Vacuum Tubes: Episode 1 - The Basics and the Diode
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- เผยแพร่เมื่อ 26 มิ.ย. 2020
- In this episode we finally dig into vacuum tubes. I cover what vacuum tubes are and the fundamentals behind their operation and then demonstrate two different diode type tubes.
- วิทยาศาสตร์และเทคโนโลยี
What is going on? Im getting older 55 now, and I have this irresistable urge to learn electronics. I was in IT my whole life but mostly software, networks, servers, hardware. No electronics really. Learning now. It's fun. Great video.
Dude let me just say this: you have incredible charisma! Most modern videos discussing these topics have a jump cut every 5 or 10 seconds. But you sir held my attention with minimal editing. And I'm 23 with an attention span molded by social media apps like Vine and Instagram. Well done!
Thank you so much!
I don't really know what to say, that's such a wonderful thing to hear!
Re-watching these older videos, I was much more laconic in my presenting style and my editing was much more minimal. I'd like to think that my newer videos have a much faster pace without losing the same presentation style I had in these (with better visuals to help demonstrate the point).
Thank you again for the excellent words!
GG
There is hope for the world! In the 90's I got into yoga, the only electrical devices I had were my boombox, tape/CD player and a guitar amp, I spent 11 years simply like that, got my first pc in my mid thirties, have to say good use of the internet is amazing given that libraries are really limited, it's being in yourself and having honed your mind and selfhood enough to ask good questions and discernment, good luck on your mind liberation.....spread the word, the idea...et al......
@@UsagiElectric
Good day, I am honestly grateful for this video. Please I am interested in electronic and I am fascinated by how computers and mordern day technologies work. Please do you have a recommendation on where to get started? I want to really start from the ground, what was the first computers and then the growth up to this point. In fact what really is electricity? I need your guidance on resources if you may. Maybe by any chance you have a video/series on this. Thank you.
I cannot begin to tell you how effectively you explained all this and made it interesting. In fact I love you explaining this using a pen and paper. Every other person would have resorted to making some fancy 3D graphics, etc., but your explanation using pen and paper is now burned into my brain! Well done!
I know this video is older now but I just have to say. I know nothing about this stuff, and this is one of the few videos that explained it in such a way that I understood completely AND had live demos! Thanks!
You can screw around with tube performance by waving a strong permanent magnet around them.
Down the corner of my street was a small factory making tubes (valves in UK) for the Mullard Company. Our portable radios had two batteries , 6v for heaters and 90v dry cell for HT anodes. Idten a metal cap atop the valve.
Looking to start some vacuum tube projects myself -- just a few minutes in and I'm learning a lot. Thank you for making these!!
Cool man. Let me tell you I am mechanical engineer and have been seduced by the dark side of the Hi Fi.... People like you make me enjoy so much and help me developing on other matters that are so interesting to learn about. Thank you very much and keep it up man!!
Vacuum tubes were my life, 50 years of servicing electronics equipment. I started with radio, tv and early computers.
Great explanation, very clear and easy to follow!
Thank you!
Your a great instructor! I been a solid state guy all these years.
First of all, I just found you today and you RULE! This is all great and new to me and hyper-interesting. I'm an old-school programmer from the 70s. I worked at Control Data, coding on the CDC Cyber 176. I found your videos on the tube computer, and wanted to backtrack to here. You are way more clever than you give yourself credit for. I like your architecture on the tube computer. I designed one also for 16 instructions, but with the idea of doing it as a relay computer. All good wishes.
Thank you!
Whoa, that's awesome that you used to work for CDC and even got to work on one of their mainframe projects! Thank you for the kind words, but I'm really just a hobbyist playing around with stuff, still quite a long way from doing proper engineering. But, I'm having fun doing it!
The tube computer architecture is really interesting, and I'm glad I chose it because I learned so much, but I'm fairly certain I could come up with a custom 8-bit architecture now that is only about twice as big. Though, I think I may save that for the next tube computer, because I do really want to see the 1-bit one come together fully.
A fully relay computer is something I also want to do in the future. The MERCIA relay computer by Jeroen Brinkman has actually been a massive inspiration for most of my computer shenanigans!
Just found your channel because I was interested in tubes as well, thank you for your work,
8:50 I think the diode symbol is backward. The arrow is the anode. ;-)
Yup, the diode is backwards in relation to the tube diode next to it.
I actually tripped myself up here by talking about the silicon diode in terms of conventional current flow and talking about the tube diode in terms of electron flow!
I’m super excited to see a future where a technology like vacuum tubes could come back. Especially with the risk of EMP attacks growing more present. I’ve been reading a lot about field effect tubes lately. It seems it might be possible to make a diode/triode/tetrode/pentode/etc the size of a transistor.
RCA actually did develop vacuum tubes nearly as small as transistors; in the 1960s I believe. But as transistors were up and coming, they never caught on.
Me enganché con el canal! Bien hecho. Voy a darle seguimiento a todos los videos en el transcurso de estos días jeej
Abrazos
I wish you were around when I started to study electronics. Started in Ham radio and building things in 1965 I am sure you were not born then. Doing a fine job.
Just subscribed: This is easily the best explanation I've ever seen of how electricity and tubes work. I hope you've produced another piece on how output transformers on tube amps work in conjunction with tubes. Moreover, I'd love a piece from you on how all the tubes on an amp work together (voltage tubes, power tubes, rectifier, ect.).
Extremely good educator you are.
Just superb content and delivery!! You're a natural! I like how you explain things clearly in theory on paper and then take it to the breadboard. Your cadence is perfect too - i like how you give time to let things sink in before moving on. I too have always been fascinated by vacuum tubes and have taken on a new passion for electronics both solid state and analog and learning as much as I can. Thanks for doing this series and I'm looking forward to watching more. Subscribed!
Thank you so much for the kind words!
My delivery in my newer videos is a little more concise, but I try to keep the same paper to breadboard to pcb theory in all my videos!
