3-36V 60W Adjustable Power Supply (with schematic)
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- Опубліковано 6 лип 2024
- Testing a 3-36V 60W adjustable switching power supply KJS-1509 made by Kejiesheng. It's in a laptop power supply shaped box with a potentiometer and a built in 3 digit LED display voltmeter. Let's see if it's any good, what's inside, how safe (or dangerous) it is and how does it work, including the full reverse engineered schematic.
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"What ever might be the best way of opening it, let's just cut into the corner. There's probably a lot of cut corners inside of it anyway" 🤣These are my kind of puns
😂😂😂😂
best electronics youtuber out here
He was absolutely right about that too
aww .. no conclusion? again? .. how am I supposed to know if it is super dodgy or just dodgy?
Insulating a human from deadly mains voltage by just a lacquer on super hot wire in baking transformer. I would say it is deadly actually not just dodgy. Also broken rezistor from new or after just a few minutes of use and the temperature during use. You can almost call it fire starter.
@@josifvissarionovich5320One use electrocution device with fire starting capabilities, QC approved
It's pretty sketchy. That transformer was horrible. That switch was a wonder too. Parts sourced from the cheapest Shenzhen has to offer.
Because it is clear... That it is SIIIUUUPER DOOODGYYYY
@@gianluca458 We still look forward to hearing it though.
Long videos don't bother me, the reverse engineering time spent doing that schematic is appreciated.
Sir as u asked, yes youngers too watch your videos very seriously ❤ I'm 23 years old viewer from India and superrrrr excited for the *cassette player* restoration and theory video ❤😊
Thanks ;) it might be the next video ;)
I'm even younger, 17 from Slovakia. Electronics have been my hobby for almost 10 years at this point. Amazing how quickly time flies..
@@DiodeGoneWild I'm 15 watch all your videos
Haha same here. I'm 18 and i love this guy's videos. Been watching for at least 7-8 years & I've learned a lot from him. His explanations are just very good. Also very excited about the cassette player restoration!
A lot of young people here! I'm also 15 years old and I've been watching Diodegonwild's videos for like 3 or 4 years
Never get tired of the long videos
17 year old guy, think I started watching when I was... Younger- ish. still watching and interested! Keep the videos coming.
And I'd like to see a restoration of that radio/tape player.
Me too!
18 viewer here, i think most younger viewer like micro controllers more then these obsolete circuit, but i enjoyed both
I love bloody long videos!
Me too!!
You are awesome 😎👍
Yessss!
5:00 Your dummy load got a new transistor :O
I'm surprised somebody noticed this detail :). The smaller transistor (BDX33C) got baked, so I put TIP142 into it.
Beautifully dodgy! Thank you for taking the time to fully test, teardown, and reverse engineer this power supply, I always learn a lot!
I’m 18 and I have been watching your videos for 4 years. You are an inspiration to young people who want to make a career in electronic; Your knowledge is gold for me. Thank you for what you do!
One of your younger viewers (24) watching till the end here, been your fan for a few years now ❤ love your videos dan!
I'm 20 and I watch your videos from 2019 at the age of 16.
Shit i'm getting old quickly😂
Haha, remember that when you turn 40, mate.
37 years old here, watched the entire video with no skipping. Loving electronics :)
Dělej svojí práci dál! Jako čech jsem na tebe hrdý a baví mě tvá videa.
I have a similar power supply, with UK plug. Mine is also about 3v to 30v ish.. No stickers on box, just pressed in markings when the box was formed. I ONLY use it to dim my otherwise bloody bright icicle window Christmas lights. I knock them from the normal 12v down to about 8v, which makes them much better on the eyes and they still look cool.
I think most of us that watch your videos absolutely love what you do, and the length does not matter. If you have something to show and talk about then let it takes a long time, unless you don't want to talk that long lol, I would not blame you. If I may, I love watching your long videos, it is like being there with you as you rip stuff apart and take the time to explain things for everyone :) (I did not mean that in a creepy way lol)
29:57 18 year old boy here and been watching you for years now, i used to take apart cassette decks and record players .w.
