This channel could never get enough credit for all the work you’ve done here on YT. Best switcher video I’ve seen. Thanks

Very good explanation of one of the “mysteries” of electronics - AC to DC switching power supplies! A few comments/suggestions: 1) You forgot to show the “AC side” GND symbol/connection to the “-“ side of the bridge. This is typically designated with a different and unique GND symbol to signify that it is DIFFERENT than the GND potential on the “DC side”. 2. The “DC Side” GND symbol should be unique and distinct from the AC side GND. They should NEVER be connected together. 3. You should highlight the main reason for both the transformer and optoisolator is to create a galvanic isolation between the AC and DC sides of the circuit to prevent stray currents, emi noise and, to safely separate and isolate the high voltage AC and rectified DC from the low voltage DC side of the circuit. 4. Finally, perhaps a mention should be given for connecting an oscilloscope to this circuit..esp the AC side and how this should be done with a high voltage differential probe or a battery powered scope that can handle high voltages. And finally, 5. SAFETY FIRST when working with high voltage AC or DC circuits. Preferably use an isolation transformer and a VARIAC. Final note: Y” caps failure mode is “open” and “X” caps fail shorted..which would cause the AC line fuse to blow. These caps control and minimize the common mode voltages and currents.

I've been looking for a while now for a clear top down approach of power supply basics exactly like this. Explained very well. I really like the approach, thank you!

@IMSAIGuy

3 жыл бұрын

Glad you liked it!

You’ve done a great job simplifying switching power supplies something that I’ve been somewhat intimidated about

@eevibessite

5 ай бұрын

kzread.info/dash/bejne/fqaVxsSBhK-8gLw.html

Your videos are excellent! Great content, explained masterfully. A pleasure to watch.

My first vid of your channel. Liked, subscribed - this is exactly the walk thru that works for me. Especially since I've taken to looking at the various power supplies I have cannibalised from computer and tv equipment. I appreciate the way you describe a device by mapping out the circuit and providing explanation about the chip and circuit operation. Nice work.

This is super helpful. I am working on a power supply for UMN smallsat ground support equipment, but my design is the bridge rectifier -> capacitors -> voltage regulators -> more capacitors type. The previous module was a switch mode power supply which somebody had bought off the shelf. While we are going with something along the lines of what I designed, but it is very helpful understanding more about the switching types of power supplies. Who knows maybe we will change our mind and I will make one of those. Thanks for the info! Usually I come to you for DIY synth stuff hah

Sir, your explanations are excellent and practical; thank-you. -Daniel

You have a gift of explaining complex stuff easy to understand for ordinary people like me who's interested in electronics. I hope you teach by profession because your really good. Anyway tnx to youtube and the net that ive seen your videos, keep it up master

@eevibessite

5 ай бұрын

kzread.info/dash/bejne/YpZ2r9CRpbvafNo.html

This is very good explanation about SMPS that we all need. Thank you

Wonderful talk. At the risk of sounding "to adult" :) I'd like to say I don't think many things in life are as Noble as passing your experience(s) forward to others. It [is] a form of immortality. I don't think we would have succeeded as a species without this one (very) important self-sacrificing attribute. You are a "good human" IMSA Guy. Live long and prosper. Cheers.

World's best smps tutorial। Hats off 👍👍

Thanks for the video, you explain the working of the components in a crystal clear manner, so even I get it, very helpful video 👍

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

Wow im 60 and had no idea how this worked. its very simple once you explained it. Thanks.

Very clear explanation on how SPS works. Thanks for sharing!

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

what a freaken lucid explanation...!!! well done man.

Thank you sir for taking so much of pain to make us understand Switching PS. You made it so easy to follow of my used to be nightmare before watching your video. You instilled so much of CONFIDENCE in me to design one of my own. Really grateful to you Sir. Hats off!!

@eevibessite

5 ай бұрын

kzread.info/dash/bejne/YpZ2r9CRpbvafNo.html

Very brief explanation and your English is quite easy to understand for me Indonesian. Well done sir. Thank you so much 👍🙂

Very good explanation, you make look so easy, thanks!

Step by step guide and explanation on how an eliminater works. I have a good number of adaptors, not functioning. I shall try to put them in order with your guidance. Thank you so much.

