I edited and annotated the original 28 minute film "Electronics at Work" down to 3.5 minutes. The annotations help explain how electronic vacuum tubes flow electrons to amplify guitar signals and rectify AC to DC.
Not to sound like a stereotypical cynical boomer, but I imagine that's probably because back then they weren't trying to stretch out a tutorial to make it 10 minutes long just for some teeny tiny bit of extra youtube money
yeah many great ones. maybe the most insane one: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OI-To1eUtuU.html. and this was like 30 years before 3b1b
I love these classic old American explanatory videos, military training videos etc. They're so clear and to-the-point, and always in that Transatlantic accent that you just don't hear anymore.
I have to give my instructors who were Automotive Techs some major credit for me to even remotely understand what is at play here. I do agree that old school physicists have a much better way of describing things than newer ones are, but I primarily think that is mostly due to the fact old school taught at a slower pace and new school flies through it.
@@Hezigrimm Agreed, the sheer volume of information available to people in the internet age, not to mention the high value placed on producing skilled and learned individuals as fast as possible to enter the workforce means that education nowadays cannot help but accelerate the pace of things to the point where a surface-level understanding of concepts is all that's necessary. Experience and genuine depth of knowledge comes after, if at all.
One of the nice things about tubes is being able to actually see the elements being discussed which makes it, in my mind, easier to understand. If I had my way, tubes would still be taught to help visualize what happens in an amplifier, even in solid state.
Same. Using heat and a vacuum to induce electron flow vs silicon doping layers near each other inducing electron flow, without heat. Its all very interesting :)
These older films (transferred to video) were very well made. The explanation of how vacuum tubes work is interesting. I am in my 70s, and in my early years of working in electronics I was building projects and doing servicing of devices using vacuum tubes. The tubes in this video are of a much older generation of the ones I worked with.
Agree. When I was not yet graduated, I was feeling like if more credit goes to Einstein than Newton and Galalio but the reality is the other way round. I mean the foundation always makes difference. So more credit should go to the founder.
I've held a General Radiotelephone Operator's License' "GROL", since before the days of the 'Supersede Order' for the "Second Class Radiotelephone Operator's License". This video is leaps and bounds above all the rest regarding "Tube Theory"!!
Thank you for this - it genuinely very useful for music tech classes. We talk about valve amps all the time without (in many cases) really understanding what they actually are.
Thank you very much, Rob. BTW: I received the StewMac 5e3 15 watt amp kit, but i have a couple of weeks DIY work to be done before we can move into the older (but new-to-us) house we purchased. As I am writing this, it occurs to me that I had better check on the StewMac warranty for the amp and parts almost immediately. Nevertheless thanks again for the video here!
mmm.... kinda. Transistors are mostly voltage controlled, where as Vacuum Tubes are mostly current controlled. Arguably Bipolar Junction Transistors are also current controlled, but, especially relative to a vacuum tubes, they operate more around the potential differences at the emitter-collector-base (or drain, source, and gate if we're talking Field effect...). This means that vacuum tubes are generally better at handling large currents relative to transistors, but most residential consumers don't have a use for a KiloAmpere of current. More over, a person might actually be able to make a vacuum tube at home. I don't think that's really an option with any of the transistors, but that's also probably not practical in most circumstances. It's great for the enthusiasts though.
Actually I had this idea roaming in my head for a couple days now, only for someone to tell me it already exists today >.>. Actually I have a slight variation and application for what can be done using something similar.
@@robrobinette Edison was a businessman, not a scientist. He had the money to put his name on patents, reports, inventions etc... Guys like Tesla were the unsung workhorses. Grinding it out at their towers all day... Getting no respect...
@@philosophyofpolitics4504 Edison was most certainly a scientist, most of the inventions he created were done by himself, without outside help. Steve Jobs on the other hand was a businessman with ideas
Thank you for sharing, and for pointing out that the full video is available. Vacuum tubes were still quite common when I was a kid, and I grew up through what I consider "The Digital Revolution" through the late seventies going through the eighties. I witnessed the demise of the LP, 8 track, reel to reel, slide projectors, and film projectors. I witnessed the development and demise of audio cassettes, VHS, and Betamax. I saw the rise and fall of CDs and the development of the dvd. I witnessed the war between Bluray vs HDDVD just like vhs and betamax. If seen the development of mp3, mp4, and streaming. I've seen numerous game systems from Atari 2600 and 5200, through NES, Wii, to XBox and PlayStation and their various associated handheld units. I remember when a 19 inch color tv tipped the scale at around 75# and was state of the art. Now we have displays that cover a wall weighing around 150# at barely 1-2 inches thick, and can project an image anywhere with no wires or cords from a projector the size of a deck of average playing cards. Personal computers were only for the rich, and only doctors, lawyers, and the occasional drug dealer had a mobile phone that was the size of a briefcase. Today, we wear and carry devices as phones that are far more powerful than all of the combined computing power of every computer NASA had when we sent astronauts to the moon. My first computer in 1998 was cutting edge technology with a 300 MHz processor, 4MB video card, 64MB ram, a 4.3 GB hard drive, and a 56K modem with 24K fax. It can't even come close to what my two year old Note 8 does. We also went from wired Ethernet which we still use, to extensive wireless home networks through 802.11 a, b, g, and n. Mobile phones are small and inexpensive enough that everyone has one in their pocket and they went through wireless technologies from Edge through G, 2G and 3G, 4G and 4G LTE and now into 5G. That doesn't even count the IOT or internet in general as we know it. All of this is only the tip of the iceberg. But now we're bringing back tube amplifiers, LP's, and the instamatic camera and now have instamatic photo "printers" that connect to our smart phones and "print" a photo that comes out entirely white and becomes a photo before your eyes, and call the technology "new." At best, it's old school with a modern twist. I'll be 47 in 2020, and as fast as technology changed then, it's nearly lightning quick today. We really do have the world at our finger tips.
