Could you please live forever? All generations would appreciate your high quality teaching skills. All the best!

I love it when I search for something like this on KZfaq and yours' is the first video that comes up. Please don't ever stop making back to basics videos. It's hands down my favourite series from you. Thanks for making these.

I swear on everything, that you are the best KZfaqr, Teacher or Professor in this World who has explained the Differential Amplifier thank you from my heart forever

I'm a retired electronic engineer, but still find these videos highly interesting. The clarity with which you explain things is fantastic. Sadly, such videos were not around when I studied for my degree, but today's budding electronic engineers have a real advantage with the availability of your videos.

Tremendous. Thanks for such greatness. Way back, it took me a while to understand how the current mirror applied to the differential amplifier. Taking the single ended output from the collector of only one transistor means throwing away the gain of the other. To add the gain of the other side in, you would need to invert and add. The current mirror is simply a inverting unity gain current amplifier, adding an inverted copy of the other side to the output. I love the neatly drawn notes and the rusty clipboard. Looks like a yellow Sylvania tube box on the left. I look forward to more.

I love the mechanical circuit demonstrator! Great work, Alan. I had never thought about trading double-ended output for higher gain as you showed with the current mirror.

This is something I am pretty familiar with, but the way it was explained was just georgeous!

It's hard to believe that a single video could be so incredibly enlightening. Hands down, the best to be found anywhere. Deepest thanks!

Your videos, especially the back to basics ones, are an invaluable learning resource. I've heard it been said that a great teacher inspires, you certainly do!

W2AEW is an awesome teacher. He has cleared up so many mysteries that I have encountered during my electronics studies. You gotta LOVE this guy.

This is a masterpiece that needs to be used by every single electronics or engineering school in the world and neighboring planets (and have every school donate another half a million dollar piece of equipment to your lab :)). I remember back in the day when I was the best kid in class but still went through a state of messed-up-ism (pardon my advanced technical jargon) till I used some stability theory and calculus math to get the common mode vs differential mode and CMRR stuff. Those videos need to be considered a national (and rural places of the world) treasure. I can't find words to thank you enough for the effort, so I'll try to do more than words.

Mechanical model!!! What a nice way of describing the concept! Very creative way, I'm impressed

Finally I managed to understand how a differential amplifier works. Thanks. Please if you can, do more "Back to Basics" videos you are making many people happy. You have a gift to spread knowledge. Thanks a lot.

Thank you so much! This video really helped me put together all the *practical* aspects of differential amplifiers that university somehow completely muddles up behind the math. Couldn't have asked for a better demo, visualization, and explanation. You're an engineering student's miracle.

The very best explanation of a difference amplifier. I saw this video and am hooked to this channel. Thanks for taking time to produce videos like this.

The best explanation of long-tailed pair ever. Thank you.

I love the practical perspective of your explanations and the way you build up the circuit step by step. Putting visual emphasis on the circuit drawings and measured values rather than the actual breadboard was a good choice as the latter serves no information other than proofing the circuit is real.

Oh wow. You've made some good videos but this was something else. I don't think I've ever learned so much from one video before.

Thank you!!! I have been trying to read articles and notes ... watched a couple of videos ... and finally found your video .. and finally I understand quite clearly on diff pair amplifiers ... I will definitely start to watch more of you videos and will follow your lessons! Thanks a million!

Incredible videos with such great demonstrations! Thank you

Excellent explanation, thank you very much for taking the time to do this. A great refresher after not looking at long tailed pairs for many years.

What a fantastic video...one of my favourites (and I'm a big fan !). I love that you led us step-by-step to an explanation (and, of course, a demonstration) of how an op amp works: that was an unexpected surprise. Thank you - I enjoyed every second of it.

I know all this - or rather perhaps I did know at one time - but really your explanations are the best. Last time I learned was from the tektronix training manuals on diff amps which was pretty pure mathematical model derivation and not at an intuitive level. Thank you for doing this and please keep going making more at this circuit building block level. I can wire up anything digital or high speed easily - but "simple" circuits like this I always find a need to refresh on it's basic workings. The next generation of EE's needs to not rely on only arduino's, 555's and such to build things!

Video has been around for awhile, but still relevant none-the-less... Thanks, nice to review some basic material and have you do the thinking so we don’t have to. Started out 98/2 analog, the last decade has been 98/2 digital for me, so it’s nice to break the rust off...

Another great video. I've been watching your videos for a while now, and find myself waiting for the next. I don't usually comment or have anything to say but I now feel compelled to thank you for the pleasure and understanding you have provided me since you started. You have such clear exposition, no wasted detail, and great delivery. You have a talent for teaching. I don't know how much time you put into these videos but they are all marvels of succinct production. Despite knowing the material already I always enjoy them. Thanks again.

