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- Опубликовано: 28 сен 2013
- Please note that towards the end of this video, where I am showing different bias conditions, that the resistor connected from base to ground is actually 4.7kohms, not 2.7k as shown in the video. This is corrected in the show notes available below. This video gives the basics of the bias point, also called operating or quiescent point, of a bipolar transistor (BJT). For a BJT, there are three operating regions: Cutoff, Active and Saturation (note, these names differ a little when dealing with FETs). The Q-point will influence the "class of operation" of an amplifier circuit. Class A, B, C and AB are discussed and demonstrated. A copy of the video drawings can be found here:
www.qsl.net/w/w2aew//youtube/B... 
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you say " thanks for watching " and i always say to myself " thanks for watching ??? THANK YOU for providing this info !!!!" you help A LOT !
Well, you are more than welcome! Knowing that people find my videos useful and helpful is what motivates me to keep doing them. So, again, I thank you and all my viewers.
***** Just jumping into the comments to say I agree wholeheartedly with Tiago, your videos and those of a one or two others are incredibly informative and extremely useful from a practical point as well.
I would like to second Tiago's comment. Thanks for the effort, real-world stuff like this is much better than whiteboarding it in a lecture hall
@@nix324 The Q-point is not defined as Vce=1/2 Vcc. The Q-point, or quiescent point, is simply the voltage and current conditions at the terminals of the transistor without a signal applied. One may choose to set the Q-point at Vcc/2, as this will give close to the maximum available linear swing.
@@w2aewand still interesting 9 years later 😂
Learned this from Professor Barry Blesser 47 years ago. You teach it the same way. The best demo i've ever seen was in his class. He set up a 2n2222 on a curve tracer showing its characteristic curves, next to it was a triode small signal tube set up the same way with a curve tracer. He held a match an inch away from the transistor and the curves went bananas. He then held a propane plumbers torch to the tube. Nothing. The tube envelope softened and and collapsed on the plate of the tube. Nothing changed on the curve tracer. The tube finally failed when it lost vacuum from the glass rupturing. Lesson 1 in thermal stability!
Better than any university lecture. I'm teaching myself about electronics for free solely from RUclips. Incredible.
Agreed absolutely! Hey, by the way, aren't you Mark Knopfler? LOL...
I would STRONGLY suggest 2 other resources besides RUclips.
lushprojects.com/circuitjs/circuitjs.html
This here is a circuit simulator that runs in your browser. It's been instrumental in helping me to learn about circuits visually and understand them on a more intuitive level, as well as being able to experiment with them hands on.
www.allaboutcircuits.com/textbook/
And this is the single best written resource I've come across for electronics. It has damn near everything you need to know, but doesn't overdo the technical details to the point of it being dry or intimidating.
These combined with the many great videos on RUclips, as well as wiki articles, datasheets and application notes make probably 90% of the material you'll ever need for your first couple of years or more of learning electronics. Videos like this are great resources, but I find they're most effective when used as a supplement to other education. If you try watching stuff like this without knowing some basics, a lot of it could potentially go over your head. And don't just limit yourself to one viewing. Nobody's gonna remember all of this stuff after watching it just once. Especially in the long term, like weeks or months down the road.
im nearly there, going to get my analogue logic done soon!!!! good luck to you my friend.
I basically knew everything in this video already but watching this made it so much more clear in my head. Much appreciated, and subscribed!
33 years ago when I was in college, I saw all this concepts on the book and didn’t understand well. And now in few minutes of your tutorial was more than enough. THANKS for sharing it.
sometimes, it's helful to understand things if a good teacher know his job. The most i know, don't know it or had forgotten how. That's a pitty....
I listen with warmth in my heart, despite the fact that I am also a radio engineer for about 30 years or like and have known all this since childhood, I am also a HAM radio guy. However, what this person does for public through the RUclips is priceless !
73s ! Kissees and hugs !
de UT5USA.
;-)
You have the best electronics tutorials. Great work!
The best teachers are not always those we have in schools... my case at least
I'm an EE, probably of a similar vintage to you Alan, and I wish it would have been possible for you to have been my lecturer at uni. Your impressive contribution toward free electronics learning is incalculable. Thank you, from all of us.
Something about seeing it in real life, not just on paper with calculations, amazes me. All the physics and stuff we learned about transistors actually works..
There are those who can and there are those who teach and then there are the rare human line output converters and you Sir are one of the best. Taking a high esoteric complexity and turning it into a lowly lament's ability to understand.
