Why Does An ATX Power Supply Have Two Main Smoothing Capacitors? How ATX PSU Works Tutorial

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  • Опубликовано: 1 фев 2025

Комментарии • 245

  • @ColinMcCormack
    @ColinMcCormack 2 года назад +87

    I am always impressed by your ability to draft up a circuit, in realtime, with annotations, explanatory notes, colour keyed current flows, and graphs. All while running a narrative. Your brain works in ways mine doesn't, and we all benefit from your desire to teach. Thank you!

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +10

      Thank You 😊

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +30

      I mentioned your post to my wife and she want's to point out that in her opinion I'm (like all men apparently ) hopeless at multitasking 😂😂😂

    • @sipansibabdreddknot5179
      @sipansibabdreddknot5179 Год назад +2

      @@LearnElectronicsRepair and thats why your wife loves you sir!

    • @Dailymailnewz
      @Dailymailnewz Год назад +2

      @@LearnElectronicsRepair Good explanation but would it be important to have two capacitors rather than one, and also is it really important to change the squar wave for a sinewave? Because the circuit get bigger and bigger and the purpose of it seems strange as the square wave can just as do the job???

    • @markanderson2904
      @markanderson2904 Год назад +1

      ​@@DailymailnewzWell yes, it's important to have two capacitors. If you had only one capacitor, you would have no Junction between the two capacitors; and it's important to have the LLC circuit for more efficiency.

  • @seabeepirate
    @seabeepirate Год назад +3

    I didn’t realize the video was 42 minutes long until it was over. Well done.

  • @bazrazin1
    @bazrazin1 Год назад +3

    the best explanation in my 20 year line, even if 1 capacitor is bad the smps won't work, have 3 cooler master smps 2 with active pfc, trying to repair since ages, no 5Vvsb present in all.

  • @spoonmanxx
    @spoonmanxx Год назад +4

    I'm just 7 minutes into the video and this is the most I have learned about power supplies.

    • @fft2020
      @fft2020 11 месяцев назад +1

      agree

  • @tonysheerness2427
    @tonysheerness2427 2 года назад +4

    You have missed your calling, you should have been an instructor. You are to clever to be playing around with flea market old stuff. Your knowledge is immense and you put it over well.

    • @spoonmanxx
      @spoonmanxx 11 месяцев назад +1

      In schools and universities, you have to follow study plans, deal with students who don't even want to be there. On RUclips, it's different. You were probably looking for a video on the topic of power supplies and you have an interest, and that's why you learn. And don't get me wrong, I also believe that the video's author has an incredible teaching ability.

  • @leearft8605
    @leearft8605 Год назад +2

    This was an excellent presentation on how this type of PSU operates, the bell analogy for resonance is the best I've seen.

  • @louf7178
    @louf7178 Год назад +1

    The thoroughness and pace is very appreciated.

  • @alanpaulsy627
    @alanpaulsy627 Год назад +2

    the effort put here is so impressive.
    Universities must include this to better their lecture

  • @messageobliquespe100
    @messageobliquespe100 2 года назад +3

    Fan fook in fantastic! That was brilliant - I was losing it a bit up until the bell analogy came in - the summary brought it all into perspective. Lots learned - thanks very much - 40yrs guessing made easier watching this 👍

  • @jamesgrant5945
    @jamesgrant5945 2 года назад +5

    I have learnt more in 45mins with you than any other presenter

  • @_ndot
    @_ndot Год назад +5

    Your explanations are gold. The fact that you explain what happens to the wave while it passes through the components and why the components are where they are, makes all the difference. Cheers.

  • @is_what_it_is
    @is_what_it_is 5 месяцев назад

    Since discovering your videos I can't seem to watch any other electronics repair guys, they bore me. I'm still learning and you're making it enjoyable.

  • @aalkounis
    @aalkounis 7 месяцев назад

    You are the best teacher I never had.
    I learned more about circuits and electronics in 42min. than 4 years in the University.

  • @davet3804
    @davet3804 2 года назад +5

    Loved the bell . Always thought about the resonance but genius to think of the pendulum as a square wave . No matter how quickly or slowly you hit the bell with the pendulum, the bell still rings at its resonant frequency . Genius .

