Howto repair switch mode power supplies #6: Basics of Linear Regulators and voltage references

In the sixt video of the Switch Mode Power Supply (SMPS) repair series we look at the basic ideas and priciples of operation of linear serial regulators. Serial regulators are used in every power circuit in order to generate stable supply voltages. Even in SMPS we will rely on linear regulator circuits to get stable voltages in order to feed integrated circuits like the APFC controller, the Pulse Width Modulation (PWM) controller chip, or the supervisor chip. Furthermore, these integrated circuits will contain highly precise reference-voltage generators, which are also based on linear regulators.
The video is built up such, that we start from a simple circuit with an incandescent lamp, and we introduce step-by-step new elements into the circuit to get a high power linear regulator. First the functionality of the series drop resistor is discussed. Next, we look into the case when the input voltage is fluctuating over time. In such cases for low power applications we can use a Zener diode in series with a fixed resistor. The functionality and the main property of the Zener diode is briefly introduced (without going into detail about avalanche current, etc.).
Next, we focus on medium and high power applications, where a bipolar power transistor is being used as a variable resistor, where the equivalent resistance between the Collector and the Emitter can be adjusted through a driver signal fed into the Base electrode.
In real-life circuits, most often a voltage reference circuit formed by a Zener diode and a fixed resistor is used to provide a stable voltage. This reference voltage is than fed into the Base of a power transistor, which in turn is able to provide stable output voltage even for medium and high power applications. Thus, practical circuits are combining Zener reference diodes with power transistors. For example, serial regulators available in three pin power packages, like the LM317, or the classical 7805, they use a similar inner circuit, where the three pins correspond to the power input, power output, and to the ground for the reference diode.
One major drawback of linear regulators is, that they dissipate a large portion of the input power in form of heat. This makes linear regulators rather inefficient. Due to the low efficiency, one also need to design linear series regulators with large heatsinks and even with active fans to extract the waste heat. To reduce the amount of power wasted, and to make more efficient power supplies, SMPS use instead a technique called Pulse Width Modulation.

[@victoraugustine7661]

As at this minute, you are the BEST teacher I have ever met.

[@DonkeyLearningIT]

Thanks for the kind comment. Though, I would say that there are other very good videos out there. The same material can be presented several different ways, and making it educationally interesting is harder than many KZbinrs want to admit.

[@tangerinq]

I like the fact that you clearly think about teaching when producing these videos. It's a rare thing on KZbin. Mostly you are doing it very well, from my point of view. I appreciate the fact that you go into the trouble of showing us the alternative, less optimal solutions, before finally arriving at how things are really implemented. As a critique, I feel that sometimes you repeat the same thing again, and sometimes that thing is lengthy. This happens to me, too, when trying to explain complex things verbally. Normally this doesn't occur in written text because then I am more aware and in better control of the information flow and structure. Not a big deal, really - it's easy enough to just skip a few seconds. Overall you are doing a great job, and you really helped me to understand the topic better and feel more confident about my knowledge. I'm not bothered by your accent at all. You are very easy to understand and that's what matters. Will be waiting for the next parts.

[@tangerinq]

BTW I guess it's out of scope for this series, but as computer repair tech, I frequently encounter laptop chargers that seem perfectly fine but seem to have trouble outputting something on the data pin, and hence laptops that expect this output will refuse to work properly with them. I wonder if you have any comment on this or any direction to point me at to get to understand this better. I can very well research by myself but knowing the keywords for Google is a much easier starting point.

[@msdesignru]

Anton * I'm with you!

[@DonkeyLearningIT]

I really appreciate constructive criticism, since that most often leads to the improvement of the contents. You are not the first one who have pointed out the issue of the repetition, and I agree with you, things should not be repeated in a video. The thing is that I was teaching only about 15 hours when I was at the university (it was more than 14 years ago), and there the idea was to repeat the main points. However, online format is radically different. In future videos I will try to reduce repetitions within a video, since if people want to watch it again, they can just scroll back 30 seconds.

[@DonkeyLearningIT]

Mostly the Apple charges are doing this, since other charges tend to use only two pins, so either there is enough juice, or there is something wrong with the charger. Now in those cases when there is a signal pin between the charger and the laptop (i.e. more than two pins), the situation is even more tricky, since often there is a two-way communication established. Namely, first a stand-by circuit will be turned on inside the laptop right after the charges is plugged in. This stand-by circuit will signal the charger, that it should turn on the high-power state. However, if the standby circuit detects some fault, or the charger has some issue and it does not send the right initialization sequence to the laptop, that is when the charge will not work as you described. For fixing such things you will need an oscilloscope, and you will need to monitor what happens on the signal pin. If the charger only has two pins (GND and +18V or similar) and it does not work, but the laptop works with an other charger, and also the faulty charger provides the right voltage, than 85% the capacitors have dried out in the charger. Due to this the fluctuation of the voltage (called "ripple") is way too high, causing the inner circuit of the laptop to do not accept the voltage from the charger.

[@DonkeyLearningIT]

I am actually surprised that also Russian guys watch my videos, since I found some really well made technical videos on KZbin in Russian. Only issue is, that they often do not have subtitles, but one can still see that they are 100% making a good explanation.

[@pedrof.7821]

Hi keep doing these awesome classes and forget that people is saying about this is taking forever to fix power supplies, you are going into a lot of detail and this makes us learn more and more. Thank you for your work

[@DonkeyLearningIT]

I appreciate your comment. Once I finish with this series and people watch it, they will be able to repairing SMPS by simple though-transmission and meditation, through the power of their mind. Just joking, but it is almost true. Making these videos takes me about 8 hours per video, since my technique is far from optimal, and my editing skills are almost zero, but I think that it will be worth it if people learn from it.

