Small Signal Amplifiers

Using transistors to amplify low-level signals.

[@stevefoster2700]

I have watched many, many hours of electronics tutorials and this is the best at explaining what the components in a common emitter amplifier actually do and why they're needed. I'd enjoy seeing videos on the negative feedback circuit and differential pairs.

[@stever3886]

seriously. ……..this 50 times the quality lecture than ANYTHING i ever got in college! time well spent watching this incredible video !

[@sandasturner9529]

Sometimes the the best things in life are paid by someone else/free to you!

[@williamwalker8107]

I like that after all the explanation of the amplifier circuit at about 1/2 way through the video he stops, looks at the camera for a moment and states "except it can't work".

[@ericlindal8008]

That guy explains everything, great lecture.

[@Skibidi_Male_X]

Like my father explaining how life works... Then says ..

[@laetitiazichy-vanlidth5882]

Waiting for that😊😅

[@henrypfister2902]

Yeah that was funny

[@mcameron63]

It’s important to understand that voltage does not flow. It is just a measure of potential energy between 2 points. Usually between a node in the circuit and ground or between 2 points. Current is the flow of electrons (or holes depending on how you were taught EE). You must have a potential (voltage) between the 2 points in order for current to flow from the first point to the other. A load is usually placed between the 2 points to perform some function. A resistor is a load used, for example, to keep the current between the two terminals of the battery from quickly draining the battery. So when he says there is 10 volts at some point in the circuit, he is implicitly saying there is a potential of 10 volts between the point and ground.

[@Swanicorn]

This is brilliant. The fact that you even mention the different faults in the end helps so much.

[@PaulSmith-tt2cy]

I'm an electrical engineer with 40 years experience and I watch videos like this to help me understand how I can help my students better and you know I just saw your video man this is awesome

[@sandasturner9529]

Thank you for your service

[@jitsinghobhi]

I have very rarely met a person whose concept is so clear in teaching, master of his subject, full regards

[@velvetdoug]

"Except it can't work" This is a fantastic video. Thanks so much

[@BrightLibra]

I remember these days of lecturing. This fellow really knows the subject. He shows it by telling us (his students) practical uses for the information. Most would just say, "The signal is amplified through the addition of a resistor here, and then one here on the negative side of this AC input." He could just stop there, smile, and take a sip of coffee. But, no - he really does know, and he wants us to know too... so he shows things would be like if this shorts, or this opens. I was enthralled through this entire lecture, and certainly plan to see as many as I can. Thank you.

[@stargazer7644]

That's because this lecture isn't aimed at circuit designers, it is aimed at technicians who will be troubleshooting the circuits.

[@georgeh1352]

Crystal clear lecture, couldn't be better. Good to do a recap of things you learned (or thought you learned) many years ago.

[@TheGspencer]

I highly recommend your videos to anyone who needs to establish a solid base for learning. Very refreshing and informative to watch.. I especially enjoyed the problem solving which reinforces the learning. After 60 years (at 81) I still truly love electronics!!!

[@richardlynneweisgerber2552]