Thanks for this short tutorial. I did all of this more the 20 years ago when I was studying electronics at bachelor level, but never really worked with it or very little. Most of the time it was for a simple application to turn something on or off... I suppose I am a generation that already has access to a lot affordable modules, op-amps, and other IC's, starting the carrier in beginning of 2000. So I will repeat these (and more others that you did) short "lab experiments" at home just for fun. You do a really good job with teaching, and also important you know very well what are you talking about! You also put the scan of the schematics 👍 You can see a lot of people already watched it, almost 300k ! Good work, thanx
Been binge wathcing your videos to learn as much as possible in as short a time as I can.
Thank you so much for sharing your knwoledge with the world!
This may be the single greatest video on transistors I've ever seen, and turned on so many lights for me all at once. I've never seen anybody used a variable power supply to demonstrate the different states of a transistor. Thank you so much! (this also tipped me over for the reason of buying a signal generator and a variable power supply, lol).
4 yrs of College and i've never been this excited. I'll relearn everything now. Thanks man, a million times over.
I'm glad to hear that this video has helped inspire you to learn more! Note that there is a link to a complete video index file in the lower right corner of the header graphic on my channel's main page.
Yess I'm currently going through your entire index. Simply awsome.
I am learn more from your channel
I was struggling with the concept of biasing a transistor and how it related to its amplification factor. I understand now that:
(1) The bias resistors only affect the operating point of the transistor and the ratio of the two biasing resistors can be adjusted to accomodate any Collector voltage and still deliver an appropriate Q-point.
(2) The voltage amplification of the transistor is dependant on the ratio of the collector and emitter resistors along with the collector voltage applied (in this case 5V)
Wow - thank you, thank you, thank you!😊
So glad you found this helpful. The only time that the base-bias resistors can enter into the gain calculation is when collector-to-base feedback is used. It's much easier to estimate gain when feedback in the form of emitter degeneration is used. You might want to check out this video on some hints & tips about common emitter amplifier design: ruclips.net/video/VWY2WQcKJgk/видео.html
I'm usually a bit confused when it comes to biasing transistors, but this video was informative enough, and had the extra visual that I have been needing. Thank you for providing this great content!
I can't believe you only have 50k subs, you sir are the best teacher on the tube.
Ian Darley Also check out Mr Carlson's lab, he's also great
Fermilab also didn't have much subscribe back then, hopefully this channels sub count also blows up.
There is not necessary beeing "The teacher" , but prominent is to spell things to understand. Well, I am not a professor legally, but students in my class where all !
nobody them forced to go, but anyway.
Alan your way to teach is absolute impressive. You're not such a Master you're a kind of God on this.
Amazing explanation, you don't know how much oh help are your videos.
At 10:55 you said "Remove that transistor from the circuit" but you actually meant to say remove the "*" resistor (Voltage divider upper resistor) from the circuit.
Thanks a million my friend
This helps me to understand Biasing an amp more than anything I've seen yet. Seeing it on the scope was worth a thousand words.😃
You shpuld be an instructor, best explanation I"ve ever seen on
saturation. Now I finally understand, when you said two things are happening
when Vc crrashes into Ve. Both junctions become forward biased. That's why Vce approaches 0v when transistor is saturated.
GOOD JOB!!!!!!
ChueyMr11 your comment opened another perspective for me. I was thinking of the base as a valve between two potential barrier and the collector and emitter short as a short ckt. Thanks..
The best video blog in whole internet
29DR194 Thank you!!
Agree! I watching this tutorial a third time and still getting some knowhow. Thanks.
Same here!!
Agreed.
When I saw the first video I thought this must be Forrest Mims
You methods are awesome. Every student basically needs a teacher like you. Desiring to learn much from your videos. Highly appreciate your work and efforts.
Thank you for the nice comments - please be sure to let me know if there is a topic you'd like to see in the future.
FINALLY SOMONE MADE A VIDEO FOR HUMANS TO WATCH 🥳🥳🥳🥳 thank you for not assuming we are all robot engineers from the future. You sir… have a nice day😊
I hope you find that most of my videos are human-worthy too!
I had my avionics license quite a few years ago. Today I am a 2 way radio repair shop. Your tutorials are so awesome! A lot of the little things one gets away from over time. It is nice to watch and say... That works!
Great description of a transistor amplification demonstration. I taught this same thing to my collage electronics class in 1980 to 2004 at Harper College in Illinois. My students love it. Thanks for caring on the great work.
Excellent as always!! Your explanation together with the visual demonstration really helps build understanding - Thank you!
