Single Supply Transistor Buffer

Support the channel! :)
/ theaudiophool
We are going to carry on learning how to make transistor circuits with one of the simpler, (but very useful!) circuits, the Emitter follower :)
This behaves very much in the same way as the op-amp buffer that we've used previously, only it runs off a single supply.

[@theengineer9910]

The explanation of each of the impedance stages + you have an explanation of loading effect which is like the most important thing to know when putting circuits together. This video is gold for why impedances are very important.

[@TheAudioPhool]

Everything is impedance!

[@swaritmahalsekar5521]

@@TheAudioPhool Can you please tell why you considered those parallel resistance R1 and R2 10 times less than 235k.

[@TheAudioPhool]

@@swaritmahalsekar5521 39k||51k = 22.1k which is roughly 10 times less than 235k

[@swaritmahalsekar5521]

@@TheAudioPhool ya but how you got to know the values of those resistors? I mean u took the ratio 1:1.3 but why is there any rule?

[@crimadellaphone9374]

​@@TheAudioPhool Thank you for being direct and specific. As a guy with Aut!sm I've struggled to fully grasp impedance and load due to a lack of resources I've been able to f!nd that just bluntly explain why impedance matters and what load is and why it matters. The power display screen really nailed it home. Every attempt at explaining it, from over a year of reading and becoming familiar with audio circuitry, they all take a long winded route that merely leaves questions that I can't ask the author to explain. It kinda pisses me off a little that's it's such a simple thing and could had been explained in a direct way that only required a few sentences. So, absolutely 100%, thank you for your simplistic approach to directly explaining it as opposed to turning something incredibly simple into a long riddle.

[@beatrute2677]

After all these years, finally I understand, all that reading and took your video to make it all Schlick together. Thanks so much man, you have no idea how much i appreciate this.

[@BioMedUSA]

Your summary following your lucid presentation just highlighted how spectacular your tutorial is - outstanding!

[@Enigma758]

This is best analysis of a buffer/emitter follower I've ever seen.

[@TheAudioPhool]

Thanks!!

[@karlschulte9231]

For US viewers: Zed = Zee. Naught is Saxon for Zero. Nice to hear such holdovers from Middle English and earlier. This young man is a fine teacher and engineer. If I were not retired I would hire him in a flash. He would have to get used to cold beer however! Ex- Motorola Dir World Technical Education/ Systems Engineering Training.

[@anthonymetcalf660]

Just found your channel and I love it. I have ADHD and I have a hard time paying attention especially when someone is trying to teach me something, so I will put on videos in the background and catch bits of them, and sometimes I can pay attention. The fact that you go at pretty close to a perfect pace for me when I do pay attention and the fact that your voice is pleasant make it very doable. I love Sam Battle too but sometimes he has a bit too much energy for putting on in the background, and on the other end of the spectrum that ASMR-type stuff makes my skin crawl. I will be delving into your content, so thank you in advance!

[@TheAudioPhool]

I have ADHD too so I'm so glad to hear that I have been able to help you. I know your pain all too well 😅😭 Good luck on your electronics journey!

[@louco2]

Thank you so much for taking the time to do these videos!

[@rallokkcaz]

I really like this video and how much you know about electrical engineering and small signal design. But I also love that the dude teaching me about EE also has a lapel mic with a missing ground lololol. If you had no noise gate, I would die.

[@elye3701]

I was interested in electronics as a hobby when I was in high school. The only texts available were the university level textbooks at the British Council Library. I was overwhelmed by the h-parameters and matrices but I did - on my very own - understand enough abstraction to derive the WYE-DELTA equivalence equations. The next breakthrough was a small British book on how to build your own radio. I then understood what coupling the AC signal to the supply lines via a capacitor meant. I could have done with a video like this. You, Dave Jones, Ben Eater and Sam Ben-Yaakov are just the sort of teachers I was missing. I lent my radio book to someone who was interested and never got it back. I built a ZN414 based AM radio coupled to my iota audio amplifier. My amplifier drives a high impedance earphone. It was just something I cobbled together and worked better than a similar design in an electronics magazine which consumed tens of milliamps. Everything ran off a single 1V5 cell. My radio was always on since the ZN414 only consumed 700 uA. My amplifier only switched on when I plugged in my earphone. There was only one adjustment - a variable capacitor to tune in to a particular station. Volume control? was accomplished by turning the ferrite bar antenna off axis to the station. I potted the entire radio into a Rothmans cigarette box(I don't smoke) and used cotton wool and candle wax as a potting compound. I reckon I can improve my iota amplifier now - half a century later.