Turning 69 this month, with a newly-rekindled, though not quite free of external crabby people getting in the way of my rebuilt workbench, two9 power supplies arriving soon for Analog and ESP32 & maybe some other stugg. Back in 2020 I re-arranged my budget, managed the most severe case of G.A.S. {Gear Acquisition Syndrome, part being an echo from '69 or so, '72ish more likely, "Yes"'s use of Eventide's massively impressive "Musical Instrument Effects", Harmonizer, Pitch-Shifter. all that. Now I just had to get all four of their "Factor Stompboxes", ZOIA & Beebo & Mbira w/pickups. and a Dobro, all sorts of MIDI Controller gizmos, i went crazy four ars straight, Reverb banned me for life., two three years to learn it all now. phew/ my mom always said I was not raised right. well once ;-) Alll just so I can have this huge driving force, "Get the workbench together, nobody sells the matrix mixer I need to loop them. So qty 100 LM13700 and a whole bunch of supporting cast members. KiCad 8 being out now, larn that to PCB. My Childish Grandiosity Gland is nearly as big as my Empathy Gland is. Underneath all this is this Conspiracy that I invented, 50Hz & 60Hz the AC Power Grid runs on has been hypnotizing folks for ages and ADHD has me doing nothing but watching videos or reading articles of other folks doing it, So, now I have to dig around and kick-out the 'living vicariously on others' successes" or worse Take Care What sorts of experiments do you do? RISC V is gardangblang tempting to switch to. after 2/3 of my life's avocation was in Micro$oft's pocket, literally for 13-14 years tech support then device testing testing the tests that test the devices . in closing, since Apriil 12, 1861, then re-doubled January 6, 2020 The Central Column of OUR Flag Pole has Indelibly Etched upon its Entire Surface; “The Preservation of Life, & Liberty, & the Pursuit of Happiness” The Right Face of OUR Flag has Indelibly Etched upon its Entire Surface; “The Preservation of Liberty, & Happiness, & the Pursuit of Life” The Left Face of OUR Flag has Indelibly Etched upon its Entire Surface, “The Preservation of Happiness, & Life, & the Pursuit of Liberty,” Formerly-United State Of America HAS NO CONSTITUTION beware the fake XR2206 function generators on eBay, Aliwhatchits, temu, all fake, most likely the close-cousin ICL8038 function generators are phony as well. i saw a couple by one guy that nearly had them sorted-out, beginning like always, "Datasheet(s)? Check, BOM in this kit? WTF! some parts are 10x what they aare specced to use., but it remains more a document to his gradually realizing, "something just ain't right with these chips." lm13700 are for the VCA at each of the two by eight inputs mixed through 8x8 Crosspoint VCAs here Outputting to a pair of eight Attenuverters, for Audio & CV for modular synth use. a thing stuck in my todo list for twenty-plus years, we'll see , but there are plenty of tools & parts, not like '82 when the Heathkit Analog and Digital Electronics kits had me integrating Boolean Algebra in with the language bits shifting bits in Venn Diagrams and Karnaugh Maps. a note to close on shhhhh i got to press play on this teacher, thanks be safe

[@R.Akerman-oz1tf]

Could have done better, but the lesson was well done; in any event.

[@noelpalacio5634]

I studied electronics about 30 years ago and graduated with honors. I can honestly tell you that you are one in a billion. The way you explain the circuit and answer all the questions that pop into my mind as I am listening to your lecture, leaves all my teachers in shame. E😊xcellent description of what is going on in the circuit. Thank you.

[@emelaokwukelechi8746]

You are really good with it. Best lecturer on the planet.

[@geoffedwards189]

Thankyou! I am an electronics novice and I get very frustrated by so called "learning" channels who don't explain what functions individual components are doing in the circuit. This is brilliant! I have subbed.

[@eitantal726]

All about electronics' Piano of Doom

[@geoffedwards189]

@@eitantal726Thankyou!

[@ericlindal8008]

Great lecture! A natural teacher. Awesome explanation of the DC blocking properties of a capacitor, you often hear of isolation and ac coupling in instrumentation . I spent much of my career in the lab dealing with instrumentation, various transducers, and digital signal processing. Instrumentation amplifiers are so important in testing and prototyping systems. Luckily I could just pick out an Instrumentation Amplifier IC from Analog Devices. Usually requires positive and negative voltages to power the chip

[@user-gp9si1op3t]

Учите русский язык. Ничего не понятно

[@daltongrantham9729]

Wow. What a teacher. Absolutely stunned at how simple you made this to understand

[@TheAnimeist]

Best practical description of amplifiers I've heard yet. The troubleshooting was icing on the cake.

[@flipvansaksen774]

Amazing lecture. Starting from scratch until the full circuit. Congratulations. I wish I had you as a teacher years ago 🙂

[@georgeg.4943]

Any aspiring novice getting started in electronics should see this video. As a former instructor and engineer I was absolutely taken aback at how elemental and complete basic instruction this video is. This is the epitome of Transistor Design 101. Takes me back to my days in 1962 when I started my transistor engineering classes. Great work.

[@certuv]

Thank you very much. In my retirement I am making a hobby of fixing radios' amps and sometimes old computers. You have explained clearly the circuits to me.

[@RobbyMatthias]

As everybody else has said; A 'brilliant-lecture' that is 'highly-informative'! Bravo!!

[@pboston6RR]

I have been using the 2N2222 for years as a switch and now I find how 8t works as an amp. Thanks for a great explanation.