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +3

      @Dave T , Yeah exactly that! The pendulum/hammer/clanger injects🙂 energy into the system but the resonance does the work

  • @paolomonai9511
    @paolomonai9511 2 года назад +3

    Dear. Rich, bell analogy to explain LLC topology is simply...fantastic! Never thought that way...regards from Italy.

  • @richardf3327
    @richardf3327 Год назад +8

    Thanks for another great vid. I'm an electrician with limited electronics knowledge (I dabble at fixing gear for myself, friends + family, mostly because I love fixing instead of replacing). I already knew a lot of what you explained but I still learned a lot. Every day's a school day. p.s. Parents: go easy on kids who take their toys apart - they may be studying electronics early but you don't realise it. :)

  • @RajA-gx5ur
    @RajA-gx5ur 10 месяцев назад

    This is the best power supply explanation on AT I have seen ! Thank you very much. Raj (India)

  • @kennytinker24
    @kennytinker24 Год назад +1

    Very informative, feel like i am back in school, new suber after watching this. Ty for your effort and time.

  • @abhb8088
    @abhb8088 Год назад +1

    practically explained perfectly ... the bell was the obsolute example for a resonator 😊😊👍👍👌👌

  • @miket1322
    @miket1322 Год назад +1

    Of several youtube videos on this subject, your video was by far the best explanation. Thank you!

  • @theshemullet
    @theshemullet 2 года назад +1

    Thanks! Another brilliantly explained subject.

  • @jasejj
    @jasejj 2 года назад +27

    The LLC circuit explanation is great. I'd often wondered about that, as it seemed logical that sending an analogue device like a transformer a square wave would not be doing the system much good from a noise perspective. The bell analogy will stick in the head nicely, thanks!

  • @LtKeyser
    @LtKeyser Год назад

    As always, a video full of well dispensed knowledge.
    Side note : not all LLC circuits are resonant. They do transform square waves into sinusoidal waves but it is not what it is called resonance.
    In a LLC circuit and basically all RLC circuits, resonance occurs at a certain frequency. The phenomenon is a noticeable voltage therefore current increase in the circuit due to combined characteristics of all components.
    Often, accidental resonance means destruction of the circuit.
    The same phenomenon applies to physical oscillators. That's how wind or troops walking at pace can destroy bridges.

  • @Catstorm99
    @Catstorm99 2 года назад +2

    That makes sense to me now why the transistors went short on the other video when one of the filter caps was open circuit. Thank you for these videos it really does help me understand.

  • @stephendennis7871
    @stephendennis7871 Год назад +1

    Very helpful to my understanding of PSU. The fact you add a sketch to explain things is great.

  • @bobs_ya_runkle
    @bobs_ya_runkle 2 года назад +1

    Very good Richard. Many thanks.

  • @JamesWilliams-vi8zr
    @JamesWilliams-vi8zr 2 года назад +5

    Thank you for explaining this along with the LLC part of it. I never quite understood the way it worked, but the way you explained it nicely. It smooths the sharp edges of the square wave.

  • @TheDivergentDrummer
    @TheDivergentDrummer Год назад +1

    Thanks so much Richard. You pretty much answered any questions I had. I have a few on the bench currently, an ATX psu from a customer computer that came in. swapped for a good one now I'll look at this one. I've got a bazillion of them here to play with.

  • @edwinwaugh
    @edwinwaugh 2 года назад +7

    I really enjoyed watching this video. So much so I'll be watching it again and maybe a third time. Your analogy with the bell was a good one. Brilliantly done. 😁😁

  • @BaZzZaa
    @BaZzZaa 2 года назад +6

    Really enjoyed this explanation mate.
    Thanks for taking the time to put such effort into this video.

  • @MikkoRantalainen
    @MikkoRantalainen Год назад +1

    Great video! I had some prior understanding how ATX power supplies work but this video explained some details I wasn't previously aware of.

  • @Coolman6564
    @Coolman6564 Год назад

    That was great, thanks for not getting bogged down in the resonant imaginary components!