@@UsagiElectric I couldn't say better words than Kurt's. Your explanation is superb.
If I could add anything, I'd tell you to replace the pair of LEDs with a flashlight bulb, to do justice to the technology of the 1930s. :)
Nice video, I am dabbling with tutorial videos myself, it's not easy! The hardest thing is knowing how deep to go.
Thank you! It's so easy to go into so much more detail than is necessary. I actually try to keep my videos under 20 minutes, but there was so much to cover that this one kind of got a little long. There was a bunch of stuff I glazed over as well, I would have loved to talk about the proper history, such as how Edmond Becquerel in France discovered thermionic emissions as early as 1853! Of course, that's just one person, to get to the point of the first diode took another 50 years and contributions from several people.
Thanks for the video, throughout my life I have felt the same as you described regarding vacuum tubes and other things (1940's Christmas light for example)
Just spent 3 hours reading Wikipedia articles. Now I can actually see what they actually look like. Thanks. 😊😊😊
Thanks for checking the video out!
Tubes are pretty simple and fun once broken down to the most basic components!
Awesome explanations. Thanks alot !
Love tubes too, I share exactly the same feeling as you said in the start of the vídeo!
Thank you! They're just such cool pieces of technology, plus they look beautiful!
Good tutorial. Thanks.
If you had say, a 24 volt power supply, and wanted to put 3 of, say 6AU6 tube's heaters in series, but didn't have a 4th tube--could you use a filament resistor of around 21 Ohms to make up for only having 3 instead of 4 tubes in a .3A loop? Wouldn't a 5 watt resistor give you about 100% safety margin, or would the resistance be much lower on when the filament is cold? Perhaps the resistor could be lifted from the board a bit. : )
Great explanation!
Thank you!
This is the way of teaching technical subjects
recall seeing old transmitters with Mercury vapor rectifiers like 866 872. Fantastic blue glow. The filament/heater supply voltage has extreme effect on tube life. Running them at the rated or less voltage is much preferable. That means 6.3 volt or less .
I would love to play with some old Mercury rectifiers, I've never seen their beautiful blue glow in person. Someday I'll try to get my hands on one and fire it up!
Thank you very much for this informative video.
I have basic understanding of tubes and this demos are great to watch; it's perfect for me! Nice to see you running tubes on low voltages - I have wondered if that would work for guitar effects and it is probably a feasible option.
It would be far easier, safer, more practical, more accessible, and less complicated to use transistors. They will do the exact same job as a vacuum tube, but using less than 5 volts. You could make a distortion pedal out of a simple 5 cent op amp chip using just a few components, in theory. I don't know much about sound synthesis, but I know enough to know there are oodles of chips out there that will help you out with that. As opposed to building your own chip out of tubes, plus any supporting circuitry.
Have you done an episode about sub-miniature valves and their use in avionics including missile electronics? Sub-miniature valves were operated at 28VDC.
These videos are amazing. Even though you don’t have a huge audience, you spend the extra time to up the production value to a great video. All the information is presented beautifully and really gets the viewer into what is being told.
Thank you so much for the amazing feedback! There's still lots of little things here and there that I'm trying to get better at, but it's a lot of fun talking about something that I find so cool!
Thanks for making such a great video! Subbed!
Thank you so much!
I've always been fascinated about vacuum tubes as well, compared to modern electronic devices, such as SMDs, vacuum tubes are way easier to work with in my honest opinion, people say that vacuum tubes are unreliable, well, I've owned electronic devices that use SMDs that have failed within a month of me buying them, on the other hand I have a non-reverb Fender Super twin amplifier that uses vacuum tubes and was made in the mid 70's, it is still functioning perfectly to this day.
So good... Fun watch. Did you not just create a voltage divider for the filament voltage for simplicity sake?
Thank you! You could get away with building a simple resistor voltage divider, but the tube filaments actually pull quite a lot of power. The 6DJ8 is rated at 350mA at 6V, which is a hair over 2 watts (and the 6DJ8 is pretty low, something like the 6080 octal power triode is rated at 2.5A at 6V!). The little buck boost converter I'm using is rated for 2A, so that makes life a lot easier (except for that 6080, nothing's easy with that beast). Ultimately, for my larger projects, I actually end up building things around 4-tube modules. If the tubes are of the same type (4x 6DJ8s, 4x 6AU6s, etc.), the heaters have the same amperage draw and I can run them in series. There's a 6V drop across each tube and with a 24V supply, that works out perfectly!
You know what’s cool about vacuum tubes is that you can put little sticker thermocouples on them, to get temperature readings. I don’t if there’s any good reason to do that, but the readings would be fun to track.
That's actually a pretty interesting idea!
I know that some tubes run much hotter than other tubes, and you could actually keep an eye on glass temperature depending on load too. Granted, at the 24V that I tend to use, the load is so minimal, the tubes stay very thermally stable, but for some big driver tubes in audio amplifiers, it could be fun to watch the temperature move around!
Nice video, and just like a conversation well done. Really love the rhythm you are going at.
So Thumbs up and I subscribed, so now I have binge watch all your vids. :-0
Thank you so much!
I like to think my editing and rhythm get a lot tighter and more digestible in my more recent videos, but it's great to hear that you're enjoying these older videos too!
OMG! Look at you with your curly hair! Adorable!
Hi there, thx for the video lecture, it's very illuminating! I have a question, need clarification about 2 things if you
(or someone) would be so kind! At 17:10 on your drawing wouldn't the LED on the left be LIT no matter with position
the PLATE switch is in (+24v or Gnd) since there is +1.5v on the LEFT LED with GND on the LED's cathode? It seems like
the HEATER battery will bias the LEFT LED at all times regardless of PLATE SWITCH! I "assume" the HEATER'S Battery Negative is to ground to complete the circuit!