[@MrAlFuture]

This was brilliant! Thank you!

[@TheAudioPhool]

Thanks for watching!! :)

[@aduedc]

Check out "Flipped Voltage Follower" and "Super Voltage Follower" or "Super Source Follower" Circuit.

[@woosix7735]

Amazing explanation!

[@overengineeredinoz7683]

Such an amazing explanation of an emitter follower amplifier, plus learn some Latin at the same time. Keep the videos coming they are great.

[@TheAudioPhool]

Glad you're enjoying it!

[@RCook-iy4xk]

You are a good teacher. You helped me. Thanks for sharing.

[@martindowney7915]

Loved that 1, great explanation for the reasons of buffers.

[@stuffandjunkanduhh5049]

What a great way to start my day. Excellent videos!

[@TheAudioPhool]

Thanks a lot for watching!

[@taylorsharp5928]

Fantastic explanation and tutorial! This is good stuff. Love the channel name too ;)

[@jerrymorales482]

You a great teacher 👍

[@realchristopher4334]

Audiophool, my feet! I have been watching videos in this channel and I yet to see this man talking about how big his horse is. This is electronix at its finest as opposed to phool of audio! I thought the man at Simply Put channel is already very good in explaining how circuits work, but this is superior! Personally, I need real world/working examples to understand, which means I need numbers to visualise and not only loads of arrows pointing here there everywhere. Simply Put gives no numbers. Some other channels are purely academic as they are purely formulae. I do not know what the heck 'VT' is until I looked hard and long for it! Likewise some literature/written form have numbers and some are solely symbols. Now that I know what thermal voltage is, I need to show off what I learnt. Et voilà! I get approximately 26 ohm! This one is easy, merely fundamental ohm's law, without the whole mad string of mathematics.

[@TheAudioPhool]

You are too kind :) Thanks for the lovely comment!

[@realchristopher4334]

@@TheAudioPhool It is my pleasure! I hope I do not appear to be sycophantic! Hahahaha!

[@Electronzap]

Good explanation!

[@tonypike8774]

Nice one A.P. Just getting started on electronics myself. It's funny how it goes with KZbin. You wade through loads of stuff. Get stuck, then unstuck.... then stuck again. Not being in a classroom you can't ask the teacher. I am playing around with piezo's at the moment so impedance matching seems really important on the face of it. Interesting, what you said about connecting stages as well. I have some issues here that I have put down to de coupling which may indeed be impedance related. Time to buffer the hell out of the problem and see what happens. This was one of the best instructional videos I have seen on KZbin. You have a gift mate. Keep it up. Thanks. Tony.

[@Steve-GM0HUU]

👍Good explanation, thanks.

[@twobob]

Think this is one of my faves.

[@jwdory]

Great video!

[@IssamZeinoun]

Dude I love this!

[@zapp442]

So glad I found your channel!

[@TheAudioPhool]

Glad to have you along!!

[@dam3969]

Great video and explanations 👍

[@mrphil1092]

Brilliant! explanation.. superb!

[@raoulselten9480]

EXCELLENT video thank you 😊😊

[@rico5870]

Awesome video!!! Thanks so much mate to share!!

[@TheAudioPhool]

Thanks for watching!!

[@jefftruck]

Simple. Thanks!

[@YoussoufLife_style]

Good job sir, thanks for sharing 💙

[@garygranato9164]

just found this channel . subscribed !!

[@terrycaster4976]

Brilliant

[@kabandajamir9844]

So nice

[@navisb8345]

Thanks brother

[@duality4y]

Nice Video you have such a nice way of making it simple and understandable! :)

[@majordabalert]

One of my favorite parts of your vids is that you remind me of Daniel Radcliffe 😂

[@Theineluctable_SOME_CANT]

Very nicely explained and demonstrated.

[@Roel_Scoot]

Very nice way to calculate the voltage divider for the basis bias, but if you take some asymetric clipping for granted (just use lower input signal, then it will never clip) a hands on aproach could be: just take two evenly large resistors for R1 and R2. An engineer (as in contrast to a scientist or scholar) could also take a potmeter and trim the circuit for the highest output. Non the less thank you for your excellent tutorial.

[@justovision]

Shocked to hear someone with a European accent talk about a 2N transistor instead of a BC!

