Common Emmitter Amplifier

[@SimpleEnough2k9]

Playing with BJTs and having a better understanding of some basic concepts is always a plus. By the way, I don't know if you changed your setup but the sound of your clip is now noise free, no more static or humming noise. Finally, yes, I'd like you to breadboard the circuit and show the signal at different points such that we could potentially evaluate the beta of the BJT just by comparing the values. Also, showing the effect of the capacitor connected to the emitter by putting it in and out for the circuit so that we can also see the effect it has on the signal would be nice. I understand that the objective is to provide basic information but when your giving such information to addicted hobbyists like me is like giving candies to children, we always want more, we never have enough ! Thanks for your time Paul.

[@isoguy.]

Awsome. I always found this topic difficult but you seem to be able to explain things so cleary. It would be really helpful if you completed the tutorial as suggested. Thank you for sharing and I hope you are feeling better soon.

[@icenesiswayons9962]

I've been going through some of your older courses, surprisingly no one teaches this stuff anymore. I think it's good that you have brought it out, because it's the basic fundamentals of what electronics is really all about. Students are jumping straight into the digital domain because computers are doing all the work we used to have to use pencil/eraser and paper for. 25 years from now no one will know or even understand how an old time CRT TV is built. It will be like the hieroglyphics when christian Coptic took over. Got side tracked, anyway wanted to thank you, it brings back memories. Wish I had my old SC61 back.

[@learnelectronics]

Thank you, I appreciate your kind words.

[@didierdelay6623]

Yes a live demo with view of the signals would be great to understand it better. Thanks

[@robwebster7406]

Thanks for the great vid 👍 was always scared about the ‘transistor’ at a young age when I started to mess around with electronics, but now with the internet and channels like yours, it’s helping a lot, keep up the great work 👍

[@davidglynnguitars8119]

Definitely build the circuit!! It would be great!! And I hope you get well soon!! Thank for the videos!!!

[@learnelectronics]

Will do

[@steve-si3oz]

Great explanation!! Better than most I've seen. Thank you!

[@golfrino]

Thank you Paul for the videos I just subscribed to you channel and i have started learning already. Thank you.

[@Laediin]

Hi Paul, Transistors have been one of those components that I really don't have an intuitive understanding of. However over the past year or so that I've been watching your channel, they have (finally) recently started making more and more sense now that I am playing around with the ETI Vocoder project from Julian's channel. I think it would be a huge help if you build the amplifier from this video, but also show how to use the datasheet to pick the various resistors to set the bias for the amplifier. Some of the transistors are obsoleted and while I can un-intelligently search around to find a similar replacement, I don't know quite how to decide if any of the resistors in the original circuit need to be updated to correctly set a different bias point for a similar transistor. Thanks for making these videos man, I look forward to each and every one of them!

[@learnelectronics]

I will be building the circuit soon.

[@MalagasOnFire]

Try this circuit with a DDS using this great help. It's like reviving electronics

[@matttodd9424]

Hi Paul great video, practical and straightforward thank you😀

[@incxxxx]

Try to do it on a breadboard and your enthusiasm will go down to zero!

[@theengineer9910]

im so glad i found this channel ! I cant describe the way you teach, theres no bullshit involved to indirectly throw off the audience, would u recommend i learn anything else with AC circuits besides filters, amps, AC analysis ? I know theres a whole lot with other components but any topics as large as expansive as those 3? I started butterworth recently and plan on moving to the other big filter designs and i ve already started making mosfet amps + AC circuit analysis is taken me to 3 phase circuits

[@learnelectronics]

I really avoided RF for a very long time because I had a hard time understanding things like skin effect. When your circuits depend upon electron positioning within the conductor you know you little margin for error. I wish I had applied myself to it earlier. I guess all of this rambling is meant to say learn RF theory.

[@theengineer9910]

@@learnelectronics glad u said something i atleast have an understanding of, RF is black magic but i did use a module set with arduino

[@mikeoliver3254]

I think I'm going to have to build this up and throw it on the scope to really get it. Great explanation though looks like a fun circuit to play with.

[@incxxxx]

Try to do it and your enthusiasm will go down to zero!

[@bblod4896]

I'll try that out tomorrow. Currently building an oscillator and I want to modulate the output of that oscillator.

[@incxxxx]

Try to do it and your enthusiasm will go down to zero!

