This video is very useful not only for high voltage power supply, but for understanding any switching design. Thank you for sharing it!

Grade school would have been so much better if they had used examples like this in math class.

Nice break out Clive. I'm a retired 17 year US Navy electronics tech from the end of the tube / bulb era and I have to commend you on your circuit explanation skills. The course of my career would have been much different had you been instructing my cohort.

It definitely helped to go over the simpler power supply schematic first.

That is a LOT of very high-quality design (and componentry) for just over ten Pounds (UK)!The isolation is superb, and the Kapton tape wrap around the pulse transformer is the icing on the cake. Excellent products like this tend to refute the popular (although mis-informed) "Chinese Crap" meme.

Commonly used on lathes and mills for running the control electronics

When Clive talked about those big huge transformers, I couldn't help but look over at my collection of Stuff from the old Bethlehem Steel Plant in Bethlehem PA. I have no clue what it was used for but it weighs 35 pounds. I was told that at their prime Bethlehem Steel bought only the best equipment for their operations. RIP Bethlehem Steel.

Oh, Clive, you are worth every penny! That initial explanation of a simple, 'idealised' SMPS was the first time I've really understood the whole system from start to finish. More of that sort of basic explanation would be most appreciated. Great work!

Excellent reverse engineering explanation - many thanks - I now understand considerably more about the mysteries of SM PSU design and operation.

The quality is SUPERB! Now that's a new Clive word! That's the way that all SMPSes should be made. With Safety in mind.

1:10 well, by now ebay sellers know that if they get an order from the isle of man, they will soon get follow-up business from all over the place.

I once built a 3-phase rectifier for the armature of a 20HP(!!) DC motor -- for a previous satellite-ground-terminal restoration project. The old control system used a 3-phase motor driving a DC generator. It was a thing of retro beauty. Lots of big relays and contactors and big power resistors and thyratrons. The control rack weighed (with the Motor-Gen sets) about 2 tonnes!

There’s also 48 volt DC switching mode power supplies that are designed like that to run on three phase power but they are usually massive as they are normally designed to output hundreds of amps of current in order to power server equipment! :)

Just raising the frequency from 60Hz to 400Hz allows you to reduce the amount of iron in a motor or transformer by 80%.

Nice anti-tracking, multiple resistors to spread dissipation, beefy over-rated components, intelligent design - I'm truly impressed!

No clue what he's ever really talking about, but still love watching. I find it quite soothing for some weird reason.

Extremely clear description of the entire circuit. A joy to follow along! Only suggestion would be to add transformer winding dot notation on the schematic for added clarity.

That's beautiful. So nice to see an actually well-made power supply for a change.

Hm, maybe this is something the Chinese industry actually makes to be used by themselves and not just shipped abroad with zero regard to anything that happens after that.

Your explanation of how a SMPS works is great! Well explained and easy to follow. I've been learning electronics (slowly) since I was a child and never clearly understood how they worked, therefore, how to properly troubleshoot them, but now I do. Thanks!

It's not often we see Clive extol the virtues of a far eastern product, but this one is an example that stands out from the crowd, and we can see that Clive absolutely loves it. Construction wise, it reminds me of the PSU in our ancient (late 1980s) STC/SDX PABX, though only single phase in our case, but with very similar excellent electrical separation and well thought out design - necessitated no doubt by the need for an ultra safe supply for equipment which all but directly coupled to ones lug-holes!

I like the way you do the things. Print the Ebay screenshot instead of paste film. Make yours films so smooth👍

About the need for 400V PSUs, recently I put together a small control box for a portable paint mixing tank... We have a lot of 4pole IEC plugs at work (from the time they were switching over from the metal-case flat blade plugs) and they're all you need for a motor, but I had to do some low-voltage control (due to the contactron turning the motor of) I had to go for a 400V-24V transformer (had to be reliable in a very harsh environment) was much more feasible than changing 30 IEC sockets and like 50 plugs on other devices

A few months ago, I started looking at designing a power supply that can supply 20-30A at 12V or 16V when powered from 300-520V DC, the twist is that it should also be able to work at much lower voltages with reduced output current. Application is an auxiliary power supply for a solar inverter. Decided to put it off and work on other parts of the system first.

wow. when winkling bits from old things i have often wondered at those triangular pads beneath the chokes. i seem to find them in old amplifiers rather often. thanks for clearing that up.