[@pedrof.7821]

Donkey Learning IT hi, dont be negative about your editing skills, as a teacher i can tell you that you are doing it just great!!

[@DonkeyLearningIT]

Thanks for the reply. Btw, what do you teach? During my studies I was also finishing a module for teaching physics, but besides those mandatory 15 hours of teaching required before the practical teaching exam I was never working with actual students. Even that is more than 13 years ago...

[@pedrocontrerasavendano8578]

we do learn alot from them and if you have the time, it will be awesome if you could continue with the series!!!

[@asjeletronica9971]

I've no words to describe how great you are by doing these videos.

[@DonkeyLearningIT]

Thanks for the positive feedback! As I wrote, there are lots of good videos out there, but often they tend to be way too theoretical without explaining the basics. This is what I try do do in my videos. Keep on watching the whole series.

[@asjeletronica9971]

I will keep watching it for sure! God bless you!

[@DDGraphicArtandSign]

So I was looking for a quick "How to fix a power supply". Now this turned out to be an excellent explanation of electronics and I wish it had been explained this way to me 45 years ago in college EE.

[@DonkeyLearningIT]

Thanks for the feedback. As you see, to be honest, there is no "quick" way to fix a switch mode PSU due to the complexity involved. Of course, after one knows what to look for, a repair can be indeed quick. I am glad that you liked the videos, so just keep on watching (I am producing new videos, because I will finish this series), and at the end with enough patience you might learn how to fix them.

[@hyblog8122]

i'm so excited to watch your next video, your are the best teacher, i have never seen a teacher who teaches like you, i really love your videos, I'm so glad to find ur videos, thank you so much to share your knowledge with us.

[@DonkeyLearningIT]

Hi! Thanks for the comment. For some reason KZbin was not notifying me on the comments, so now I go through them one by one. After the update of the GUI some things seem broken. They should really fix it.

[@SOSO-by4dn]

I WISH I'D SEEN YOUR VIDEOS WHEN I WAS IN ELEMENTARY SCHOOL. THANK YOU.

[@mbender8653]

I really appreciate your detailed videos, as when I dive into a switch mode supply, the more details I know the easier & safer the repair becomes. Thanks for your time & efforts in widening our knowledge.

[@DonkeyLearningIT]

Thanks for the positive feedback! Some people do not appreciate it that I do not just jump right into the middle of practical repair. The issue is exactly, that without knowing the background, trying to repair SMPS is both dangerous and also it is just trying to play the lottery by exchanging some parts. After we cover all the basic principles, it will be *so much more simple*.

[@P_Manom]

Dear Donkey Learning IT; I really appreciate your time and efforts making such learning videos especially very helpful for newbies like me. Keep it up👍👍👍 ... since its not a language training but purely a technical topic, I don't bother about Asian, Russian, European, German or whatever accents you speaks. Once again thank you.

[@atdzsny]

Sounds to me a strong Hungarian accent with rare exceptions. E.g. Z in Zener is a bit Germanish. :) There's no such thing as a European accent, though, as that would include very different ones like French, Slavic, German, British, Scottish.

[@jkohutiak]

fantastic how it works series. but none of this told me how to repair anything. still gets my thumbs up.

[@sirnewhill]

This is a really good series and I´m so looking forward to the next episode! Thanks for taking the time to make this!

[@pramodkumar-sc9lv]

still waiting for the rest of the project on smps. thank you for your effort and energy that you bring in your videos.

[@DonkeyLearningIT]

Luckily I have finished a larger project in the job, so I should have not more time during weekend to produce videos. In fact, I _almost_ promised myself, that during the winter I will publish a video every week.

[@paparoysworkshop]

As a new subscriber, I am looking forward to more of your videos. Keep up the great work.

[@DeAudiofilosyLocos]

Man, I do appreciate the masterclasses on electromagnetism, but I'm just trying to fix my Sony ES CD player 😂😢. I'm still watching 😊 and subscribed

[@gregorye6075]

Thanks for very good tutorial. I am getting back to electronics after many years, watching your videos helps a lot !

[@DonkeyLearningIT]

Electronics is always fun. Even if one gets back to it years later, it is just as interesting as when someone is young. In fact, now via KZbin one can learn stuff which was not available at all years ago, or one would had to pay thousands of dollars for a specialized course in PCB design, etc. Have fun!

[@arzz11]

Man you are damn good.... I never ever seen this type of explaination. Your analogies are beautiful. Please continue this series.. I loved it.

[@DonkeyLearningIT]

Thanks for the comment! I am glad that you liked it.

[@JAF-jw9yb]

Hey Donkey, so glad to hear that you are putting out the next video soon. I like that you have a relatively smaller viewership. It means that the people who are watching are serious about learning and provide more competent, meaningful feedback; without all the trivial, cluttering comments. As for the language, don't worry about it! You are a great teacher don't change ONE thing. Martin Kuliza with the epic long comment hit the nail on the head. Not sure about the confidence thing. Your self-questioning has actually helped me see what you were saying and your videos are so informative that I enjoy sitting through the slow parts. Even if you had a ridiculous stutter, speech impediment, and an annoying voice I would still watch. Hope that when you move to asia you will still make videos for us! I've been doing my own reading and thinking but everything online I've read says that the value of the components do not determine output voltage that rather the output is dependent on source and the Duty cycle only. A fact which I believe is reductive to the point of being incorrect. Just not exact enough mathematics. Anyways, TO THE DONKEY HERD!

