I believe that regulator output has touched the heat sink which is directly connected to the collector of the big transistor which caused that Cap to blow

That regulator for the fan made contact with the copper from the cooler and got shorted because you didn't isolated the board under! 🤣🤣🤣

I built that kit in 2019 - building it into a housing and added 10 turn pots and a Volt/amp meter. And it works great !! Best thing ...... unlike many of the constant current power modules you can buy - this one actually does a great job with current limiting !! It actually limits current down to 2.5 mA. Great for power injection and testing diodes !!

beware!!! :D that kit is wellknown, and have some flawless, too. the most easier flaw to fix is using for AO's a local power supply, like a Zenner and a resistor, calculated for no more than 30V over AO's, negative power included! it's a -5V on negative, so, 30-5=25, but there are no 25 V Zenners, not 3 terminal stabs, so, 24 volts. most easier is to use the already present 24V, for cooler. some small adjustment for resistors, and is perfect. of course, you need a nicely strong mains trafo, 24V or a bit more. or a bit less, if you accept a bit smaller voltage on full load... :) (written immediately after i seen the kit... is a wellknown for me! :D now, play to the finish... i'm really curious what you will find about... as a side note, is a really antique schematic, older than 60 years, in some variants. one of them use 3/4 AO's in a 324, and the last one is used as overload indicator, doubled as relay activator... :P ) later: min 13: to much current on a diode in the bridge! it's what happens most of time, without dealing with small smps's :D also, looks like you don't set the 0 volts, that blue multiturn is used to set the 0 volts, because this is a "virtual ground" power supply. for same reason you fried it first time with a 19 v laptop brick! :) lemme see... you just repeated the very same mistakes me and a lot of people does for the first time they meet this schematic, and, later, this kit... chinese started to manufacture and sell those kits some 15-18 years ago! :) i patiently seen the video to the final... Sorin, that blue led is NOT "power on" led, but "overload led", it need to be on only when you load the PS with more than your current limit! :) why is all the time on? some of these kits are correct, some not... some have a slight different schematic than the original in that part, and led is on the opposite directions, and is on all the time. other kits have wrong orientation printed on pcb. looks like electronics-diy point com shunned out that power supply, even this was their top-grade reason to check their website, a lot of years... you can find a lot with a google search, but i have trust in "radioscamateurs" sites, so... check the link down. i have not patience to search exactly about setting-up procedure, i had done it for some kits, and leaved it alone... also, with a bit of more searching, you can find a giga-talk about that schematic on a romanian forum, in power supplies section. a forum i leaved it for some years, even if i was one of the only posters there, for a lot of years, too... :) să fii iubit. :) www.qsl.net/z33t/dc_0-30v_0-3A_eng.html

12:40 if you go frame by frame first you see big spark that looks like it comes from transistor and then smoke + red glow from the capacitor on voltage regulator for the fan. I think that regulator touched fan pipe and capacitor on fan regulator shorted over the transistor 😎. FYI when you pause the video you can move forward and backwards frame by frame by comma and dot keys on the keyboard 🙂.

It's not only you, when I try to build something to show someone, sometimes I have such "luck" as well.

The best way to learn electronics is this building something from zero. Nice one

It's funny... you went from "Electronics Repair School" into "ElectroBoom" in this video... loved it Sorin... :)

Gotta love the fact that your videos are so "organic". You also include fails along so we can learn from that, coming to a conclusion in the end and learning a new fix or a new way to blow up electronics, haha. Keep it up, Sorin! Looking forward to the next upload. Have a nice evening

13:35 - Strange thing you didnt stop video recording and check what sparked. Its power supply for fan, little capacitor. 12:39 spark. I believe that green pcb touched heatsink, and heatsink is soldered to the back of that big transistor. 18:29 you placed isolation tape on back :D

I originally posted something like this in response to someone's question, but it seems a lot of people miss the issue, so I'm posting again with some elaboration. This is intended for use as a bench power supply. With a bench supply you really need to be able to deliver full rated current into a short circuit or close to a short. You may not need to do this often, but the need does arise. Your power supply needs to be able to survive it. When the output current is set to maximum and the output is shorted, the power dissipation in the transistors will actually be more than 100% of the full rated output power of the supply. If the supply is rated for 5 A and 30 V, that means the transistors would dissipate 150 watts, *minimum.* If fact the dissipation will be even greater because the voltage across the transistors will be equal to the full unregulated voltage from the bridge rectifier and filter capacitor. For the 30 volt supply that might be 35 volts (or more). At 35 volts the transistors would dissipate 175 watts at 5 A. That is a lot of heat to get rid of! If you use the regulator for some specific application where the output voltage is not very low, the situation is different. With high powers it is important to be careful that the transistors used have adequate safe operating area. "Second breakdown" can limit the allowable steady-state power dissipation to something well below the nominal rating of the device. With low voltage this often isn't a problem, but it very definitely becomes a problem when you get up into tens of volts.