[@thelongislandguy]

Also look at 2N3904. It has the same gain as the 2222 but at lower current.

[@miguelmouta5372]

This is real expertise in electronics and in teaching. Congratulations Sir.

[@pasanwaidyatillake5758]

He is going so deep on the topic... Wonderful

[@Tyler75D]

Absolutely the best video I've found on this topic!

[@G0USL]

Excellent explanation, I learned small signal amplifier design 40 years ago. This was a great refresher. Thanks again

[@garygranato9164]

this is the most descriptive explanation of the a transistor amp i have found so far. thank you for making this video.

[@pierusa123]

I used this circuit with a coil and variable capacitor to make a simple radio back in 1967. Thanks for the lecture.

[@robertpeters9438]

This is the best description of transistor operation I have seen.

[@masterchain3335]

Oh wow, this was the explanation of transistor amplifiers that I've been waiting for my whole life. I've seen some great explanations about the math and calculating the values, but I've never really understood why any of these resistors are even there in the first place and what effect they actually have on the circuit.

[@locustvalleystring]

You just cleared up decades of fuzziness on those small-signal amplifiers. Spelling out the individual component functions helps a lot. Thanks.

[@ta6hbe]

Excellent demonstration and lecture. Thank you very much for your contribution. I studied Electrical and Electronic Engineering at my undergraduate degree, about 25 years ago. You are the first lecturer, I have ever heard, that actually clearly explained why a transistor arrangement like this, actually has inverting characteristic of the input signal voltage. You are a brilliant teacher, as far as I am concerned. Thank you again!

[@MrDoneboy]

This video is by far your most complex, Bob. Especially, since you said trial and error, is the best way to determine the component values!

[@PaulSmith-tt2cy]

The straw is such an excellent analogy of the transistor because what you're doing is pinching the bass diner in majority carriers and I like your fact that I really like the example of the minus sucking instead of the positive pushing makes a lot more sense

[@smaransuthar663]

Thank you, the first video that actually explained it in depth.

[@Polynuttery]

That was near perfect. I wish I had been able to learn from this guy 40 years ago.

[@sophiestabilitron3771]

Excellent lesson, master! Thank you. A supposedly week long lecture about transistor biasing was discussed by you in this almost an hour video. Very clear and concise. I also learned new, why that capacitor on the emitter side should be there. All the best!

[@georgeadeka7984]

This 1000 times better than what I went through. I am beginning to believe our lectures never mastered what they taught us. They were just teaching by memorizing

[@daveb7999]

I sure do know a lot more about small signal amplifiers than I did before watching this video. Thanks for this great lesson, consider me subscribed! You really do have a way of explaining what is going on in these circuits. The circuit really makes sense now, remarkable! Thanks again!

[@frederickbowdler8169]

A great summary of amplifier design principles.

[@tn7198]

I've been trying to learn about audio effects, starting with transistor based circuits for boosting a signal, overdrive, etc. It has been surprisingly complicated! This is one of the best explanations I've found in the last 3-4 months. Your explanations are outstanding.

[@eolhcytoos]

Clear and concise presentation. I particularly like the way you reinforce the understanding by briefly revisiting an earlier explanation of the said part. Probably the best explanation of small signal amplifiers that I have come across. Excellent!

[@joseantonioteixeiraazevedo5166]

Amazing! Impressive! I've never seen anyone "reason" circuits this way! Thank you very much.

[@josefbuman7907]

Best explanation about the working of an ssa I ever heared! Great video!!!

[@MrAssembler]

I really appreciate the Troubleshooting part at the end, troubleshooting is where the thinking and understanding happens.

[@beatlessteve1010]

I loved the lesson, total flashback for me of when I enrolled at ITT-Technical Institute for an EET Degree back in 89". You reminded me of my Electronics fundamentals teacher Mr. Kotwika, who was a long-time Navy instructor and began teaching in the private sector at ITT.

[@mitchnn]

Wow, finally understand how transitor work!!!!

[@MattFieldPhoto]

This is an absolutely excellent lecture - well done

[@amrhafez8369]

Excellent explanation. I remember learning the same principles from stogy texts explained by stuffy professors. This is much more clear and simple. Of course I would rather use FET's, but I always struggled with BJT circuits. Thank god for op-amps.

