You are a natural teacher. You have the unique ability to transfer all of the key information in a manner easy to understand and to the point. Excellent!
I know a lot of the online material on the internet sort of shows this isn't understood and just adds to the confusion, or essentially leaves you to have to fill all the gaps in before you can fully understand what is going on.
@@Zapgod At university? Not really I think :-) At university you learn for 3 months only what is happening at the P-N junction when transistors are not even mentioned. And when you start learning the transistors then you learn these configurations *in details* - certainly not in just a few lessons.
Even 11 years later, this video is still a great resource. There's one issue I'm having, though: Everytime your phone dinged in the video I looked for my phone thinking I had a notification. The ding sound of your phone sounds nothing like mine- so I have no idea why I even think it's my cell phone. I guess I'm Pavlov's dog.
Excellent instruction. I'm studying for the Advanced Amateur Licence (Australia) right now and videos like this one are a great help. Thank you very much.
Many years ago I ran across a circuit in a magazine (remember those? :-) that I just had to try out. It was a single transistor in a common-base configuration that allowed me to use a small 8 ohm speaker as a microphone. Worked well, that did! So that's not just "mostly RF"...
I appreciate your clear and uncluttered presentation. As a software engineer getting back into electronics (after a 35 year hiatus...), it's videos like this that help bring back the tinkering skills I've forgotten. Thank you.
Just a quick thanks for your really helpful explanations and demonstrations. I understand more in a 10 minute video from you than hours of formula obsessed textbooks. :)
This was a great tutorial for transistor amplifier connections. I never expect it open my mind to deeply understand the connection and the effect of changing the value of resistor as you did in common emitter. Your 11:08 is very valuable for me.Thank you very much
VERY VERY well explained, it's like magic. This directly relates to schematics I've seen for RF circuits and it makes it easier to understand WHY the different setups. Keep them coming Alan!!!
You are awesome, clear and precise, You didn't stumble once or pause and mutter Ah-Ah.Now I understand the miller effect. You explain this better than a college professor.Good presentation, thanks
Another great explanation! I had never thought about cascode amps like that, but it makes a lot of sense. Have you ever worked as a teacher/tutor professionally? You'd be the best!
Succinct and well paced. Nice to have the book and lab in combo...separate classes often have a different feel and temperaments especially when lab partners have not done any preparation.
I should comment on your videos more often, as you are awesome. You really fill a niche nobody else covers as well and concise as you do I was wondering where the term "common" originates for these setups and also so I am never confused again, what are all the other names given to these circuit that mean the same, such as emitter follower. Thanks again.
Thanks very much for this video, it was really insightful and helped my understanding of these circuits a great deal. I think it would be great if you were to scan in the pages of tutorials like this, and post them online, so that the viewer is able to "play along at home" and have them for further reference. I for one would really appreciate it! Thanks for the great videos, you're an excellent teacher and have made so many concepts make more sense to me! peace chris
Very nice. This 11 minute video probably took you 11 hours to prepare. Impressive. Thanks. I like "rules of thumb" for using one configuration versus another. Please consider comparing BJTs to FETs (to Op Amps?) in the future.
Really you are awesome teacher ever ..... because you are teach with practical....so I humbly request to you jast same type video upload all time... please please please...
I am so grateful for people like you who spend time instructing others. Please excuse my ignorance, but what are you referring to when you talk about common? Many thanks.
+John Wilde When you say Common-emitter, Common-base or Common-collector - you are referring to the terminal that is NOT carrying the input or output signal (it is the common reference point). Thus, for a Common-emitter amplifier, the input is the base and the output is the collector, etc.
For an emitter follower, it helps to stabilize the collector current with two additional transistors. That way the B-E voltage is constant, the gain is closer to 1, and the already low distortion is even lower.