[@DonkeyLearningIT]

That was a funny comment, I liked it. *Donkey powa* for ya all! Just joking ;) I am grateful for people giving feedback, especially if it is constructive criticism. I probably could have a lot more subscribers if: 1.) I would monetize my videos, since KZbin would make money with it, and they would promote it more. 2.) If I would actually make two videos a week. Lets hope that some day I will get there, but first I need to take care of my daily jobs and chores. 3.) When I improve both the contents and the production value of the videos with better audio/video/lighting, and try to make more fancy figures, but also provide better explanation. Many people like colorful figures, in spite that they do not learn anything from them, so I am not sure whether I will ever add more graphics. The "questioning myself" style is a cheap teaching methodology tactics, where people are forced to think about what they just heard, which is proven to make neurons fire in the brain, and make new cognitive connections. At least that is what they thought me when we were doing teaching about 14 years ago. Moving to Asia is just a long time dream/goal of mine, since I am fed up with the way how the EU is being run.

[@rsnytlnet606]

Billion thanks to you Sir for the 6 videos about SMPS. I request you to upload 7th ... . Waiting for the 7th... I have learnt a lot from you. The language you use the examples you give are perfect and very simple to understand the concept behind the scene. I have done my graduation but never got this type of clear understanding about the power supply. Thanking in anticipation. Thank You very much.

[@DonkeyLearningIT]

Thanks for the encouragement. I have about half of the 7-th video produced, and now after the big heatwave I got a cold because I was sitting next to the fan all day long. Once I am better, the 7-th episode will be up.

[@carlosgomes6074]

Thank you for your very simple explanations on your videos.

[@kiswahilikitukuzwe2547]

Much respect and appreciation from Kenya for the time, dedication and patience you have put in this wonderful series to impart this invaluable knowledge in such a simplistic and holistic way!!!

[@omar7amdi]

Practical information is hidden by the professor during collage classes .Thanks.

[@dannygeorgeson4760]

G'day Donkey, Congratulations on the Six episodes to date, what a commitment. Your systematic building block approach and in depth explanations are excellent. Given your commitment to detail I can see numerous tutorials to come. Hopefully once all the building blocks have been explored you can use actual Cct. diagrams and boards to explain their operation. Perhaps you could consider a video on personal safety and the dangers of testing SMPS. Also the need to isolate earths from test equipment, like CRO's, so you don't inadvertently destroy input channels. Best wishes for the festive season. Cheers Danny

[@DonkeyLearningIT]

Yeah, I intended to do lots of videos in this series, since there are several details which need to be addressed indeed, especially when it comes to safety. However, as you see, in the last two months I got sloppy and have not produced new videos in the series :( Due to holidays now I got time tom make new videos, and continue the story.

[@KitKat-qg4xj]

This set of videos are the best I've ever seen.

[@DonkeyLearningIT]

Thanks for the feedback. I am actively working on producing the follow-up videos. Once the heatwave going through Europe is over, I will be able to sit down in my apartment without sweating all over my keyboard and upload more contents.

[@sureshy16]

Hi sir, your video and way of explanation with live example are awesome, looking for more and more video similar to above .. Once again thank you 🙏

[@jongalindo6091]

dang,,I'm bleeding for continuing video on switching power supplies. #8 and further,,,, great job.

[@zalisco1]

Hello there just to say thank you so much for making to understand electronics .Your tutorials are very well detailed it's 10 out of 10👍

[@AliensInc.]

Best thing I've seen on SMPS yet. Very informative. Keep up the good work, I'll be waiting for the rest of the episodes in this superb series.

[@DonkeyLearningIT]

Now during fall/winter I should have a lot more time to produce new videos, so yes, I will finish this series for sure! Also, I am happy that even Darth Vader likes the content instead of using the dark side of the force on me ;)

[@AliensInc.]

OK cool. I'll be checking everyday for new eps. btw, seems you got some good humor too, don't worry I'm as kind as a kitten :)

[@KalinZahariev]

Тhis is so informative and well presented, you have the gift of a teacher. Thank you!

[@hughieandrolf]

Great videos. Many thanks. I find your content stands up on its own and I too, don't think you need to worry about spending a lot of time editing, especially as you are uploading without consideration for financial reward. You asked for feedback on pace. I watched all 6 videos in one go and found it easy to replay sections a way of recapping and repeating sections that were new to me and I didn't grasp first time. With that facility easy to hand, I would prefer to recap what and when I need to, and relieve you of the need to recap and repeat within the videos allowing you to move along a little quicker. It must take a long time to prepare shoot and edit content and I would imagine you have only so much time to spend on this. I agree that having a grasp on the principals is vital, and It's fascinating to know about the nuances of ferrite materials and how frequency dictates manufacturing composition but at this time I don't know how much or how far along this detail is on the 'necessary - useful - interesting' balance in SM PSU repair. I am not saying it isn't interesting and well presented and for a nerd like myself, its great to watch, but I think I would rather I lost a little detail and polish where possible to reduce your time commitment than risk you getting bogged down and losing and focus of the goal before completing this particular series. I would love to see a future series discussing the pros and cons in application of one component or principal over another. Many thanks once again. Irrespective of my comments It's still all excellent stuff and I'm left wanting for more!

[@DonkeyLearningIT]

Thanks for taking your time and giving a honest feedback, appreciate it. In the future videos I will try to reduce the repetitions within a video, so that in the same amount of time one can focus on more wide content. As for the inductor core, I had to go through it, since otherwise people will not understand why one has a power resistor in series with the Source of the power FET (I will show in the 9-th video) for current feedback going to the PWM controller, and why does the PWM signal look in the way it looks in a switch mode PSU.