[@elboron6774]

As an eletrical student this is by far the best video I have ever watched, thank you!

[@Kevkimkayla]

No words to describe how grateful i am . Ave been dying to make my own fm/am transmitter to switch things wireless n have some fun but failed terribly.after watching this content,my hopes resurrected I got a revelation. do me a favour pliz, continue to the fm /am modulation part. I can now amplify my mic signal n the colpitts ascillator effectively, thanks alot

[@robertgast5953]

Ive been busting my brain trying to figure out transistors as amps, turns out most of my issues were using a circut like the one in the first half of this video. Not a single other person has told me its almost impossible to calculate predictable repeatable results using the first circut shown here.. Best explatation of common emitter ive watched!

[@raymondjackson6069]

Thank you. Guys like this make this world just a little better! One learning video at a time...

[@krzysztofzagrodny8892]

Excellent lesson, many thanks. You are doing great job!

[@muratkaradag3703]

Finally a good video that explains a circuit, and what happens when you put certain devices into it and what effects it has! I think most of us know the single devices and how they work, but only if they are alone, not if they are matched together!

[@barryfandango863]

This is great. Thankyou. After years spent try😅ng to understand this stuff you bring a real clarity to the subject.

[@hankosaurus]

Very useful lecture. Thank you! I was a little puzzled by the positive current flow perspective at the beginning. I was taught that electrons go from the cathode/emitter/source to the plate/collector/drain and are attracted to (sucked to, so to speak) the positive terminal of the B+ battery. Hearing that the current was sucked towards ground got me confused for a few seconds while I sorted out your perspective.

[@alkharusi1717]

You are the best 👏👍

[@michalis1256]

Just brilliant! I've been looking for such a video for many many years!

[@particlecloud]

This is very good. I have minimal electronics knowledge, never understood much about amplifiers beyond basic transistor operation. The tutorial was easy to follow and I now know a lot more. The logical step-by-step build up of the circuit is an excellent approach.

[@NedBoukharine]

Thank you very much for this luminous exposition of the subject. I have taken electronics courses in college quite some time ago, got excellent grades, but never reached this level of deep comprehension of the topic after listening to your lecture. My understanding was based more on rote mathematical heavy guns rather than the pragmatic simple method you use. A testimony that a good teacher is hard to come by and he can make a big difference.

[@LISANCACOM]

Excellent, thanks. Your education skill is amazing.

[@Tetrakan]

Great lecture. And I’m so impressed at how, in a video delivered more or less like a real lecture with almost no editing in postproduction, how infrequently the speaker says “um” or “er”. Master level public speaking and teaching skills!

[@hacksontable5850]

This is by far the best explantion I have ever seen on this topic. Thank you very much.

[@youtubeaccount931]

Thinking about the circuit in terms of both AC and DC components was a breakthrough for me. thanks!

[@sharpnote1480]

I learned electronics in the Navy. The Navy taught electron flow. Of course, college taught hole flow. This video is teaching hole flow. Both work but I am danged if I can just switch back and forth quickly. Because I am old, we were taught electronics using tubes. It was easy for me to visualize the electrons flowing from the cathode to the plate. Then we were taught transistors. The transistors instruction used hole flow. The instructors didn’t have a clue about hole flow so the instruction was very weak. However, I realized that everything worked fine if one viewed the emitter as the cathode. As a technician everything was good.

[@PrincePloppy]

Really well explained. I subbed. You are a great teacher. I'm 4 years into learning electronics, so am always regoing over what i've learnt. You help make this clearer.

[@danstark462]

That was a lot of information and insightful. I learnt a lot. I am saving this in my electronic folder.

[@naris7572]

This is brilliant. A super practical lecture from an experienced one telling the the things with a simple and intuitive words. Admired.

[@m.edwardburton6247]

Great video! Thank you very very much for your time and effort. I'll be viewing the others on your channel.

[@opal177]

Thank you. Lucky me to have come across your channel. Even I have understood now.

[@paulschumacker9901]

Another advantage of the emitter resistor is that it dramatically increases the input impedance looking into the base. This is really important when trying to amplify a signal from a device with a high output impedance, such as a dynamic or ribbon microphone.