I am much obliged for your kindness in preparing the videos and sharing your knowledge. I've been putting together the circuits you present and have been having pretty good luck with them, though I'm getting clipped low end sine waves above 1K htz. Is it impedance problems, is it a voltage attenuation? What to do? It is surprising how a small change in the value of a component often makes a circuit unstable or worse
Finally a clearcut explanation about the common and different aspects between the three BJT configurations. Might I suggest to maybe give a short explanation about the use of coils (and capacitors), say, in a common emitter configuration, inspired on the same philosophy of this specific video?
I've never heard of a common base amplifier before. Common collector and common emitter I already know, but not common base so I learned something today.
This brings back a lot of knowledge that I'd forgotten about since I dropped out of EE school... Especially the common-base circuit. Aren't common-base circuits usually drawn with the base facing down, and aren't common-base circuits also common (pun not intended) in power supplies? I seem to remember seeing and using circuit diagrams that extend the maximum current of a 7805 by letting the 7805 control a 2N3055 power transistor in common-base configuration.
This was my first video from your channel and man, from here I can only imagine how much wisdom and knowledge you would have ... So that's why I wanted some guidance - Can you please share some good sources ( books, vids, anything...) for getting the vast knowledge of electronics ? I know experience is a very important part of learning in this field, but here is the thing, how can you get experience if you don't know anything !? I mean How to start ? How you started ? Plz Help this generation of new Electronics Enthisiasts. Pardon my awkward English. Thank you.
Learning is a lifelong process, and it is a different process for everyone since everyone learns things differently. Some people learn best by reading, others by seeing, others by doing. For me, it has been a lot of reading and a lot of doing! When I was a teenager, I poured through the Engineering Notebook series by Forrest Mimms, striving to understand the circuits in them. I worked in a TV repair shop while in high school and learned a lot there. I experimented a lot with electronics, and still do. I also loved reading analog Application Notes from the old National Instruments, Analog Devices, Linear Technologies, Texas Instruments, etc. linear IC manufacturers. Still love books like The Art of Electronics, as well as old books like the Op Amp Cookbook, etc. I studied and received a BSEE degree and have spent the last 35 years in the electronics industry as a design engineer, test engineer, product engineer, validation engineer, application engineer, etc. So, for me there was no single, simple path - it has been (and continues to be) a lifetime of learning - through reading and experience. I can't over-emphasize the power of experience. Start experimenting, keep experimenting - you will fail and fail often, but you LEARN much more from your failures than you do from your successes - so don't let failure discourage you.
Great video. Minor error you might want to fix with a caption - at 5:51, you said common emitter instead of common collector. Thanks for the great series.
I'm confused about the cascode configuration. How does it negate the bandwidth limit of the common emitter? The miller effect is still there right? Doesn't it need to run through the Common emitter first? I initially thought was that you said something wrong and that a common collector feeding a common base would make more sense. Great Video as always.
Excellent intro tutorial on the amplifiers, Alan! I got a question on that: On the cascode amplifier, the signal passes through the common emitter amplifier first and then passes through the common base...so it seems that the bandwidth reduction effect is still there on the first stage. Is this effect reduced just because the voltage gain (Av) for the common emitter is minus one on the cascode configuration, or something on the common base prevents the inverted signal from being coupled back by the capacitor effect and reduce bandwidth?
mauro sobreira It is because the voltage gain is reduced to -1 on the common emitter stage. This minimizes the Miller Effect. The Miller Effect is the multiplication of the C-B capacitance by the voltage gain. Since the magnitude of the gain is unity, the C-B capacitance doesn't get multiplied like it would in a single common emitter gain stage (without the cascode).
An Excellent Tutorial. Thank you very much. Keep the good work on and if you have some time for different types of multivibrators , it would be really good. Thanks in Advance.
Excellent video! Now I know what to do with all those hunks of silicon with the wires hanging out of them I have behind my stacks of tubes in my basement! You've managed to "wake up" things I learned years ago! RW
Very helpful! Couldn't find a better video that broke it down like yours did. I searched your site, you don't have any more in depth videos on how the BJT works do you?