Tubes never went away. Guitar amps (high end ones) always used them, as well as niche HiFi amps. LPs also, but there has been a resurgence since about the early '00s. Instant cameras aren't all that good, I don't know why people use them, I do love my 35mm film though.
Wow, I just found out you have a RU-vid. I have to thank you from the bottom of my heart for all the time you took on your website to explain the AB763 circuit. I went from not knowing a single thing about amp circuits to doing my own repairs on a fender drri during the pandemic because of your page. I even managed to re cap it. You do such a good job of explaining it to a lay person. Thanks again, and a side note I enjoyed the story about the military training plane that was a shit design/catastrophe waiting to happen
Does the heating element take time to heat and start closing the circuit? Because the transistor can swich on and off very fat. Does the vacuum tube swich on and off fast too❓️
This is what makes America so great, these instructional videos are clear, articulate and very instructional. Much better than many RU-vid videos today.
Wait, so is the signal input clamping the Waveform output up? Makes sense if we decouple the DC shift. Then it would work like a bjt amplifier. Can anyone with tube experience confirm? It almost seems too easy
Good day Mr Rob .....I'm new to your amplifier site and couldn't find any contact infos so decided to leave a message here ............How can we thank you enough for all the infos you have on your site ,......this is MASSIVE work !!!..........don't know how you found the time to do this but Thank you SIR !!!.......................Lou
When i was 10 years old, last.. 40 years, my trsurs were to colect those Tubs. I was so intersting, watcis all wires, grids use? I watced hours by hours. When we open our Blcj whote T.v I was so quries wat is all this elctronics part. This clip realy wonderful.
I'm sorry to say that PCs have never had tubes in them. There were tube based computers in the 40's and 50's but by the time the PC came along in the 80's tubes had been replaced by transistors and integrated circuits.
Those aren’t vacuum tube. Vacuum tube is a dead technology replaced with transistor and integrated chip. I’m assuming based on “huge vacuum tubes”, most likely you are referring to large capacitors and diodes I think.
The power tubes idle at half output power so you can increase and decrease current flow through the power tubes so both positive and negative voltage on the grid is amplified.
The tube amplifies only negative voltage. The damping of the electron flow IS the amplification. The plate current flow is inverted in relation to the grid negative voltage. How does the tube amplify the positives then - it doesn't. The tube is biased for the signal to always be negative. That means, a positive, low DC voltage is added to the cathode, or a negative one to the grid. So the positive half-waves at the grid become negative, just less negative. At the output a 1st order high pass (capacitor or transformer) filters the DC offset out again, to have a pure AC signal. Keep in mind this only describes the class A (most common and simple) amplifier type.
@@westelaudio943 Dumb question perhaps, but where does the extra energy (or electrons?) come from to amplify the signal? Feels like we get something from nothing when the grid is in place.
@@jasonvincent2367 From the B+ supply voltage going through the load and then to the plate. The tube doesn't add power to the signal itself, it transfers it to the plate curcuit by varying it's resistance depending on the instantaneous grid voltage. Thus, based on Ohm's law (current decreases with resistance), it forms a voltage divider with the load. The load receives a signal that's amplified and inverted relative to the input (and DC biased, if the input is AC). Usually, in an AC curcuit, a high pass element is then used to remove the DC bias (offset) to get pure AC again.
This is fantastic video, but I can't find the answer to one small question: What is the difference between the anode and cathode that allows the cathode to emit electrons while the anode cannot? Is it just the fact that it's heated? And if that's it, then what is the temperature difference in question? I've seen vacuum tubes running, and the entire thing gets super hot. Is the ability to thermionically emit electrons a sudden change with increasing temperature?
Electrons are only shed at high rates when metal is near white hot. Heated cathodes glow yellowish-white they are so hot--much, much hotter than the anode.
The voltage difference between the grid and cathode is the "closed circuit". The cathode and grid are both referenced to ground so that forms the closed circuit. The voltage difference between the grid and cathode controls how much current flows through the tube.