Then when you move the PLATE switch to GND the Left LED is still on (being biased by the heater battery) UNTIL you
move the bottom switch from GND to +24v to bias the RIGHT LED! NOW the LEFT led has reverse bias and turns OFF,
while the RIGHT LED now has proper bias and TURNS ON! The LEDs going "ON and OFF" really has "nothing" to do with
the PLATE, but the biasing of the LEDs by the Heater Battery....I think???
Isn't PLATE CURRENT occurring ANYTIME the HEATER is working AND the PLATE has +24v...BUT not when PLATE is
switched to GND?
Lastly and most importantly, "will" the LEDs "truly" ever feel the "influence" of the +24v at the PLATE? I mean, the true
PLATE current is from HEATER to PLATE ONLY...except for any additional "current" running up the LEFT LED being
limited by the resistor value...but overall negligible since LEDs really can't pass a lot of current...I think??? THE +24v
WILL NEVER BE MEASURABLE AT any place other than the PLATE...not on Heater nor the LEDs...correct???
Hopefully, I made some sense!!! Perhaps I'm chasing too many electrons...lol! Anyone's feedback is appreciated! Thx!!
I love tubes sounds, even i dont understand them in my early days discovering them in guitar amps
Hello, this video was amazing! I love vacuum tubes and also own some nice ones such as GU-81. But I struggle to find some nice project to use them in, accept tesla coil with dangerous voltages involved or tube amps (I can't tell if a guitar is tuned or not, so this is essentially useless to me and really expensive). Now, this was one of the best vacuum tube videos I've seen on DIY vacuum tube projects. Keep up the good work and thank you so much :))
Thank you so much for the praise! I'm kind of the same way, I have pretty significant hearing loss in my left ear, so vacuum tube amplifiers don't really mean all that much to me. But, vacuum tubes were used in all sorts of interesting designs and circuits back in the day, so I love the idea of exploring different tube circuits but doing so at a safe voltage. Turns out, most tubes respond pretty well, even at tiny voltages.
Having said that, I'm no so sure how well the GU-81 would perform at anything lower than phenomenally large voltages, even the heater requires 11A at 12V! That's an epic tube though and one of the more beautiful tubes out there. One day I'd love to play around with one, hopefully without hurting myself, haha.
@@UsagiElectric I like to play with HV (more like styropyro style) eg. Tesla Coils (I already made some), in fact I would like to make GU-81M VTTC (Vacuum Tube Tesla Coil). But I don't see any application where I can use tubes other than this. I would love to make some sort of tube calculator (Mr. Carlson's Lab had a video about vacuum tube OP Amp, which can even do differentiation).
@@michalvarsanyi612 HV scares, but I would like to build a Tesla Coil someday, they're just so cool! Mr. Carlson's Lab is a fantastic channel and I loved the video he did on the OP Amp. One of my goals is to actually build a low voltage tube OP Amp. It won't be near as precise, but if I can get it mostly working without needing +300V to -300V, that would be awesome!
Had an old radio as a kid with a nice green glowing eye I love them too. Greetings from the kingdom of Eswatini
Was that a level indicator ? Used to get them on tape recorders.
Thank you very much for this.
What was the minimum voltage you used that still gave a diode effect?
Really interesting experiment. I too was always put off by the high voltages. I remember old portable radios that had batteries providing a hundred volts or so (if I remember correctly).
Thank you! I never actually tried to see how low I could go with the diode, but all these were done at 24V. I will say that in my early experiments with triodes/pentodes, I actually was able to see some effect with voltages as low as 6V. This is an unlisted video, but it shows my very first attempt at playing with a pentode (th-cam.com/video/SDvdMl7H9UI/w-d-xo.html). I knew so little when I first made that video and I have some things set up... poorly. But even so, you can see that there was still a measurable effect at just 6V which shows just how flexible tubes can be!
There where a few vacuum tube portables that ran at lower voltages like B+ 27V, filaments 1.5V. Some tubes ran at car voltages B+ 12 V , the portables sure used up batteries…
@@donwebber7034 It is still within living memory that once upon a time, running the radio in your car with the engine not running could rapidly run down your battery to the point where you'd be stranded with not enough charge left in the battery to start your car. There were quite a few "stranded boyfriend and girlfriend" jokes made which referenced that exact situation. I even remember at least one Archie Comics story with Archie and Veronica in exactly that situation. Yeah... they definitely used up the batteries fast.
The more I study about radio I learn about th something else like “ vacaum tube “ again my brain is overwhelmed with all this info
Yes! Vacuum tubes!! I especially enjoy the Soviet made tubes, extra cool tubes IMO
Didn't think I was very interested in vaccuum tubes but you pulled me in. Could you connect the LEDs to ground and + respectively and eliminate a switch? Also, does a tube diode have a voltage drop like a silicon diode? How much?
Thank you for the kind words!
You can pretty much hook up a tube diode in any way you can hook up any regular solid state diode. I only had the weird setup here to try and demonstrate that electron flow was indeed only occurring in one direction. The primary limiting factor is going to be the amount of current the diode can move. The 6AL5 diode I'm using here is a signal diode, so not really meant to move all that much current. For higher power applications, there are some much larger diodes with huge plates, or if you need really high power you can even upgrade to Thyratrons!
A voltage drop across the diode is something I hadn't thought of before! There is indeed a drop, but it's not quite like a conventional solid state diode. I believe the drop across the diode is proportional to the amount of current flowing through the diode. In the 6AL5 datasheet, they state a 10V drop across the diode when set up as a half wave rectifier with 60mA of plate current. Different voltage and current should result in a different voltage drop. However, if I'm reading the chart right, at 10mA of plate current, the voltage drop is just 2.5V.
Of course, I could be totally off the mark, I haven't tried measuring voltage drop across the 6AL5 yet, that's a project I should definitely give a go one of these days!
Thank you very clear video :)
Thank you for checking the video out!
Great video! Also, OS Giken shirt? :-) What kind of car do you have?
