Transistor Amplifiers - Class A, AB, B, & C Circuits

[@TheOrganicChemistryTutor]

Final Exams and Video Playlists: www.video-tutor.net/

[@miguelmalatechannel3792]

Why class b are not loud sound? I make it and I tested not loud what's wrong my make

[@miguelmalatechannel3792]

I increase a voltage and amps and same sound not loud?

[@mahjabinbintemannan8924]

First year of undergrad to last year of it, you are literally saving my life, be it calculus, linear algebra, your explanation is unparalleled. I was struggling with this topic, i have an exam today, I almost gave up on the topic, and you explained the whole thing to me in 30 minutes. Will always be grateful to your for this quality contents.

[@efass6289]

This man has been my messiah for Honors Algebra II, Honors Pre Calc, AP Calculus I and II, Honors and AP Chemistry, and AP Physics... I stan Thank you so much for all of your help, I am now going to Carnegie Mellon as a double major in math and computer science. I honestly think my understanding and love for math has greatly been facilitated by your videos, and I plan to use your videos for college and beyond!!

[@efass6289]

@the noah lucario best of luck man! if you're using OCT I'm sure you'll do great

[@PunmasterSTP]

How are your studies going?

[@hervemarie966]

There is like magic in your voice and explanations, they are clear, precise and the essential is said to allow us to always learn something. THANKS.

[@KonstantinFilipov-q7n]

0:17 - Class 'A' amplifier 7:59 - Class 'B" amplifier 11:45 - Class 'AB' amplifier 13:10 - Class 'C' amplifier

[@PunmasterSTP]

Wow, you make this stuff seem as easy as A…B…C…. Keep up the great work!

[@rootuser265]

He just helped me in calculus and now he is here again. Can you do a tutorial of revealing your face? Really appreciate what you are doing, I should ve just paid you $10,000 for tuition fee not college. My college teachers suck.

[@dariusaarav2886]

instablaster...

[@artay9608]

Ever since we went to online classes cause of the quarantine. You’ve helped me a lot. Thanks!

[@user-ub5su9vj6d]

9:55 +cycle Vs -cycle. Great job. Good and clear explanation. 😇😇😇👍👍👍🙏🙏🙏

[@axle.student]

Thank you. This is the best description I have found so far. I need to create a very simple preamp to use a peizo ceramic disc as an audio receiver as well as an amp for audio transmission via a piezo ceramic. I had what I thought was described as a class A with the addition of the small signal transformer to match with the high impedance of the piezo capacitor, but I may have ended up with a class C. . I am not a electronics engineer. I know my way around a circuit board if I have a base circuit to work from, but designing circuits (esp audio signal) stretches my current ability lol . Again thank you. Oh, I just looked across your other videos and your channel is gold :P

[@RadiantBloom]

Nice video. NPN -Not Pointing iNward. PNP - Perfectly iNward Pointing.

[@Octeeve]

PNP - Pointing neutral Point, NPN -Not Pointing Neutral

[@robertismond7788]

Thank you I just recently started tearing apart Old amps ect and building my own circuits ....was slightly getting confused till I watched this great explanation 👍

[@manfredcaranci6234]

Just what I was looking for to assign my class this week. Your presentation is excellent.

[@Greg_Chase]

At time 5:30: "...transformer *_C O O P U L L E D_* class A amplifier...." "COOPULLED" - it's supposed to say COUPLED. Not COOOOOO - PULLED I point this out because - apparently, this voice IS SYNTHETIC! They did a really good job with the volume inflections for the words, and for the cadence. This one little error - saying "cooo - pulled" instead of "COUPLED" - was the giveaway. Remarkable how high the quality of this synthetic voice is. The error in the software that creates this voice is easy to fix (I'm a software engineer). Right now, the mistake being made is this: "coupe" is a type of car. It's pronounced "COOP" And the -led suffix is used everywhere: "STUMBLED", "MUMBLED", "TUMBLED", and is pronounced "ULL'D" So the software is mistakenly combining "Coupe" with "ull'd" and pronouncing it "cooo-pulled" I can't believe how good the voice is. I was 100% convinced it was the author of the video speaking.