Very clear and to the point. I think this is the best introduction to transisters I've ever seen. I agree with others here when they say you are a great teacher. I do so wish you had been around 30 years ago when I was learning electroinics. You would have been very tired of me!! Again, Great Job and lI ook forward to your future vids! You have never let me down.....vids are always informative!!!!! Thank You!!
Transistor BIAS is always a very hard subject to visualise. You just made that so clear, so simle and easy to understand.
Thank you so much for showing the difference in amplifier classes, it is one thing to read about the classes, another to see that its just a shift in bias point.
This is how electronics need to be taught. That's equal to a ton of reading. Thank you sir.
This has to be the best demonstration of how a transistor works. Transistor operation is something that is nearly impossible to understand without a dynamic visual demonstration. Thanks!
Mind blown.....visualization makes the difference between a shaky grasp and solid understanding. Thanks!
wow you are a great teacher. i am doing this for a hobby and you explain how components work and it is making me want to break out the bread board. It is fascinating how much precision there is to make things work. I have spent so many hours getting ready to start playing with this stuff. you really explain this stuff so well and all the applications. thanks again.
There are a ton of nuances in doing effective analog circuit design. It is amazing how many "bad" designs you find out on the web...
Jesus, now I finally understand. Thank you, thank you a million times, easy to watch and understand
I'm happy to hear that this video helped you.
Wow. It just doesn't get any better than this! Thank you Alan.
I've watched a lot of videos trying to explain this but none have come close formulating things so clearly. Well done, great tutorial!
It doesn't matter what you have posted or what you will be posting Alan, I'm gonna watch every single one of them. my Stay at Home goal. Back to basics and RF section are my favorites.
You have a gift for explaining a very complicated subject. The way you use the oscilloscope to illustrate electronic theory is amazing. Thanks.
certainly one of the best tutorials on transistor biasing on youtube....very clearly explained...thankyou
Very interesting approach, quite different than the usual classical way, but, could I say, more practical, mainly for a first contact, ... or just for personal curiosity about the various points of view that we can have for this technic. It is simple, enough to position the subject, then to the point toward a result, finally, some details are added to enforce the main possible variations. And the "transition" between the various "scenes" is smooth and relevant. Really good composition, not just mastering the subject, but how to explain it too! And given that this kind of presentation is hardly doable "in a book", that is also a perfect use of the medium (youtube). A brillant technician AND a talented artist !
This is so much clearer than any other explanation I've seen yet. A testament to how well you understand the material.
Very clear and much easier to understand the way explain it than what I have read in books. Great video!
Unbelievable tutorial. Principles of Operation taught as well as video display of voltages & signals that demonstrate those principles. Congrats.
I have watched many videos on transistor biasing, but this one has finally made the concept completely clear. Thanks for presenting this tutorial!
Man... I just discovered your channel today and I learned more in 4hours than in 4 weeks searching on RUclips and Google... wow keep going!!
Wow, very cool description of bias point and operation. The visuals are especially helpful. Thank you for this!
The best way to watch these if you're learning like I am is to follow along with your own breadboard. Except I've watched this a couple of times already to make sure I didn't miss anything.
Great video. I've taken electronics classes in my EE program that break down all the math and believe me I've worked all the theory and math. This simple vid really helps clear up the physical design understandings and to see how the changes work.
Very interesting and I have been in electronics for many years but am not 75 years old and just playing around with solid state circuits. This video brings a lot of theory and practice back to mind. Thank you so much for a job well done and well explained, 73 W2AEW from Ka3lTN! I do still hold an extra class ticket!
Thanks a lot Mister, I believe you are very talented as a electronics teacher. Clear, simple, easy and, above all, pleaseful to follow. Fogs about transistors are now dissipating! Waiting for more, riccardo -Italy
Clear explanation and easy to listen to. Well done.
I'm a huge fan of the demos that you do with the lab equipment! It really helps to bring your point home and allows me to conceptualize the lesson.
Thanks. That's exactly why I try to mix theory and practice into each of my tutorial videos.
A very good explain and demonstraition how a transistor works.
RF-Amplifiers are not use class C mode in regular case - that's depend on the used channel coding or modulation mode. Every modulation mode who detects the frequency instead the amplitude of the carrier, can be use a class C mode amp - all other don't.
I know I'm late to this party but this was very helpful indeed for a hobbyist like myself! Your examples w2asw are much easier to understand than others here on YT. Thanks very much for sharing your knowledge!
Best demo and lecture ever! Thank you !
A very succinct explanation of amplifier classes . Always appreciate these tutorials, many thanks for your time.
All the positive comments are well deserved. Excellent info. Best to you...