Thank you! And nice catch on the shirt! I have quite a few cars actually, check out my website for some pictures and build threads on some of them: usagimotors.com/ (Not shown on the website is a 67 Cosmo that's mid-resto, a 71 Fairlady Z that's in need of a resto, and an 88 300ZX SS that's waiting on an engine rebuild).
'Modern' incandescent bulbs are filled with an inert gas, although early bulbs were evacuated.
Interesting! I didn't actually know that. It seems that Argon with a bit of nitrogen is a common fill gas. I wonder if, after the filament burns out, enough voltage could be supplied to cause the argon to breakdown and glow? Granted, that's super dependent on the amount of nitrogen and overall pressure, but that could be a fun little experiment!
Yes, it can, but at much higher AC voltage like a tesla coil or an ignition coil, etc. It doesn't glow very bright tho.
Good day. @UsagiEletric, i am honestly grateful for this video. Please I am interested in electronic and I am fascinated by how computers and mordern day technologies work. Please do you have a recommendation on where to get started? I want to really start from the ground, what was the first computers and then the growth up to this point. In fact what really is electricity? I need your guidance on resources if you may. Maybe by any chance you have a video/series on this. Thank you.
08:50 the diode symbol should be inverted. You draw the cathode of the diode, where the anode of the tube is
Yup, the diode is backwards in relation to the tube diode next to it.
I actually tripped myself up here by talking about the silicon diode in terms of conventional current flow and talking about the tube diode in terms of electron flow!
The Vacuum Florescent display and the magnetron in a microwave oven are some of the remaining applications for the vacuum tube.
I love me some VFDs!
But there's actually still a ton of different uses for vacuum tubes today. Tubes do really excellently at insanely high voltages where silicon tends to breakdown. Things like Klystrons, Gyrotrons and Traveling Wave Tubes are all still in active use I believe. Also, they have the coolest names ever, haha.
Great video. Very good coverage of the subject. But, if you think a few hundred volts is "high voltage", you probably won't like my CRT videos. Back in the day, TV repair guys referred to anything below 600 volts as medium voltage and below 60 volts as low voltage.
The 6AL5 is not a power rectifier. It is a dual diode used in an FM discriminator in TV audio or FM radio receivers. It is (was) some times used as a phase detector as well. But, generally it is signal level diode not intended for power supplies.
Thank you!
And you're absolutely right, a couple hundred volts is very far from high voltage! I'm a bit of klutz and an idiot though and tend to stick my fingers in live circuits, so anything that can give me a good shock classifies as HV in my book, haha.
The 6AL5 is an excellent little dual diode, and IBM used them quite a lot to build logic gates too. They don't move a lot of current, but they're great moving signals.
And also : All tubes can function as rectifier if cathode and any other terminal is used.
This property can be used to test if tubes are in order.
In RF oscillator circuits, all triodes will work even if the plate supply is AC instead of DC supply.
Regards.
At 15:46 you must have misspoke when you said if the diode is not functioning and then proceed to describe current flow when the plate is at positive voltage. I would think that that’s when the diode is allowing thermionic sourced current to flow and is functioning / active.
Also because of the diode function the 1 diode never lights up but by providing it the diode effect is confirmed.
If it did light up that would indicate that the cold plate was emitting electrons.
I mention these things just to further the discussion.
Your external switching and diode set-up serves to prove that the vacuum tube only allows current or negative charge carriers or electrons to flow from hot plate to cold cathode but not the other way and so exploits thermionic emissions. Great job with your experimental set- up in the lab with the use of leds as a visual indicator of current flow. All in all the best video I’ve seen on directly heated version of vacuum tube diodes. Also nice to see the current limiting or load resistor on the “hot” side of the vacuum tube diode for a change.
Thank you!
And I made a pretty big fatal flaw in this video and that was trying to talk in both terms of conventional current flow as well as electron flow. It's so easy to get all twisted up when speaking about both of them at the same time, so I should have just talked about electron flow because that's what makes the most sense for vacuum tubes.
Also, in hindsight, I think I could remake this video to be much, much more concise and better edited now, but I would hope that to be the case after about two years of making videos, haha.
May sound silly to ask but could you use the heat source from Plutonium 238 or could you reverse the system to run of cryogenics for a reverse effect ?
That's actually an awesome question!
Reversing the effect I don't think would work because the extreme heat is needed to get the electrons moving. However, I love the Plutonium idea!
Plutonium 238, being the material used for the RTGs that powered a lot of earlier space probes and satellites, puts out quite a lot of heat. If a small enough piece of it could be made and then a cathode slid over it, I could totally see it working! Aside from the fact that the tube would now be fairly radioactive, this would have quite a few benefits, but the chief of which would be that the filament is no longer necessary. That means that the actual current required by tubes in logic circuits would be almost nothing!
Now, this could be expanded even further to something like Nuvistors ( en.wikipedia.org/wiki/Nuvistor ). These were super small vacuum tubes that were about the size of early metal can transistors. Instead of a filament, a tiny pellet of Plutonium 238 could be used as the heater and the metal casing could be built to block the radiation. Then, these could be chained together to make logic circuits that have equal or maybe even less power draw than the early transistors had.
Thank you for the awesome question, and now I'm going to spend the next few days thinking about what could have been if nuclear vacuum tubes had been a thing, haha.
@@UsagiElectric Plutonium 238 has a half life of 87 years and glows at a heat of 1050 degrees emitting Alpha particles. As you mentioned NASAS RTG uses plutonium 238 ,however, they use the see beck effect to convert the heat into electrical power with an efficiency of 8 to 12% vacuum tubes operate at 35 to 40 %. Most definitely a more efficient way of extracting this energy. I'm an inventor that covers Quantum mechanics and self sustainable energy systems currently working on 3 projects for sustainable, limitless, renewable energy with Aston university. I have one innovation that can kick out a limitless, mobile 300 Kw of energy. Feel free to text me if you are interested 07902684117.