[@Ares-sm8uk]

That one clear, detailed and overall good explanation. Thank u.

[@carmelpule8493]

The class A amplifier with a resistor in the collector is inefficient because the quiescent bias current without any signal is still passing through "a RESISTOR" and so that is wasted power. Since at the collector the transistor is "a current source" one can short circuit for a DC current and that is what the inductor does, where at DC, it has no voltage across it and so it does not use any power when there is no signal, The useful current is when there is a rate of change in it and so the transformer is used to replace the collector resistor. It should have been noted that his cannot be done in the emitter as at the emitter the BJT is a voltage source and one cannot short circuit a voltage source as one can short circuit a current source. Congratulations for this video , an excellent presentation.

[@shaywhoop4040]

No kidding, you're a literal life saver

[@KenTeel]

Question: using electron flow (not "conventional current"), looking at the Class B amp at 9:44, the positive going input signal will turn on Q1, which will cause electrons to flow from the ground, through RL, "through" the output capacitor, up through the emitter and collector of Q1, to Vcc. When this is happening Q2 is turned. After this happens (and the input signal goes back to zero), the output capacitor is charged with a positive on the side that goes to the emitters, and a negative (electrons stored) in the side that is connected to the load resistor. When the input signal changes, and goes negative, Q2 turns on and Q1 shuts off. This makes the resistance across the emitter and collector, of Q1, very high (very little current flow through Q1.) As Q2 begins to have electrons flow through it from the ground, up through the collector then through the emitter, the electrons are "pulled" by the positive charge on the capacitor (the plate connected to the emitters,) and electons will flow into the plate of the capacitor that is attached to the emitter of Q1, while the other side of the capacitor (the other plate) will send it's electrons down to ground, through RL. Correctamundo?

[@PoboyMusic]

This guy knows about everything.

[@manishnaidu-wy6ji]

Thanks It's easy ti understand now than in lectures

[@peterwan816]

WTH...... I was literally searching for informations about audio amplifier on KZbin and I know you because I used to watch a lot of video from you to help my high school study (like physics and maths) but MAN you literally know everything OH MY GOD ?! you not only shocked but also scared me XD you are amazing, how can you literally know everything ??? man you must have lots of degree OMG XD

[@gopalshekar986]

Great video, good explanation 👏👌 3:50 - "Vce - collector to emitter voltage should be half of collector supply voltage "? I sppose VC, collector to ground , should be half of Vcc, the supply voltage. The collector- emitter saturation voltage is typically less than 1V.

[@rajveerajmani]

You sir are a SAVIOUR thank you SO MUCCCH!

[@amaleltahir8249]

I usually go to these videos to help me with my algebra class.

[@martinx1783]

I learned more knowledge from this in 17 minutes compared to the 5 hours lecture in my uni

[@jackevans2386]

1:31 "coopling capacitors" ?? They are 'coupling' capacitors. ie. They 'couple' the AC signal from the previous stage to the next stage. They don't "cooople"

[@jarekferenc1149]

Most of the capacitors couple. But HIS capacitors cooople. Pls, do not argue with capacitors, they know better what they do.

[@Enigma758]

9:44 Any reason a single coupling capacitor couldn't have been used directly past the ac source, and then split off to the two bases?

[@robonkenhout7965]

Amazing! You're good at this. (I mean the explanations) Many try, few succeed. I saw this exact formula (for Ib) on another video and was a little perplexed. Now, much clearer. Thanks!

[@RijuChatterjee]

lol I like how he says "coopled"

[@RijuChatterjee]

@@AndysRamblings Lol nah it's mostly an isolated quirk of pronunciation nothing wrong with the video

[@thething6936]

@@AndysRamblings wouldn't want to do that this man helped me get my distinctions😩

[@diywithreza]

I'm going to comeback to this video 3 years later when I'm finished with college, wish me luck!

[@oliverer3]

Organic chemistry has really changed since I was in school.