[@antonnym214]

Thank you for the suction idea as an analog to explain resistance. I understood that just fine.

[@johneagle4384]

Thank you! We all see these circuits with resistors and capacitors, but no one explain their function in the circuit.

[@hotjanin1988]

Thank you for an excelent explanation on how does the circuit work

[@mscir]

Great class, thank you. If you ever decide to use a signal generator and oscilloscope to demonstrate gain and distortion, etc. that would be a welcome addition to an already great class. Thank you.

[@guilletrost1319]

your presentation was very clear, especially for those of us who don't speak English daily.

[@davidmukege6967]

Can't find more likes to thank this lecture. Its soo imformative. Thank you. +1 new subscriber

[@binuabraham3875]

Sir, Thanks a lot. For this great lecture. Keep posting such greatful lecture. God bless you.

[@jw228w]

great video.the whiteboard and eraser is a game changer by taking away components that are not necessary for the instruction at the moment. John

[@ric8248]

This is an absolute masterclass.

[@davidjackson2115]

Thankyou for your time in sharing yr knowledge. Fully explained. explained. Ill have to rewatch with more time and care as my mind was thinking if you had the bottom side resistor and not the top then it would be in phase. Im wondering about mosfets. And thinking of a circuit that switches at a frequency say 50khz and feeds the ac signal through most then shorts out the 50khz - im thinking how they do band width modulation. Ill have to check yr site, but if not can you do such a comprehensive vid on bass and trebble, Ive always hated the graphic equalizers as in the studios they like have a hundred etc... so here is public joe pissing around with his 5 or 7 band wheres the old bass and trebble with loudness sounded much better and quicker / simple to adjust without screwing the sound completely up. Also - the "magnetic amplifier" Ive always dreamed of building my own amp with something like six amps, 2 bass / 2 mid and 2 trebble with the two amps split, one value and the other amp transistor and being able to adjust between the two and I figure you adjust the three twins with the balance of tone between valve and mosfet with a Master Volume.

[@jhoncharlesdf.1599]

..from last comment, Yes Its a amazing explanation, any people can learn from your channel Mr Teacher!!, very nice to listen!, thank you!

[@alguti2000]

I'm familiar with signal amplifiers, although I normally use op-amps. I use formulas from the datasheets to determine values for resistors and capacitors for the circuit behavior I want. However, I really didn't understood how all of these physically works. That is, until I watched this video. If I wish I had a professor that explained it like he does -- formulas would've made more since back then, making them easier to learn.

[@acj2789]

Thanks. There's a danger of confusion around 9:28 where you say: 'We usually think of the positive side as pushing electrons.... the negative side is like a vacuum sucking them back the other way'. What you actually mean is not electrons but conventional current, which flows from positive negative. The electrons go in the opposite direction; they're not pushed by the positive side but drawn to the positive side.

[@robertsteentjes3870]

So many of us and yours skills are so great...

[@laurencehand12]

Very good explanation. Thank you! You've earned my subscription.

[@tvamos73]

I tried all this failure modes in simulator (LT Spice) and I found this to very interesting. :) I love your oscilloscope.

[@TheApplianceCrew]

Excellent video and explanations, thank you!

[@RHSGH]

That is really informative. So detailed and of course truly explained. Nice. Thank you so much for this helpful video.

[@daveharveys]

Really like your practical approach to problem solving. Transistor calcs are very long winded and as you point out very rarely work in the real world due to variation in tolerance.

[@Bobsmith-yf9oy]

Thank you, this is brilliant. Well done ❤

[@marvelupthrustenforcer3573]

one of the lectures i have ever had on small signal amplifiers.IT HAS NEARLY ANSWERED ALL MY QUESTIONS IN JUST ONE LECTURE

[@berryj.greene7090]

Absolutely excellent!

[@jrsolomon5960]

Best lecture on small signal analysis

[@KeithRowley418]

I remember learning this way back in 1973 in 1st year college.

[@fano72]

awesome video, you really explained it. you are a good teacher.

[@michaelrogers3078]

You are an excellent teacher.

[@bloguetronica]

Nice video! Very well explained and concise.

[@danielraducu9073]

Greatest teacher ! I salute you Sir !

[@NetworkDirection]

This is absolutely amazing, thanks!