I've got a few more that use BJT transistors - like one that talks about frequency response of a common emitter amplifier, and another that talks about BJT differential amplifiers (long-tailed pairs), and more.
good job! I obtained the reverse. For common emitter the phases of in and out are the same. For common colecter they are shifted by 180 degrees and the same intensity.
Great teaching tools as always.Would be nice in your video's if you would show how the test Leeds are hookup to test equipment so i could preform the test's also as you only show the board.Would be great if i could download your notes
Question about 6:31. When you say that a low input impedance loads down the circuit you connect to, could you expand on what you mean by that? Or point me towards material explaining that.
Dmoles O A circuit with low input impedance will require that the circuit that driving the input have the capability of providing sufficient current to drive the input to the desired voltage. If the preceding circuit can't provide this current (weak driver, high output impedance, etc.), then the voltage will be reduced or distortion will occur (or both). If the circuit has a high input impedance, then the demands placed on the preceding circuit are much lighter. Ideally, you'd want the connection between the circuits to have no affect on the voltage appearing at the junction. This is why test equipment like multimeters, oscilloscope probes, etc. have a high input impedance - you want to measure the actual voltage appearing at that point without affecting it (loading it down).
Hi Great video I just want to make sure I got this correct all of these circuits take an ac signal and amplify it to a dc biased signal so the signal will be seen on top of an dc signal. If this is correct I would like to know how to you get this signal back to ac?
Hi w2aew, could you explain what the equations mean at 2:50 ? The only thing I recognize is Ic which is collector current. I guess Rc means the resistance of the collector circuit (ie. 680 ohms) but that's all im able to figure out. What do re, gm, Vt etc mean? What's A in the eqn below? What does it represent? Is it A=(Rc/(re+Re)*(gmRc) ?
Yes, Rc is the collector resistor. The remaining parameters (re=small-signal emitter impedance, gm=transconductance, Vt=thermal-voltage, etc.) are all parameters used for computing the small-signal gain characteristics, and come out of a simple model for the transistor. The parameter A is the voltage gain. These parameters are explained a little more in a few of my other videos: Common Emitter amp gain and frequency response: ua-cam.com/video/NizrzRKQqII/v-deo.html Common Emitter amp design tips: ua-cam.com/video/VWY2WQcKJgk/v-deo.html
The input signal level is what causes the transistors depletion area to either be narrow or widen. The input signal level is opening and closing the transistors depletion area?
Hi Alan, - could you explain the role of Emitter resistor (degeneration or "negative feedback") in a video - this confused me a lot when started learning about the different configuration. I am sure many people would benefit from this :) - especially with the great way you have of explaining things!
Hey Allan. as you know Ive been in college and we are finally working with bjt transistors. In a common emitter isnt the AV gain rc/r'e because re is bypassed with the cap. and also the output impedance of a common emitter is usually low so that most of the signal gets out to the load?? All the best ve1qet
In Common Emitter amplifier configuration it can be seen on scope that when bypassing the Emitter resistor along with huge gain increase there is also more signal distortion, as it should be. Thanks.
I'll figure out some way of attenuating the input signal to less than what either of my two signal generators produce which is about 1/2V minimum. I'd like to be able to attenuate into the millivolt scale. I'll also try tweaking the gain and the bias. Wish me luck. Thank you!
They work exactly the same as NPN, except the polarities are all reversed. In a very simple sense if you turn any of these circuits upsidedown and change to PNP, that'll work.
@@w2aew I have heard that, but in my limited experience it seems not to be the case. My understanding is dismal to say the least... but is there something about drawing vs. pushing current... I've noticed PNPs work better in some applications than others like synchronizing an LED to music, for example. I've tried using a single PNP as an audio preamp and couldn't get it to work... though it's easy with an NPN... Have you made a video specifically regarding PNPs? As always, thanks for taking the time to reply and for making high quality educational videos.