[@boonedockjourneyman7979]

Are you making your videos with an intelligent Czech lady tonight? You kept my wife awake the whole show. We need a new series. Electronics for women with boring husbands! Well done.

[@DonkeyLearningIT]

Haha, that was funny! Wish you all the best for the both of you ;)

[@tohariparjoko6869]

Waiting for the next part #7. It's a very usefull video, many thanks from Indonesia.

[@geez6666]

You are freakishly through and clear in ur thinking. Thank you so much

[@DonkeyLearningIT]

Never heard this before, but I take it ;) Thanks for watching and commenting.

[@agstechnicalsupport]

Great video on the basics of power regulation & use of voltage references

[@makarlsson123]

Really looking forward to part 7. Great videos and thanks a lot for all time and effort you put into this!

[@DonkeyLearningIT]

I am also looking forward to the day when the 7-th video is finally done. However, Winter is coming ;) So it means I will have more time for producing videos.

[@mariojimenez2472]

Very clear explanation. Thanx for sharing your knowledge.

[@FrancisRodgers]

Also waiting for part 7! Great series and thank you for sharing.

[@ernestberry5226]

great stuff ! Thank you for uploading this it has helped me greatly. I am excited to see 7.

[@mista4637]

Already Subscribed.. Thanks a lot.. nice presentation. Systematically arranged.. easy to digest even for people who has no previous knowledge of electronics. Thumbs up.. keep it up.. Thank you a lot

[@DonkeyLearningIT]

Thanks for the positive feedback. I am half way done with part 7. I am a lazy donkey-a$$ during summer, that is for sure...

[@coloradowilderness3139]

Donkey Learning IT. Your understanding is crystal clear. Thank You very much.

[@jordantan9487]

Hi, i really like your videos. You really made it so much easier to understand how the power supply works. Well done! I am eagerly waiting for for the continuation of this series of teaching videos.

[@DonkeyLearningIT]

Thank for the comment. I promised myself a million times that I will upload at least one video a month, but than always something comes, or I am simply useless during the weekend. Don't worry, I will upload more videos soon.

[@ishmailkamara96]

yes of cues is good

[@nisri1567]

Really fine job, fantastic! Deep detailed explanation, keep doing it. A little beat deeper about the Zener Diode function could make the subject matter more transparent. How the zener diode controls the varation at the input side. And try to demostrate it on bread board, with Voltmeters or Oscilloscop. Great thanks.

[@ronniepirtlejr2606]

Great job! You should use the d15xb60 full bridge rectifier chip. You can screw it to a heatsink and take up to 600 volts. They are dirt cheap!

[@DonkeyLearningIT]

Well, in this video we are not even talking about diode bridges yet, we assume that we feed in pure DC to the circuit.

[@manaharlotia7233]

excellent as usual n very very clear Demonstration. tutorial 6.thanks

[@DonkeyLearningIT]

Thanks for the positive comment as well.

[@ronshinall]

Thank you for the videos. I look forward to part 7!

[@korun99]

hey man.this is one of the best vieos i ever seen.cant wait for #7.pls make more more videos where you explain electronic how it functions.best greetimgs from germany.

[@DonkeyLearningIT]

Thanks for your positive comment. I was always postponing the work on KZbin videos, but in the coming weeks I will really publish new content, since apparently people watch these videos, which surprise me considering that I have not uploaded a new video for more than 2 months. Grüße aus Österreich.

[@guyfradasyl88650]

please continue this serie. i learn a lot

[@ojoimmanuel]

Really waiting for the next video. Thanks for the detailed explanations.

[@DonkeyLearningIT]

I also can barely wait when I will have time during the weekend to finish the video. I have a portion of it produced, but not the whole deal. This weekend I will upload what I have, no matter what.

[@Frozenskin]

Feed me! ;)

[@Obishman]

Hi, thank you very much for your videos! I hope you will upload part 7 soon

[@DonkeyLearningIT]

I promised myself that I will put more effort into making videos. So far here it was nice warm outside, which I like. Now the spring and winter is coming, so I should have plenty of time producing content instead of walking outside on sunshine.

[@AnDy-pl2ks]

Very nice video series -- so well explained, thank you very much for this!

[@strikerjoe07]

Great video.Please upload the #7.thanks.

[@abscomm]

I have had so many "aha" moments watching your videos. Thank you.

[@DonkeyLearningIT]

I am glad that it helped. However, I have to play the devils advocate, and tell you, that in fact there is something very important what is missing. Namely, one needs *feedback circuit* from the output to actually be able to control the voltage. Of course, for that we need to go through about three more videos to understand first optocouplers and why they are necessary.

[@abscomm]

I am totally hooked on your videos and just know that after watching them will have the best understanding of the power supplies ever. Thank you for all your hard work.I will be following all the way to the end.

[@nigussiemendisu6688]

Really really your demonstrations is attractive and fantastic I like it very much and keep it up

[@DonkeyLearningIT]

Thanks for the positive feedback!

[@azucarestaurant]

Excellent explanation. The best I saw on youtube. Thank you a lot.

[@DonkeyLearningIT]

Thanks for the kind comment. I would say there are better videos out there, in fact this one I put together a bit in a rush. However, most videos focus either on way too much mathematics/theory, or they just build circuits and do experiments without explaining the basics.

[@ricgoco3450]

Thank you this video very precise and details for dummies like me

[@DonkeyLearningIT]

Thanks for watching. However, do *not* consider yourself a dummy, since what matters is that you are interested in something. Thus, it is only a question of time until you will learn it.

[@tibitec8008]

Very well done. I hope we get a 7. part. :) Thank you very much

[@DonkeyLearningIT]

Part 7 is already half produced. It will be finished and uploaded this weekend. If the flew would have not hit me in the middle of the heat wave, two videos would have been long up.

