#198

[@MickHealey]

I wish I could wind my age back by 50 years, and still have your videos. Learning would have been so much easier. Unfortunately, I was taught by people that felt the need to show how clever they were at maths, leaving me lost. But, you do awesome demonstrations, with brilliant explanations. Thank you.

[@purza95]

DITTO! Well said!

[@oakspines7171]

The way they teach students in college here in the US has been helping Asian countries to pass us. Companies like and promote that so they can have excuse to hire all foreign engineers and work them like slaves.

[@jimmyzhao2673]

@@oakspines7171 You can rest assured knowing that while US students are learning about critical race theory, gender studies, blm, abcdefgq+, the Chinese students are learning Math, Science, Engineering. China will eat USA's lunch !

[@jonahansen]

@@purza95 Yeah! Me too! I was able to "seat of the pants" it, but always got lost in the detailed analysis sections of the textbooks.

[@andymouse]

@@jonahansen Same !

[@codijack9577]

In the world dominated by Java, ARM, ... your videos "back to the basics" are awesome! They are like shake off the dust from my analog soul. I love them and keep on going!

[@w2aew]

Awesome comment - made me smile! Why should we through a million transistors at a problem when just a few will do!

[@robertcalkjr.8325]

*****
I prefer analog myself - they just seem to be warmer and more fluid.

[@maciejyt]

There is no analog, digital and pulse electronics. All is electromagnetic field theory. Analog and digital are just simplified theories. Nowadays microprocessor systems should be analyzed via analog and field theories because of their speed. Tracks on PCB are not digital connections but transmission lines with impedance (frequently differential pairs) and sometimes tracks are so long and bit rates so high that track works like a shift register and you can find several bits on one track one following another. So in fact we live now in analog word more than 20 or 40 years ago. Moreover EMC problems mixes digital with RF technology. Digital world is only for software boys, who do not understand what is happening inside the box :)

[@berni8k]

*****
So true, there is some beauty in making something work with just a couple of transistors. I am fairly experienced in electronics but i keep using mostly opamps for any analog stuff. Thanks for teaching me new things

[@sayantanmaiti2513]

Codi Jack that's awesome comment. Number of engineers working on such discrete analog circuits, power amplifiers have reduced a lot. But Alan's videos always give us hope.

[@AppliedScience]

Cool! I had never heard of this type of circuit. Thanks.

[@w2aew]

Thanks Ben! Glad you liked it!

[@m1geo]

I always love it when two excellent channels collide! 😍👌

[@pauldery7875]

At 66 years old, I find it fascinating trying your circuits, I wish I'd kept with it when I was young, thank you.

[@technobubba4]

Don't give up - you're still YOUNG !!

[@rrangana11]

I have studied about this in amplifier design during my college days and seen in many transistor power amps… but after 29 years I am seeing working of this circuit in a scope.
Awesome to see this ….. Thanks man… you rock.

[@Peter46350]

I love the way you explain! I've seen various videos on the subject and also about class AB amplifiers, but no one seems to think of playing a pure sine wave so that people can actually hear(12:20) how the distortion disappears with the bias change, and not just look at graphs.

[@maciejyt]

Very good lecture as always :) You can also use your beautiful oscilloscope (FFT function) to show how harmonic content changes with regulation and how it is connected with FFT function in our ears.
Best Regards

[@w2aew]

maciejyt Yes, or course, but didn't want to stray to far from the video topic at hand...

[@purza95]

I work with these "Push Pull" everyday service electron microscopes. All the scan circuits utilize a push-pull circuit. I remember learning about the PUSH-PULL circuit in college, but never fully understood how to compensate for the crossover distortion until NOW! Your videos/ instruction is "Priceless" and should be required viewing for any electrical engineer student!

[@riccardoiii9882]

I love how you go really deep into components analysis and let me discover some new feature every time. These are the best videos about electronics that can be found on youtube. And I always wish I was as smart as you are!

[@aduedc]

Thanks again for great educational clip.
I have seen this circuit on the push-pull Amps, but never understood it well. Now, I understand them well.
I guess by extension we could do Vth Multipliers in MOSFETs.
Thanks again for great Educational Clip.