Thank you for going all the way with the schematic
15 years old now, watching for... 3 years? Awesome videos
for me, the best adjustable power supply is always the combination of a well known good PSU (like an old laptop, original repurposed psu) in combo with a buck-boost board. It offers CC, CV, and it's safe because the original PSU is safe and properly isolated. It's so dodgy to control an output of a bench adjustable PSU in the same transformer as the PSU's own auxiliary psu and have to deal with such a mess because of that
29:59, I've been watching your channel since I was 15, now I'm nearly 19 and it's helped me a lot in regards to analogue electronics. Maybe I found your channel due to not having my neurons necrotized by Tiktok/Instagram/whatever normies scroll nowadays. Now that I've won several national and state electronics competitions here in Romania, I'm looking forward to attending electronics and telecoms college, where I'll continue watching your videos :)
I'm 19 years old and thanks to you I got the love for electronics. I've been watching you for a couple of years now and I gotta say that I appreciate your work and I love your cat and dog. This year I'll go to college and study electrical engineering (hope I can make it out) ✌💙
Memorable quote at 21:30 "What's the isolation distance here? Just about nothing!" ❤
Thanks for this one! I've seen A LOT of people using this sort of adjustable power supply that looks identical but sold under different generic brand names. It seems the appeal of them is they're cheap, easier to use and smaller than a lab bench power supply, easily bought on Amazon with next day delivery and can easily be permanently mounted into something. Always suspected they didn't meet minimum electrical safety standards but good to see it proven beyond a doubt in a teardown. This also explains why people often have issues with the output sagging under load even within the 60W spec or the output ripple interfering with circuits.
A good quality laptop power supply from the e-waste bin followed by an adjustable buck regulator module might be a better option.
Ja, a REAL 60 Watt supply, followed by a decent buck, or one of the buck/boost modules, much safer, better performance, and, if you put it in a case, you can "open up" the laptop supply, for better cooling... even put in a small fan with a thermistor control.
@@lohikarhu734 these days there are even such devices where you plug in a laptop TypeC charger and the device asks the charger for the nearest voltage then buck/boosts it internally to the setpoint. But that is more expensive I guess... And there is also TypeC PD-PPU standard to ask the charger for a specific voltage not a predefined step, as if the TypeC standard is not overcomplicated enough! :P
Is this the power supply Tech Tangents uses sometimes? 😉
@@Petertronic Yeah pretty sure he does use an almost identical one with a comical brand name on stream, but I think he knows it's not of good quality, he just bought it because cheap and Amazon next day, I don't think he's permanently installed any of them in projects at least, he just uses it for temporary testing (I think?).
25 years old here. Watched till the end :)
Nice to see young people here too.
Yes Indeed I watch your videos till end. Gaining knowledge which my university took years to explain. UA-camrs such as EEVBlog, Fran Blanche, Andreas Spiess, Great Scott, Electroboom, Marco Reps, Ben Eater, Imsai guy. are such a blessing to me for getting such knowledge. Being from the "Tik Tok" generation I still consider myself as a old school guy. Choosing electronics as my hobby was a great decision which saved me from this new fangled generation addictions.
When you hear that ringing noise, it means that part of the voltage range is achieved not by PWM only, but also by varying the efficiency of the converter by varying the frequency - which is meant to be stable at any given ultrasonic frequency, around 140 KHz or so.
I would avoid this power supply at all cost. Sadly, it is destined for a loud bang. The people who made it tried various combinations of part values until they achieved the widest voltage range, irrespective of all component constraints. We designers learned a lot of mathematics for a purpose...
Cute little power supply.
Highly recommended to destroy multiple electronic devices that require a stable DC input such as notebooks.
It also functions as an excellent high frequency jamming device.
But wait, it can do more! You can use it as a heater and the fourth and final (literally) function of this 4 in 1 device will be as a lighter.
You can light your ciggies off of the snubber resistor
There are barely any sources out there from which I learn so much than from your channel! Keep up the incredible work!
29:57 16 years old here;), have been watching you since 2023
Im 15 years old and have watched this video to the end once with 0 skipping!
