12V 2A LED Power Supply test - with schematic
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- Опубліковано 18 жов 2024
- In this video I test a Chinese 12V "2A" switching power supply designed for LEDs, CCTV, routers, etc. It cost me only $ 1.80 including shipping. The actual current capability is about 0.5A and the safety is quite questionable. It's a classic 2-transistor switching power supply with an optocoupler, but it's quite underrated, has poor mains isolation and misses basic safety features like a fuse. It may be dangerous and it can only supply 1/4 of its rated current.
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Great teardown and analysis! I really appreciate your videos because you not only break things like this open, you take the time to reverse engineer them, actually draw a schematic AND explain it. That's quite impressive. You are helping more people than you realize. Thank you for making your videos!
Thanks, I will keep making such videos :).
Great breakdown and analysis.
Your intelligence and insight are greatly appreciated.
The way you elongate the syllables on some of the words adds to the general air of wit and sarcasm as you gradually break down the 2 Ampère myth of this device.
Keep up the good work!
You are a very good teacher. Few years ago I had a hard time trying to understand how this type of power supply works. I think it is also called 'ringing choke converter'. Thank you very much.
Great video as always .Keep the good work sir .You are the best teacher .I have learned a lot from you 😁
Na mě udělalo opravdový dojem, jak jste bravurně odizoloval kabel kombinačkama. Respekt!
No jo, to jsou léta praxe :D
good insight. also Like the way how you opened the case its always a headache for me.
you are a winner, best of the best !!
Thank you for all your hard work on this. When you started the tear down, you mentioned that although the P/S was labeled as being rated at 2A, it actually was only able to supply 0.5A. As you went through the tear down, I kept waiting for your conclusion to tell us what component(s) should probably have been changed, to make it a true 2A P/S. I'm not complaining at all, just saying. Anyway thanks for this and I liked how you explain the circuitry. Thumbs up!
Thanks for the video, Dan. I had a similar power supply and I could not understand why my photo frame didn’t work. Checking your video and trying to prove the same on my power supply I found that at 10ohms resistor my voltage was only 2.8V, at 5ohms it turned off, at 20ohms my resistors went smoke :) I used 1/4W resistors which are probably too small wattage for this setup.
A great video! A good one. I just purchased two of these and I really need 2 Amps. They are currently in transit to me.
Thank you. You just saved me from frying up a valuable piece of electronics, had it not been for this video, it would have costed me $30 to replace!
I like the way you explain. Plain comical and just nice
Very good and clear explanation of how the circuit functions.
I've used a similar transformer to make a 40W flyback. It worked, but took a lot of optimization. It goes to show 24W is possible, but the designer hasn't seemed to realise that!
NNNI
Yes, the trick is to go up in frequency. The amount of energy you can store in the core times the frequency is the power.
If you are making stuff for a narrow mains voltage range, it is even easier.
This was really one of the best presentation. I've seen 👍👍👍✌️
yaayyy a new video
"The construction looks very Chinese"
-DGW 2017
👁️💧👄💧👁️
I like the way you said "ARE YOU KIDDING GUYS? THAT'S RUBBISH!" its cool!
"This looks like a chinese board" 😂👍
Very good explanation and analysis, thank you
Awesome video very detailed look forward to seeing more👍👍
The diode in the secondary is only rated at 1 amp, that's a clue.
Exactly. Because it only rectifies half of the wave the maximum continous output of the power supply is half of its rated amperage.
At 6:26
The main transistor generally stays on until the 40 Ohms in the emitter has enough drop to turn on the other transistor. The 10nF should be big enough that this happens before the capacitor charges too far.
The input side capacitor need not be big if the output side one is fairly large. Nobody is going to notice a bit of ripple in the output if the amplitude is smallish.
If I was going to use something like this, I would add a fusible resistor on the mains input to restrict the inrush and protect against shorts.
Hi, I really like how you describe the circuit operation in these type of videos. It might be nice if you could also show actual waveforms on a scope at the various points as you describe how the circuit operates. Cheers!
Very good explanation, I understand so much. Good job!! Thank!!
"the conclusion is.. it's rubbish." 😂😂😂
😂😂
You sir are a total badass!
Great video!
I just wish my high school science prof was good at explaining as you
I was just looking at a large number of 6v 2A adapters on ebay, and they all looked like that one for the most part. Most curious, the photos of every one had the output specs printed on it blurred or blanked out.
Thank you for the warning. That's why I came here.