@@w2aew You'll have to forgive my ignorance. I'm still new to electronics as I only developed the interest about a year ago, or so. As in most fields of study, the more I learn, the more I recognize my own ignorance. There is so much to learn and your clear and concise videos have been, and continue to be, such a big help. Sincere thanks for the education, and especially for taking the time to reply to my, what must seem, inane queries.
Hi Alan, do you have a video where you show how to calculate values for emitter by-pass and coupling caps? Having a hard time finding a succinct way to demo this to my class.
Some of the info might be in this video: ua-cam.com/video/VWY2WQcKJgk/v-deo.html For the emitter bypass, you choose a cap value that gives you a reactance that is 5-10x lower than the emitter resistor at the lowest frequency of operation. For the coupling caps, it really comes down to looking at the impedances on either side, and picking a reactance that gives you the coupling that you want at the frequency extremes.
Reviewing the (great) old video... I haven't tried a common base amplifier yet. I wonder if it would be suitable as a pre-amplifier between a modulator and the final drive amp on a transmitter?
@@w2aew Common base proved to be the magic sauce. See ua-cam.com/video/ei9r2BTER8k/v-deo.html I'm still working on the power amplifier stage. Any suggestions on optimizing a shorten AM (1MHz) antenna of about 30ft? I experimented with loading coils and pi filters but with poor results compared to my other higher frequency builds. Thanks again for the education!
Another excellent tutorial, still not clear about the common base amplifier though, not sure I understand how the transistor works by connecting the signal to the emitter.... Time to hit the breadboard!
Everytime I think of an electronic topic I need to better understand, I search your channel first. You are an awesome teacher. Thanks for all you do.
After wasting my education for too long, I'm starting to learn about this stuff. I really appreciate the pros/cons/uses summary for each.
You are a natural teacher. You have the unique ability to transfer all of the key information in a manner easy to understand and to the point. Excellent!
That was 3 months of lectures summarized in 11 mins. Excellent tutorial!
I know a lot of the online material on the internet sort of shows this isn't understood and just adds to the confusion, or essentially leaves you to have to fill all the gaps in before you can fully understand what is going on.
Bro they teach us this in 3 days then test on day 4
@@Zapgod At university? Not really I think :-) At university you learn for 3 months only what is happening at the P-N junction when transistors are not even mentioned. And when you start learning the transistors then you learn these configurations *in details* - certainly not in just a few lessons.
@@ChupoCro in the navy, this is how they train
Alan, 9y later I keep rewatching your videos. The best, most concise explanation. You are possibly on the best teachers I ever had.
Thank you, Sir
Seriously, this is the BEST transistor explanation on the web. EXCELLENT work!! Thanks.
It's the best I've seen as well. It's crazy how many persons make it more difficult than what it is.
I realize this was done several years ago, but is by far the MOST LUCID explanation on the three common configurations. Thank you so much!
I just do not have a words to express how I love your videos. Thank you Sir.
Ever time I try and teach this part of BJT applications, I end up showing this video. Students really get it.
That's so nice to hear - I'm very glad to know that my work is helping people!
Even 11 years later, this video is still a great resource. There's one issue I'm having, though: Everytime your phone dinged in the video I looked for my phone thinking I had a notification. The ding sound of your phone sounds nothing like mine- so I have no idea why I even think it's my cell phone. I guess I'm Pavlov's dog.
Excellent presentation. I learned all of this over 30 years ago it is good to see someone teaching this as a needed refresher for this old man.
You are an uncommon teacher.
Excellent instruction. I'm studying for the Advanced Amateur Licence (Australia) right now and videos like this one are a great help. Thank you very much.
Simple, elegant and efficient. That’s about as good as an explanation can get. Well done!
This video explains the concepts so clearly and concisely. Perfect really.
Many years ago I ran across a circuit in a magazine (remember those? :-) that I just had to try out. It was a single transistor in a common-base configuration that allowed me to use a small 8 ohm speaker as a microphone. Worked well, that did! So that's not just "mostly RF"...
A very good video, even down to the camera tracking your pen as you moved from circuit to circuit… very impressed! God bless, Bill.