[@CrispyCircuits]

Thanks. I actually watched this video quite a while back, but I couldn't follow it at all.
Now it makes complete sense. Although I understand Calculus well, which is not the same as doing derivatives and integrals, which really doesn't matter as much as understanding what it means. I have trouble following the math. I really guess that's a little bit of boredom, but I'll pull that in after a little bit. It's important to do at some point.
I'm 53 now and thrilled to be getting back into electronics again. I did it very very young age and without hardly any money. Now I can actually buy some decent equipment. I'm starting to be able to use it, too.
I'd enjoy using some good textbooks, but only with a group of people. Technical learning is a bit boring as DIY. Practical applied learning is fun now. Finally.
Thanks again!

[@RyanJensenEE]

Before watching this video, I was aware of Vbe multiplier circuits -- thanks to a coworker. However, I was NOT aware of the push-pull output application! That is brilliant!

[@zekerandolph1397]

The datasheet of many older op-amps (that show the internal schematic) will show the Vbe multiplier biasing push-pull outputs. For example, LM741.

[@yoramstein]

Allways saw on audio shcemas the 2 or 3 diode. Never saw that multiplier- I wil look for it on the schemas of the op amps. Thanks for this comment.

[@burakg7246]

Totally love your videos. They should be shown at universities. You logically develop the ideas and everything makes sense.
P.S.: Watching this video again and seeing that I've already commented, so I will edit this one. You need to publish a book where you can fold the pages as you do in your notes. It was fun as a kid and would still be :)

[@kilianod5150]

That was great! Push-pull amplifiers biased with two standard diodes really cant compare to this method when using discrete components, but that's always the standard text book example of how to reduce cross-over distortion and never works well in practice I've found.

[@rossthompson1635]

Brilliant! Thank you. I know this video goes back a bit, but it is sincerely appreciated, a super clear explanation. I am researching Vbe mulipliers as I want to come up with an alternative to the multi-diode bias spreaders used in vintage hifi. The breadboard will be coming out very soon!

[@thecombatengineer7069]

Thank you for taking your time to publish these and showing off that BEAUTIFUL Tek MDO 3104.

[@Ziknazoo]

Great video! You didn't mention of a key point, I think... At least as far as the Class B/AB amplifier goes. If the Vbe multiplier is thermally coupled to the output transistors, then as they heat up and their Vbe drops, so does the that of Vbe of the Vbe multiplier transistor and the bias current through the output stage (and hence distortion) remains more or less constant through the operating temperature range. Also, it can help prevent thermal runaway...

[@w2aew]

Very good points.

[@patlaw53]

Where is the button for 100 thumbs ups? Like Mick Healey below, you have in 13 minutes explained something that I totally missed when I was getting my EE degree. Then again, the $36,000 oscilloscope is helpful! :)

[@adastra123]

Thank you. I have a clear headed understanding of it thanks so much.
People like you change the lives of people like me.
People like you empower and give confidence to people like me.
Just thought you should know that.

[@coolguy_ff]

Amazing video dude!!!! My first comment on CZcams. Just can't help. SO CLEAR, better than my analog circuit professor lol :)

[@w2aew]

Great! I hope you like the rest of my videos just as much!

[@Afrorack]

Good demonstration. I understand the use of Vbe multiplies in amplifiers better

[@billfield8300]

You obviously put a significant amount of preparation into your videos and your command of the subject is obvious. The result is a professional and easy to understand lesson. . Much appreciated!

[@gkdresden]

In my amplifier output stages I use to couple the transistor of the Vbe multiplier thermally with the output stage and I use a constant current source (f.i. E-103) instead of Rc. In this way you can get a very stable bias current through the output stage.

[@w2aew]

+Nicolay pelov. The bulk of the current flows C-E. The B-E junction is only carrying base current, which is the collector current/beta.

[@robertralston2395]

Very nice demo, thanks for making it. I always enjoy your tutorials, both the drawn circuits and then the demo on test equipment. Very real stuff. Thanks.

[@jimstand]

Thank you for making EE videos to educate students and professionals And thank you for not doing old TV tear downs or how to use heat sink compound videos like the guy below the equator is doing.