That's not a class Y capacitor. It's a class "why?" capacitor.
The best UA-camrs ever 👍👍👍
Nice video as usual.you re a genius man.thanks for teaching us
Great stuff.. you are super entertaining too..
Lot of knowledge, very impressive...bravo !
Looks good! Where can I buy this adapter?
I use these PSUs on a daily basis and I'm very keen to have one that is safe to use. Can you recommend a good, safe PSU that is reasonably priced . Or what should I look for in a PSU that will tell me if it is good and safe ? Great work, btw.
Great explanation thank you! Enjoyed the presentation tremendously.
nice video i like the way you opened the case :)
because the adaptor is very chinese 😂😂😂
Why wouldn't show how to redo it to capability of real 2Amps?
Like it ur clear check n testing...good learning.
Thank you very much for your explaining
i have one and opened it. there were cables that looked burned but not connted to anything.
Is it expensive to upgrade this ps to 2A? Perhaps next time you can come up with some theoritical diagram which part to replace so it can be used as its claimed power...thanks always...from your biggest fan in the Philippines - Dennis
Buy a PSU from a good company, it is cheaper and safer.
it's not expensive at all ,you must replace first capacitor up to 10 microfarads ,10 ohms resistor with 2.2ohms 1w and final diode with some 3A fast diode and everithing is OK
so cool ,i like this test
I actually have a bunch of those "2A" 12V PSUs. Now I want to put them under load and test them. Surely there must be some crappers among them?
Your musical speaking is unique 😜🤣🤣🤣
Yes
Great video! Thanks. I almost but that thing. Do you have any recommendations where i can get a good DC adapter 12V 2Amps?
Another great video, thanks. The psu is dangerous and not designed for 2 amps output. I would bin it ...maybe save the case. I have some power resistors for checking the current in power supplies and they are a quick way to test whether the unit is up to spec or indeed working.
Good and illustrative video. Thanks. I too had ordered such poor quality power supply based on spec.
What if you replaced the 10 ohm shunt with a smaller value resistor?
Would it try to supply the 2A and then set the transistor or transformer on fire?
Maybe we can "improve" the design :D
Did you change your colour?
I thought of that and put 2 ohm resistor instead of 10 ohm and change the output shottkey diode to 3A one. That seem slightly improve the current to about 650mA without significant drop. So I went all the way and remove the resistor and put jumper wire across. The result is BOOM, burned both transistor.
The conclusion I think we need to increase switching frequency, so it can handle the extra current efficiently.
It's very simple: With surge of power hungry electronics, power supplies should be more powerful. Chinese give no crap about the power, they just changed lettering on the sticker. Easy hack.
There's a cheap Chinese power supply, usually 12/24 volts DC 15, 20 or 30 amps, and they usually claim 360 watts. They're very generic, would you be able to get your hands on one?
Even without such analysis it's obvious that little box can't deliver 12V @ 2A. High wattage power supplies are packaged like laptop power supplies (a larger box and with a separate AC cord).
I bet replacing that 10 ohm sense resistor with one much lower, like 4.7 ohm, it would fix it
It would be great if you could do modification video to make this power supply works properly, or any other cheap electronics from china.
There's this super popular power supply board in China, XK-2412DC. Would you like to get your hands on it perhaps?
Yes, I definitely would :).
Using this XK-2412DC supply: coudl I increase the voltage to 14,4 v???
Yeah Diode, how do we arrange it? Do we sponsor you the purchase price, do we drop ship it to you, or do you just get one on your own?
Siana Gearz ask him for his address with pm and drop ship as gif for him :-)
If you don't mind drop shipping it to me, I definitely won't refuse :). give me your email so I can send you my address.
Thank you for this video. I got one (didn't used it yet), sort of a regulated one, with lots of adapters, that is why i bought it. From 12 to 24 volts and 5 A,...Maybe i need to test it before i use it for something.
I gotta study these power supplies
This video is a GREAT LESSON!!!. Thank you very much for this video. Every year i try to make a smps from 220v to down. And i fail every each year. Please make a video about very basic, usable smps with psu transformer.
You can for example try a very simple SMPS with a high integration chip. Something like this:
danyk.cz/impulz4_en.html
Or you can try a single transistor power supply like this:
danyk.cz/iz_odv_en.html
Maybe I will make a video how to build a simple SMPS one day....
would have like to see some waveforms at the diff stages...great video!
i need this, really clearly explain, thank master
how many more of these power supply vids are you gonna do
neukázal by si nám nějaké tvoje výrobky/vynálezy ? Na tvých stránkách toho je dost, video by bylo supr (y)
Yes bro..you are amazing.keep it up with more helpful video.