@@UsagiElectric IIRC, Pu-238 is an alpha emitter, which would be easily stopped by the cathode sleeve. Even beta particles (high-energy electrons) from isotopes in the decay chain would be stopped by the rest of a typical tube structure. The alpha particles might lead to a slow buildup of helium gas in the tube, alpha particles being bare helium nuclei.
The big worry would be if any isotopes in the decay chain were gamma emitters.
Bảo Trần Q
0 seconds ago
Hello , I really admire your passion and contribution to the field of electrical engineering. I have a question and hope that your expertise can address it.Do you think that a triode that uses a household power supply with 220V and 50 Hz be able to give an output power with 60KV, 30 Khz and 1 amp. Basically, my question is Can a triode function like a transformer of high Voltage and Frequency? Thanks
Thank you!
I'm not sure I fully understand your question, but I'll try to answer as best I can!
Triodes are essentially just a switch, they need additional components to get them to oscillate. Additionally, most triodes have an upper limit to the amount of voltage that can be applied to the plate, and it's usually in the hundreds of volts. Now, it is possible to use a triode as an oscillator to generate HV through a transformer. For example, this is the HV circuit in my HP 150A oscilloscope that generates 5kV:
i.postimg.cc/tTp4q49X/CRT-Schema.png
The 6AU5GT is set up as an oscillator that generates a high frequency oscillation that goes into the transformer. This gets boosted to a couple kV and then rectified through the 1X2B recitifier. The oscillator tube never sees any voltage higher than about 400V, and the 1X2B rectifier is intended for high voltage applications.
However, it's important to note that while this is generating some HV, it's no where near the 60kV you're thinking of, and even further away than the 1A. 60kV @ 1A is a terrifyingly large amount of power, and will require some seriously specialized equipment. There are some tubes and thyratrons specifically designed for such insanely high power applications, but that's well out of my realm of knowledge. I definitely recommend checking out Photonic Induction's TH-cam stuff or Styropyro's TH-cam stuff, they both have experience with dealing with very high voltage and high power applications and give much better insight than I can!
Love your channel, thank you for sharing your knowledge! I came across some random tubes that test great, but know if I can swap or roll these on my SET amp. Can you share your insight on whether I can swap these tubes with my 12ax7 and 12au7 tubes in my current configuration.
The tubes in question are:
5879
5814
5687
5751
Hi. Very great video, loved it. I am writing a project for my school about vacuum tubes. However, just watching your videos is not enough for the school. They need sources, but you mentioned that you have read a lot about Vacuum tubes. What books or web pages did you read?
Thanks
Hi, thank you so much for the kind words!
My primary source for information has actually been the IBM 604 customer engineering manual: www.bitsavers.org/pdf/ibm/604/
The IBM 650 manual is quite good too: www.bitsavers.org/pdf/ibm/650/
There's also some really great information over on Valvewizard: www.valvewizard.co.uk/
Also, this Army technical manual is great too: tubebooks.org/Books/army_theory.pdf
Oh, and speaking of Army, the SAGE is awesome just to marvel at: bitsavers.org/pdf/ibm/sage/
I hope those help!
@@UsagiElectric Thank you so much. This will be great help. Subscribed! ;)
Are you willing to share your sources for tubes and sockets? Do you have favourite suppliers?
Sure!
Though, I don’t really have a source for tubes. About 10% came from random salvage, but the rest were just lucky buys on eBay. I’m not particularly picky about the type of tubes I get, so I search for large “tube lots”. Though lately I’ve bene focusing on the 6AU6 pentode as it’s plentiful and decently affordable. So I just keep an eye out for good 6AU6 lots on eBay.
Sockets on the other hand is a little more difficult. For prototyping on the breadboard I have about six 7-pin sockets and four 9-pipn sockets set up like this: i.postimg.cc/kMW72bcr/IMAG3143.jpg
This is perfect for the low voltage prototyping that I do, and the sockets were sourced from some scrap electronics. However, you only really need a handful like this so they can be sourced from a ton of places. There are cheap used alternatives on eBay, or new sockets can be purchased from a few suppliers around. Or, keep an eye out on Marketplace/Craigslist for some old vacuum tube organs. They often have a ton of good dual triodes like the 12AX7 and matching sockets.
When it comes time to start building larger circuits, I’ll cut PCBs on the mill with holes sized to fit these 1mm PCB headers: www.mouser.com/ProductDetail/Harwin/H3161-46?qs=p%252BybrH12zCFIuSSHm88cAQ%3D%3D
I hope that helps! Let me know if you have any other questions!
Hello, could you give me a list of all the tubes you used in your video?
The 6AL5 is a double diode with separate cathodes. Such diodes would naturally be found in early AM radio recievers as demodulator tubes. One diode rectified the signal going to the grid of the audio amplifier and the other diode would be wired to let the negative voltage trough (other half of the AM 450kHz IF) and create the so called AVC or AGC (automatic volume controll or automatic gain controll) sometimes it was just controlling the recievers front end and IF amplifier section to adjust the gain of it so that I'd does not get horribly overwhelmed with a nearby powerfull radio stations signal, and when you look for other stations weaker ones then it lets the gain go as high as it can let it go. That negative voltage was often used to controll the grid of a "Magic Eye tube (as an example 6E5) which would indicate how strong is the signal showing you two things at once-how on center of the stations frequency you are and how strong is the signal.
No I'm not a gray bearded tube enthusiast :) I'm 18 and I play with vacuum tube stuff a lot most often amps and I even build them and right now I am building a switch mode powerfull power supply for my next 2x100W upgrade :)
The 6AL5 is a fantastic and versatile little tube!