One of the best lectures I have come across on differential transistor circuits leading to op-amp design. Excellent work!

Once again, Alan, a nicely demonstrated and explained talk. I could have used this video when I was studying electrons a decade or more ago! You put a lot of work into these demos and I for one really appreciate this. Thanks Alan.

I had to watch this video series few times. But when finally it clicks, the feeling is incredible. Thank you so much. Very grateful for the amazing videos.

I went to a pretty good school. I gauge this by the technicians and engineers that I have met in the field that attended my school compared to other schools. Also I gauge this by the fact that I always seem to end up as lead technician or lead engineer. In all honesty though, I think I would have been a much better professional if I had teachers like you, Derek Banas and Dave Jones(The Crazy Aussie). Of course I cannot forget that the great Forrest M, Mins III. You guys are fantastic. Not only do you cover complex subjects, but you do so in such a way so that a student can instantly see the uses for certain circuits. I applaud you all.

Yes, stay motivated. You are a great tutor. From your vids, and some others, and some independent fiddling I am starting to recognize some of the building-block circuits: here and there. Cheers, Mark ******************

Always good to see what I already know explained in an excellent way.

Never seen a clear explanations of electronics like that.thanks a million of times Alan.

Really enjoyed the video and it's progression through alternative circuits to get better performance.Keep up the great work! Explained very well.

Beautiful explanation of why current sources / sinks are used in differential amplifiers. Thank you for preparing and posting this video.

Thank you or the video Alan. Your prep is time consuming and very professional and much appreciated. Your explanations are easy to follow. LTP's are the more complex of Phase Inverters used in the analog amplifier world, and I got a lot out of your explanation.

Thanks for taking the time to go over this in detail. I found it very helpful.

I really enjoy designing circuits with discreet transistors, to get to understand electronics at a deeper level. Your explanations on the steps taken to form the basis of an opamp, is superb. Thankyou for the work you do to present very imformative lectures on circuit design.

God bless ya! You know that old phase "use it or loose it". Haven't done this level of theroy since college. Great review of diff amps and I really appreciate all your videos. Keep up the good work! 73s KB8NIV

Thank you for the valuable contribution ! Even the mechanical simulator alone is something that will be very useful in understanding differential amplifiers. I am happy I came across this video.

Thanks for taking the time to explain this. I can appreciate the amount of effort that went into this.

Sir, you are the best when it comes to integrating theoretical knowledge with practical applications. Thanks for all of your videos

Excellent explanation, visual aides, and demos. Thank you!

Great job as always. Clear as mud. You make the material easy to understand. Keep making great video. Thank you for your time and effort...

Great instructional video. I've been around a long time but I actually never have seen a mechanical diff amp ! Thank you making these videos.

I not only enjoyed the video, I loved it! Thank you so much, I am a constant follower of your videos and they are all great. Very good insight from them. Please keep going on!

Yet another example of why oh why weren't my teachers like you? Great video, as always it's a pleasure to watch!

I've been blowing through your videos but I must say this video blew me away!!! Watching your videos just seem to click

Fantastic. I like the "mechanical" display, neat idea. Thanks for the videos.

Another deluxe video. I tried searching your videos while trying to replace an opamp to drive the pass transistors in a PSU ( discrete components had higher voltage ratings than most opamps ). It cleared some things up, thanks :) Keep it analog, w2aew! :)

This a a great video!! Really enjoyed it! I loved that mechanical simulator!! The "Back to basics" series is GREAT! Kind regards!!

Excellent instructional videos! Thanks for taking the time to do them. I have turned many young hams on to your clips. Very well done!

You do very good work..... and plenty of it.....I taught electronics for about 4 years and it's one thing to know a subject and quite another to be able to present and teach it effectively....you obviously like to teach.....I admire and appreciate your efforts.....rgds, AK5XX La Grange Texas

Thank you so much for explaining this matter in such a clear way. Big fan of your videos!

Great explanation of the diff amplifier with very helpful test setup for demonstration. Thank you so much fpor your work!

What an amazing explanation with physical example. Absolutely love it

beautiful job on an important circuit concept!! the mechanical device is very useful. and the gentle merge into the op amp concept. thank you. this one is worth a couple of watches.

Great demonstration. I'm looking forward to watching more of your videos.

Excellent explanation. Simple and to the point!

Everything just clicked together, very well explained, thank you.

I love your style Alan, I think back to 1984 and study at electronics voc tech. I am always great full for your videos.

