Every Component of a Switch Mode Power Supply Explained 

Hi everyone, I've had several comments about the lack of a section going through the controller circuitry, this was intentional in an attempt to keep the video simple and digestible by focusing only on the "power" components. There will be videos coming soon on PWM control and MOSFET gate driving, though I should have mentioned this in the video and still given a brief overview of the circuit, so sorry about that. Thanks for all the nice comments!

I'm a 50+ year old electronics graduate and lifelong hobbyist and I have to say this is one of the very best explainer videos I have ever seen. I know how switch mode PSUs work but I still felt as if I learned a lot due to the approach taken. You are a natural educator with an engaging personality, eloquent and clear delivery, and an enthusiasm that shines through. Stripping the circuit back to basics and using the mechanical spring analogy will help a lot of non EEE folks grasp this topic. This is the first video of yours that I have watched but it certainly won't be the last. Keep up the good work, and thanks! 🙏

How many years I have been looking for someone to just plain and simply walk through a circuit like this. Thank you.

I really like the way you built up the schematic by starting with the basic layout and then adding components to describe the complexity. By so doing, you effectively started with the foundational components and built on that. Well done!

As a ham radio op….. those “annoying” emc components are a thing of beauty!!!! This was probably the best explanation of SMP PSU’s I’ve seen - bravo!

That was the best explanation I’ve ever seen in decades of being a tech.

As a 76 year old electrical engineer, I found this Brilliant!

This is the only video i have ever watched fully clearly explain all the components of the switch mode power supply in my life.

This type of explanation is what I need to see. Often, an instructor just buries you with theory. It becomes overwhelming, and my brain just turns off. Thank you for taking the time, and I welcome further videos.

I’m almost 70 years old and I’m industrial electronic technician. I found you to be a genius. Thank you very much. Joe

I am what people normally called "dumbass with a tool's " its means I have or can have any tools but to stupid to do anything with it. so I'm just poke something around until it's either broke or blown. your video and explanation are really godsend to me because English are not my mother tongue yet I can follow what you are explaining...keep up the hard work man....

As a computer engineer and power engineer, I liked your explanations and demo of increasing the frequency so that you can reduce the inductor size but with limits due to the heat, spillage in your case 🙂

It's been almost 50 years since I sat in a classroom and had one of the best instructors at the Sears Technical College explain the new switching power supplies most new portable tv's would be using. He used a blackboard to do the same type of visual association of circuits that he was lecturing on. You have the same dedication and enthusiasm and have earned my respect! Keep up the good work.

I've studied and worked on electronics for the last 20 years and this video finally clicked in a couple of concepts that had been banging around in my brain for years regarding smps. Hands down the best switch mode power supply video on RU-vid. Subbed

Bravo! Where were you back in the 70's when I needed you? Impressive. Refreshing.

I have learned more within 20minutes of watching this video than I have learned in 20 lessons in electronics class. Great video!

The best explanation of SMPS I've ever seen so far.

I think if you watch a few Big Clive videos you'll see that there is an alarmingly large number of appliances from dodgy parts of the world with poor or non-existent isolation!

I sat through watching the circuit building up for 20 minutes and I feel I could watch it for another 20 minutes as I've never got lost anywhere. That is one impressively easy and coherent explanation.

I'm a 77 year old retired electrical/electronic engineer and my education was obviously back in the days of poorly written books, chalk boards (as classroom visual aids), and sliderules. I couldn't have imagined the ways we teach nowadays, and I am so impressed with the way you described this power supply by starting with the basic circuit and then explaining why all the extra parts are needed. Excellent!

Wow I’m an electronics guy and this video is a masterclass for anyone interested in learning and understanding electronics! Saved here and will be sending this link to lots of people when trying to explain something. Very very easy to digest, amazing

I really like the way you broke it down to the most simple possible circuit that could work and then added on the extra components sorted by function. That made it far more digestible.

I have been an electronics enthusiast for 10 years now focusing heavily on SMPS design things although your analogies where very helpful, this video is simply brilliant.