[@Vidya1939]

TKQ,SMPS fundas getting clear slowly , go ahead sir

[@gedeon1980yt]

Good job. Please go on with this amazing work ! When we can expect next part?

[@user-zj1ms4fp5r]

Great Job keep up the good work

[@maz9398]

thank you very much for the fantastic explain, please continue ...

[@CHzwaves]

Great Video....Thanks for sharing 😊😊

[@kabandajamilu9036]

So nice and educative

[@luqasxXX]

for 6 episodes I was wondering if you are German or Russian - now I know... vielen dank.

[@DonkeyLearningIT]

You got me! I am actually a Russian donkey who is a secret undercover agent on a donkeyfarm in Germany ;) How did you figure it out btw? Was it the Zener?

[@EkholmAndreas]

Teacher! I'm looking forward to your next video! ;)

[@redsquirrelftw]

Been interesting in building my own SMPSes (mostly for fun but possibly for actual use cases) and these videos are really helpful! Looking forward to the next ones. One thing that I can't seem to find concise info on is how do you power the electronics (ex: microcontroller or SMPS controller IC) from mains so the rest of the SMPS can start? Would be nice to cover this in a video. I have a few ideas myself but curious how it is typically done.

[@DonkeyLearningIT]

If you are interested in SMPS design, first you should design switch mode low voltage DC-DC converters. One can learn a *lot* from those designs, and still stay on the safe side, not playing with lines voltages. Please watch my video in this series on the Stand-by circuit, that explains the main idea how is the microcontroller and the SMPS controller being powered.

[@minkorrh]

So, theoretically, you could use PWM to dim an incandescent bulb also, as the width of said pulse would determine the average brightness of the bulb in a given time period? In my limited knowledge and experience that would be more efficient than using resistance to dim the bulb as you're not wasting the excess power as heat? I've commented at 3:51......I should wait until the end of the video as I think you may be going in that direction since this is a SMPS video lol. By the way.....very informative videos explained in a way that is easy to grasp concepts. :))

[@nyambemundopu1168]

Excellent explanation. You're elaborate.

[@DonkeyLearningIT]

Thank you for watching and for the positive comment!

[@suhailasaba1051]

At 5:13 Why 50% wasted power ? The current when the resistor is connected will be smaller than without connecting the resistor. Power across the resistor is R times I squared. Or Power is equal to 6 volts across the resistor, which is half the 12volts that was across the bulb, multiplied by the current through the resistor and the bulb which is smaller than that in the first case when the circuit had the battery and the bulb only.

[@martinkuliza]

Hello Donkey I'D LIKE TO GIVE YOU SOME FEEDBACK (One Engineer to another) and also One European to Another My name Martin Kuliza, i was born in Australia, My Parents are Serbian. I'm guessing you a Slavic, you are probably Russian or somewhere in Europe so.. Donkey = Osel or Magarac in serbian, is that correct hehe My Friend i have taught many students electronics and I.T. and this is what i have found 1. You (the Teacher) must be confident in yourself to begin with. i find that seem to be self concious and you question yourself. Why do you do that ? clearly you know and understand what you are talking about so, Why question yourself YOU ARE A GOOD TEACHER... ok, Keep doing what you are doing and .. THAT'S THE END OF THAT DISCUSSION. ok 2. if you are worried about the language thing..... DON'T WORRY. Yes there are some minor things and i'll point them out for you, but.. it's not really a big deal Here is the one thing that i think you could change in the language When you say ELECTRICAL CIRCUIT focus on the word CIRCUIT you say it like this (Phonetically) SIR .... KU.... IT and i understand why, because in europe we pronounce things like that PRONOUNCE IT LIKE THIS...... SER .... KIT because even though the spelling would suggest to pronounce it as SIR KU IT (Cir Cu it) it is actually pronounced as SER KIT or more correctly . if you can do this IT'S S....RRR ... KIT but it's easier to say SER... KIT beyond that when you said ZENER DIODE you didn't say ZENER you said TSENER but that's ok, that's a european thing. and i'm not going to correct that or pick on it so.. yeah.. only the way you say circuit sounds OFF, other than that, you have no problems in the way you explain it the explanation is very good 3. i've watched all 6 of the videos so far, You are doing very well my friend... ok as for ... are you too slow or too fast or whatever NO... YOU ARE NOT TOO SLOW, you are going at the right speed (considering that people need to absorb this information) for the first time 4. AS FOR PEOPLE WHO ARE COMPLAINING this is an important point donkey... some people want to listen and some people are just little bitches (Male Picke) ok i get this stuff all the time and i've learned this either a person wants to learn engineering or to be a technician or they don't now... you get the type of person who really really wants to learn and listen and that's great we take the time to teach them then you get the type of person (here on you tube) who wants the quick answer. Now.. as much as we want to help them, IT NEEDS TO BE UNDERSTAND THAT NOT EVERYTHING CAN BE A QUICK ANSWER so. when someone tells you, Make it quicker or Make it shorter, or talk faster or talk slower Understand this a) Given what you are explaining... IS THEIR REQUEST REASONABLE because you need to understand YOU CANNOT MAKE EVERYONE HAPPY and.. if you try, You'll end up make everyone upset CONCLUSION Stick to what you are doing Keep doing it at the speed that you are doing it, You are doing very well Don't try to impress everyone, Just try to Please the MAJORITY of people and be confident in yourself a few months back i had a guy ask me about the last level of pacman .and why it can't go beyond that level hence i had to explain 8 bit computing to him and the basics of binary and Error and Overflow and Overflow Error and so on there is no way this can be a 3 sentence explanation a few years before that i had a guy ask me to explain "how was electricity created" as in AC and DC so obviously i had to go into Faraday's Law and Ohm's Law etc and basic electrical theory, clearly this can not be explained in 3 sentences so.. there are people WHO ARE WILLING TO LISTEN AND LEARN and then there are impatient people who are destined to never learn TEACH WHO YOU CAN TEACH IGNORE THE REST AS THEY WASTE YOUR TIME that's my feedback my friend You're doing well, Keep going with this , i'm actually referring a student of mine to watch this, so that when i don't have the time to be with him, this can be his homework GOOD WORK DONKEY, Keep going and stay confident YOU'RE A FUCKING LEGEND .. ok