Thank you so much. This is the best explanations that I ever saw.

Thanks for this tutorial. could you please explain how the voltage control feedback through the optocoupler actually controls the voltage. It seems to me that by slowing the switching, the frequency of the AC output would change, but surely the voltage is still a function of the ratio of the windings.

Thank you so much for explaining this, very easy to understand!

Best explanation I have come across. Thank you. You got a new sub.

Very nice explanation. Congratulations, Sir. 👍🙏

The world's best teacher thanks sir

one of the best teacher on youtube

Thank you my brother for sharing all this great knowledge really appreciate your work I have a SMPS that use to work from 100v to 240v AC but recently started working only at 240v can you please tell me what might be the problem why it's not working at 110v anymore thanks in advance.

Excellent presentation!!!

The best explanation! Thank you.

great ! Thank you for help me out from darkness. I will try repair my computer supply once again after this vdo clip.

Thanks, master great lesson. Thanks a lot for the fine explanation.

Great autopsy. Nuts and bolts eliminate "black box" go no go concept. Like knowing reason for the capacitor across winding of transformer. Y makes sense in that location. Although I still prefer linear supplies.Thanks for the look.

awesome walk-thru!

I enjoyed watching this. Thank you.

Thanks for sharing. It's a valuable lesson

Hello, thank you for the great explanation, I have a question please, when I design a smps how can I define the output voltage and current?

Thanks for this clear explanation..... I also like how you can simulate all electronic components by your fingers😁

Thanks for good explanation.

Nice video, well done, thank you for sharing it with us :)

Excellent!!! And the HP 32S... I had one... and a 45 before.

Thanks bro. . For sharilng this video. Explained Very well. It's big help for me, As a beginner, very useful for trouble shooting of power supply..

explanations are excellent and practical ,Mérci monsieur

Thank you, very nicely explained.

beautifully explained .thank you indeed

Excellent explanation 👌

Thank you for your great videos. 👍

You are the best, man!

Great video! The Class Y capacitor is the correct choice for inter-transformer windings applications like the one you were looking at. X capacitors are used to prevent fires. Y capacitors are used to prevent shock. Y capacitors are more expensive, so it's common to see X capacitors where you need Y, but less common to see the reverse (unless the capacitor is rated for both, which is very common).

You are good teacher . thank you for lecture

At kast I understand how a Switching Power Supply works - thank you.

Really clear explanation thanks

d '"drawing a schematic" part, pointing out d individual components, n basic explanation of d role/function of each component (optocoupler, zener diode, voltage divider, n so on) is excellent! thank you. GOD BLESS.

Brilliant, educated me, thank you.

Thanks for sharing your knowledge Master

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

Great! Clear explanation of what can be a complicated subject. However, you didn't mention how the controller ic gets its power. Thanks for the vid.

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

Thank you.. Simple explanation ❤️❤️❤️

Thank you so much for sharing 🙏🙏🙏

Great video, thank You fo sharing.

Nice explanation 👌

Doesn’t the blue capacitor you talk about in the end interfere with the isolation of the high and low voltage part?

Pointing each component on the board and explaining the function on your sheet, one of the best explanation of a switching power supply I've seen so far. Can you do the same on a more complicated power supply like a computer SMPS.

@IMSAIGuy

Жыл бұрын

computer supplies can be very complicated and explaining how one works is probably only valid for that one design.

It would be interesting to see the wave form at different points in the power supply I’m assuming the output would be like a pulsing square wave d c you see is that correct? Thanks

A big thanks, very interresting.

That was a good explanation.

thanks a lot for this video,god bless u bro

Best Explanation❤

That Y-capacitor is unlikely connected as in your schematic as it would make the EMI worse. It probably be connected from the secondary GND to primary GND instead. Connecting the ~2nF capacitor the way you drew will give quite a good shock to an unsuspecting user touching any part of the secondary side if the secondary GND is left floating.

@Deno-technologies3081

Ай бұрын

The Y-cap is to isolate the primary from the secondary. Though, it has to connected such that one terminal to the Secondary GND and the other to the +ve primary.

Love the HP32S! I still have and use my 32SII from High School. LOL

Thanks a lot Teacher.

This is very complicated stuff. Thanks for trying to explain to me how it works

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

Nice and good explanation!