[@gamtogujju]

You are just brilliant and know very well how to explain with so ease, claps buddy!

[@shreyaskulkarni9345]

1:30 am. Today morning is Electronics exam & I'm watching this ... Like if ur doing the same 😉😉👍🏻

[@bennguyen1325]

This guy is the entire university.

[@dartplayer170]

Great explanation however there is a mistake in the Class A analysis. The 25% efficiency for capacitive couple output requires a load impedance equal to the output impedance of the amplifier according to the Maximum Power Transfer theory. You have not included a load. You are correct in saying that the maximum compliance is achieved with Vce = 1/2 Vcc when there is no load. However, when a load is hooked up according to MPT compliance is maximized by making Vce = 2/3 Vcc. An ac load line is required to determine the previous statement. In theory, matching the load to the output impedance of the amplifier provides 2 equal current paths and thus wastes 50% of the efficiency across the Rc resistor. This explains why the transformer coupled amplifier can attain a theoretical maximum of 50%. In Class A mode the transistor conducts for a maximum of 180 degrees and thus wastes at minimum 50% more of the efficiency. Thus, capacitive couple efficiency is >= 50% x 50% = 25% and transformer coupled >= 50%. The extra efficiency losses are due to design problems, loss of power by other components and loss of power in because the linear region of the transistor is slightly less than 180 degrees. That is the saturation and cutoff regions are unusable.

[@hariharan-yi8tf]

How u have knowledge of every field 😯

[@kolinevans9127]

Always more to learn lol : D ... Questions With the class C could not one place a resistor at the ‘E’ which would mean that the voltage drop across this would mean that the junction between the E and the resistor will have some voltage in ref to ‘ground’ example 1v , this would then mean the E has 1v ref above the Base if the base is ref to ‘ground’ Another question, could you trace the ‘current flow’ in a basic AB amplifier for amusement and insanity? The only way this device can function {for me} is if the ‘N’ junction is equalized to the ‘P’ junction when they are merged , I.e they effectively became one device with two junctions and a equalized 0 central point that is because the N from the NP>N equalizes with the ‘P’ of the P

[@akabomb]

"coopling capacitor" lol good and informative video though, thanks

[@josianemartinez6062]

I also noticed that he pronounces couple as coople. I wonder if his pronunciation is due to some regional accent? Curious.

[@danielgaewski8344]

Say coople... one more time..

[@joseph-jamesharding4815]

this guy is smart, i swear he knows everything maths/ science/ engineering based ahaha

[@JohannY2]

You explain the HOW good, but rarely the WHY.

[@anastahiliutawala3879]

Thank from Tanzania

[@C-130-Hercules]

Amazing video 👏

[@sand0can1]

Probably you should mention something about DC biasing and superimposing the A/C signal so that it oscillate around Vb. For example offset 0.2V A/C by 0.8 DC so that compound signal oscillates around 0.7-0.9V

[@abulfazibrahimov1990]

Thank you.From Türkey 🇹🇷

[@ikhwanmirza402]

Hye, may I ask? How is the working for Class A amplifier without AC input? Now I am doing a mini project, the title is Audio Amplifier for Cell Phone (Class A). Can you help me?

[@lohxinru3021]

Awesome 👏 Your voice is sweet

[@surakeneni1310]

None of videos out there regarding class ab single supply's voltage will explain what makes each transistor on and off for base of each transistor is always 0.7 greater than the emmiters of both transistor for 360° of input signal(emmitter follower concept). So how???? Help me out

[@lovesoni3169]

is this small signal or large signal amplifier? and can I use this method to make a audio amplifier(loud speaker)?

[@tinkerman9525]

Great video. But a opportunity lost. Should explain it effects on audio and rf. Reproduction of A class amplifier is near perfect reproduction of input. The best. Effieciency is 4000w in 1000w out. Fot rf it is class A , AB (SSB) and C(CW FM) that is always used for comms. 👍👍👍👍waiting for next video.

[@roncaruso931]

Coupling is pronounced "cupling". I've seen many class AB amps that do not use diodes. The class C amp is used in high level AM final amplifier in transmitters.