[@DonkeyLearningIT]

Hi Martin. I truly appreciate you taking your time and writing that *epic long* comment. You are providing good tips and contributions towards making my content better. Regarding your remark that I should be more confident, it would be good if you could point it out the time/location in the videos where it feels like I am questioning myself, contents sound fishy or similar problems. Namely, I think that the issue is most probably related to not putting the intonation on the right part of the sentence. If this is the case, this is one of the things which I would need to improve. Therefore, I would be grateful if you could write a couple sentences explaining what you meant, and how it should sound/look. As for the word "circuit" you are not the first who is pointing it out that it should be pronounced differently, so I will try to take care of this in future videos. For the Zener diode the issue is that the guys name is of Swiss/German origin, so it should be pronounced that way. I know that the English pronunciation sounds different. After uploading a couple of videos and looking at the feedback, I have to fully agree with you. Some people think, that they can learn something in 5 minutes which takes a decent technician weeks/months to figure out. In fact, most of those technicians never had explanations available, only books. Even the large majority of my "teachers" were mostly occupied by their own research/business, and teaching was just a "necessary" activity to get paid by the university. Thus, the lectures were mostly just applied mathematics without much explanation. Many people do not realize how much they can learn from KZbin (not necessarily from me, I mean in general), since there are really awesome videos out there. I wish this would have been there when I was a young kid.

[@martinkuliza]

hello Donkey 1. You're Welcome for the epic long post HEHE and my time 2. re the lack of confidence.... Ok, i'll go through the video's again and i'll get back to you 3. RE zener diode pronounciation... oh.. really. i didn't know that. that being the case i have to agree with you, it then should be pronounced TZ for Z. that's cool to know, thanks 4. RE " since there are really awesome videos out there. I wish this would have been there when I was a young kid." Hell yes could you imagine what our electronics life would have been like if we had videos like this back in the 80's and 70's hehe holy shit You're right, kids today don't know how good they have it to have access to everything instantly

[@martinkuliza]

Rico R Just a heads up if you are referring to me when you say to Donkey " please ignore anyone who is cutting you up on how you say certain words. I don't see him uploading videos that explain things like you do. " can you please understand a few things 1. Just because a person does not upload videos to you tube does not mean they don't know anything 2. Having a you tube account and being a content provider is a major head fuck, given all the bullshit that you tube comes up with 3. I'm actually considering starting an account but re considering because of all the bullshit that you tube come up with 4. I WAS GIVING HIM FEEDBACK 5. there is a big difference between telling someone what is wrong with how they are talking and picking on someone 6. i actually have a lot of respect for donkey so.. What exactly was your point was it to put me down ?

[@martinkuliza]

Rico R Seriously mate What the fuck are you talking about i asked you a simple question Question being... Were you referring to me ? all you had to say was ... YES or NO and all you had to do beyond that was, just give a simple explanation of the direction you were going in instead, you came up with this load of crap ok..... not sure what to say really NEXT I have a grip what makes you think i don't ? I'm not angry or upset in anyway my conversation with donkey was pleasant and it ended on a positive note WHY CAN'T YOU JUST LEAVE IT AT THAT RE "Donkey doesn't complain about all the KZbin crap he just creates content to benefit the community. What was your excuse again? " I agree he does create content for the benefit of others so... what's your point here, what was my excuse FOR WHAT.?? i don't follow where you are going with this question did i do something that i'm not aware of ? as for insecurity Mate, you know what, i could tell you , i'm not insecure but then you would just say , that's what an insecure person would say so.... whatever mate form your own conclusion, i don't really care all i know is you just spat out a lot of bullshit for nothing and now i have to clarify said bullshit. lastly LET ME ADDRESS THIS "You are arrogant, annoying and creepy buddy. I have always been a bit wierded out by guys like you who seem to think you know content creators like donkey to make such a claim that he was being insecure in his videos. Let's just say he was what business is it of yours to point that out anyhow... It's creepy dude... Then your correcting his speech which if your goal was to make him less insecure as you stated is kind of a contradiction no? Your "feedback" comes across as creepy and offensive." Mate... if you think i'm arrogant, annoying and creepy well.... i would say i'm not but.. ok, it's your opinion i guess but you need to understand this is you tube and misunderstandings happen all the time due to lack of tone of voice.. ok next... i don't SEEM TO THINK i know anybody, *That's your assumption* ok i was just pointing out observations next... now.. let's say he was insecure *what business of mine is it ?* you ask MATE... I'm going to type this in big fucking bold writing so you get it *HE ASKED FOR FEEDBACK* ok i gave it to him simple as that then, you decided to get your panties in a knot for me giving feedback... so... calm down.. ok Donkey didn't take it personally.... why should you me and donkey are both European, we are both engineers we understand each other so... WHAT'S THE PROBLEM ? next.. correcting his speech to make him less secure MATE. *Are you on fucking drugs .. or what ?* do you believe that if a person corrects another person on speech, that the only reason for that would be that i would want to demean the person WTF are you talking about mate ? My wife is european, i correct her all the time, BECAUSE SHE ASKS ME TO it's called *Self Improvement* i'm going to type this in big fucking bold writing as well. so you get it *WHEN I CORRECTED DONKEY, I WAS DOING HIM A FAVOUR BY GIVING MY OPINION AND GIVEN THAT I'M EUROPEAN AND THAT I SHOW UNDERSTANDING FOR THE LANGUAGE, I WAS SHOWING HIM RESPECT BY GIVING MY FEEDBACK SO THAT DONKEY COULD BETTER HIMSELF,........... THAT'S WHAT ENGINEERS DO MATE,....... WE IMPROVE OURSELVES AND OUR KNOWLEDGE* ok so.. Please understand that 1. I'm not a dickhead 2. I was not being rude 3. i was not trying to demean or make donkey insecure Seriously.. what sort of sick fucked up person do you think i am this is a seriously stupid comment on your behalf.. in my opinion but hey.. again.. this is you tube and misunderstandings happen all the time but.. can you now understand where i was coming from and can you understand how simple your answer should have been but since you went on a big dummy spit we now have this monster post DON'T WE ? hehe so..... yeah. maybe you'll think next time