@IMSAIGuy

Жыл бұрын

Thanks!

I love the video and explanation.

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

VERY VERY THANK YOU 🙏🙏🙏

great job

Does that mean that when the optocoupler led stops working, that the output will go overvoltage and possibly break your connected device?

What could be the voltage drop on the var resistor on the dividing network should there be an overvoltage scemario? Will that be zero

If you have AC line voltage it seems silly to rectify it first then turn it back to ac before stepping it down. Why not just step it down directly from the line voltage without the intermediate rectification? I know this is a 2 year old video so, probably won't get an answer, but I am curious. I 100% appreciate the way you just broke it all down and drew the circuit and explained every detail. Fascinating. You might just be my new favorite YT channel.

@IMSAIGuy

11 ай бұрын

requires very large transformer. switching supplies are smaller and more efficient.

@fo76

9 ай бұрын

@@IMSAIGuyWhy do you need a larger transformer to make 12V AC out of 120V AC than making 16V pulse modulated DC out of 164 V pulse modulated DC? Also, why is the output of the rectifier 164V DC, when the input is 120V AC? Im just beginning to learn electronics, so please excuse my dumb questions... 😊 Great video, by the way - love your channel! Keep up the great work!!

@jvk-pj8jr

9 ай бұрын

@@fo76 The line voltage is 60 Hz. In this switch mode design the DC is switched at more than 1000 times that. Transformers at low frequencies require a lot of iron which makes them big and heavy. Even 50 Hz transformers are significantly bigger and heavier than their 60 Hz equivalents. That is one reason why aircraft use 400 Hz AC rather than 50/60 Hz.

@d614gakadoug9

8 ай бұрын

@@fo76 They certainly are not dumb questions. When no load is connected to a transformer the primary winding just looks like an inductor. With sinusoidal AC applied to the winding there will be magnetic field at the same frequency created. In an ideal inductor the voltage and current will be out of phase and the power will be zero, even if the current is high. But there is resistance in the primary winding, so you want to keep that current quite low so you don't waste power according to I²R in the resistance of the winding. That means you must make the inductive reactance quite large to make that "magnetizing current" quite small (the reactance of an inductor is 2 • pi • f • L, where f is the frequency in hertz and L is the inductance in henries and the reactance in ohms) At AC mains frequency (50 or 60 Hz, depending on where you live) that means you need quite a lot of inductance. That translates to lots of turns of wire and/or a large iron core. The inductance is proportional to the square of the number of turns. When the secondary winding is connected to a load, current that is in phase with the primary voltage begins to flow in both the primary and secondary winding. The current in the secondary "cancels" the current in the primary, so there is no change in that magnetizing current we had before. But the primary and secondary currents are now determined by the load connected to the secondary and the turns ratio of primary to secondary. We have to use wire that is large enough to carry the current without getting too hot. It's hard to get the heat of the winding of a transformer, so the wire is much bigger than we'd use if it were just a single conductor in free air for the same current. We already knew how many turns we'd need, so now we more or less multiply that by the cross sectional area of wire to get the total cross sectional area of each of the windings. We have to be able to fit that into the area available in the "window" of the core. If we need lots of turns of heavy wire, we need a big core with a big window to be able to fit the windings. The bigger core MAY change the inductance of the primary, so we may use an iterative approach to arrive at the best combination of core, wire size and turns. Usually we check some published tables that give us a good starting point, though. If you raise the frequency, you can get tolerable magnetizing current with far fewer turns of wire. That means you can use a smaller core.The core material must be different at high frequency because some energy is lost in the core material itself. "Hysteresis" and "eddy current" losses are the big players, but that's a topic unto itself. At line frequency "silicon steel" is the usual core material. For switch mode power supplies the usual core material is ferrite - a ceramic made mostly of iron oxide. There are many formulations of ferrites. Most companies that make ferrite cores will offer three or four that are suitable for switchers, each with somewhat different properties. As for 164volts - AC line voltage is specified as RMS - Root Mean Square. If you divide a whole AC cycle into tiny time increments, take the instantaneous voltage in each of those intervals, square it, calculate the mean (average) of all those squares and take the square root of the mean you get the RMS voltage. AC mains is a sinewave. The peak (from zero) of a sine wave is 1.414 (square root of 2) times the RMS value of the sinewave. So 120 VAC gives you 120 x 1.414 = 170 at the peak. When there is no load, the input filter capacitors charge up to the peak voltage. (RMS is used because heating (power) in a resistor is equal to the RMS voltage squared divide by the resistance, just as with DC the power is the voltage squared divided by the resistance).