I appreciate your clear and uncluttered presentation. As a software engineer getting back into electronics (after a 35 year hiatus...), it's videos like this that help bring back the tinkering skills I've forgotten. Thank you.
You got the best tutorial basics of transistors! No one else seems to show the real thing. You got both! Great video! It helped a ton.
Just a quick thanks for your really helpful explanations and demonstrations. I understand more in a 10 minute video from you than hours of formula obsessed textbooks. :)
This was a great tutorial for transistor amplifier connections. I never expect it open my mind to deeply understand the connection and the effect of changing the value of resistor as you did in common emitter. Your 11:08 is very valuable for me.Thank you very much
Wow, yet another superb video..simply the best set of electronics tutorials on UA-cam. Hats off to you sir!
VERY VERY well explained, it's like magic. This directly relates to schematics I've seen for RF circuits and it makes it easier to understand WHY the different setups. Keep them coming Alan!!!
I never get tired of watching.
You are awesome, clear and precise, You didn't stumble once or pause and mutter Ah-Ah.Now I understand the miller effect. You explain this better than a college professor.Good presentation, thanks
Another great explanation! I had never thought about cascode amps like that, but it makes a lot of sense. Have you ever worked as a teacher/tutor professionally? You'd be the best!
Coming from Applied Science that's the best recognition one can have 🙂 Thanks for your great channel you're making the world a better place👍
Thanks, love your videos. By far some of the best electronics explanations/tutorials on youtube.
Succinct and well paced. Nice to have the book and lab in combo...separate classes often have a different feel and temperaments especially when lab partners have not done any preparation.
Now this is teaching! Thank you for uploading! :-)
I should comment on your videos more often, as you are awesome. You really fill a niche nobody else covers as well and concise as you do
I was wondering where the term "common" originates for these setups and also so I am never confused again, what are all the other names given to these circuit that mean the same, such as emitter follower. Thanks again.
The content u give is so thorough and wholesome. solid lesson, thanks so much!
Thanks very much for this video, it was really insightful and helped my understanding of these circuits a great deal.
I think it would be great if you were to scan in the pages of tutorials like this, and post them online, so that the viewer is able to "play along at home" and have them for further reference. I for one would really appreciate it!
Thanks for the great videos, you're an excellent teacher and have made so many concepts make more sense to me!
peace
chris
Clear, concise and well structured explanation. I am impressed, thank you for making these!
Very nice. This 11 minute video probably took you 11 hours to prepare. Impressive. Thanks. I like "rules of thumb" for using one configuration versus another. Please consider comparing BJTs to FETs (to Op Amps?) in the future.
Great video! A common base amplifier is also great as a preamp for a low impedance microphone. Low noise, high gain.
way to break it down in a clear, easy-to-understand manner. cheers!
I got terrble grade on my electronic course 20 yrs ago. I wish you were my teacher back then. I would have love electronic.
Really you are awesome teacher ever ..... because you are teach with practical....so I humbly request to you jast same type video upload all time... please please please...
Awesome video -- as a beginner, this sort of explanation is priceless. Many thanks.
A good refresher course,amazing what I forget over a weekend.
I am so grateful for people like you who spend time instructing others. Please excuse my ignorance, but what are you referring to when you talk about common?
Many thanks.
+John Wilde When you say Common-emitter, Common-base or Common-collector - you are referring to the terminal that is NOT carrying the input or output signal (it is the common reference point). Thus, for a Common-emitter amplifier, the input is the base and the output is the collector, etc.
+w2aew Many thanks! I am getting there, albeit slowly. You are a great patient teacher.
I know that this video has been around for some time but it has been really really helpful.
WOW WOW WOW a BIG thank you. I really appreciate all your videos but the BASIC one are out of this world. My hat off ! :-)
For an emitter follower, it helps to stabilize the collector current with two additional transistors. That way the B-E voltage is constant, the gain is closer to 1, and the already low distortion is even lower.