Hello, I made the first prototype switch mode PSU in the very early 70s for a now, long extinct company called APT at West Byfleet. When I say that I made it, I mean that an engineer gave me a circuit diagram with a box of bits and a lump of plywood to mount it all on. The engineer was entertaining and rather frightened of his creation and would try to get others to turn it on for him, if he failed in finding a sucker he would use a broom stick. At times when he had the thing running, you would get the odd person walking past bang his bench and send him through the roof which, was an understandable reaction; as a capacitor would occasionally explode showering the place with metal foil. One of the few times in my life when I didn’t feel like I was working. Happy days!

Amazing how you explained the power loss as water leakage, Thanks for the great Contant !

BRAVO Sir! I failed out of electrical engineering 30+ years ago. I have a successful career in IT systems, but always wanted to know how the circuits worked. Looks like I have a new favorite place to watch. I send my highest respect from Canada.

I learned more about electronics and circuit design than I expected. So much information packed in this video with simple and comprehensible explanation, great job. Can't wait for the video about how the controller circuit works.

I'm gonna say this , this is probably THE BEST EXPLANATION VIDEOS I HAVE EVER SEEN ! I hope you were my teacher during my school days

Maybe the best explanations I've ever seen regarding these components and systems. Earned a sub.

All of the other comments are spot on. Just wanted to say thank you for exceptional content. One of the best electronics explanations I've ever watched, and I've watched hundreds, if not thousands!

"Know what I like about you, you know about the system and your coherent with your explanation(Very Smart). I like your plan diagram and your input on each device. Know that you are appreciated." 👍

The way you started with the most fundamental components in your schematic and built up the complexity was simply genius!! What a clever way to go about it. As somebody who spends a lot of time drawing electrical schematics myself, i can tell you put in a lot of work just into the drawing itself (and obviously into the rest of the video as well). What an amazing video overall. Instant sub. Please keep up the great work.

2 years ago I had a strong curiousity about phone charger and also was looking to diy one solar DC charger and ended up deep in the rabbit hole trying to understand these. I always thought I should have wrote a blog post to analyze what I learned and share also but never did so I'm glad to stumble on this amazing refresher better than anything I would have written! Thanks

WoW!! I knew the basics of switching supplies but this was quite thorough examination of essentially all the components of a commercial supply! I learned a lot!

This was the best circuit explanation video i've ever seen. Please continue on this theme!! You're criminally under-rated.

Extremely well made, thorough, well-spoken, good order, good background info to prime us. I’ve seen very few instructional videos better than this. Kudos.

Please keep it up Awesome content Would love to see the switching ps in more detail

This is now my essential SMPS explainer, will always point people towards this

Inductors as springs, an excellent analogy, and the two buckets, brilliant. I have spent much of my career working on SMPSUs in one way and another, this was a truly excellent introduction. It can be hard to believe how ubiquitous SMPSUs and variants are, they are in every aspect of modern electronics. Thank you

After taking a second look at the video, I think it delivers everything that is promised in the intro, and it seems to be downloadable. I think there are good reasons why all these designs need to be in public somewhere. Residences across the USA depend on similar devices to not catch fire every day. Some people have 12 of these things plugged in 24 hours per day. I did get distracted and confused by the spring, and the buckets. Thanks again.

This is a work of art! You would have saved lives in EE college

Even though I've been occasionally fixing SMPS's for thirty years, this was very insightful. Would be nice if you'd address the control loop and bootstrap too in a comparably easy to digest format. If you're tempted to do that then try to find a PSU that doesn't integrate everything in a single tiny chip or find a block diagram for the chip.

The algorithm "thought" i might like your videos and boy, was it right! Well done. Can't wait to have time to watch more of your videos!

I agree with the sentiments expressed in the comments. This was a great explanation. A lot of videos will explain things, but the approach you take is unmatched in my opinion. I'm a 50 year old electrical troubleshooter/technician for a fortune 500 company, my focus is in testing the final products we produce, and the processes are very exacting. So I have a really good understanding of all things electricity, both high and low voltage applications. But I learned from your excellent presentation, and can't give you high enough ratings. Please keep up the good work!

This is insanely useful, thanks. I'd love to see more circuits broken down like this.

Welcome back 🎉 Yes we'd love to see what make that charger small in size but more efficient

The 'black chip' you refer to at <a href="#" class="seekto" data-time="1315">21:55</a> is/are Opti-Isolator(s). Their function is to isolate the "Hot" from the "Cold" (high voltage from low voltage) circuit to prevent 'backflow.' This was an excellent presentation, and I thank you for your effort.

awesome!!! good job. For those wanting to understand the controller......read the data sheet! It monitors the output voltage and primary conducting current and adjusts the PWM driving the gate; often between 0 and 49% duty cycle, but sometimes very different as suggested necessary by the discussion in this video on the 'turndown' (or boost).