[@ats89117]

You put out a lot of really great videos that I am finally getting to go through. Thanks for all the great content!

[@DavidLeeMenefee]

Thumbs up. You obviously put a lot of care into your videos which are very helpful. Thanks, David Lee...

[@w2aew]

ElectronicWizzard Thank you. Many people do not realize that every minute of published video can often represent 20-30 minutes of work - between preparation of materials, study, building, testing, note preparation, actual shooting of video clips, editing, etc.

[@robertcalkjr.8325]

*****
Most people that think like that have never done anything. They think writing books are easy also because they have never tried to write one. I would estimate that you spent at least 5 hours on the video.
Thanks for your efforts Alan - I greatly appreciate it!

[@francomarianardini681]

excellent video, Alan! cristal clear explanation, the use of the oscilloscope clarify and complement a lot the theoretical discussion. I have to say I am impressed by the clealiness of your written material. It should be published as a book a it is! congrats!

[@polawo]

Thanks for a great video with the actual theory behind it.

[@Rich-fr5td]

Thanks Alan, Excellent Video! You are a Superior teacher with impressive examples.

[@akm3726]

Great video! I hadn't seen this use of a transistor before. It looks very handy.

[@mosfet1780]

Absolutely magnificient video and demo!

[@user-nd1be9yr8w]

This the best explanation about the VBE multiplayer ....... Thank you ..

[@agustinferrari144]

Hola Alan!
I finally subscribed to your channel. This last of yours, short and to the point, as usual. It allowed me to understand how it the multiplier works and what it is good for.
You rank top in my list.
Gracias.

[@duality4y]

I love these videos so much!

[@JonJeffels]

Thanks for yet another great video, Sir. Been following you for a while on here and always look forward to new content from you!

[@fazlerabbi2666]

this is beautiful demonstration

[@FreddyBNL]

Very clear, well illustrated and concise explanation. Top. Thank you.

[@allaird1]

Great vids been watching a lot since I found you! Love the 465B and the 485. Learning a lot from your stuff thank for putting in the time!

[@spaceheater1]

Thanks for all of your videos! I am currently expanding my electronics knowledge by troubleshooting a Fender M80 bass amp, which has distortion at the output, and this sheds some light, hopefully.

[@marcioandreyoliveira]

I'm subscribed to many CZcams channels but your is the one I like the most.
Your explanations are straight to the point, very easy to follow as well as instructive.
Keep the amazing work.

[@chuckm3262]

You're putting a lot of work and time to teach people interested in electronics Thank You.

[@misterthekaitheman]

Very useful and very awesome indeed! The explanation and presentation are very clear and nicely interpretable, I like it! Awesome other videos on your channel aswell! You've earned yourself a new sub, keep up the work good man!

[@hartmutberger5611]

Thanks a lot for sharing this, I enjoyed it.
Another nice property of this circuit is its "build in" temperature compensation of the output stage bias current.

[@andymouse]

Awesome, I just made the connection with this and a amplifier circuit I'm ( Trying ) studying !.....cheers.

[@solitaire5142]

The best 13:23 I`ve spent so far this year:)

[@w2aew]

The year is still young, so I hope it gets better than this! ;-)
Glad you enjoyed my video!

[@Edgarbopp]

Really enjoyed this. Such a simple yet power circuit to have a adjustable voltage drop.

[@mortenrolsing7137]

Thanks a lot, i realy love your videos, they are the best.
You are realy good at explaning things so that i understand them.
Greatings from Denmark

[@gregwoolley]

Cool. Very interesting. Thanks for explaining it so well.

[@Enigma758]

Great tutorial! It's probably an obvious point and not sure if it was mentioned, but the transistor shunts away enough current in order to maintain the Vx voltage drop. It will even maintain that drop when the supply voltage varies. That was another key, for me at least, in understanding how the Vbe multiplier works. Also, I think there is a required resistor between Vcc and the output otherwise the output will always be at Vcc.

[@ChrisGJohnson]

This is great - very clearly explained. Thanks.

[@Pwaak]

I sure did hear the raspyness come and go! Very interesting...Thank You!