Perfect video! THanks you a lot. It is very clear and I like how you showed the example on the oscilloscope right away.
love your videos, always learned a lot in a short period of time, winner tutorials !!
Great video! I just learned this in class it it was awesome to have you wrap it up.
Excellent exposition. Good effort expended in your videos . Well done. Thank you.
I am much obliged for your kindness in preparing the videos and sharing your knowledge. I've been putting together the circuits you present and have been having pretty good luck with them, though I'm getting clipped low end sine waves above 1K htz. Is it impedance problems, is it a voltage attenuation? What to do?
It is surprising how a small change in the value of a component often makes a circuit unstable or worse
Ideal.Best way to learn by practical approach, lesson to future. Thank you SIR.
Ooh...I could have used some of this for my Electronics exam this morning. I love your videos!
I second this! I'd love to have an in depth explanation of input and output impedance.
keep up the great work!
peace
Beleive me, you have a gift to explain electronics.
thank you so much for this video i love the way you explain how CB,CE,CC works.
nice job BRAVO
Finally a clearcut explanation about the common and different aspects between the three BJT configurations. Might I suggest to maybe give a short explanation about the use of coils (and capacitors), say, in a common emitter configuration, inspired on the same philosophy of this specific video?
Excellent explanation and tutorial!
Best video I have ever seen on transistors 👍👏👏
Great explanation, very nice balance of basic things with some more advanced info.
Great video. Very nicely explained.
I've never heard of a common base amplifier before. Common collector and common emitter I already know, but not common base so I learned something today.
This brings back a lot of knowledge that I'd forgotten about since I dropped out of EE school... Especially the common-base circuit.
Aren't common-base circuits usually drawn with the base facing down, and aren't common-base circuits also common (pun not intended) in power supplies? I seem to remember seeing and using circuit diagrams that extend the maximum current of a 7805 by letting the 7805 control a 2N3055 power transistor in common-base configuration.
Dear Sir you give us a lot information in your tutorial i like it very much thanks
Thanks for the good vid man!!! Im in 4th grade and working with transistors for the first time! Helps me alot!!!
This was my first video from your channel and man, from here I can only imagine how much wisdom and knowledge you would have ...
So that's why I wanted some guidance -
Can you please share some good sources ( books, vids, anything...) for getting the vast knowledge of electronics ? I know experience is a very important part of learning in this field, but here is the thing, how can you get experience if you don't know anything !? I mean How to start ? How you started ?
Plz Help this generation of new Electronics Enthisiasts.
Pardon my awkward English.
Thank you.
Learning is a lifelong process, and it is a different process for everyone since everyone learns things differently. Some people learn best by reading, others by seeing, others by doing. For me, it has been a lot of reading and a lot of doing! When I was a teenager, I poured through the Engineering Notebook series by Forrest Mimms, striving to understand the circuits in them. I worked in a TV repair shop while in high school and learned a lot there. I experimented a lot with electronics, and still do. I also loved reading analog Application Notes from the old National Instruments, Analog Devices, Linear Technologies, Texas Instruments, etc. linear IC manufacturers. Still love books like The Art of Electronics, as well as old books like the Op Amp Cookbook, etc. I studied and received a BSEE degree and have spent the last 35 years in the electronics industry as a design engineer, test engineer, product engineer, validation engineer, application engineer, etc. So, for me there was no single, simple path - it has been (and continues to be) a lifetime of learning - through reading and experience. I can't over-emphasize the power of experience. Start experimenting, keep experimenting - you will fail and fail often, but you LEARN much more from your failures than you do from your successes - so don't let failure discourage you.
@@w2aew Thank you very much for your kind words and your time. Very motivating.
Great video. Minor error you might want to fix with a caption - at 5:51, you said common emitter instead of common collector. Thanks for the great series.
Thank you for a very well made tutorial :) Are those glossary notes you are using accessible somewhere?
Best explanation , i think yes, thanks for making this video
awesome demo, especially for the common base. Thanks fot the great content sharing!👍👍
The common base is the hardest for me to employ.