This brings some hope for humankind ;)
@@DiodeGoneWild it sure does! especially since i’ve almost lost hope in humanity lol
That 7-segment voltage display is an off the shelf module. I've bought bags full of them at hobby stores. They're often designed for convenience to run off the voltage they're measuring, which explains why it gets dimmer as you decrease the voltage to minimum--sometimes they have a separate supply pin you can use if you don't want to do that. They're not very accurate but they are good for just sticking some kind of indicator to give you a rough idea of the voltage present somewhere.
Opäť ti chcem poďakovať za toto veľmi pekné video, bolo tam spústa zaujímavého a poučného obsahu. Tak ten osciloskop, ktorý si si tak pekne opravil ti už vykonáva cenné služby, ako som si všimol, tak to je paráda a teším sa spolu s tebou.
Aj keď nie som elektrotechnik, súhlasím. Tieto videá majú svoju kvalitu. Žiadne nezmysly, žiadna "dráma", proste fakty a opisy, názory, s ktorými sa stotožňujem.
The transformer is baked. Baked! ♨️
Nice reference to Shango066 😁
And a nice video as always 👍🏻
I was 12 when i started watching your videos now i'm 16 and i love your videos. This power supply is a prototype of self dismantling power supply the next ones will be dissoldering components it will speed up recycling🤣
Senin videolarına hayranlıkla bakıyorum, En ufak detay bırakmıyorsun bilinmeyen,
Teşekkürler
Man, si much work you put into the video, it's impressive
4:49 The transistor in the test load magically changes
Potentiometers made in the USA and Asia are usually marked with an “A” for logarithmic taper, a “B” for linear taper, or a “C” for reverse logarithmic taper.
It clearly has B50K on it, which is linear, 50 kΩ. So why would the voltage adjustment be so unusual? Also, this is just a switch mode PSU with modified feedback and a voltmeter. Easy to make at home from some old laptop charger. Much safer, too. This is SYUUPER DODGY!
How do u modify feedback for stability if making adjustable? Just add extra turns to factory feedback? Thx@@imnotbeluga007
As I remember from old days A marking was for linear in Europe, B was exponential and C was for logarithmic potentiometers
@@imnotbeluga007 Because it is in the feedback path.
Suppose we set the 5.1 kilo resistance at the bottom of the potentiometer to zero. and remove the resistance of 13 kg. Now we calculate the output voltages in three positions of the potentiometer
1- slider @ low: the output voltage will be infinite (theoretically).
2- slider @ middle: output voltage 5 volts
3- slider @ high: output voltage 2.5 volts
It can be seen that despite the linearity of the potentiometer, the output voltage is logarithmic. Of course, here, due to the presence of 13k and 5.1k resistors in the feedback path, the logarithmic curve has been reversed, which can be found by calculating the voltage in IC 431.
@@jankomuzykant1844 It seems that this marking is reversed in Europe
I have couple of similar products. Double feedback look probably is the reason why 3-12V version tops potentiometer halfway while 3-24V version adjust after turning pot more than half way too. Brilliant!
Thanks heaps for the great videos, the education and the entertainment.
Pots marked with a B are linear. Pots with an A are log, and those with C are reverse log.
Good luck finding a new pinch roller, or, if needed, the play/record switch; for your upcoming "compact cassette player" restoration. Rubber drive bands, lubricating grease and oil shouldn't be too much trouble finding. Maybe finding a usable cassette could pose problems also.🙃
Pinch rollers tend to bulge in the centre with age, which causes the tape to be pushed into the edge alignment guides, which creases one edge of the tape, which renders that tape useless. Been there, done that, while repairing this stuff, back in the '70's.
I've always considered the transport/switching mechanism for cassette players and VCRs to be great human achievements. 🙂
I like the dog! Great analysis, as always.
Super bloody interesting. Keep them coming.
Thx for your work, all your videos and schematics dear DGW. Great! God bless you!👋👋😌
You the best as always, thank you!
i absolutely love your videos.thankyou for takeing your time to teach others.there has been ome things you disasemble with brute force and i have takeing some apart myself and wish i could have showed you .like those high voltage generators from tasers.anyhow great work dgw..thanks again
naaaice video as always!
15:26 *accidentally summons the devil*
I always watch the whole video :-).
Being almost 40 I immediately recognized the thing you showed at the end: a 3D-printed audio version of the "save" icon! :-).