[@martinkuliza]

oh the last point "Listen he is producing great content sit back enjoy his videos and if you don't like or agree with stuff then make your own." I KNOW.. he created great content i fucking downloaded all the videos mate you don't need to tell me his producing good content and, if you have read my post, i even said to him he was making good content and i told him he wasn't going to slow, even though he was a bit self unsure about it so if anything I'm trying to boost his ego, not squash it down... ok

[@wedaralalagethusharakaruna1752]

Very useful.thanks.sri lanka

[@siddiquishoaib7929]

Waiting for your next video on this topic.no.7 video.

[@TerryDeSimone]

*** - Why didn't you show what values of resistor & zener would be used, and how u came to those numbers?

[@leonardtrograncic9109]

If you put half voltage across light bulb or any resistor you will get one quarter of power, not one half. To get one half of output power you will need sqr(2)/2 or 71% of initial voltage. Best regards.

[@gerhardgroenewald6560]

Please we want more!!!!!

[@DonkeyLearningIT]

That is good ;) Btw, there are two more videos in this playlist, and I will upload this weekend a third one, so if you got the time, go through those as well.

[@sudhirpatil3434]

Wow- great explanation!!

[@dproldan1]

Great videos, keep up the good work!

[@solomontesfaye6452]

wonderfull job...keep it up

[@dalefirmin5118]

This video series is only about half complete. What is missing is how to check the transformers and coils for opens and shorts with a function generator and oscilloscope or a ring tester, how to test the capacitors for value and ESR, how to check the transistors, how to check the controller ICs, checking the waveforms, etc. In fact, we only went through about half of the components in the block diagrams in the discussion of function, so I would guess only about a third complete.

[@DonkeyLearningIT]

You are *absolutely right* since we have not even went through one third of the material. This series will take a while to finish, but it should be useful for people who intend to learn about it instead of just trying to do it "blindly" and get lucky.

[@jimkovacs7]

WAITING FOR NO. 7 ! BLESSINGS...

[@DonkeyLearningIT]

Thanks for the blessing, I could really use some, since not doing right now well health-wise. This is why I was not uploading new videos, since after the job my eyes are tired, and my head aches. Still, sooner or later I will have enough power to continue this series. I have not abandoned it, only I am just down and under the winter :(

[@jimkovacs7]

Hey, hope you feel better soon ! I live in Venezuela, so no Winter, but I can understand, you are very dedicated and meticulous in these videos. It is difficult to send Blessings to DONKEY LEARNING, but I imagine you do not get out your real name or location because you do not wish to, so we will honor that. Anyway, Donkey (jeje), may the Lord give you Light and Energy to continue illuminating us all, GOOD JOB !

[@DonkeyLearningIT]

Thanks man! I already feel better just by thinking about Venezuala. Although the country has its issues (every country does), the whether there should be nice indeed.

[@bc070400765]

Excellent Video.

[@DonkeyLearningIT]

Thanks for the comment. I just found out with my new earphones that the audio is not a good quality. I hope that future videos will get better.

[@umarali-vt2te]

Very Good video as always, thx!

[@kapilkdev]

great, waiting for part 7

[@DonkeyLearningIT]

Don't worry, it will be up soon, it is half way done. During summer in my apartment I cannot close the windows otherwise I pass out from the heat, and with open windows the noise is too disturbing...

[@priyadighasahoo174]

Great sir please upload next video

[@dreamfly555]

So if the input voltage increased from 12v to say 14v, what is the voltage between C and E of the transistor? Since the base is fixed because of the diode, therefore the "resistor" is fixed, then there seems to be no regulation at all. What do I miss?

[@DonkeyLearningIT]

You got *exactly the issue* with the simplified circuit I am presenting in the video. Namely, for regulation we will need an *error amplifier, and a feedback* loop. These will be presented in upcoming videos, since even so my videos are too long. Statistically speaking for 90% of the people it is fine to get the message, that in a 3 pin serial regulator there is a reference diode and a power transistor. If I would have included the discussion about the error amp and feedback, the video would have been an hour long. KZbin format is very different compared to classroom, so I must keep the videos short. Keep watching, in the following vids I will be talking about the rest of the circuit which makes it regulate.