Thanks for the tutorial! This is going to help me a lot designing my amplifier.
I'm confused about the cascode configuration. How does it negate the bandwidth limit of the common emitter? The miller effect is still there right? Doesn't it need to run through the Common emitter first? I initially thought was that you said something wrong and that a common collector feeding a common base would make more sense. Great Video as always.
Excellent intro tutorial on the amplifiers, Alan! I got a question on that: On the cascode amplifier, the signal passes through the common emitter amplifier first and then passes through the common base...so it seems that the bandwidth reduction effect is still there on the first stage. Is this effect reduced just because the voltage gain (Av) for the common emitter is minus one on the cascode configuration, or something on the common base prevents the inverted signal from being coupled back by the capacitor effect and reduce bandwidth?
mauro sobreira It is because the voltage gain is reduced to -1 on the common emitter stage. This minimizes the Miller Effect. The Miller Effect is the multiplication of the C-B capacitance by the voltage gain. Since the magnitude of the gain is unity, the C-B capacitance doesn't get multiplied like it would in a single common emitter gain stage (without the cascode).
***** Crispy clear, Thanks!
An Excellent Tutorial. Thank you very much. Keep the good work on and if you have some time for different types of multivibrators , it would be really good. Thanks in Advance.
Excellent video! Now I know what to do with all those hunks of silicon with the wires hanging out of them I have behind my stacks of tubes in my basement! You've managed to "wake up" things I learned years ago! RW
Very helpful! Couldn't find a better video that broke it down like yours did. I searched your site, you don't have any more in depth videos on how the BJT works do you?
I've got a few more that use BJT transistors - like one that talks about frequency response of a common emitter amplifier, and another that talks about BJT differential amplifiers (long-tailed pairs), and more.
Thank you! Very clearly explained and shown experimentally.
WHERE TO FIND THE DETAILS....??
You explain the best way.
Thanks a lot, greetings from Argentina!
Another outstanding video. Useful information for all. Thanks.
What is the transistor number 2n3904 ?
Any common NPN transistor like the 2n3904, 2n2222, etc. can be used in these examples.
good job! I obtained the reverse. For common emitter the phases of in and out are the same. For common colecter they are shifted by 180 degrees and the same intensity.
Great teaching tools as always.Would be nice in your video's if you would show how the test Leeds are hookup to test equipment so i could preform the test's also as you only show the board.Would be great if i could download your notes
Yet another great review. Thanks, Alan.
Question about 6:31. When you say that a low input impedance loads down the circuit you connect to, could you expand on what you mean by that? Or point me towards material explaining that.
Dmoles O A circuit with low input impedance will require that the circuit that driving the input have the capability of providing sufficient current to drive the input to the desired voltage. If the preceding circuit can't provide this current (weak driver, high output impedance, etc.), then the voltage will be reduced or distortion will occur (or both). If the circuit has a high input impedance, then the demands placed on the preceding circuit are much lighter. Ideally, you'd want the connection between the circuits to have no affect on the voltage appearing at the junction. This is why test equipment like multimeters, oscilloscope probes, etc. have a high input impedance - you want to measure the actual voltage appearing at that point without affecting it (loading it down).
Hi Great video I just want to make sure I got this correct all of these circuits take an ac signal and amplify it to a dc biased signal so the signal will be seen on top of an dc signal. If this is correct I would like to know how to you get this signal back to ac?
Hi w2aew, could you explain what the equations mean at 2:50 ? The only thing I recognize is Ic which is collector current. I guess Rc means the resistance of the collector circuit (ie. 680 ohms) but that's all im able to figure out. What do re, gm, Vt etc mean? What's A in the eqn below? What does it represent? Is it A=(Rc/(re+Re)*(gmRc) ?