I'll definitely defer to you for it's usage in radio operation, my audio game is really weak, haha. But, it was used pretty extensively in IBM's computers. One of the uses was combining a 6AL5 with a 5963(12AT7) dual triode to build a dual NAND gate. But, in general, it was used pretty much anywhere a diode was needed within the logic of the computer. Even after germanium and selenium diodes became available, IBM still preferred to rock the 6AL5 in the majority of cases due to how tough the tube was and also how the 6AL5 has practically zero reverse leakage. I've actually used the 6AL5 quite a bit for building logic circuits when I don't want to use any silicon at all (check out my most recent "In A Minute" episodes).
That's awesome that you're playing with tubes at such a young age (although at 36, I'm still considered young in the tube game)! If you've got a place where you're sharing your builds, let me know! I love checking out other's projects!
@@UsagiElectric I was just pointing out where the bulk of the tubes went in consumer appliances :) some VTVMs used it for the AC range since a vacuum tube diode has basically 0forward voltage. The only caveat is the output impedance at low low low voltages causing significant deviations and need for non linear scales.
The 6AL5 was the first hand choice for tube radios until detector tubes didn't exist. After that you had a noval single tube with a single triode and two diodes going to ona cathode and bam you have all the mean os IF decoding and AF amplifying IN ONE GLASS BOTTLE. Back then they would call this "modern tech" :D
I'm more of a audio tube person so yeah I tend to work with ampliffiers that have an exces of 400V on the anodes. (EL34 20W push pull) or one of my latest creation with two KT88 tubes that runs the anodes real high at 600V for ultimate 120W sine tube power...all that powered from a single switch mode power supply. Life as a nerd has never been simpler hah. Just obtaining the tubes became an expensive hobby over the time.
@@adam207321 You know, I have a few 6T8 triple diode triode tubes and I always wondered what they were used for, but decoding and amplifying in one tube makes a whole lot more sense! I was trying to figure out how to use them for digital applications, haha. They would work great as a three input NOR gate though! Late vacuum tubes started getting really specialized and interesting, cramming more and more stuff into a single tube. One of my favorite tubes in my collection is the 6D10 which stuffed three triodes into a single tube - granted it uses a duodecar base, which aint super easy to find a socket for.
400V and 600V on the plates is just mental to me! Especially considering I'm doing all my tube stuff at just 24V, haha. But, for proper audio applications, more voltage can give some proper power. The KT88 is a properly good audio tube as well it seems, I bet that amp puts out an awesome sound! My only proper experience with tube amps is getting my grandfather's old Magnavox Concert Grand radio back up and running. Which uses quite a lot of 6V6s and puts out one of the best sounds I've ever heard from a stereo!
@@UsagiElectric 6V6 is a octal equivalent of a EL84..not like a 100% but if you were to switch them for that they would work no problemo maybe you would have more gain with the EL84s more desireable for guitar players. 6V6s were also used in some american radio gear from the 1950/60s. Mind you in very expensive home sound system setups back then. The KT88s are just EL84 but MAGNIFFIED. By a lot since the plate dissapation of one KT88 is more than two EL84s.
About the voltages in audio: you can build a GU81 amplifier with 2kV on the anodes and also build a 2A3 or 300B tube amp with 300V on the anodes or a 6C33 with 150V on the anode. Its all about the plate characteristics of the tubes. Very speciffic. Granted generally running higher anode voltages will give you a lot more power when you match your load impedance and run far more into class B than AB. But you can tripple or quadruple your power output. And half the lifespan of your tubes doing that.
The 6T8 seems to have two diodes common to the cathode of the cathode of the triode and one completely separate one. In radio use the cathode of the triode would be grounded so that the voltage on the anodes would go negative creating a negative bias for the rest of the tubes in the radio chain to change the RF and IF and in some cases AF gain too.
We know that the output voltage is dependend on the voltage difference of the grid and the cathode. You could put a resistor in the cathode so that when you put a voltage on either of the diodes it would pull the cathode higher or closer to the grid voltage and then reduce the current trought the anode and make the output go high. I see a really compact OR gate out of this :) With also a this input the grid. Im sorry Im not really a digital guy so I dont know how else could you use the grid for input.
@@UsagiElectric it would all need to be carefully biased tho
One thing about vacuum tubes is that you can make them. Not easily, but you can (see, for example Dalibor Farnt here n youtube)
A (late) friend of mine found himself with a surfeit of spare time, around 1942, somewhere in Germany, after his Spitfire engine failed. He set about the project of making a radio out of tin cans and jam jars. He didn't succeed, as he was wrestling with the vacuum issue when some real valves rolled under the hut door one night. Obviously he stopped at that point but it probably was possible.
He had no idea where these valves came from, so neither have I.
BRO! Where were you 14 years ago when I had been trying to learn more about these things for a research paper at TSTC!?? I swear I had to read up on all kinds of old dirty books on these things from my school's old library (in the section that was poorly lit because no one bothered to change the florescent bulb there). I remember coming across three books; one from England, one from the US, and one from Russia, and I swear I spent a whole week and weekend coving everything you just covered in less than half an hour. The problem was all these books were written by people who clearly knew less about this stuff than I did. I hate how the internet is slowly catching up with everything we are asking real questions about.
Haha, 14 years ago, I still didn't have a clue what vacuum tubes were myself!
It's really wild to me that most EE programs have completely eliminated vacuum tubes from the curriculum. Tubes are an excellent way to learn about how electrons move through a system, and they're much easier to wrap your head around from a fundamental standpoint than trying to figure out what kind of physics are happening inside a transistor.
The best resource I've found on understanding tubes so far has actually been IBM's customer engineering manual for the 604 vacuum tube computer. It's still my go to whenever I need to look something up!
www.bitsavers.org/pdf/ibm/604/
The indirect heating may have some other practical reason : there may be undesirable effect when powering a filament as an emitter. one lead will always be more positive than the other and absorb electrons too, which may cause an imbalance of some sort. No idea if AC or DC is better for filaments, but DC is a constant imbalance, while AC is a constantly changing imbalance. Indirect heating was maybe a way to reduce the problem.