  • @AppliedCryogenics
    @AppliedCryogenics Год назад +1

    I appreciate the clear explanations, as well as saving power supplies from the e-waste bin.

  • @MrOwl1985
    @MrOwl1985 2 года назад +1

    I learned so much from this video, I feel like I owe you money now 😂. Thank you so much for this. You have a new subscriber.

  • @Leezorc
    @Leezorc 2 года назад +3

    Brilliant Explanation! I don't recall a great explanation in my electronic classed where theory meets reality. I really enjoy your videos. Keep em on.

  • @kalli71
    @kalli71 Год назад

    this video tied up so much about what I learned from you in past videos - thx!

  • @tenlittleindians
    @tenlittleindians Год назад +3

    I learned a lot! I always thought transistors were low voltage devices. I can see now that I could fry my oscilloscope if I were to randomly probe transistors inside one of these supplies!

    • @Brian-yt8fu
      @Brian-yt8fu Год назад +2

      Be careful connecting your oscilloscope to the collector or drain of a FET switching transistor. I have done it but don't recommend it. Best to use a high voltage probe to prevent damage to your scope.

    • @Gengh13
      @Gengh13 Год назад +1

      A video that could be helpful:
      ruclips.net/video/xaELqAo4kkQ/видео.html

  • @MrJessejamesharris
    @MrJessejamesharris 2 года назад +2

    Addicted to your videos now, so glad I found this channel, I have learnt so much and find your description of circuits very clear and easy to understand. Thank you sir

  • @knightwar3
    @knightwar3 2 года назад +1

    Great explanation I was wondering why there's two caps instead of the usual 400V caps, now it makes sense. Thank you

  • @kabandajamir9844
    @kabandajamir9844 2 года назад

    The world's best teacher thanks sir

  • @paulk8io445
    @paulk8io445 Год назад +1

    Nice job. Thanks for the description, very visual, loved the bell analogy, I will use that.

  • @dennis2494
    @dennis2494 2 года назад +1

    Thank you for making the operation of that circuit easy for me to understand,. I really enjoyed yout explanation.

  • @markhonea2461
    @markhonea2461 Год назад

    Quite a good presentation. Liked the bell analogy.
    I'm honing my understanding of the functions of and the relationships between these components and the resulting outcome. With your help. I really appreciate it.
    Would it be I were just approaching career age level of life, but that is not the case. Strangely, I never feel like an 'old dog'. Never have felt fully 'grown up'. I suppose my inate sense of curiosity multiplied by a strong desire to understand things, (and then put that to use)divided by my age , in years√ has helped to learn new tricks, everyday, which we all know, an old dog cannot.
    There may be an algebraic formula in the preceding lines, and it may need to be revised, and I would absolutely and happily accept any input from you all out there in comment land. 👍

  • @davet3804
    @davet3804 2 года назад +3

    Brilliant job , one of your best yet. Thanks.
    So , if you did change the value of BOTH of the large caps to a lower capacitor value (not voltage rating) it would still work but at a lower max output .

  • @russculley3619
    @russculley3619 Год назад

    Brilliant! Many, many thanks! I have to say, all of your tutorials are simply amazing. I have learnt so much. Thank-you again!

  • @peterbonham5540
    @peterbonham5540 2 года назад +1

    gave you a thumbs up especially for the bell analogy

  • @dtvking
    @dtvking Год назад +1

    Great explanation Richard. Love the Bell idea, it makes sense. Many thanks

  • @uquarosh
    @uquarosh 2 года назад +2

    A good simple explanation, of a complicated circuit. Thank you.

  • @surgingcircuits6955
    @surgingcircuits6955 2 года назад +2

    Excellent video ... worth watching several times to internalize. Thx!

  • @kwankunghkg
    @kwankunghkg 8 месяцев назад

    Excellent explanation of LLC resonator circuit for higher efficiency. Thank you very much.

  • @Liberty_Prime_Is_Online
    @Liberty_Prime_Is_Online Год назад

    Thanks for the recap on Bridge rectifiers, hadn't seen that since 1st or 2nd year Electrical engineering degree.