Hi! I just wanted to say I love your videos and that I really would like to have more of these back to basics videos. I find it much easier to understand a concept if I have a lot of videos on the same concept, but from different creators - everyone churns out some unique features. Although, you are simply the best! What I'm trying to say is that: don't get out off by the fact that others have done videos on the exact same subject, like really simple stuff, cause it's useful anyways and you'll still be better than them! Thanks again!

Your mechanical simulator of a diff amp was brilliant. As someone who tends to "learn visually", that gave me quite the thrill.

Most of the time i don't understand completely because I dont know enough. But i still watch over and over, go back study a little, and re watch. Till i understand some of it at least. I wish i had an opportunity to study all of this.

Amazing explanation. Can't ask more than this. Keep doing the good work and thanks, I have a viva today and genuinely, the concept is crystal clear now.

Another belter Alan, thanks, wish you had been teaching at my college! Time to hit the breadboard and play!

I loved the mechanical circuit demonstrator!

i should have had such teachers like you at my technical schooling - Thank you very much and 73

It cannot be better!! Keep doing these great videos!

Excellent, excellent insight into the inner working of the differential amplifier.

What a superb tutorial, Alan, you rock! Thank you!

The subtle point is in the basic diff amp the shared resistor current will change with increasing differential voltage at the input. This will affect the differential output. With the current source replacing the Emitter resistor the current in effect can't change. It is fixed with the high impedance to ground . The output resulting from the differential input is then wholly down to the change in Vce.

Salute for mechanical demonstrator. Respect. Hats off. You can demonstrate identicality with dual transistors in one package like 2SC1583. Cheers from Indonesia

Wow! This is great. You are so good at this and know so much!

Nice explanation and neat demonstrator too.

Really really really really thank you so much for this video, sometimes im afraid of asking some doubts I have in class because nobody says anything and they seem to get all so easily. Grazie mille.

excellent, clean, and clear. As always!

excellant coverage of this topic. Thank you!

You are a great teacher.. Please keep them coming

Really surprised by the mechanical demo and by the voltage change by touching the transistor!!! Excellent video!!!!!

Thanks. Your channel provides much valuable information. Thumbs up.

Great stuff Alan, Your ability to draw good clear schematics and explain circuit function is amazing. You should definitely keep all your drawings and consider publishing a book someday. I would love to see a back to basics that covers "capacitors" and how and when and why to choose a given "type". ex. poly, ceramic, tantalum, silver mica. and what are each of their favorable and unfavorable characteristics for a given application. Digital electronics, RF, analog, audio, high frequency, etc. thanks and keep up the good work. Dwight N7KBC

There are two unique points I love about this video. 1) the variation of diode operation due to increase in temperature. 2) Your mechanical simulator ! Thanks for the crazy video !! Wish I could work with you.. Thanks again, much appreciated !

Absolutely great! Awesome teaching.

Great explanation, superb!

Interesting, gotta check back on this one!

Alan, excellent video! It is great to revisit old knowledge stored in the back of my brain a long time ago... :) I can't really understand one thing: how can someone gives thumbs down to your back to basics videos?!? The information is there, your english is very clear and the circuits and examples are spot on. Perhaps people were thinking this covered some other subject, despite the title and description? Oh, well...

on daily basis you are solving my years long confusions. Thank a lot. -/\-, from India. Surely one thumbs down frm someone will because either he doesn't understand English or the subject itself.

Thanks so much for your 'back to basics' videos - the are brilliant.

woww what a great video !! hope you continue to do this good work ! really enjoyed !!

Thanks Alan, thats really refresh my knowledge. Many thanks

Great video!!understood really well..great explanations..Keep up the good work!!

Another excellent video, thanks for sharing.

Awesome explanation.

Thank you so much for this video. I understood so much better from your video than a book.

Very helpful video. Thank you!

Best video on the subject ! Thank You !

Generally I tend to watch the video's even if I don't really understand what's going on and this video was no exception... I found myself watching till the end wondering why I would need to know about this??? Then at the very end I'm told that this circuit is basically the beginning to a discreet op amp... Wow... This is the first time that I have ever watched an episode of electronics who done it LoL... Had me trying to guess all the way till I was like oh ok that's what it's for Hahahahahaha.... I think that now I have to re watch the video now that I have an idea of what this circuit could be used for.... Actually I kinda like the idea of a discreet op amp... Might have to look around for a video on that topic... Anyway... Great video by an awesome teacher..

You have helped me a lot. Thank you very much.

Excellent explanation. Thanks.

I always feel like thanking you after every video i watch. Thankyou! Amazing as usual!