[@Sjampster]

I never heard of this type of circuitry. Thanks for introducing and explaining it!

[@stuartgartery2717]

Thank You for Your really informative and enlightening videos. I now have an understanding of Vbe Multipliers and also what cross-over distortion is. I see that another 'aka' for this circuit is a 'Rubber Diode' according to Wikipedia.

[@Infinitesap]

This is really awsome :). please makeup more of these videos with schematics and walkthrough like this.
respekt for your work. Best on the Web. thanks

[@ThingsWhichArentWork]

Thanks Alan - You explained that very well and I learned something new. Cheers!!

[@craighollinger9972]

Nice explanation, thanks. I've built a number of audio power amps over the years and they always used this circuit to set the O/P stage bias.

[@thromboid]

Great explanation, thank you! Just what I was looking for. :)

[@Linksimpson]

Thanks again this is another super clear explanation of a useful circuit to have in the analog arsenal.

[@Starcraftowns99]

Excellent explanation. thank you!

[@samueledardengo505]

Thank you very much, this is just what i needed!!!!

[@simonyoungglostog]

Just what I was looking for. Thank you very much.

[@Wil_Bloodworth]

Oh well... I was following along with the videos but this one lost me. Too much above my head so I'll come back to it when I learn more of the basics. Thanks for the video!

[@w2aew]

You'll get there!

[@hariharank2363]

Nicely explained ... We are about with few students, every one understood clearly....

[@fredhamilton1701]

Great tutorial - sure wish CZcams and teachers like you were around when I was learning electronics!
I'll admit to skipping around a bit, so I might have missed this, but did you mention that another great thing about this circuit, particularly in the push-pull application, is that as Vbe changes with temperature, the multiplier's output will track the Vbe shift of the output transistors? So if you cancel the crossover distortion at one temp, it will stay cancelled as temp changes?

[@RexxSchneider]

That's why in the classic Bailey Amp (from 1968), the bias transistor is mounted onto the same heatsink, close to the output transistors, to ensure thermal tracking. Do a search on the web for "30-watt High Fidelity Amplifier" if you're interested in reading a full description of the amplifier. I built one of these over 50 years ago and I've still never heard anything sound better.

[@0MoTheG]

Thanks, I thought this would be a disadvantage. As the junction voltage easily changes by a factor of two it is really a terrible idea to use it as a reference unless that is exactly what you want for compensation.

[@billfischer7085]

Info is great! App is golden! Thank You. Bill

[@JasonOlshefsky]

This will work out handy for a project I'm working on now: converting an 8mm film projector to high-power LED. I'd like to have a control circuit at 5V, and the original bulb was rated 30V at 86W, so I figured I could use the power tap for it. The power tap supplies about 38VRMS, so I expect to get around 40VDC or more at low currents.
However, to use, say a 7805, I'd need a maximum input voltage of about 30V. This circuit will be an easy way to drop 20V or so to drive the 7805 for the low-current logic. I'll need to keep an eye on the temperature, though, as Vbe may drop as low as 400mV ... thankfully the current is quite low, but I'll probably use a relatively big transistor nonetheless.

[@TheBdd4]

Thank you for another excellecnt video and interesting subject.

[@stuartmp1974]

Awesome video really helped clear alot of things up. I built the curve trace (octopus circuit) and followed along on my oscilloscope. works perfectly. really helpful.

[@cthree87]

Another great tutorial, thanks!

[@GunsofBrixton89]

Wow... I just read up on this and your video really helped piece everything together; Thank you!

[@acmefixer1]

Thanks for the great video. Often the amplifiers use some diodes and add negative feedback to reduce the distortion. I think the designers should do it right to begin with and not try to hide the problem with negative feedback.

[@dachew57]

I was just wondering how to improve the audio quality of a simple low power push-pull audio amplifier. Thanks for a great tutorial and demo!

[@dixsusu]

Great video as always, i"ve learned this back as superdiode circuit .

[@efox29]

This was amazing. Love it.

[@kolinevans9127]

great video, thank you for sharing the info.

[@danw1million]

Fantastic video!

[@mehmetdurna3115]

Wow, nice educational material. Thanks Sir!