  • @kennyrmurray
    @kennyrmurray Год назад

    You really do make a great teacher! Some of the others just run through everything g way to fast at least for me. Not enough time to think about what they are saying, but you are great!!! Thank you! I said this before but you should build a single to 3 phase converter. I think it would get a lot of views

  • @screen-protector
    @screen-protector 10 месяцев назад

    Thank you for commenting and attaching this video, it's a new to me, but I've watched it. I mean the video :D cause I didn't have LIKE on it till now. But, I will use it for my apprentices and technicians as it's a GREAT resource for them to learn. Like a all in one :).

  • @pukkimi
    @pukkimi 2 года назад

    I am fixing an old Iwatsu scope's power supply and it has dual diodes for 12V, -12V and 5V rails and the anodes are actually connected together. And a single 4ns rectifier diode for the 54 volt rail. Not sure if it was done for added current handling, but the specs for rectifier diodes were hard to meet with newer components when I looked for replacements. The 54volt rail consumes the least current so they used an ultrafast 1 amp diode for it, but other rails are higher current.
    I ended up replacing the 1 amp diode that had burned with a 4 amp rated diode that had a matching forward voltage/current curve all the way to 1 amps. And I only found one that had matching speed, capacitance and forward voltage when I looked up from Mouser :)

  • @ferna2294
    @ferna2294 2 года назад +1

    GOLD. The bell made it much easier to understand it.

  • @shagreobe
    @shagreobe 2 года назад +5

    Very well explained as always. Thanks Richard

  • @mrtom64
    @mrtom64 2 года назад +8

    Very well explained, in fact, clear as a bell.

  • @DarrenHughes-Hybrid
    @DarrenHughes-Hybrid Год назад

    Thank you, thank you, thank you! I learned a lot of very helpful information and now understand this stuff better!

  • @ianhuxstep211
    @ianhuxstep211 2 года назад +1

    a good video. Most of the power supplies I have worked on with 2 smoothing caps have either been as you describe here or they are 110 240 switchable or even autosensing using a thyristor between midpoint and bridge for 110 240 selection, of course, most modern PSU's have PFC so no need for the selection.

    • @jakoblarsen9526
      @jakoblarsen9526 2 года назад

      I was waiting for him explain the clever way of allowing a 120/240 voltage selector for free in the design as well. like this i.stack.imgur.com/1jiaD.png

  • @MrCristianTudor
    @MrCristianTudor 2 года назад +5

    Much obliged for your amazing work in educating us!!!

  • @J.D-g8.1
    @J.D-g8.1 Год назад

    Thank you for this very detailed and easy to understand video. And yes, i did like the bell analogy! :)

  • @pererakumar3967
    @pererakumar3967 Год назад

    thanks for your teaching you do a great service for the people who like the electronics. long live with the god's blessings....

  • @mansjacobsson5823
    @mansjacobsson5823 2 года назад +1

    Thank you again!
    I kind of got it, well I thought I got it, until it hit me... Why take an AC signal and convert it into DC, just to turn it back into AC? Seems like a waste of energy and components. Silly question? I'm really trying to understand this, and your help is invaluable.

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +1

      Not a silly question actually. So the mains is AC but a high voltage. We need a low voltage DC. Yeah you are correct in wondering about this, because in many cases the power supply has active PFC, which basically does the conversion 240C AC --> 380-400V DC --> low voltage AC --> low voltage DC. I'll think about how best to explain this but the answer is most probably it is the most efficient way to do it.

    • @budgiefish
      @budgiefish 2 года назад +1

      @@LearnElectronicsRepair I think the easiest way is to say that for higher power applications it's much more efficient, much smaller and much less expensive than a linear transformer PSU at 50/60Hz - DC is required so it can be 'chopped up' into a much higher frequency AC which can work with relatively tiny transformers, the main downside being noise. Probably not the best explanation but it's what's in my head :)

    • @mansjacobsson5823
      @mansjacobsson5823 Год назад

      @@LearnElectronicsRepair But I'm referring to the pulsed DC on the high voltage side, at timestamp 28:00. So, with the answer from @budgiefish, it means that the sole purpose is to speed up the frequency?