@wims58ej

5 ай бұрын

Thanks!!@@d614gakadoug9

Thank you sir... Although I remember having already subscribed, now it seems I've not, and thus I'm (re) subscribing... Great explanation skill.

This is great explanation about SMPS. I’m come from Taiwan. I just say the Y-Cap, it should be across between Pri. ground and Sec. ground. The some noise from X’fmr will be closed loop thru Y-cap. Maybe it can high voltage in pri. But we have to think about the stress on there.

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

Thank you for a clear explanation. Why does the frequency affect the output voltage? Why not just set a 555 timer to pulse @ 50Hz? I couldn't understand why the feedback is neccessary....

@d614gakadoug9

8 ай бұрын

This circuit is called a "flyback converter." The name comes from a sort of similar circuit that is used to sweep the electron beam across a CRT, like a TV screen. When the beam gets to the end of its sweep of one line it "flies back" to the other side. If you look at the voltage waverforms those in flyback switcher are kind of similar and the circuit is similar, though the CRT circuit is concerned with making magnetic or electrostatic fields rather than generating voltage (in a TV it actually does both - manages the magnetic field to sweep the beam and generate the high voltage required to make the beam). Anyway - with a flyback converter you aren't actually transforming voltage directly. Each cycle delivers a "packet" of energy. If the current requirement of the load increases and the packets are being delivered at a constant rate (frequency) then each packet must be made bigger to maintain the voltage across the load. The feedback circuit detects that the voltage at the output is not what it should be and commands the input side to adjust the size of the packets. If the voltage is too high, make the packets smaller. If it is too low, make them larger. This is "negative feedback." The are made larger or small by adjusting the amount of time the switch on the input side is ON - "pulse width modulation." Feedback circuits also make sure that things like power losses (inefficiency) in the circuit are corrected for. The feedback circuit doesn't need to know what is causing the disturbance, only that it is happening and a change must be made in the appropriate direction to correct for it. It's like controlling the speed of a car with the gas pedal. You don't really need to know if you are fighting a headwind, or going up hill, all you know is that you need to push the pedal down so your speed is maintained. Feedback also corrects for variation in the input voltage.

thanks for fantastic job , just wondering if you could tell me about transformer wire size the primery and secondary or if possible to make a video about how to make step down /up transfarmer . many thanks

Hi, well done instructional video although with small inaccuracies in the description of the voltage conversion on the transformer - it is not AC, but modulated DC (creating an AC inverter with a sine wave is difficult). Well, now to the question of why capacitors "X" are used somewhere and "Y" somewhere - it's for safety reasons - that's why the design is also different, these capacitors work mostly in high voltage circuits and if they fail, there could be damage, or unpleasant accidents. X and Y contain not only how the capacitor will behave in case of failure, but each of the types must meet different safety requirements - these are marked with a number after a letter - for example X1 or Y3: The X-marked capacitor must be cut in case of fatal failure Conversely, the capacitor marked Y must not be interrupted There are also capacitors marked XY - they must meet the safety protocols of both classes. Due to the different design, they also behave differently in the circuit, thanks to the design, capacitors X can be used as a voltage reducer in AC voltage circuits, where thanks to the capacitive reactance, the voltage will be reduced almost without the power limitation that would have to be taken into account when limiting the voltage using resistors . Nice day 🙂 Tom

@Den_Electro

Жыл бұрын

Hi, friend. Watch my video! kzread.info/dash/bejne/ZIWmmKycnZvdkqQ.html

Fantastic video. If one were to build their own version of this, when sourcing the transformer, what things should one look for? We know it needs to handle a certain amount of current and that it needs a 10:1 ratio to step down, but are there any other things to look for?

@theoldbigmoose

Жыл бұрын

The data sheet has a nice little blurb on designing the power transformer. I found it useful

Thanks very much for the video. How I wish you can show the signals for each section on an oscilloscope.

it's an perfect explanation, thank you....

tkx master , so great you help me to understand lesson on school./.