[@pink_mist]

I believe the two equations for Vb and VB should equal to one-another. Because they measure the potential from the same point to the same reference point. Then Ib should equal to Vbe + VE/(Rb2). Also from VB equation, Ib should equal to Vcc*Rb2/(Rb2+Rb1)*Rb2. Please let me know if this is correct. Thank you for the video and your time explaining this concept

[@keithking1985]

nicely timed music jingle, just when you give us the answer!! "GOD HAS SENT HIM AMONG US, TO TEACH US IN THE WAY OF THE CIRCUIT!!! IT'S A SIGN FORM THE ALMIGHTY IM TELLIN YA PEPOLE"very cool as usual.. thanks Paul..

[@Cyrusradplus]

Why in most rf common emmiter amplifiers we add an inductor to collector for increase impedance at the collector??

[@alicekichlu215]

THANK YOU FOR YOUR PRESENTATION,THIS IS A GOOD REVIEW FOR ME ON THESE CONCEPTS.WOULD YOU GO INTO THIS IN MORE DEPTH?

[@learnelectronics]

Yep

[@gl0sek]

So is that the basic circuit for an audio amp just without all the filters?

[@learnelectronics]

It's a class a amp. The least efficient, but the most linear. It would make a nice little audio preamp.

[@sahebdarkhor]

Hi.what is difference between video amplifier and audio amplifier in equal circuit?

[@robertcalkjr.8325]

Thanks Paul. Nice brief lesson.

[@learnelectronics]

Welcome

[@SS-mj2mq]

Nice I like the way out well done 🤓✌️💯. And thanks for explaining this very clearly it helps a lot.

[@jonathanrodriguez8219]

Nice explanation~~

[@georgechambers3197]

Paul, I'd like to see this on the breadboard also. It'd help to understand better. Thanks for more amplifiers and another good explanation!

[@learnelectronics]

Will do and thanks

[@mousamupadhyaya8053]

Can you give a life to the circuit you've drawn, say in the next video {hoping for amplifying headphone jack signal to speakers}.

[@PoiSonSonic]

I've learned the Common Emitter from the Art of electronics and they are omitting the Emittor capacitor 8:10. Why would we want to use it?

[@Shadowex2000]

If you feed an AC signal into the Base, as the amplified current flows out of the Emitter, the voltage at Re can rise high enough at certain points of the AC wave, to remove the forward bias of the Base-Emitter junction. The capacitor shorts out the AC signal to ground at the output due to its low AC impedance to prevent that.

[@SimpleEnough2k9]

@@Shadowex2000 Makes sense. Understanding how components behave under different circumstances makes the circuit analysis much easier. Thanks.

[@PoiSonSonic]

Thank you, that'll keep me thinking for a while

[@learnelectronics]

The caps decouple the AC input from the DC bias of the amplifier.

[@robertcalkjr.8325]

Just go to Page 84 and Figure 2.25 shows the ac-coupled emitter follower.

[@michaelpadovani9566]

I learned something here and wouldn't mind seeing it in action on a breadboard.

[@unforgiven818]

Great videos, can you do a vid explaining how to choose and calculate the decoupling capacitors I.e. accros the emmiter, input and output caps, thanks

[@LeeCruz337]

It would be very helpful if you could explain the math behind RC IC IE RE VB and VE as people just getting into this like me have no idea what the math is thats why i am researching how to design a AMP circuit i need to know how to calculate those values based on say car or home audio input an voltage.

[@QrchackOfficial]

Any chance of a follow-up with why 20k and 3.6k "will give us a nice bias", why Rc likes to be 1.2k, and the like? Would really enjoy a more in-depth look without "magic values" to understand the why.

[@learnelectronics]

As I said in the video you uave to consult the datasheet for the particular transistor you wish to use.

[@hero96559]

But the data sheet doesn't mention any thing about Resistor values.. There is a design constrains in order not bias the transistor either in saturation or cutt-off regions... Consulting the data sheet is well important but the way how to design is the most important..

[@20thcenturyboy85]

Thank You!

[@Cyrusradplus]

Hi i made a common emmiter amplifier for 200mhz signal with 2× gain I can amplify a 50 mv p-p to 100mv p-p but I can't do it for 2v to 4v p-p Why what values should be change???

[@rickloresto9647]

sir....im planning to build this type of circuit...im newbie in transistor amplifier but i have a background in electronics...forgive my questions ...these are..... (1).is there any formula for finding the values of all resistors in a circuit or its just by setting an arbitrary values and check the waveform on an oscilloscope...in my case i dont have oscilloscope....im just relying to a speaker by listening to it if its good.... (2)is there any formula for finding the values of all coupling capacitors in a circuit or just setting your own values and check it again in a scope...why you used 1nf ...why not electrolytic capacitor.... (3)with your transistor 2n2222 circuit ...is it possible to hear the output to ordinary speaker or you need another transistor ampliier stage ....thanks sir in advance and with sharing this simple new video....i love simple circuit as the old saying goes .....SIMPLE IS GENIUS

[@learnelectronics]

Gp to the datasheet for the particular transistor you use to get the values. Yes you can hook up a speaker to this circuit.