Learning by doing is the best way to lean and to achieve experience and not be afraid of the unknown or new. Smoke is good, smoking lessons from Sorin are funny, familiar friendly and very infesting always. All the best “moșu!”. Big hug!Cosmin from Switzerland 🇨🇭!

so satisfying to watch the soldering process

I noticed that your current limit led is constantly on, it should only come on when the current limiting kicks in. On my board the silkscreen had a error and the transistor that controls the led needs to be rotated 180 degrees that will make the led work correctly.

Thank you, your videos make electronics fun again.

I bought few years ago one of the RD tech power supplies from aliexpress, I have a 32V 5A and it's been very good.

Mulțumesc, Sorin. I wasn't sure how I was supposed to connect the Ammeter to the supply. My attempt resulted in the D882 transistor shorting out because I tried powering the meters from the fan output. Tried your method and it works flawlessly!

I went thru this adventure a couple of years ago and I was unlucky at first. Transistor blew up almost instantly at 2 amps. Later I got scammed with fake Toshiba transistors on amazon. Ended up using a 13007 extracted from an old ATX psu and problem was solved. If you have a proper power transistor with proper heatsinking, the thing does it's job. Have in mind that with this circuit, if it overheats and shorts, it will send the full unregulated power to whatever you have connected at the output.

As always Brilliant Just wished you pointed out how important the input toroid/transformer is.

there is that properly calibrated wire love it man thanks for video been trying to find parts for making one from junk tvs

Would love to see an updated version video with all the mods you suggested a case and some testing done to it using your oscilloscope on the output for example. Plus if any more mods you can think of... Thanks for sharing though!!

Love the video😊I have the same power supply. It arived from china with dead amplifiers, and after few day transistor and big rezistor died😅I replaced them by original ST tranzistor and royal ohm rezistor and it works without problem😊

Great tutorial! Nice music at 23:55 😉

Fantastic, Sorin. My linear power supply i made with atx desktop power supply, using - cable blue -12v and yellow cable + 12v with aliexpress regulator 2956. -12v with +12v i have + 24v alright? Also, have a generic aliexpress meter voltage/current (als288 maybe) conected in serial mode with out - and out + . I am using 1 year no problem, but, i recomend using diodo retificator 4amp in +12 (its possible calibrate diference 0.7 volts on meter adjust) Its my homenade power supply setup; DIY Ever!

As built the transistors are passing 5+ Amps (100+ Watts), but they are not dissipating anything near to that, which is why the fan/heatsink are coping and the transistors remain fairly cool. If you hooked up a 35V transformer as you suggested, then particularly when used at lower voltages the transistors will be dissipating much more power and thus get hotter, to the extent that you'll probably need a bigger fan/heatsink combination. Which is why many power supplies switch transformer windings in and out dependant on the voltage required at the output.

The little buck converter board was sitting right on top of the copper heat sink. Wild!

I bought a panel like that when I was a child. I didn’t have a soldering iron, so I made one myself using a screwdriver, a copper coil, and a transformer. It worked for a short time, until the coil burnt out.

Ive been expecting this so long thanks Sorin

Nice! I build several working great though...but take care and replace IC with good ones, I'm using TL701 instead ''originals'', also I replaced R7 with 3x1ohm/5W in parallel , gives like 0.33 and let more current flow too.

Belle vidéo, j'ai aussi réalisé cette alimentation, j'ai appris des choses grâce à vous, merci !

hello zorin, can you detailed the connection using the ac transformer to the board to avoid blowing up the 3 ic's, planning to follow these project of yours. thanks a lot.. a follow up video or explanation is so much appreciated. more power to your channel. :)

Nice video.keep going sorin,may i ask what model is the camera you record with the one you use to record from top,i checked you tools link but you haven't included

Thank you. great work.