This certainly helped to diffuse some of the mystery about how smps's work. Quite a nice discussion and very detailed. Curious on part of your explanation (and I also see some comments below on this subject)..... the transformer you've stated as a 10:1 ratio (164vdc one side : 16vac second side.... 10:1) Many smps's provide for 115~265vac on the input. How would you account for the left side being roughly 317vdc:16vac .... 20:1).... but still work properly for a 115vac feed?? Can the feedback mechanism into the DK1203 handle that range effectively? Or would an auto-switcher for 115/230 have an additional stage in that secondary??

@IMSAIGuy

9 ай бұрын

this was a very simple video. the transformer inside does not have typical sinewave AC voltages. it is a short duration pulsed DC signal actually. you are transferring current really.

@brianwheeler887

9 ай бұрын

@@IMSAIGuy I kind of figured the current was the transfer rather than voltage. Very much appreciate your fast response! Have a great evening Sir!

@d614gakadoug9

7 ай бұрын

@@brianwheeler887 This is a "flyback" converter. What is actually being transferred are "packets" of energy - neither voltage nor current, as such, but energy. When the switch is ON energy is stored as a magnetic field via the input ("primary") winding of an inductor. It is NOT functioning as a transformer for power delivery, When the switch turns OFF, the energy stored in the inductor is delivered via the output ("secondary") winding to the filter capacitor and load. Of course voltage and current do come into it, but in terms of charging and discharging of the inductor. Because of this behavior there is no direct relationship between voltages and turns ratios. You can produce 12 volts out with 165 volts in with an equal number of turns on the primary and secondary. In practice you wouldn't do that because it is inefficient. The approach to the turns ratio is based on producing the required inductance, which is related to charge and discharge time for the two parts of the switching cycle. edit: forgot the wide input voltage range issue With modern control circuits and very fast switching devices it is possible for a flyback converter to work with a wide input voltage range, even though the duty cycle must be adjusted for both load power requirement changes and input voltage changes. Doing this does require that the switch be able to deal with the high current at low line voltage and the high voltage (at lower current) at high line voltage. Similarly the inductor must be designed for these issues. At moderate power, up to at least several tens of watts, the compromises are practical and not very expensive. Once you get over a hundred watts or so the compromises are less likely to be acceptable though certainly not impossible. It is now common, and actually required by regulations in some places, to use a first stage that is "active power factor correction" which makes the AC line input current sinusoidal and in phase with the input voltage. The circuit normally used is a boost converter that produces about 385 to 400 volts output, quite well regulated, from any input voltage between (typically) 85 VAC and 264 VAC. The circuit is moderately complex and requires some big parts, but the regulated DC out of it can simplify the down-stream converter. (an interesting feature of the PFC boost converter is that the input current must be directly proportional to the instantaneous input voltage but inversely proportional to the average input voltage)

Do you know where I can buy the ef 20 transformer? Ebay and amazon don't seem to have it. Thanks

this is such a nice video...thank u thank u very much

very informative and nice video i want to add that the blue capacitor always attached between two grounds . in diagram you showed that the one leg is attached with the output of ic i hope you understand

You at least partially answered my question regarding that blue capacitor across primary and secondary windings. I have a power supply which has a significant AC signal on the secondary output side in the 60 Hz range. When I remove that strange blue capacitor with AC signal on the secondary disappears interestingly enough. So I remain a little baffled maybe you had more information regarding the so-called Y capacitor. Ethan

Thanks A million!

I did not understand the snubber circuit thing you mentioned about the capacitor in series with the resistor

i can say u r great helper

Subbed!!! I LOVED!!... your explination, because most of the KZreadrs put out a poor explination, thank you sir.

@IMSAIGuy

10 ай бұрын

Thanks for the sub!

Can we us a Mov because it can protect from high voltages?? and a fuse to protect against high ampre??

so how does the oscillator works, does the IC just make it randomly?, very confusing part

Hi, great video. Can you explain this to me? Why is one single rectify diode on the switched ac enough, when a full bridged rectifier is used on the mains ac? Thanks Claus

@IMSAIGuy

Жыл бұрын

it is rectifying pulsed DC not true AC

How was the capacitor value calculated (10 micro farad)?