[@rickloresto9647]

thank you very much sir

[@gregwoolley]

You didn't explain why you chose those resistor values.

[@learnelectronics]

The answer to that is dependent on the specific transistor you're using and the type of circuit you're using it in. But generally you want to shoot for the middle of the linear range. So as an example, let's say an npn transistor goes from .8VDC to 3VDC from cutoff to saturation. So half of that is approximately 1.9 volts. So you're going to bias using ohm's law. You know the voltage. You know the current? Now you can solve for the resistor that you want to use to put you at that 50% linearity.

[@abscomm]

You just seemed to pluck resistor values out of thin air. How did you arrive at those particular values?

[@learnelectronics]

As I said in the video, you must consult the datasheet for the particular transistor you are using.

[@abscomm]

Yes, you did say that, but it would be very informative if you could step through that process rather than just inserting numbers with no information as to how they were derived.

[@martinolesen9930]

Hello Sir, is it possible to show how you actually choose the four resistor values?......you start with Re=220 ohm.....how did you choose this value....not 22 ohm......not 100k ohm......what is the thought process (calculations) for this value......and the same question for the other three resistors?

[@learnelectronics]

You choose resistors to put the transistor in the middle of it's linear range at idle current. you have to check the data sheet for the transistor you are using, then you can employ Ohms law.

[@Dopeyyapper]

First one to comment lmao love your videos keep up the good work

[@madeo8480]

huh?? This circuit is probably the most frustrating one to learn. I've read and watched many tutorials and nobody seems to explain why the resistors are picked for their values. All of them just randomly pick the numbers based on their experience and assume it'll work. Only then, they start doing the calculations... But that doesn't explain why those values were chosen. Why did you pick Re at 220 ohm ?? Why pick RC for 1.2k ohms ? Why pick Rb1 and Rb2 for 20k and 3.7K ??

[@learnelectronics]

They are not random numbers. The resistors are each chosen specifically to put the transistor into whatever phase you're looking to put it into. Usually the active region. Now you choose the base resister to create a current from a voltage. You use the data sheet to know what current you need. You choose the emitter resistor to prevent thermal runaway. You can't learn everything in one video. The most important question is " how do I want the transistor to behave"?

[@madeo8480]

@@learnelectronics Thanks for explaining this, but it is still quite confusing to me. I tried for learn this circuit for a long time, but I ultimately gave up. Instead, I use OPAMPS for amplifying signals and transistors for simple switching purposes. I love OP AMPS , but at the same time I feel like i'm cheating.

[@doktordzwonek9306]

Anyone why did he use such values? Like why 1.2k on RC, why exactly 220 on RE etc.

[@larryshaver3568]

i have a bunch of 2n2222 transistors

[@PoiSonSonic]

Sir, please try to reduce the heavy breathing. Thank you

[@SimpleEnough2k9]

If you would have health conditions perhaps you would be less complaining. Instead of commenting negatively consider be more constructive. Saying "Thank you for your time" would most likely be more appropriate, don't you think ?

[@cwebs1000]

Mikle, You are an IDIOT!

[@PoiSonSonic]

Uh, please explain. This is literally the first video I've seen from the man. Sorry for not watching previous videos in order to learn the private life of the man. Comment is just a comment.

[@SimpleEnough2k9]

I understand that a comment is just a comment but under some circumstances they may get offensive even if this wasn't the intention. Take a few seconds and read the clip's description FAQ section, you'll have a better understanding of the overall situation. Would it be here or any other place you planned to attend, always analyze your surroundings, never judge a book by its cover.

[@PoiSonSonic]

I see where you're coming from, still, I'm not so sure loud breathing is extremely difficult to solve. Do you know if the author has tried different types of microphones? Some pick up unwanted noises much more eager than the other ones, and if we speaking channel growth here, the audio quality is of the essence. If you watch some videos from "isaac arthur" channel, you'll see how unfixable speech imparement is handeled. Also, let's give Paul some credit, he was with the Navy, he can handle stong words. p.s. great community here, no sarcasm.

[@E-BikingAdventures]

So for 9V Vcc you end up with 1.37V bias(Vb). Why is it not 4.5volts. You offer no explanation for anything. No reasoning for the values you chose. What the voltage at the collector should be. Nothing. Ya ya I know. "Bite me"!