Yes, Rc is the collector resistor. The remaining parameters (re=small-signal emitter impedance, gm=transconductance, Vt=thermal-voltage, etc.) are all parameters used for computing the small-signal gain characteristics, and come out of a simple model for the transistor. The parameter A is the voltage gain. These parameters are explained a little more in a few of my other videos:
Common Emitter amp gain and frequency response: ua-cam.com/video/NizrzRKQqII/v-deo.html
Common Emitter amp design tips: ua-cam.com/video/VWY2WQcKJgk/v-deo.html
Very good ... please post for FET & MOSFET also
please do!
The input signal level is what causes the transistors depletion area to either be narrow or widen. The input signal level is opening and closing the transistors depletion area?
Hi Alan, - could you explain the role of Emitter resistor (degeneration or "negative feedback") in a video - this confused me a lot when started learning about the different configuration. I am sure many people would benefit from this :) - especially with the great way you have of explaining things!
Hey Allan. as you know Ive been in college and we are finally working with bjt transistors. In a common emitter isnt the AV gain rc/r'e because re is bypassed with the cap. and also the output impedance of a common emitter is usually low so that most of the signal gets out to the load?? All the best ve1qet
I appreciate and enjoy this tutorial very much, Thank You!
In Common Emitter amplifier configuration it can be seen on scope that when bypassing the Emitter resistor along with huge gain increase there is also more signal distortion, as it should be. Thanks.
I'll figure out some way of attenuating the input signal to less than what either of my two signal generators produce which is about 1/2V minimum. I'd like to be able to attenuate into the millivolt scale. I'll also try tweaking the gain and the bias. Wish me luck. Thank you!
Thank you so much for making my concepts more clear...
Great lesson! Do you have a video on PNP transistors? I've used them as simple switches, but I find them rather confusing...
They work exactly the same as NPN, except the polarities are all reversed. In a very simple sense if you turn any of these circuits upsidedown and change to PNP, that'll work.
@@w2aew
I have heard that, but in my limited experience it seems not to be the case. My understanding is dismal to say the least... but is there something about drawing vs. pushing current... I've noticed PNPs work better in some applications than others like synchronizing an LED to music, for example. I've tried using a single PNP as an audio preamp and couldn't get it to work... though it's easy with an NPN... Have you made a video specifically regarding PNPs? As always, thanks for taking the time to reply and for making high quality educational videos.
@@w2aew
You'll have to forgive my ignorance. I'm still new to electronics as I only developed the interest about a year ago, or so. As in most fields of study, the more I learn, the more I recognize my own ignorance. There is so much to learn and your clear and concise videos have been, and continue to be, such a big help. Sincere thanks for the education, and especially for taking the time to reply to my, what must seem, inane queries.
Best explanation I have seen! 73's
Very nice videos with full of information - thanks!
Hi Alan, do you have a video where you show how to calculate values for emitter by-pass and coupling caps? Having a hard time finding a succinct way to demo this to my class.
Some of the info might be in this video: ua-cam.com/video/VWY2WQcKJgk/v-deo.html
For the emitter bypass, you choose a cap value that gives you a reactance that is 5-10x lower than the emitter resistor at the lowest frequency of operation. For the coupling caps, it really comes down to looking at the impedances on either side, and picking a reactance that gives you the coupling that you want at the frequency extremes.
Reviewing the (great) old video... I haven't tried a common base amplifier yet. I wonder if it would be suitable as a pre-amplifier between a modulator and the final drive amp on a transmitter?
Could work well.
@@w2aew Common base proved to be the magic sauce. See ua-cam.com/video/ei9r2BTER8k/v-deo.html
I'm still working on the power amplifier stage. Any suggestions on optimizing a shorten AM (1MHz) antenna of about 30ft? I experimented with loading coils and pi filters but with poor results compared to my other higher frequency builds.
Thanks again for the education!
With class C RF amp, can you explain how it can be used/ modified to an AM or FM transmitter, BTW your tutorials are very clear and easy to grasp.
Another excellent tutorial, still not clear about the common base amplifier though, not sure I understand how the transistor works by connecting the signal to the emitter.... Time to hit the breadboard!