I cant word how many times everything just clicked. such a great video!!

Love the content, you really have to see all of the power supplies in person to see and feel the difference. Can't wait for the next video!

I have noticed how power supplies have shrunk over the years, but had no idea how this was achieved. This video has been a great help. Not least because, to school-level me, a transformer is a trasformer - never heard of an inductor before. Thank you.

I've been working with electronics my entire life, especially in the Ham Radio world. This was one of the best explanations of how a switch mode power supply works. Bravo, well done!

You are very good at explaining, I really liked the real life analogies.

would like to see some more detailed explanation about how snubber circuit do what they do, especially how it does so without disrupting the rest of the circuit

Being an electrical engineer designing these monsters too: I congratulate to this clear explanation. Well done!

Brilliant, absolutely brilliant. A really clear and understandable explanation from someone who has prepared well, with a clear delivery and and engaging approach. Thank you I've learned much today.

You are simply a genius. I now understood this phenomenon pretty very well.

🥰Loved this video. I've been waiting for a KA Stroud of switch mode power supplies for ages and here it is. Thank you.

One of the better explanations of a SMPS that I've seen. Well done!

That was the best description of a switched mode supply I’ve encountered. Nice one!

Great explanation and I see what you did there, "annoying EMC regulations". Good one! lol

Great video buddy, that was a nice explanation. Could you also do one for how power factor correction works in these power supplies? Thanks

For the past few days I've had a little devil whispering to my ear that I don't need to buy a power supply for my project, that I can just build my own. I'm glad I saw this video first.

Thank you for taking the time to explain that SMPSU in such clarity. I have repaired quite a few of these things over the years and have self learned quite a lot about them (including keeping my fingers off the bulk cap!!!). However it is always in my interest to learn and make myself better in my line of duty as an electrical technician.

This was a LOVELY and nicely done video. But...please, if I may ask - draw your schematics on some white or light background, not "black on green". It is rather hard to see. I´m speaking for myself, of course, since my eyesight is poor and needs a little more contrast.

FULL BRIDGE RECTIFIER!!!!

Great explanation of SMPSU's workings. I've made a good living repairing these mythical beasts in the 80's & 90's, mainly because I was the only one in our team daft enough to work on them live !! Subbed 👍

This is my favourite youtube channel now. I really need a break from all the mindless rubbish on youtube which seems to be becoming more of its focus

Thank You :) That was very educational and interesting and entertaining. Nice explanation and good explanation and description of the circuit and functions. Amazing how the density of power supplied have increased over time so much, almost like Moores laws for switching power supplies. Something nice about those old magnetic ones, they last a lot longer, even if less energy efficient.

Why miss the control part?

One of the best explanations I've come across, thank you!

Best regards from this side of the world and THNAK YOU for detailed video, this is just better than a university course and I appreciate the hard work you did for video, animations and flawless explanation.

I simply clicked on your video as a matter of interest. I have nothing to do with electronics, but have a natural curiosity about it. The analogies and filming techniques you used to explain the theories were quite brilliant. Well done and best wishes with your channel.

Superbly brings out the evolution in power supplies,size reduction plus greater power densities achieved etc.

Thoroughly enjoyed your lesson on SMPS. Thanks a lot for putting up this tutorial for us.

I did my EE diploma 30 years ago. I don't think we learned anything about these. Well explained. I now have a good understanding. I'd love to see some videos on how to test and repair common failures in unknown circuits. Maybe start with what we should be seeing at certain points of the circuit, and if its different, what to look for.

You explained quite well and restrained yourself from using super-technical terms to help those of us who are not schooled in electronics, to understand these very important facts about power supplies. Thank you sir!

I loved the explanation and style of delivery. Well done, you've gained another subscriber today. Thanks for sharing.

This is the best explainer I’ve ever seen on SMPS’s, you have a gift for teaching!

It does my heart good to see a bright young person explaining electronics so well. I started studying electronics since 1983 or so. Yes - we have come a long way.