Also, using leads of a transformer to power filaments on a mains-powered equipment could be the more practical than having to generate DC for them too, especially back before solid-state semiconductors. If the filament supply is isolated, the emitter and filament can be linked together like you did and can be set to any voltage while keeping the filament active. This would allow much more choice in circuit design.
It's interesting that you mention that, because that's actually a genuine problem with Vacuum Fluorescent Displays! So much so in fact that VFDs designed for use with a DC supply on the filament, actually place their filament at a relative angle to the plates, so that the less positive side is closer and the more positive side is further away. That way they can ensure consistent emission across the entire filament and subsequently consistent brightness out of the fluorescing plates.
Although, I think the primary reason behind indirect heating is that it allows the cathode to be coated in a material that enhances emissivity. That means that the filament can be heated to a lower temperature for equivalent emission, giving longer filament life with no real impact on performance. Granted that's probably just one of a hundred reasons why indirect heating became the standard, it's still an interesting thing to think about!
@@UsagiElectric using an angle to make DC VFD's is interesting, it sounds indeed like an easy fix :D
I guess using indirect heating of the cathode makes sense as you put it, especially if electron emmission grows with surface area and is enhanced with a special coating.
That reminds me, there's a someone on youtube that makes hand-made vacuum tubes (called glasslinger), and used sometimes a special emitter coating directly on some filaments, but i don't remember if that person also made indirectly-heated cathodes..
very clear and understandable, you are great teacher
Thank you very much!
In the first experiment, the LEDs are glowing from the filament supply. Or else, you should see the LED turing on/off if you connect the plate supply to VCC/GND
The filament supply I have set up on the 5642 diodes only shares a ground with the rest of the circuit, and shouldn't be imparting any current flow. However, LEDs are super sensitive, and I think between my fingers and stray capacitance in the breadboard, we're seeing just a slight glow on them.
The indirectly heated cathode is more efficient because it's coated in chemicals (metal oxides) that have a higher thermionic emission that plain tungsten, so you get more electrons out of it for the same temperature.
If I overvolt the heater voltage at 4.5v instead of 1.2v how long do you think the tube will last? a few hours? 200 hours? I know it is a strange question. Long story short is a client wants the tubes to be "brighter". I purchased the tubes dirt cheap. I was able to buy 400 for the price of 10. I could give the client 10 replacements. Also would it be safe? My understanding is they simply burn out not shatter. I am simply using the tubes in a guitar pedal circuit with filament voltage not any other (high) voltage. I know it is silly but the client came to me and is just throwing huge money at me. Also would it be possible to use this tube as a clipping diode in place of a traditional diode?
1.25V? How nice of them to design the heater to be driven straight off of a bandgap reference :P
Haha, they were really forward thinking back in the day!
You know, though, I'm not entirely sure why they used a 1.25V heater. At first, I thought it was maybe because it was meant to be a battery powered filament, which helps with isolating it from the rest of the circuit in a directly heated tube, but most battery powered tubes I've come across have 1.4V filaments, because that's what the "A" batteries at the time were rated at. Also, the 5642 tubes is also rated on the order of kilovolts, so it definitely never saw use in radio circuits. I'll have to do some more reading into this!
How do you make positive voltage on the anode please?
You don't necessarily make positive voltage on the anode, you just supply it to the anode from your power supply!
Nice video, full of interesting and clearly explained principles. The drawing of the diode though at 9:00 into the video is the wrong way round. Electrons carry negative charge (obviously), to if electrons move to the left, the "current" - i.e. the flow of positive charge - moves to the right. The arrow triangle should point to the right, not the left. Maybe this is corrected or explained away later in the video - if so, my bad. Have a nice day
The descovery 2:38 is actually most linked to Edison and his lightbulbs that were powered by dc so the electronics were always traveling in the same direction and caused a discoloration on one side of the bulbs where they were repeatedly hit by loose electrons
Seems there are two options low voltage high amperage, requiring use of thick heavy 0 to 6 gauge power cables to move power or one can use very high voltage with low amperage meaning you can use thinner 14 to 20 gauge solid core power cables.
Good video! Just a little point at the start the diode you drew is reversed if electron current flow is what you are talking about ( vs conventional current). Ah I see later in the video you are talking conventional current.
Thank you!
Conventional current flow vs electron flow is always confusing and doubly so when talking about tubes! Ideally, I should always refer to everything in terms of electron flow, but old habits die hard sometimes as I was initially taught conventional current flow.
If it helps any, the arrow (or anode) in the diode symbol is like a wind vane; it always points where the wind is coming from, not the direction the wind is blowing. ;-)
I had the luck to learn Electronics starting with VACUUM TUBES, so I am not afraid of them or the HV involved.
would a tube with a higher voltage filment boil more electrons off the cathode than for example a 6bq5
Yup! Though, it's not just limited to voltage. Essentially more power through the filament to burn it hotter boils more electrons off. For example, the 6080 dual triode is a properly large power tube and it uses a 6.3V @ 2.5A filament to burn nice and hot!
Do you have any magic eye tubes I think those are cool looking
I didn't for the longest time, but I recently got some good looking VU tubes (not quite magic eye tubes, but similar concept) that I really want to build something with!
The filament lamp is usually filled with the Inert gas, Argon. Vacuums filament lamps are rare.
Wonder if you could make a vacuum tube without a tungsten filament, replace it with a uv led since uv has enough energy to move electrons, perhaps use a material in which when uv light hits it it throws off more "free electrons"
Would drastically reduce power demands and heat issues, also could open up different drive characteristics since also the led could also be digitally controlled or even pulsed at different frequencies or even intensity
7:55 instead of thermionic emission, you use photovoltaic emission....
Lightbulb filaments do not operate in a vacuum. The glass enclosure is backfilled with an inert gas, without O2, at a pressure lower than atmospheric @14.7 PSI. This enables heat from the filament to be conducted to the air while preventing the glass envelope from exploding due to expansion of the gas inside.