[@successthruknowledge]

Did he call the capacitors and transformers of the Class A Amplifier 'coupling capacitors'? His pronunciation is unfamiliar. Also I'm experiencing trouble making this circuit work in the app iCircuit. Anyone familiar with it. How do I set the elements of Vcc ? Also, I'm very hazy about the logic and strategy for how these circuits are designed. Nice that he clarified that current can't flow in reverse across the emitter of the transistor.

[@huyninh2236]

May I ask whether transistor amplifiers different from power amplifier? I found some circuits in the Internet and it has small differences

[@hamidbesharati3688]

Hi .is it pussible to amplify a fast edge squre wave (rise time=30ns) with 10 Vp-p to 100 Vp-p and with rise time being less than 60ns?

[@donniumar767]

FOR CLASS A AMPLIFIRE WHAT YOUR REREFERANCE FOR PSU SMPS OR TRFO?

[@antblakeee4177]

i don't know how you do it man😁😁

[@abuhenababu]

Good Job

[@abuhasan3726]

Nice and cool voice

[@TheRojo387]

I bet you could replace the diodes with transistors whose base and collector are coupled, on the class B.

[@markandoyo2204]

Which Guitar Amp belongs to the Class type? and which the 88key keyboard Amplifier belongs to the class type?

[@musiclyrics1860]

How about the efficiency, if we put transformer instead rc in the output

[@antonioarin3697]

Can you pls upload a video in AB and B amplifiers circuit analysis. I have a test coming in a day.

[@arduinorobot1216]

Amazing and super

[@arsalanuddin3661]

Great Video

[@beatlessteve1010]

Coopled?..why is c1's polarity different than c2?

[@rickymiravalles2687]

Which class of amplifier design has lower THD or sound clear or best ? kindly enlighten me ty

[@jarekferenc1149]

AB

[@fernandohood5542]

Would have been good to explain the biasing on the B and AB.

[@rx6910]

It's a great explanation, but you didn't show where the speaker + and - should be, also the + and - for input and output. Beginner like me would have difficulties understanding them.

[@minhajsixbyte]

great video. can anyone tell me what software is he using to draw

[@BharathKumar-kx4kt]

How if we introduce 2diodes how we can reduce the crossover distortion can you explain still

[@iaronbartal8393]

whats the function of RB on the last 2 circuits?

[@progamermajsc7230]

Can someone explain to me why he puts a negative voltage supply there. I'm new to electronics so I don't know. I just think it's because some positive voltage goes left instead of to base. This means some of that extra positive voltage needs to be cancelled out by going to a negative source.

[@laptech3767]

What college did you graduate?

[@arbymohamed6136]

Thank you

[@etg9080]

Since the class A and Class C are off for negative cycle, does it not half the data could be lost?

[@francoisdreesen9684]

With 2'12" left you draw the polarity of signal generator wrongly to put the transistor in cut off!

[@ابواحمدلكهرباءالسيارات]

شكرا

[@antoniohenriquez8800]

What tool is used to draw on screen?

[@uygarglk]

Ah, it says on Razavi's RF Microelectronics Class A has a max effect of 50 %. Why is that?

[@acamphibiousguys2006]

What is mean by voltage divider and its use

[@jarekferenc1149]

The voltage divider constantly supplies 0.7 V (dc) to the base. This is to just open the transistor. If any (positive) input voltage is added, base current increases accordingly, so there are no distorsions at the output. If there is no voltage divider at the base, you will have pure input signal that opens the base. The problem is that the base opens only if input signal is higher than 0.7 V. So, everything below 0.7 V that comes from the input signal source is simply lost. This causes distorsion of the output. The remedy is this voltage divider that you asked about.

[@Mindlagoon]

If you're going to talk about the different classes of operation then the first thing you should do is explain what the differences are, i.e. class A conducts over the full swing of the input, B over just +ve or -ve swing, etc, rather drawing a common emitter amp, complete with bias feedback, and saying 'this is a class A amp'. There are other ways of implementing class A.