I’ve been trying to tinker with circuits for the last year or two and so much educational content is either a refresher of the simplest fundamentals or way over my head, introducing a daunting collection of terms and concepts to make an incredibly steep learning curve. This, however, is the best way I’ve ever seen any circuit explained and it’s simply brilliant. Thank you!

Great video! I liked your explanation of how to use inductors to do the energy conversion with the spring and the spark - it's so difficult to talk about basic concepts when you learned them long ago, but you did a great job keeping it simple and informative!

yes please more videos on smps. Diagnose and repair of common problems. Would like to see a list of common symptoms and their causes and solutions. Great presentation, Thanks

You did a great job explaining SMPS’s. Your step by step approach is clear and easily understood. The piece that really made the light in my head come on was how you created the schematic as you described each component. It really made the operation of the power supply almost painfully obvious. Thanks for the video. Luckily, I just happened upon it. I will checkout your channel and I look forward to seeing what else you’ve produced, I’m sure it won’t be disappointing. Thanks again!!

Great video, but what I would like to see is oscilloscope pictures of the power as it goes thru each stage of being fixed, especially that part where you filter and smooth the output, that would help us make better sense of what is going on in each step. Thank you for doing all that work!

Great video! The way you explained each component and what they do and why they are in the circuit in this specific order, was excellent!! Much appreciated!

I particularly liked the bucket analogy along with loss simulation. Lack of control circuit description should indeed be mentioned and definitely deserves at least one if more videos of similar length. I liked this as first touch of your channel and subscribed immediately.

Really excellent! step-by step in easily digestible bits with plenty of visuals and graphics!

How come this channel does not have Billions Subs?

Thank you sir, Working principal of SMPS circuit through visual and oral explanation we are really lucky generation to listen 🙏

Where have you been all my life. Great content! Great style, and simple enought for a 55 year old to sincerely understnad. Not a single over the head explaination. Spot on! (needed this education, in case it wasn't clear). Thank you for your time and efforts. THey are greatly appriciated.

Absolutely excellent video, the best I have ever seen! While I understand the principle of switch mode power supplies, I never really knew the nitty gritty of the implementation. What a delight to watch someone who knows what he's talking about explain it in simple terms. Well done! All the best, Rob (physicist by training) in Switzerland

Just want to say thank you very much for the great video you made !!

Congratulations on this brilliant video! I teach electrical engineering and couldn't stop listening for two reasons: 1. Your clear and easily understandable explanations. 2. Your voice and beautiful accent. I wish I could teach as well as you do!

At <a href="#" class="seekto" data-time="615">10:15</a> Awesome job with the buckets example! I liked how you layered the two. Beautifully done.

Simple enough to understand and to the point, well done

By far the BEST explanation out there on a Switch Mode Power Supply. The only problem I have with these smaller, newer and thus assumed better SMPS is that they are 'noisy' in their output. Maybe okay for charging a battery but not so good for delicate electronics or for LED lighting were some will pickup the flicker off axis.

I was designing 1000W SMPS with DC backup back in the early 80's. What you explained in 20 minutes took us years of design and testing to accomplish. Outstanding video, but wish you had finished it off with the same sort of simple explanation of the feedback and control circuits doing the regulation (opto or xformer). I don't think it would have added more than 5 minutes and would be well worth it to have a complete explanation in one video.

First video I seen from this channel and instant subscribe. I always look for whether a video is essentially trying to educate or to impress, recognising the sliding scale between these two extremes. This video is the most extreme educate position, more than any other electronic video I have seen. The layered approach separating the core principles from the noise suppression complexities is fantastic. Quite simply I understand the entirety of a SMPS better than ever due to this. In *all* other videos, when I compare my understanding to an actual SMPS in front of me, I just lost confidence in the basics I had learned because of the obvious increase in complexity in the reality before me. Your layering approach has resolved this stumbling block that I had not been able to overcome previously. I have gone to great effort to word this comment as precisely as possible because you have done something truly remarkable right here. In addition, with any complexity or jargon encountered, you immediately provide a simple abstract model with which to gain the required understanding. For me these two things are the core aspects of teaching which you implement perfectly. The world is suddenly a much better place. I sense a learning binge incoming that may well turn all my disparate chunks of knowledge into a far greater whole that I will be able to do so much more with, and with much more confidence!

The absolute best material for smps!! Thank youu so very much for making this video. I loved the intuitive explanations and teaching style!!!