Electrons don’t really flow, they just drift. The electromotive force carried by the electric field is really where your energy comes from. This took me many years to figure out.
Hi, may I ask, hope somebody can help, is it safe to replace a preamp that uses 12ax7 tube with 12bz7?
They fascinate me the same way playing video games from cassette does.
Interestingly, I don't ever remember playing games off of cassette tapes. I think here in the US, floppy disks rose in popularity so quickly, that cassettes kind of fell by the wayside as a means of data storage. But I absolutely do get nostalgic thinking about old 5 1/4" floppy disk games!
I saw the first few minutes of the video..Don't know why
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I clicked the subscribe button on my own🙃
Thank you so much!
how did you come to see vacuum tubes as a kid?
Are there any non Facebook forums or telegram channels where i can talk about valves and maybe find some mentoring?
I get a very fluorescent light vibe from it
Hmm… 16 seconds in and I’m already reaching for the subscribe button…
Thank you so much!
My instructor used to say "Thats not a light bulb, that a florescent luminaire. You can tell the difference because bulbs are planted in the ground"
About 23:00 is not right? Direct heat is always more efficient as, well, it is directly heated. But the reason I was told in class and may I quote some random note in the internet as below the reason to use indirect heat ... use AC and isolation : "The main using an is to isolate the rest of the vacuum from the electric potential across the filament, allowing vacuum to alternating current to the filament."
I am not sure also whether it is related but I can see for the twin triode (or diode) here so you can use one element to heat two ...
I didn't go into nearly enough detail here, but the answer is a little more complicated.
Using indirectly heated cathodes definitely provides isolation allowing AC to be used for the filament, which is great for building more complex circuits. But, the having and indirectly heated cathode provides one more massive benefit - the cathode can be coated with something that greatly enhances electron emission, usually something like barium oxide. This means that the cathode doesn't have to get as hot to attain the same level of emission. So, an indirectly heated cathode can be heated to around 500C, but a directly heated cathode may need to be heated to double that to obtain the same level of emissivity. But this also means that depending on the coating and operating temperature, more emission can be achieved than a directly heated cathode because the filament is far less stressed in an indirectly heated setup!
There's also other benefits too, like you mentioned being able to use one element to heat two or more cathodes. So, depending on application, construction, materials, etc., either an indirectly heated cathode or a directly heated cathode can be more efficient!
@@UsagiElectric Agreed. But avoid misunderstanding may I think this line "So, an indirectly heated cathode can be heated to around 500C, but a directly heated cathode may need to be heated to double that to obtain the same level of emissivity. " ... using the same energy and hence as you said it is more efficient in one scenario. The scenario of two element e.g. many double triod and the rectificer I used in front of me that use two cathode (to gain the two phase of AC to become all +ve phase of DC.) is a different scenario. Even so, now I think about it, it may be more about pin and AC still.
you haven't been terrified by a tube unless you have been a USCG LORAN-C transmitter tech working on transmitters with F-1086 final PA tubes, water cooled with 21.5KV plate voltage putting out a megawatt of power to the tower.
You ain't kidding! That sounds terrifying just reading about it, haha.
@@UsagiElectric the fear, and respect, made us really into good technicians. the transmitters were enormous, most of the maintenance was done from the inside of the equipment. the largest (AN/FPN-45) transmitters had input amp stages made of little bitty baby tubes like in your video through multiple amp stages to a final PA section of 8 F-1086s, in push-pull config, 4 tubes per side. They put over a MW out to a either a top-loaded 1/4 wave monopole (625' or 1250' live tower) or a sectionalized 4-panel antenna hanging between 4, 700' towers. I spent many years at 3 tube transmitter stations like that, and also many years at newer solid-state transmitter (AN/FPN-64) stations which did not use tubes, and put out slightly less power. Good channel, btw.
man, you just look smart, you could tell me vacuum tubes are edible, and I would be all like... sweet!
Haha, thank you so much!
I think the glasses and grey hair maybe make look a little smarter than I actually am. Thanks for checking the video out!
*ECE20002 BREADBOARD!*
It's actually a Miyako EIC-108 Breadboard! I've had it for years and picked it up when I still living in Japan, it's been an excellent little breadboard!
genial retro solid
I'm not entirely sure what you're going for, but thanks for checking the video out!
Where can i get some, to Nigeria
Oooh, that's a tough question.
I have no idea how prolific electronics from the 40s and 50s were in Nigeria, but if you can find some old radios or something from that era, they usually have some good tubes in them. Also, some sellers on eBay or other online sites might ship to Nigeria as well.
very instructive videos. it would have been better if you built the devices on video. its hard to see all these small cables.
3:00 Understand it is a kind of figurative speaking; but I think the electron generated are not looking for any positive thing. It was just emitted with a negative characteristic (or field thing if you do not like entity but field). If there were any negative or positive sign around it will operate with it or them (or the field), just not in future we add in positive and negative grid …
I did do a bit of a personification here, but the sentiment isn't entirely incorrect. The electrons that boil off the cathode or filament inherently have a negative charge and will be attracted to a positively charged element within the tube. The grid itself doesn't (or rather shouldn't) absorb hardly any electrons at all. All the grid does is create a field with a charge that can be changed. If the field has a negative charge, it repels the negatively charged electrons and they float around in a sort of "cloud" around the cathode. If the field has a positive charge, the electrons are attracted to the positively charged grid, but more importantly, the immensely strong positive charge of the plate presents a far greater attraction. So, the electrons fly right past the grid and get absorbed by the plate.
So, in a sense, the electrons aren't "looking" for a positive thing, but something with a positive charge (the plate) will attract them, while something with a negative charge (the grid) will repel them.
I always wondered where Napoleon Dynamite went.
hello sir please help me i need 6j9 9 pin tube data sheet