Very nice sir..I'll try to make this..

Thank you Sorin.....Like this DIY theme

Thanks for the info. 👍

Excellent video! Thanks :)

Great video thank you.

i built two of the power supplies powered up and op amps burned up so i change op-amp to lm741 because higher voltage rail and use dip sockets. i also also use 2n3055 as output transistor. used if for five years now

great video and great cheap supply i have it too 😉

This guy is adorable! I like watching his videos, but this one is hilarious too. Kind of ElectroBoom. Depending on what you need the PSU for, I would consider buying 60$ labor PSU for repair and diagnostics.

Hello Sorin. Will you be installing small value resistors in the emitters of the those 2 transistors?

Properly calibrated fire extinguisher in order sorin. I use one myself. And remember, no capacitor, no shorted capacitor. 😂

Great i love those diy Kits love them

I still have this kit somewhere assembled, ending up never using it but is there as backup, just in case. I got it for free because it was lost in mail somewhere so aliexpress give me refund, package arrive 6 months after that. btw fan will have much more problem with lower voltage, with 19V transistors don't need to drop too much but if you lower your voltage to lets say 1V and try to push 5A for long time that little heatsink would have hard time :)

thank you very useful, greetings from Indonesia.

29:00 You are wrong. Here the variable resistor has to deal with 100W, the transistors not. If you configure a low output voltage at max current, then the transistors has to deal with 100W. I guess they will desolder from heatsink and blow up. Lets try. 😂

I feel really good about my soldering skills after seeing this 😂 but seriously thank you for showing me this kit

Hi Sorin, is current limiting functional? That diode on the pcb should light up only when overloaded. I have made a double stabilized source from these modules. And I had to replace all the ICs on both. And many other changes besides. Try to short-circuit the source, with a set current of 3A, and then you will see what the temperature will be on the transistors. :)

12:38 Sorin, the power supply specialist! 🙂

I think I'll stick with the linear power supply I got from CPC! Great video as always though :)

On mine the output to the display is up to 33v. Connected as you do. The display is rated 4.5 to 30v. I touched its components and the transistor gets very hot. So a step down regulator is needed?

I built one of these kits, but haven't had a chance to even check if it works, as I don't have a suitable transformer. it was an entertaining enough project, and maybe I'll find a decent 24v transformer in something at some point in the future to test it out.

Maybe we should all buy the same kit and sorin do a live stream and we all build the same kit together that be fun? Anyone

Salut Sorin. eu am facut aceasta sursa de alimentare si tot mi se ardea OP-ampurile si nu stiam de ce. eu am cumparat un traf toroidal de 24v AC dar in gol scotea 27V. traful trebuie sa scoata fix 24 V in gol ca sa nu arda integratele. 24V AC inmultit cu constanta capacitiva de 1.4 dupa redresare si filtrare o sa ai in jur de 33.6V maxim. cu 27V in gol inmultit cu 1.4 ne da 37.8V care ard integratele pentru ca nu sunt proiectate pentru o astfel de tensiune. tensiunea maxima admisa pentru TL081 este de 30V DC. ce este peste le arde si nu stiti de ce sursele nu functioneaza. pentru integrate folositi un soclu si a-ti scapat de problema cand ele se ard. frumoase videoclipuri Sorine. Ma bucur ca avem asa romani priceputi si peste hotare. o zi faina!

Can you please show the quality of its signal on the new oscilloscope you bought?

thanks Sorin, I bought the same kit, what kind/rating Transformer should i get for this kit to be able to get 30v 3A out of it?

Nice video! Just one comment, you said the heatsink/transistors need to dissipate 100watts. But I guess most of the 100 watts gets lost as heat in your resistive load. You could measure it.

Great Videoo🔥🔥

This is what I was looking for. thank you very much. Will you be working on more power supply projects? Like Chinese power supplies with ovp/ocp and buzzer for short circuits. Love and Respect you and your Work. APPRECIATED ❤ LOVE FROM KARACHI PAKISTAN SIR

Whats the negative voltage doing in the curquit????

Please, do you have a solutuon with what We can change the transformer ?

Love this show!

If I insert a 24volt Zener diode in the regulator ground lead this will in effect increase the max output to 48 volts which is what I need , however can the rest of the components take the increase in voltage?

