Vacuum Tubes: Episode 2 - The Triode (Part 1)

In this episode we build upon our new found knowledge of vacuum tube diodes and take a look at one of the most ubiquitous vacuum tube types out there: the triode.
I do recommend checking out the episode on diodes as that background is definitely helpful in wrapping our heads around the triode.

Vacuum Tubes: Episode 1 - The Basics and the Diode

[leosbagoftricks]

Great video! Understanding Vacuum tubes really helps with getting the fundamentals of electronics. I was a little confused by the notion that the transistor circuit is "Digital" and the tube "Analog" not really the case, really you are demonstrating the Vbe threshold voltage of the transistor, which a vacuum tube does not have.

[kaypope]

I have been searching so much to find a vacuum tube video and finally I am here. Thank you so much for posting the video!

[videotaperetro]

Hello, well explained and not as hyperkinetic as many youtube videos. Glad to see someone is bothering to explain this technology. But I have to tell you that your idea of ​​tansistors is wrong. A transistor is as analogous as a vacuum tube. But it works with different voltages and impendances. A tansistor as well as a vacium tube can be set to work as a switch. But also both as a very analog amplifier. Otherwise we wouldn't have music amplifiers with transistors today! And this: The first digital computers worked with vacium tubes! And before with relays, now those were the only 'digital' components. You can only close or open them! The fact that something is digital is actually an interpretation of a signal. An agreement, which is a 0 or 1, we agree on and call it digital. So basically there are no 'digital' components. But we construct the circuits in such a way that they work within very strict standards (voltages) and therefore 'switch' at very strict voltages.

[dustinolsen]

Just a note indirectly heated cathode tubes were designed to reduce noise so you can use AC on the filament and for isolation of the cathode for "self bias (cathode resistance)"

[ivan]

There are differences in working conditions between a BJT and a triode, so the comparison is not fair to the transistor.
The transistor only works linear in a certain bais, so you shouldn't make a digital switch circuit by BJT then tells everyone transistor is "digital" or non-linear. (I know you didn't use the word "linear", I assume the word "analog" is the same meaning) (Needless to say, linearity can not be defined by the lightness of a LED as well, )
And the definition of "better sound" is not to recover the sound signal, people like tube amplifiers because they generate sound with a special taste of flavor. Which has the opposite meaning of what you said, a good signal recovery ability.
I've seen that you said when you were learning these things you kept hearing people said triode is analog and the transistor is digital. These comments may come from someone that likes tube audio amplifier rather than transistor amplifier. Which is not accurate in electronics engineering. I know this explanation is easy to understand. But I think it is better to use accurate and correct terms and viewpoints when making a video to teach someone new to this area. So that people would not misunderstand.
Despite that, I think your video is great on teaching tube applications. This is why I write these words and hope more people knowing the beauty of electronics engineering through videos like yours.

[adailyllama]

I have been looking for an instruction on how to wire and use vacuum tubes. Finally a very simple and straight forward example of a triode. Thank You!

[Otakutaru]

I must say... you're not doing the transistor justice by wiring it like that. To take advantage of its active mode just put some resistor between collector and base. Doing just that and tweaking some resistor values will make it much more linear

BJTs are current based, tubes are more voltaje (signal) focused AND COOLER, that's the upside

EDIT: Just realized the barrage of elec-heads bashing on the exact same thing I just said, sorry~

[easton]

Really great video. Best explenation of vacuum tubes I have seen. In all their simplicity vacuum tuubes are a really facinating piece of engineering.

[adam]

If you were to put a J-Fet instead of a transistor in there you would have a more accurate representation. Since a transistor is a current controlled device. Your 1/16th turn goes like this: you hit the .5V threshold and the base current shoots right up. If you were to current drive the transistor you would have the same effect as voltage driving a tube. Except now the tube would go from 0 to 100 very quickly because the input impedance of a vacuum tube is basically almost infinite for DC ....notice how I said almost

[edb]

Thank you for the time and effort you spent to produce this quality and informative video. Well done!

[yvesbouchard]

Well done! Excellent straight-to-the-point presentation of tube analog signals. It's amazing how getting to understand thermionic emission helps in understanding PN junction. Many thanks!

[sivoltage]

Thank you, concise and easy to understand. Really great example of what's actually going on in those mysterious glass lanterns!

[shortridgegregory]

This is an excellent explanation of the Triode. Thanks!

[ChrisPinCornwall]

This series is SO interesting. Thank you very much.

[saturntony]

Well done, this was very very cool, thanks for sharing 😊

[tossedsaladandscrambledegg]

Oh man! I am having flashbacks to my Naval Electronics courses at NAS Memphis in '84.

[russoft]

Uhhh, that transistor is used in analog and digital circuits. The difference is that the biasing point is different. Once that's right, much small signals result in much larger output (more gain). At least that's what I'm seeing here.

[possible-realities]

5:00 When the grid voltage becoms positive with respect to the cathode, I believe that you start to get grid conduction - you get a forward biased diode between the grid and the cathode. Afaik, most vacuum tube circuits try to stay away from this region, but I know there are uses for it as well. At least you want to make sure to limit the grid current because it's probably not built to handle as much current as the plate and cathode.

[gooball]

you said that the transistor doesn't want to be in the in-between state. don't you mean that it just has a higher gain? why not just add an emitter/source resistor?

[stamasd]

Triodes are essentially transconductance amplifiers: a small voltage in the grid circuit controls the current in the much higher voltage plate circuit. Sure, you can convert that current to a voltage using e.g. resistors and such, but they are primarily voltage-controlled current sources. Modern transconductance opamps like the 14700 do the same, and like them they are used in high-end audio equipment.