  • @randyhammer7777
    @randyhammer7777 2 года назад +2

    Brilliant! Devastatingly useful! Thank you! Liked and Subscribed.

  • @suehunt622
    @suehunt622 2 года назад

    ding dong.............. ive never heard it put like that before. it really makes the point. thank you richard

  • @steverhenius6734
    @steverhenius6734 2 года назад +3

    Fascinating - great design and explanation.

  • @MarkC-1970
    @MarkC-1970 2 года назад +2

    Thanks for the very educational video. LLC is a new thing (at least it is to my old brain when thinking about SMPS LOL).

  • @piano1145
    @piano1145 Год назад +1

    Brilliant work. Really clear. Thank you!

  • @humidbeing
    @humidbeing Год назад

    Why rectify the AC, only to convert to +/- square wave to put through a transformer? Why not stick the AC straight into the transformer to derive the lower voltage rails, then rectify only on the secondary sides? Especially if sine waves are more efficient at driving transformers than square waves? Just discovered your channel -- you're the first person I've seen explain ATX power supply topologies in this much detail. Thank you!

  • @garrybrewster5821
    @garrybrewster5821 2 года назад

    im sorry, in respect to your knowlage of electronics love your work (1) {12:45}' neutral is zero ' my understanding any A.C. current is ( positive is above zero & negitive is below) though we do see it in a way it apears to flip over, (2) i had this problem myself with R.F. high frequency a.c. ...ground, neutral, earth, ..and i will say thank you for sharing you knowlage with us cheers

  • @mikebrowning1624
    @mikebrowning1624 2 года назад +3

    Explained very well. Thank you.

  • @kobusvorster2831
    @kobusvorster2831 Год назад

    Great explanation, always enjoy your videos...

  • @davidc6459
    @davidc6459 2 года назад +3

    Great video, very well explained.

  • @hernancoronel
    @hernancoronel 2 года назад +1

    Love this video Richard! Thank you!

  • @michaelhawthorne8696
    @michaelhawthorne8696 2 года назад +1

    Nice explanation Richard but I am a bit confused about the negative voltage pulses you have drawn on the first full wave bridge rectifier.... I believe that line would be a steady 0V ....
    Subbed and liked..👍

    • @FrozenPaint
      @FrozenPaint Год назад +3

      That's actually a good catch.
      I suppose if you used the mains neutral as your reference you'd see negative pulses on the DC ground but I'd expect it to be a half wave instead of the rectified wave as drawn.

  • @alanwhite4003
    @alanwhite4003 6 месяцев назад

    Brilliant, very well explained 👍

  • @noone-zq7my
    @noone-zq7my 11 месяцев назад

    Very interesting watched pretty much the whole thing, wish there was more on what's driving the two power transistor bases though .

  • @romancharak3675
    @romancharak3675 2 года назад +1

    Great Stuff ! Thank you, Richard.

  • @fixfaxerify
    @fixfaxerify 2 года назад +2

    Thanks for this explanation. You drew the transistors as BJTs was that intentional or a mistake?

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +4

      @fixfaxerify Intentional. In this circuit the transistors are almost always BJT. In fact I've never seen ATX use mosfet here, though the 5V STB supply is usually mosfet driven

  • @adiseshukumpati24
    @adiseshukumpati24 Год назад

    really enjoyed the video
    and learnt something new

  • @bohdanked
    @bohdanked Год назад

    I'm the first time on this channel and the explanation was excellent. Was wondering for a while how these power supply work. Also what I would like to know is how the driving square wave selected? Why is it in MHz range? Does the frequency of the square wave changes based on load, if so, how is the load balanced on different voltage taps (3.3V, 5V, 12V) ?

  • @TheEmbeddedHobbyist
    @TheEmbeddedHobbyist 2 года назад +3

    Its true to say the transistors are driven in antiphase but you have to remember that there needs to dead time where they are both off. As any overlap In the switching pulses will short the power rail out.