Great video Sorin, I would use a bigger capacitor too on 5A for better filtering. Great stuff

Great Sorin.

Hi sorin great video again I would love to see how you would build or modify a ebike motor controller I want to make one that can maybe run with 1 36v battery and be able to adjust or just boost the power to the motor for short periods or to run it at 72v I think it would be a good video especially using your special calibrated wires 😂 ect. Thanks for all the really helpful stuff you have taught me, hope you are well.

12:39 You shorted the little switching power supply with (heatpipe cooler) the collector of the transistor

Sorin, I keep trying to figure out what soldering iron you have, can you please let me know. Thank you

hi Sorin, I'm using this circuit since 6 yrs. lately D882 get burnt, I replace it but agian burnt, I found the cap 0.22u next to D882 damaged I replaced with used one works for a while but again D882 get burn i remove the cap and it worked fine till now, couldn't figure why.

Is it possible to use laptop mosfets to build a power supply. They have 30am ratings . Maybe some way to re use from old motherboards?.

nu te supara dar am ras ca lumea la 12:40 ,... multumim mult pt video. foarte bun,....

Salut. Daca pun 3 sau 4 tranzistori in paralel, sursa poate duce 8..10Amperi?

Buna dimineata! Can you tell me more about the transformer? How many Watts or Amps does it have? I like this project, but I am afraid If I put it in a case, the transformer will be the first to burn. That and adding a breaker on the output so it clicks instead of blowing a laptop up LOL. Mulțumesc!

Hello, interesting video. Can you share the parts to understand how it works (Transistors, chips...) Thanks. BTW, can we replace those transistors by N Channel mosfets ? (more available and can take more current)

nice project

Hi, Ive been looking for one of these that works correctly.. I have seen another channel that can only get 23V from the board. @8.35 you get 23V with a 24v AC transformer. 24v AC rectified to DC gives 33.9V DC, with a little loss here and there in the circuit the output max should be 30V DC. Have you managed to find the fault and fix this?

Hello Sorin , i love how you fix things , i watched a lot of your video, may i know how can i buy this things by the way im from Philippines

Finaly good quality picture from microscope!!!

Hello sorin... is that working 30volts ac transformer without change the value of resistor?

I still remember very well the First Video!

No ICs were hurt in this video! Awesome

but Sorin. The transistiors are not actually consuming 100W, so cooling should be fine. most of the power is taken by the resistor/load

How can we add the relay for clicking effect of short circuit?

You've spoilt us today 😂😂 🔥🔥

Hello🤝very nice power supplies 👍👍👍👍👏👏👏👏👏👋👋👋

😉 I made such a modification on exactly such a PCB-PS month ago

The voltage on the output rectifier and capacitor filter is 24*sqrt(2) = above max rating of 7812 And seems small switching regulator short to the heatsink

Sorin be careful, warming up a heatpipe that much can very easily make it explode. And if it doesnt explode, it loses some of the ability to move heat to the heatsink

i bought this a year ago. the achiles heel here is the low voltage and high current. a 3V motor powered by 1.4V and 0.8 - 1.5A for an hour caused the failure of the big transistor. the loud one. sorin, i will appreciate if you can find a way to make this power source to sustain 0.8V and 3A forewer. typicaly for ram/cpu power testing. for cooling i used the 775 heatsink from intel quad core cpu. no fan. transformers are available in some cheap speakers with amplifier. usually 2.5A, -11 and +11V = 22V. or this expensive sorins fancy toroid.

Nice one

No capacitor No problem love it 😊

I made a modification, I use a 551 watt battery, I got 35v and 15 amps, now I'm working on another transformer.

Regulators dont need to dissipate the full power to the load i.e. 100W but a fraction of that, that's why your fan made it.

What I think happened is the bottom of the small DC-DC converter touched the copper heat pipe which is soldered to the collector of the big transistor, so.........you can figure out the rest :))

I have a switchmode power supply (50v 10amps) and i want to regulate the current to constant current 6amps How can i go about it

on that lil 5v board, the cap on the end blew... magic smoke 🚬 .. i watched it frame by frame...

When you put the variable resistor on the bench next to the toroid you got an induced current which was too much for the capacitor.

i remember that bbq party lol , and i did it , thank you for all

how much would a transformer like that cost? OR...for hobbyist applications, what power should the transformer have or does this thing even matter and just the output voltage which has to be 24AC?