[@dalefirmin5118]

What you missed is that you are looking at the voltage between C and E of the transistor and thinking that you are trying to regulate THAT voltage. This BJT (Bipolar Junction Transistor) is configured as an "emitter-follower." This is the ONLY amplifier configuration where output is taken from the emitter. The "input" is actually the transistor BASE. An emitter-follower provides unity voltage amplification between it's input and output--in other words, between the base and emitter. Let's call the bottom of the diagram "ground", which is tied to the negative terminal. The zener diode holds the voltage at the base at a constant value above ground and this configuration--unity gain--will hold the emitter voltage constant dependent only upon the base voltage. The emitter voltage "follows" the base voltage providing no voltage gain. ("Gain" also meaning "negative gain".) The base voltage is fixed so the emitter voltage is also fixed. The voltage drop across C and E will increase or decrease as necessary to maintain the base-emitter voltage constant. Power is dissipated mostly through the transistor. Since this configuration provides no positive voltage gain, the transistor cannot provide regulation when the voltage drops below the set voltage (4 VDC, in this example) plus the transistor's forward junction voltage drop (typically 0.7 V for a silicon transistor), or roughly 5 volts in our circuit. (It cannot "boost" the voltage--it can only "buck" the voltage.) How high the supply voltage can go depends on the power ratings of the components and the maximum voltage that the transistor and zener can tolerate before breaking down. And, in case you were wondering, the value of the zener in this configuration that will provide a regulated 4 VDC output is 3.3 volts. This is the desired output minus the base-emitter forward junction voltage drop for a silicon transistor--roughly 0.7 V. You should get the actual value from the transistor's data sheet.

[@kingtune6836]

You are exellent ... I have LG 3DVD Mini Hi-Fi System MDD64-A0U ... The problem is it is not producing sound,,, everything else works fine but no sound ... Could you please guide me on how i can troubleshoot it?

[@ActivateMission2ThisTimeline]

Does the current flow from the minus to the positive? The diode placed into the circuit will on conduct current if is is placed with the arrow pointing to the minus.

[@DonkeyLearningIT]

You should check my new video on this series (#10), where this is explained. Zener diodes are reverse-biased in a circuit. Namely, a forward biased Zener will have a voltage drop of only 0.75V, similar to a traditional diode. On the other hand, a reverse-biased Zener will produce the Zener voltage.

[@shivaprakashk2395]

Simple and clear

[@DonkeyLearningIT]

Hopefully the PWM episode will not have to wait 4 weeks to be done. Keep watching the videos, and let me know what should be explained in more detail.

[@micronetwork]

Hi, waiting for episode #7 Fantastic serie. Are you going to include som troubleshooting also? then the Cisco power is highly wanted

[@DonkeyLearningIT]

I got about half of video 7 produced, than I was having a flue, and now I barely got time next to my job. *You can bet on it* that I will include troubleshooting. But that is exactly the point, that systematic troubleshooting can be done only after one goes through the most important components and principles.

[@panervideo]

Thank you, sir , I,m learning on your video

[@paulmorrey733]

Thanks

[@aliali-et7xh]

Helo..i have 3 damage powr supply..atx 24pin..what thing part allways have to replace? Tq for your video learning..good

[@viniciusmv7727]

3:36 also when you half the voltage on a resistive circuit you will dissipate a quarter of the power.

[@DonkeyLearningIT]

Yes, however you will still dissipate *half* of the total power on the resistive series element. Thus, the overall efficiency is still 50%.

[@udeshharshana9204]

Good Video

[@DonkeyLearningIT]

Just drop by when the SMPS video is ready, that should be even more interesting.

[@praviama]

good tutorial as always....thank you

[@DonkeyLearningIT]

I have seen that there are really good lectures in Hindi on YT regarding all facets of IT and applied electronics. As I always stated, Indian education is already a lot better than the one in Europe or in the US.

[@praviama]

but i am not indian....LOL

[@DonkeyLearningIT]

Sorry, I thought from the username. In any case, Asia is slowly getting into the position to dominate science and industry. Europe and US are fading away when it comes to teaching and innovation.

[@martinkuliza]

LMFAO thats funny

[@caroman6761]

great Videos, thanks !!! When will next Videos coming???

[@N7-SYS]

where the other parts are comming??? please make an entire video on repairing switching power supply

[@albertudo8143]

Thank you Sir

[@ilanbinkovitch6054]

I answered you , yesterday .

[@ilanbinkovitch6054]

and again, yesterday :)

[@ilanbinkovitch6054]

2 more. local DBs = none

[@borayurt66]

Season finale with a cliffhanger...

[@user-mx4vs5eb3u]

Hi when can we see your next upcoming video part #7

[@DonkeyLearningIT]

I am about halfway finished with the video on the basics of PWM. Either today late evening, or tomorrow evening I will upload it.

[@DonkeyLearningIT]

Sorry, this was supposed to be the response to an other comment. Clicked on the wrong thing, sorry...

[@DonkeyLearningIT]

Well, companies are producing profit by making us work for them, and sadly in many places the employer does not care whether the employee is learning something or not. This is why I always say to younger people: if you find a job where they invest in you and they educate you, stick to it, because it is worth *more* than a better payed job on the long run. I will now start producing videos again, since the summer is over, and the good weather is all gone...

[@Boskorp]

Thank you for the good step by step explanations, looking forward for your next episode :)

[@premrajsingh1873]

when are we getting video # 7 ...love the step by step explantation...good job

[@korun99]

hey meister.meinst du du könntest mal so ein tutorial machen für fehlersuchen auf tv mainboards?DASWÄRE EIN TRAUM!!!!

[@donmarciano1981]

Wait a minute. 1/3 of a primary voltage doesn't make a 1/3 of a power. Power changes by root square of a voltage. P=U*U/R