[@TheAudioPhool]

I've gone over to the dark side

[@justovision]

@@TheAudioPhool Good to keep a selection on hand. The extra gain of the BC547 let a 3.3v control signal from an RPi switch a 5v load where the 3N3904 didn't work.

[@fredkelly6488]

Yet another stellar video! One aspect I had trouble following was why the voltage divider after C1 has an equivalent impedance of R1 parallel with R2, rather than R2 alone. I thought this signal was unipolar, so how could current pass from the node after C1 through R1 to +9V? Thanks so much!

[@TheAudioPhool]

This is actually such a good question :) AC signals see the power supply as a short circuit, so long story short when we are thinking of changing signals, +9v is also ground! (we call this sometimes AC ground or virtual ground). If this is confusing, draw out the circuit (i always have to 'see' things visually myself), but instead of just putting +9v and ground, connect all the +9vs to the positive terminal of a voltage source, and all the grounds to the negative terminal of the same voltage source and you'll see the loop! I'll be sure to mention this in a future video because that is definitely something that confuses a lot of people. Thanks for watching!! :)

[@Ricobass0]

Unless you put a capacitor between the emitter and the load the q current will be 2mA not 1mA

[@dahlavibez5726]

Mate just what I'm looking for . Top dollar U r

[@martingerken7094]

which type of capacitor should I pick? if electreolytic, how to orient it?

[@rickybrenay6249]

more videos please

[@drstrangelove09]

Suggestion: The "nought" in "nought point six" is not needed -> "point six" works.

[@FloydAtema]

Thanks for the great content! Lots of buffers have a cap on the output. Why did you leave this out?

[@zainabiftikhar7746]

Plz mention the apparatus used to make buffer

[@chepeteybala9045]

Would that same values work to buffer the triangle wave on a 40106 oscillator?

[@swaritmahalsekar5521]

Can you please tell me how we select Ic = IE =1mA? Let's suppose if Im designing a buffer amplifier were the IE also plays an important role so on what basis do we select it?

[@simonyoungglostog]

Great explanation. I have a question relating to the R1 and R2 values, if that's ok? Why 10 x greater and not 20 or a 100 times greater?

[@TheAudioPhool]

It should be at least 10x greater to prevent attenuation. In electronics we generally take 10% to be an acceptable amount of attenuation because we have 5-10% tolerances in our parts so we have to design our circuits to be robust. If you go greater than 10x you will get less attenuation, which is good! Large resistors do inject more noise into circuits but this only really makes a difference for really precision circuits which we won't be worrying about for a little while. thanks for watching! :)

[@simonyoungglostog]

@@TheAudioPhool Noise, ok, that's a good reason. I was thinking along the lines of minimising the current wasted down the divider route.

[@TheAudioPhool]

@@simonyoungglostog There's always a tradeoff to consider in electronics. If you're operating off a battery less current might be more important than a bit of noise, for example.

[@simonyoungglostog]

@@TheAudioPhool I'm beginning to understand that there is a very elastic nature to electronic circuitry. Thankyou for taking the time to respond.

[@kaybhee6]

goot

[@munguciwalter5806]

Hi thx it very good explains now help design ab amplifier please

[@swaritmahalsekar5521]

Also please tell me how that capacitor is forming high pass filter I simulated the circuit at 50hz I'm not getting the proper signal. Ripple like signal is occurring please help me

[@joeshmoe7899]

Was thinking the same. Why an op amp, when a simple one transistor amp will do?

[@VandalIO]

How did you learn all of this magical stuff ?

[@TheAudioPhool]

I have a degree in Electrical Engineering and have been doing Electronics as a hobby for about 7-8 years :)

[@blackmanops3749]

I'm a little rusty, but I was using 2N3904 and 2N2222 back in the 70's. Hasn't anyone made a better audiophile grade transistor?

[@Steve-GM0HUU]

Did you ever find a better audiophile grade transistor? All I know is that the 2N2222 and 2N3904 are good for AF and RF up to at least several MHz.

[@blackmanops3749]

@@Steve-GM0HUU Suprisingly no one has offered up a better choice.

[@petersage5157]

So if a buffer protects one circuit element from another, anything that serves a protective function could be described as "buffy"? The idiosyncratic language patterns of Sunnydale suddenly start to make some sense.

[@dantheman1998]

why use buffer over a transformer for coupling?

[@alvarobyrne]

thevenin!!!!!

[@namename8986]

Use an opamp for Rs 0 hehe

[@markderlo212]

I accidently deleted my comment and the link with schematics ... 😓