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +8

      You are totally correct but let's not over-complicate this when I'm trying to teach the basics of what is going on here yeah? 😉

    • @CXensation
      @CXensation 2 года назад +1

      True - but luckily the SMPS controller chip is working it out for us !
      This deadtime ensures the one transistor is completely off before the other one is on.
      The controller always put in some 4% dead time minimum, but it can be adjusted on a dedicated function pin.
      This is by the way used as an extreme start up condition using a capacitor on this pin, which makes for a long dead time (pause) at initial startup.
      Also called a softstart, as the transistors are only briefly turned on for the first few cycles.

    • @Freeknickers24
      @Freeknickers24 2 года назад +1

      @@LearnElectronicsRepair that actually keeps it simpler by keeping it in high detail.

  • @coloradowilderness3139
    @coloradowilderness3139 2 года назад

    Amazing ability to tech complex ATX PSU. Pls make some latest ATX PSU anatomy.
    Go Ahead.

  • @timstanford3443
    @timstanford3443 2 года назад +2

    Great analogy! Love the video

  • @dethdelr9574
    @dethdelr9574 Год назад

    Hi I have been watching you for awhile. I love your informative videos. Power Circuits are my favorites. You may have already answered the question. But what happens to the Drive Transistors if the neutral side is not connected? Does the High side MOSFET get the entire 320V load?

  • @TwoDollarBill000
    @TwoDollarBill000 2 года назад +1

    Good explanation, thank you.👌🍒

  • @mreaper2265
    @mreaper2265 2 года назад +1

    Yes i did learn, apreciate it.

  • @jamesjones-yn1sv
    @jamesjones-yn1sv Год назад

    have you done a video on assembling your own ATX break-out box/ panel. or fitted a manufactured
    breakout panel to an ATX power supply

  • @themanieq
    @themanieq 2 года назад +1

    Maybe couple videos about intermittent failures? How to diagnose them, some tips'n tricks.

  • @mosfettg6857
    @mosfettg6857 2 года назад +1

    Great explanation I loved it '👍

  • @daz41262010
    @daz41262010 2 года назад +1

    what an awesome explanation :)

  • @marinvidovic763
    @marinvidovic763 Год назад

    Very nicely explained !!!
    Thanks!!!

  • @friedelectronics
    @friedelectronics Год назад

    I like the detailed explanation of this, but could we also get a tldr version too?

  • @LabBrios
    @LabBrios Год назад

    Great video! a very clear explanation. I have a question, If one of the main capacitors are blown, is it necesary to replace it with exactly the same capacitance? What would happend if I use a 330μf along the other 470 μf? Will it shorten one of the square wave cicles? If so, how would that propagate?, Will it be hard on the 12v and 5v capacitors? or Will it affect the duty cycle?

    • @gatheesha22
      @gatheesha22 Год назад

      hey i have exactly the same problem how did you manage?

    • @LabBrios
      @LabBrios Год назад +1

      @@gatheesha22
      I have spent a good hour on that psu. The end result having missmatched caps was pulsed 12v rail, and a lot of inestability. I would love to have an explanation on the topic. best regards

  • @CXensation
    @CXensation 2 года назад +2

    Great explanation ! 🥂

  • @GlishaSo
    @GlishaSo 2 года назад +1

    18:53 "It was that moment when he know he fck up" :D what a jump i jumped same moment like you :D

    • @LearnElectronicsRepair
      @LearnElectronicsRepair  2 года назад +1

      And I just had to leave it in the video of course 😉

    • @GlishaSo
      @GlishaSo 2 года назад

      @@LearnElectronicsRepair haha it was amazing you needed to leave it in video for people who learning electronics know what can happen with all this funny stuff :) ! Respect!

  • @robertmonroe9728
    @robertmonroe9728 Год назад +1

    28:20 You forgot 1uF polypropylene capacitor in series with the winding. This is critical. Actually it holds the charge.

  • @khasem87
    @khasem87 Год назад +1

    the video was very informative , thanks

  • @jamesmdeluca
    @jamesmdeluca Год назад

    Greetings:
    The time it takes for the bell clanger to swing from one side to the other provides the "off" time between pulses to the output transformer allowing for the sinewaves to ring out.

  • @gordonemery6949
    @gordonemery6949 2 года назад

    Hey up nah rich great vid m8 learning all the time 👍antiphase is my word of the week KTF