[@m1geo]

Loved this, Alan! Thanks!

[@MrNetmask]

great as always!

[@jamescox9571]

Thanks for the tutorial!

[@marshsmello]

Excellent video, attracting excellent crowd!

[@FPiorski]

10:00 Oh that's sneaky :) Using the Vbe multiplier here is pretty much the perfect application because of it's temperature coefficient.

[@davidbeauchesne7399]

Another gem! Thanks.

[@Julian-vp3xj]

this looks like a very fundamental building block, that I have not seen before. I suspect it can replace zeners as well for introducing arbitrary voltage drops.

[@omarel-ghezawi6466]

You continue to produce excellent videos. Good effort. Thank you.

[@michaelhawthorne8696]

I DO like your videos Alan but in this case I have always used 2 diodes in series to eliminate the cross over distortion of an Audio output stage. I'm sure though there are other uses for this circuit and the example is used as an alternative method to eliminate distortion, and here of course you have more control.

[@ladronsiman1471]

Perfect class! ..In French slang we say "La classe'"

[@DefekCs]

Ough snap! This was super-useful! Thanks a lot! ;)

[@paulking283]

I'm glad to come across your video on Vbe Multiplier. As I'm in the process of building a transistor stereo amp and in that, it uses a VBE Multiplier Power Regulator to regulate the power supply for the amp. I was wondering if there is a more up-to-date design to serve the same purpose or transistor amp should have transistor power regulator, thanks !

[@w2aew]

Without knowing specifically how the Vbe multiplier is being used, it would be difficult to recommend a different or more up-to-date design. If you're simply after a more up to date way to providing an adjustable voltage drop, then the most common modern solution would be something like the LM431. www.ti.com/lit/ds/symlink/lm431.pdf?ts=1644827857475

[@DavePKW]

Excellent presentation. Thank you so much.

[@chrisgroenewegen3756]

Very good and helpful explanation! Great stuff.

[@Theineluctable_SOME_CANT]

Great content!

[@mrdouble]

Absolutely love your circuit explanations. You have a real knack for taking all my unrelated knowledge about electronics and tying them all together. Please more circuit / discreet explanations. I found myself logging on just to see if you have any new videos. I have never did that before. Keep being bad ass. Thanks
Also, just an idea, maybe you could make a video on ham radio and why it's interesting. I swear I don't get it. I go to hamfest but I go to buy electronic supply's and testing equipment. I just feel like I'm missing something because it seems like with my love for electronics i would be lured into it but man I got nothing. Zero interest and it bothers me immensely

[@robertcalkjr.8325]

Micheal Double
Communication. If all other forms of communication are lost, Ham operators can still communicate and help people. My uncle John in Missouri was a Ham operator for a long time. He passed away a couple of years ago. I don't know what his call sign was though.

[@w2aew]

It would be difficult to encompass what makes ham radio interesting in a video - because every ham gets something different out of the hobby. Some like the challenge of making contacts with low power, some like building and using homemade equipment or antennas, some like playing with the latest technology, some like morse code, or using satellites, others like ragchewing with friends, etc. So, it all depends on where your interests lie.

[@MichaelLloyd]

Micheal Double I like Ham radio because it expands my interest in electronics into the realm of RF circuits (aka black magic and voodoo :o) ). It has also taken me into the realm of tube circuits which, believe it or not, are interesting. I found Alan's CZcams Channel because of my search for how to use an oscilloscope for Ham radio. His ability to explain things in a simple and concise manner makes this site one of the top CZcams channels for me.

[@kb7skb]

Another fantastic video! Thank you.

[@jospicant]

It's a wonderful video again.
Thanks a lot.

[@Cyrob-org]

Very clear as usual...thanks

[@1959Berre]

I guess I could use this circuit to replace a fawlty diode-cluster composed of 4 diodes in series (SDVSVT4HG) clamped on top of the power resistors. That diode-cluster should act a a temp sensing device for feedback to the bias circuit. Helas, those diodes are out of spec and unobtainable. I guess I have to figure out which transistor could perform similarly temperature-wise and replace those bad diodes. Thank you for this interesting video

[@blacklightning7227]

cool circuit 👍