Looking forward to see you repair that tape recorder!
I am at a point were I actually wait for Diodegonewild videos to review these cheap aliexp power supplies. Not that I have any doubts of their expected multiple problems, but just to confirm and see a detailed analysis. Great video!
30:00 21 years old watching your videos here, looking forward for your next uploads.
Thank you for your detailed videos
Thanks for this video. And i have to say that i just love your accent.
Young, Yep 21Year Old, Engineering Student from India.. Yep I learnt a lot of things from this channel and i didn't skipped any part of video for even 10 Seconds.
9:54 This IC is Current Mode PWM Controller OB2263MP, SOT23-6 case.
Thanks :) sometimes these smd codes are hard to decode...
I'm 19 and have been watching you for a few years now; you still made me feel really old lol ;)
I'm twice your age and I'm a walking dead ;)
@@DiodeGoneWild I've already turned to dust. Thanks for all the videos. Watching from Hades, you are very popular here amongst the shades ;-)
so much to learn here! thank you!
I was curious about this type of supply from Aliexpress .... thanks for sparing me the trouble and expense
"Maybe you don't even have to open it, who knows?" 😆🤣😂
"10 seconds of attention absolute maximum rating" 😂😂😂
29:50 watched the whole thing. Very entertaining video and great explanation of the schematic. Keep it up 👍
It is nice to see your "new" osciloscope on a video.
Priceless video, an absolute joy to watch. your "cutting corners" gag was prophetic. Please do a video on restoration of the cassette player, and your marvelous cat is becoming very judgmental.
Very nice Thermal camera!
Yes, theory of operation of casette deck (and video) mechanism is always welcome!
Great content.
I like electronics so much! Even though i finished different High school i still cant forgive myself that i didnt learn those stuff in elementary school to pass into Electrican Enginnering school :(
Still as 21 years old i love to watch those stuff from which i learned a lot!
No problem for 30mn vidéo ! I like it !
nice work
What?! Already over? As long a video is entertaining it couldn't be too long.
Great video! What a dodgy piece of crap. I would have been highly shocked if it was NOT total garbage... But it lived up to our expectations... And yes, I watched all the way to the end! :-)
I learned most of my electronics knowlage from your videos. I'm 15 and i like tinkering with electronics and arduino. And I'm from turkey and i would like to see more of your bloody long videos :D
I really enjoy your videos and although I am into electronics for three decades, I still learn a lot. I may not be the youngest viewer, but 47 is not too old either… 😅
When you see the spikes and say "Geezess", it's golden...close behind, the temperature of the bottom of the case:"Bloody Hell!"
Accurate and meaningful comments!
Cassette tapes invented in Eindoven 😊
When Philips was an absolute powerhouse of research and development.
you can make 1hr long videos and i will still watch it from start to end. i have watched every video of this channel from start to end since i had subbed in 2017. the video was something about chinese water heater i think. and the chinese death lantern is also one of my favorite video. back then i was 13 .
Nice dodginess :). Looking forward to the restoration :)
I'm still here. It was a very thorough analysis. I enjoyed it. For what it is I think that PSU is pretty good. Well. the mains isolation is pretty bad in places. I certainly wouldn't expect more than an amp out of that PSU either. That ripple though. I would have liked to have seen ways to mitigate it. I have put Pi filters on PSUs and that knocks the spikes down a lot. I'd be interested to see Dan's take on it though.
i’ve got one of these that i use frequently to briefly test resale electronics with a DC barrel plug. It’s a very nice adapter to have, so i don’t have to go through my whole box of dc adapters. I’ve got all the same issues that you stated here, the potentiometer sucks and it’s rather cheap in it’s build. it seems this adapter can output useable DC to most electronic devices, but very rarely i’ll have stuff not power on with this adapter specifically. then i plug in a normal adapter and it works fine. I think this adapter tends to struggle with inductive loads more.
I'm curious if replacing the linear taper pot with a logarithmic taper pot would make the adjust more linear or super logarithmic.
Maybe sometime you might try the DIY load mikeselectricstuff came up with: A length of wire in a bucket of plain water! The water does a great job of cooling it and the wire is still a better conductor so you don't have to worry about shorts as long as you can keep the wire from contacting itself. Just need some regulation to keep the current consistent.
