) My bet is the caps are fine, and the tester reading a short is due to the transformer winding. Edit: I say that because if only one cap was bad, both would read bad (referenced to the grounding point) again due to the path through the windings.
I don't know why...but this always reminds me of Dexter's Laboratory. 😁
This is an awesome little tool!...Too bad the caps are potted in the transformer...or is it?..Nope, just means a transformer unpotting video! .... You have my vote for a transformer unpotting rebuild! I love all you do!, you make electrons proud! Thank you for sharing your electrical adventures!
Correct? It seems that the capacitors were only included if necessary. Perhaps they are not included in the transformer
Thanks for the video. I vote for de-potting :D
You have an infinite capacity for taking pains and doing things right. Accordingly, depotting the transformer is CLEARLY the only proper move. And along the same lines, that old 2 MFD cap looks so cool, how hard would it be to open it up, insert your new cap, and keep the vintage look? (Easy for me to say as you're the man actually doing the work.) Anyway, nice job as always.
That's a cool little 'scope!
Definitely not a very good idea burying those caps in the transformer; looks like they might of got the idea from Atwater Kent. Guess they didn't know or care if capacitors had a limited life span.
Nice repair as always, thanks for taking us along Paul!
I dont think a De-Pot would be that exciting its just Tar on a transformer core .I believe more education could be gleaned from a XFMR replacement specially when the exact replacement isn't avail.
apollo robb You can wind your own transformers. At these sizes it's not difficult, only tedious.
Hi Paul.
Another good video, you could show both ways of dealing with the transformer as you discribed before you make a commitment on the direction you wish to take. It's just an idea you could use.
A brilliant explanation of what you are doing, keep up with the videos as I am learning lots from you.
Cool stuff
Please Depot the transformer. It great teaching tool. Thank you!
Thank you for this great video sir!
It is always enjoyable to see a true master of his craft at work :)
I would very much like to see the transformer de-potting as I have never done that myself & am curious about it.
But I do understand that it would be very messy & difficult so if you decide not to do that video I would still like to see the way you replace the current one..
Microfarad but it's got a capital M, wouldn't that make it Megafarad? I mean, granted, I don't think I've ever HEARD of a megafarad capacitor before, but this is an ancient device...
Wow. I was completely absorbed by this video. Forty-five minutes flew by like it was nothing! I didn't intend to watch all of this in one sitting. Fantastic job, again.
And, I must also chime-in and request a de-potting. It sounds simply dreadful, but popcorn-worthy entertainment!
Depot? Seems the I's have it. I wish I could become a patreon, but can't yet. So maybe share with us here on plain old free UA-cam. I have potted guitar pickups, but never deported anything. Interesting, to say the least. Love your channel! Thanxz
That's a cute little scope. National probably saved one cent per unit by buying the power transformer with the capacitors built in. If a cap shorted, it would be replaced as a unit. Encapsulated caps like those could last a few decades, so making them replaceable didn't make economic sense at the time.
Your testing device shows substantial leakage, and I'm surprised it worked at all!
They would have not potted it before attaching the mains cord, so if it was a bought in part, it not only came with condensers but with a mains cord as well. The potting was probably done for more than one reason. The condensers would have lasted longer as you say, that would have been a reason in itself apart from possible cost saving. Also it allowed for a more compact construction and it would have been safer (no exposed mains coupled parts).
Yep lets see the de-potting I am a little curious about the Cap or Caps inside and if the Potting material had a affect to why the Cap's have failed. And as always it's always a treat to hear you explain things that many others just can't seem to do well. Thanks for the great content...
There's paper caps In the transformer??? Never heard of that before. Then again, I work on guitar amplifiers mostly.
I personnaly would leave the paint work as is, shows off its age. Antique dealers call it Patina (Hope I spelt it right) and makes the antique look, and feel more genuine. Keeps its value too.
It'll never be a Tektronix that's for sure. Imagine if they had todays scopes way back then, what sort of advances could have been made I wonder....
Having said that, it looks cute. Jack Ganssle had a scope from 1946 in one of his videos, (Episode 7)
Are there caps in the transformer or is that just leakage trough the winding's, would it be worth testing with a megger first. I hope you washed your hand after handling that 600 volt capacitor as they often were filled with an oil that was highly toxic containing pcb's (Polychlorinated biphenyls).
So many things I like about your videos, however the thibg I love the most is your walk-through and explanations of schematics! Thank you!
De pot it :)
You could play oscilloscope music on it!
One more great video again.
Thanks for sharing.
And of course.. Depot..
hihihihi
73 DE PU2SRZ.
Thanks for stopping by Silvio!
I"m in awe. The smallest CRT in electronic history is working as expected; yet you are considering depoting the transformer because of a 5uA or so leakage of those two capacitors. Its safety consciousness at its best; as well as angst free dedication in face of a gooey mess.
Maybe the potted capacitors was part of some planned obsolecence / need for replacement parts from national? Or maybe it was for "safety" if the capacitors blew they would be sort of contained. Interesting to pot them though as it does make servicing them very difficult. Any thoughts as to why they might have done it apart from design error?
Do the capacitors have pcb oil in them?
It appears that the CRT is the ONLY active component in this system!
I found it! Did a little online searching and I found this exact model. Just as on the schematic, this is the Model CRM oscilloscope, made by the National Company. A little more searching resulted in finding a similar product manufactured by RCA: the Model 151. It uses the same CRT tube (913), however the RCA version has a few more functions, and RCA called it an "oscillograph."
Supreme Test Instruments also had a similar product to these two, except that the Supreme version used a 2" CRT instead of the 1" used by National and RCA.
If I am not mistaken (which I could be!), I believe the schematic of the CRM, or a generic equivalent, can be found in the 1937 ARRL Technical Manual.
Thanks for taking the time to write Erzahler!
+Mr Carlson's Lab: You are most certainly welcome, Mr. Carlson. Actually, it is I who should be thanking you, for teaching us all of this great stuff! I love the old tube gear, and I am always learning something new about it (well, new to me, anyway!), thanks to your UA-cam channel. 😊👍
73 de NØJAA.
Erzahler, I used to have an early oscilloscope that used a 6U5 or 6E5 Magic Eye tube for the display, I believe it was a Dumont or RCA device as I recall. Dumont's patented Magic Eye tube was a forerunner of the CRT, and Dumont stupidly sold the technology and the patent to RCA as I recall. That technology was to eventually prove invaluable in oscilloscope and radar design , and that patent would have been worth a major fortune post World War II with the explosion of not just oscilloscopes but television.