Very well explained. Wish I had seen that when I was doing HNC electronics many years ago as that was the best transistor circuit operation explanation I've seen. Thanks for posting it
Fantastic Tutorial - One of the best I have seen on the net anywhere - Thank you so much!
Seriously one of the best explanations I have heard so far.
Awesome way of explanation. Thank you for your contribution to educating the folks. Keep it up...
You produced a wonderful video and made technical stuff very understandable! Very impressed and I am going to use this demo with my students. Keep up the excellent work.
Thank you! I hope your student benefit from some of my videos!
excellent tutorial, I really learned alot from this tutorial, especially with the DC waveforms watching the base voltage versus the collector voltage, going from cutoff through the active region and into saturation, that visual demonstration clarifies what is written about this subject in the textbooks.
Thanks for your tutorials.
Damn, dude, you give GOOD mentoring!
You truly make it easy to see the relationships between the various transistor terminal volts, amps, and resistances.
Good on you!
I will keep following your vids!
Cheers,
Dave
Thanks for teaching us so practically by demonstrating what's really happening in there , u r the best of all you tubers on making us understand this topic
So adorable teaching ..... seriously ......The Best teaching I ve seen .....Thank you so much !!!
Incredible. Thanks, Mr Wolke.
Thanks a lot Alan for yet another crystal clear tutorial, you are a gifted teacher.
Great series of the basics. Thank you for your time.
Great series of Circuit Tutorials videos!, thanks for all the efford you take to make the videos.
I always enjoy watching your videos Alan! Thank you for sharing your insights ! 73's , Gary Grove
I've been looking at some other videos on BJT behaviour. This is a fabulous step-by-step tutorial. The scope shots at the end brought it home for me. I'm looking forward to wiring this up and playing with it.
73 AI7GU
Just stopped by your fantastic channel. I must admit that I relearn a lot of stuff that should recall from my engineering studies but back in the days (late 80ies) it wasn‘t presented that good. Keep up the good work.
Learned alot from this video. Great to have that visualized on the scope. Thanks for posting this sir
Thank you for taking the time to make this. That was a very clear explanation and a good demonstration.
Excellent Video - you are truly one of the best instructors, ever ( of course you have more great test gear in order to demonstrate these circuits than any instructor I've had- even in my electrical engineering classes at a major state university, which is a shame, but true).
Yes I have re-watched this video, You are explaining the classes while operating you camera. My mind was amazed at your multitasking and thus did not take much in this time. I'll re watch later.
Again very interesting.
Absolutely blew me away, I love amps, so need more input.
I wanted say this dude is the best. easily understood down to business thank you.
You are the Horowitz and Hill of youtube. Thanks for the great videos.
Thank you very much for taking the time to make this tutorial, now I really understand how the transistor works as an amplifier.
Really helped. Amazingly explained in simple terms. Crystal clear.
how I wish I watched this when I was still a student..Great video,,very clear and very understandable..,good combination of lecture and actual implementation
+marhsall 27777 Yes, opamps and general amplifier circuits were explained very poorly at my uni, this video covers more than I learnt from the course :p
I absolutely agree; this is better than any lecture I received on DC transistor biasing from my University education.!
This is a great tutorial - thank you for your very clear explanation. This has helped me tremendously! Really well done.
Oh dear! You saved my life with this wonderful video
Alan, great videos! Thank you for taking the time and sharing your knowledge!
I am so glad I found this vid. Thanks for one of the best explanations and examples on this subject.
Exceptionally well explained! Thank you!
Thank you for devoting your time, knowledge, and effort for making your very informative video's, I love them and thank you once more!!!
Nice video w2aew. Really appreciate your videos they go alot more in depth than most tutorials and books
All of your videos, including this one, are fantastic! I hope to find (if you already did one) a MOSFET "back to the basic" video! Thanks for all of your work
+theawt I do have one on the basics of JFETS and MOSFETS:
ruclips.net/video/oambDFa0Pr8/видео.html
Thanks man!
Great introduction to amplifiers. Loved it. Looking forward to your next teaching video.
Very instructional video. Thanks so much for these Back to Basics videos. Please keep up the excellent work!
Now this is a real eye opener.
Thanks for the video.
Best of the best!! Absolutely loved the explanation!
huge thanks sir. nobody exlains it this easily!
Thx Alan, now every thing is clear. By the way, you channel is my best in electronics engineering on youtube.
Love these back to basic tutorials!
This is a great explanation of operation of amplifiers. Not used to hearing voltages to describe transistors because they are current amplifiers but if you just remember the resistor values it makes more sense... The saturation comment about the base to collector voltage is something that i think isn't well known.