In this video bro really gone a total rabbit hole ☠️
Please make more long videos like this one. I hope that you will make a 2 hour long unedited video
8:40 I know enough about probing to always be suspicious when I am doing measurements like this (but not enough to know when I'm doing it right, haha). I trust that Dan is doing it right, but for anyone who is less experienced than him, here's how you can end up accidentally seeing that kind of noise when it's not really there:
At multi-MHz frequencies, especially with power, I worry that I am picking up the magnetic field in the loop formed by the probe and its ground clip. Also with digital scopes when you're operating close to the bandwidth limit you can often have apparent ringing that's actually caused by the scope's sinx/x interpolation and not really present on the true signal. Dan said 100 MHz which is well within the safety margin for a 500 MHz scope, however a digital scope does not always operate at its maximum sample rate! Usually they are nice enough to display the currently used sample rate and bandwidth so you can check.
Not to mention, always be sure that your *probe* can handle the bandwidth! Usually to go past 10 MHz you need to be using a 10:1 probe, or a switchable probe in the 10:1 mode. For high frequency, low impedance signals, instead of buying expensive high frequency probes you can sometimes get away with just using 50 ohm coax with a resistor.
Very good vidéo. I have this kind of alim and I like it , just for low power of course .
Thanks for the video, really intresting. Can you do a video on the active full bridge rectifier & graetz bridge rectifier( bridge rectifier with capacitors on each diode )
12:20 why I did laugh too much after watching this 😆😂😅
Is a difference in using this PSU (or other universal power device) on the 230V or 110V? I saw this one baking itself at more than 100C, what would happen if used on the same conditios (output voltage, load) at the 120V mains input? Would the efficiency be the same? And the power output, temerature of the semiconductors, switching frequency?
And, overall, an universal mains device (100V-240V) would benefit being used at lower mains voltages (lower the temperature, increase the life of the device) or does not matter?
I think that running it at 110V~ would bake the MOSFET, because a lower voltage would result in a higher current but also a higher duty cycle.
@@DiodeGoneWild I was asking this myself just because I recently got two iron core insulation transformers 2:1, one of 500W and one of 1000W and I was thinking to use one to power some 100-240V devices, to improve theirs life span.
Great video as usual. Now I'm just wondering where that horrible switching noise at the output came from. The only thing I can think of is if that snubber circuit really was faulty from the beginning.
Hello. Generally PSU ripple measuring is 50 Ohm oscilloscope input resistance, 20 MHz BW limit, no alligator clip due to its wire, most probes have spring which can be put on instead of alligator wire. How do you measure ripple?
I didn't understand what made the voltage drops when the circuit warmed up.
I guess the overheat protection in the chip reduced the duty cycle.
Thanx sir....can u reverse engineer godox sk300 flash unit?
Watched the whole video, didn't even blink, i guess i am crazy😅
Your dog was looking a bit overheated there. Buy him a cooling ice cream. Puss cat, total cool dude, as always 😄😄
I have a wuzhi wz5012 CNC buck boost converter not giving output.can you please show me the problem with it?
Do all smps just looks so similar?
Thanks @DiodeGoneWild for this video , i appreciate the hard work behind these videos. Very rare channel that gives correct information. I have a question that i couldn’t resolve: you state that flyback transformers have always an airgap. Why is so ? Because having an airgap will increase flux leakage and lower the inductance seen at the primary side and these are negative effects. I understand that it will decrease the core saturation considering the same current. But would it be more convenient to lower the duty cycle instead of putting an air-gap to have a better efficient transfer of energy. Can you make a video expressing the physic equations highlighting such a choice? Obviously i went back to my power electronic book (Mohan) but couldn’t figure it out. You would be the first on internet to explain this subject.
I both admire your opinion and your skills of power supplies. So I have a question for you. Where would I find a good schematic for a power supply to go from 120 volts AC 8 volts DC to charge two 18650 batteries?
Always a great pleasure to watch your product reviews of chinese hightech. :-)
It would be great to also measure the efficiency at half the claimed load (What input wattage at 30V 1A?).
Do that tape deck man, I’d love to see that.