[@progamermajsc7230]

Can someone please explain what RB and R1 does.

[@kolinevans9127]

My next inclination would be to ask what an ABC amplifier looks like? lol , {I wish I was joking : D }

[@amaleltahir8249]

Nice!

[@PotatoChips-jy9pk]

How did you know what I was thinking, dawg!?

[@dajidmorel2152]

How have an amplifier with (Vs/Ve) = 1000 ?

[@StinkyEla]

how do you know like, everything from chemistry to electronics to psysics and everything

[@johsanch5667]

rB in the last ckt?

[@ediz2000]

bro how are you so smart

[@netx421]

Class a has a sound that is better than the others. I'm not too worried about efficiency but I am in sound quality. You need some larger transistors like a tip122 and use lower voltage like 5 v 1a to power them. Less resistors and no voltage divide just place a 1k resistor or pot between the base and collector for biasing and bam nice little amplifier

[@thatdrh]

This guy from the east coast?

[@Shashwat_raman_shukla]

I thought it's organic chemistry but nvm I'll digest it

[@chrislykins4600]

Are you mark wahlburg?

[@felixlucien7375]

Is there anything this man doesn't know?????

[@novakattila]

None of these videos explain how a signal flows through an amplifier and what happens...Pretty disappointed

[@mr.decoder4843]

JG please teach about "host guest" & clatharates in organic chemistry

[@rods6405]

Sorry this is pretty poor explanation your jumping between dc and ac voltages at 7:45 the primary of the transformer is a short cct for DC voltages but a impedance for ac voltages. better explanation here www.circuitstoday.com/transformer-coupled-class-a-power-amplifier

[@johsanch5667]

hello tupvian

[@ColocasiaCorm]

Coopled

[@cbcdesign001]

Interesting but stop saying coopled, its coupled as in married couple.

[@NorMeeme]

🤓☝🏻

[@noelbacs9728]

Can you discuss a active tone control circuit.

[@joshmick]

😂😂

[@rafaelladehumo]

Bet you are fun at parties

[@johnettipio]

I guess you will just have to coop with it.

[@shannonroberts5080]

Oof, over 200k views here and there are so many errors in this video, particularly in the class B and class AB descriptions.

[@davidtobi4184]

Explain pls

[@shannonroberts5080]

@davidtobi4184 That was a long time ago that I made that post, so I had to re-watch to see what I was criticizing. Here are some more detailed comments: 1) Class A description is very good - EXCEPT when discussing transformer coupled Class A. The transformer does not store energy (significantly) and the magnetic field does not collapse. That would be an accurate description of a flyback transformer configuration, which this is not. Also, coupled is pronounced 'cup -ld' not 'coop -ld', but who cares about that. 2) The description of Class B is good. But when he describes Class AB by adding 2 diodes to help bias the transistors in order to remove crossover distortion, that's still Class B. Class AB is when you intentionally bias the transistors such that they conduct for MORE than 180 degrees of the cycle but less than 360 degrees. It's a delicate balance because you want to remove crossover distortion, but you don't want to get into Class AB, which is less efficient, and has distortion of its own. Usually you don't use diodes to accomplish this, but rather a Vbe multiplier or 'rubber diode' circuit. Transformer-coupled tube amplifiers are often Class AB, but the designers had to minimize tubes and efficiency was already out the window with those anyway.

[@shannonroberts5080]

@davidtobi4184 Class C is also not quite right since he says the capacitor and inductor charge each other up back and forth during the positive cycle - they do that during the negative cycle too. One other thing - the Class B schematic had a capacitively coupled load in one of his schematics. That's pretty weird. I'm sure there are some low power cases where you could do that, but for any significant amount of power, that capacitor would need to be prohibitively large. Overall, this is pretty good, I just don't like that he's speaking from a position of authority here when there are so many basic mistakes.

[@davidtobi4184]

@@shannonroberts5080 as confused as I am, I actually see your point, it's very valid

[@davidtobi4184]

@@shannonroberts5080 thanks alot for this detailed explanation