Good job
*left eye twitches*
The words "cheap" and "power supply" shouldn't be used in the same sentence...
The transformer should be in principle capable to transfer 24 W. But I guess the switching frequency is too low for this. In general I don't like the flyback smps. I don't understand why the people don't use double acting forward converters. They are also very easy to design and to calculate. And the voltages at the mains power supplies are stable enough.
Is the emitter on the optocoupler directly connected to the base of the 2SC945 transistor ? Does it not have current limitation?
Have you seen such ‘Xing Ling’ SMPS modernized, using 1 MOSFET SSS2N60 + 2 auxiliary BJTs? In case you saw, or made a video, could you please share the link?
Thank you
And have a blessed Holiday season!
I've never seen that type of pipe clamp before; what is its manufacturer?
@DiodeGonewild, i have made all circuit as you mentioned in above video. At no load, there is fixed 12V. But when i am applying load ( 12 Volt relay), transistor 13003 heats up and burning within 5 seconds. I have replaced three transistors. Can you help me in this regard that why it is happening?
Zajímalo by mě, jaké výstupní napětí zdroj skutečně dává při zatížení. Předpokládal bych, že takový pokles je do značné míry způsoben extrémně tenkými a dlouhými dráty od výstupu.
KUBA64
Many idiots never understand cheap product goes to cheap consumers. You can design and make one with your expectations and see how much it cost.
As a follow up why not to improve this PS by correcting it?
Adding protection and for example changing the current sensing resistor and increasing the switching frequency...
that would be very interesting and a way to learn how to give some use to this rubish...
What's the purpose of 2.2nF, 1Kv capacitor? Seems like providing AC ground reference for output AC ripple.
Thank you very much,Your explanation is amazing,please upload working of 12volt 400watts Chinese power supply using ic ka7500
hi i knew right away that you are a neighbor from cz, otherwise a good explanation :D
I like your accent. Hilarious
WHICH IS?
nice vid. it is posible to modify that circuit in order to make it safer? can you do a video about that? or maybe can you do a project of making a 12v 2A smps PSU using parts of an old PC PSU? Thanks
The fuse built on a PCB is called "Chinese Fuse".
king of reverse engineering and schematic
Very helpful thank you very much.
Sir, today I have made this circuit by looking at this diagram, but no voltage is coming out at the output, please tell me what could be the reason.
Are you from CS? Sounds like a Czech colleague
This is art. 🤗
Thank very much!
Im very intrigued a power supply could be made using no this simply, while this probably isnt that stable it still should be much more efficient than the old linear tech
Im gonna attempt to build one of this myself, it may catch fire though :D
Very helpful ur tear down,
Mr Diode, jak muzu udelat 1 mode driver from 5 mode driver. Thank you. Vlad
What's the sense of placing optocoupler if 1kV capacitor connects mains side and output?
I just bought two of this power supply...when I receive them I'll let you know is it the same...
Like it, thanks for sharing :)
I think you did a re run of this , but interesting to watch both old and new video of PSU , dog hilariouso in second
Are you kidding me guys , is sooooo beautiful 😂😂😂🎉❤❤
Excellent. Can you show a way to improve it and get to 2A?
Shunt the 10 ohm current sensor with another 10 ohms. I don't think that will improve the reliability of the circuit, though. Good luck, and check the transformer for smoke.
This slightly improve the current for couples of milliamps. The supply needs more optimization by increasing the switching frequency I suppose.
And use a faster transistor, like a FET. Then beefier wire and bigger core on the transformer. And a better output diode, and bigger cap on output. Outside of that, it's a fine circuit.
James Van Damme hehe.. i.e replace everything except the board😅
You are awesome..
i'm getting confused, according to schematic you draw, in transformer is going DC power.
How about the complementary power amplifier? I want to learn it!
Nice video! Silly question: What is the 2,2nF 1kV capacitor for??? Why it's there????
It's there for interference suppression. This one reduces the high frequency noise at the output.
Thanks you very much! I have wondered this thing so long. Thanks again! :) Your videos are great.
DiodeGoneWild sir i beg to disagree. The cap is to reduce EMI to pass certifications on undesired emmissions. It has no effect on output noise.
nice one good diagram explaination