23:11... "times two" writes three

Thanks for those videos Clive, they make it rather easy to actually understand what is happening inside devices you might have around you (well, a 500V PSU is probably not one of them, but anyway :P).

Well explained and always clear photos and circuits. Thanks Clive.

Certifying this stuff is hard: Every single part will be either shorted or cut (put into one of its failure modes) before the circuit is tested, and the circuit must not catch fire, explode or have overvoltage on secondary. There are many permutations even for a small number of parts, so it gets very pricy, too. I hope that the chip has a safety feature which stops switching if the optocoupler fails.

This was a fantastic episode. I really feel like I am getting the idea. Thank you.

Excellent video! Helped a lot in understanding the main difference between a low voltage power supply and a high voltage power supply. Thanks for the detailed information. :)

That thing meets or beats Sola and Phoenix Contact supplies. I would install that without hesitation. e: About half of the three-phase machines we built tapped their control power directly from the mains, and we only ever used single-phase like these for that application. A couple of air handlers in the plant actually used a full three-phase 480 VAC:24 VDC supply, which always vaguely worried me, but clearly it's fine.

Running across two phases at 208v is common in the US for some high rise places where they don't take the neutral up. Some principle as this. Hence why a lot of appliances are rated 200 to 250v as the US uses -120v and +120v to give a 240v potential, and then using the different phases to create the slighly lower 208v voltage. If all that makes sense.

I think the snubber network on the primary side is mainly used when the power supply has low load. And the shunt over the output diodes are for absorbing that rapid pulse mentioned before the diodes have time to turn on.

I wish I was smart enough to understand even a word, but I still enjoy your videos! 😊

Clive, you seem excited about this one. Enjoy your videos very much. Cheers from Perth Western Australia. 👍🇦🇺

Awesome Clive! Fantastic timing also... I was in dier need of some easy relaxing content to sit bk and soak in ✅👍🏻

LMAO "MOSFET-y like things" That made me laugh so hard it hurts. I love Clive's videos.

This was an excellent explanation of the power supply. It was very well thought out, and easy to follow. I like the use of the linear regulator to adjust the feedback output voltage. That is a clever use I had not seen before. I don't like the use of parallel diodes on the output rectifier to get s higher current rating. The two diodes in a single package have good chance of matching since they are most likely on the same substrate. However it is highly unlikely that the diodes in separate packages match, especially over temperature and this could lead to current hogging. It would be interesting to see how much emi it generates. The snubber across the output rectifier at least shows they were thinking about it. Thank you!

This made me very aware I had dun a Dunning-Kruger, having watched a great many of these sorts of videos from the back of the class. Earlier I would have been hard pressed to tell the difference between this and a bottom of the barrel power supply!

I would expect 3-phase to low-voltage DC supplies to be readily available because the standard residential supply in Germany is, according to what I've learned from the German maker channels I'm subscribed to, 3-phase. It looks like just about all electric appliance motors in Germany are 3-phase. It's also really nice for power tools, and means the difference between consumer-grade and professional-grade mills, lathes, table saws, and similar tools is probably much smaller.

Brilliant explanation...I learned a lot of random bits and bobs....I am hoping to find some analysis off Grid connect inverter and IGBT welder products on your channel

Its Very common in industrial equipment to not have a neutral. Its common to only feed with 3ph+PE. Hence there is quite a few variants available. Both from 3ph->1ph+"N" and 3ph->DC. The former is usually always present to create an isolated system supply.

Great video as always BC. Thank you.

An issue that often arises in valve amps comes to mind here. When putting the two 68uF caps in series, the exposed end of one of the cans will have 250 - 300Vdc on it!

best one yet Clive, basics are the best :) this is what makes life real....

Don't forget the dots on the transformer. A flyback is wound with oppositely wound windings unlike any other type of transformer. (Technically is isn't even a transformer, but a (not-very-well-)coupled inductor)

Switching supply saves shipping weight, and cost. Reminded me in 1980 the eng VP confused a sales rep when he told him we needed the brute force transformer. Because we charged $5000 for the receiver and customers thought it weighted enough to be worth the price (had only 2 Z80s, 8k ram & 2 2708s).

The snubber across the primary winding is of the voltage-clamp type, which should not be used with a flyback topology. At least only with great care and consideration.

Great vid Clive...Very well explained..

I really find your explanation of ccts, although l can read ccts and understand the basics I've not got depth of knowledge that you have so l find your diagnosis rare down very enlightening! I've mainly worked on transmitter repairs Lf to Hf 20w to 20kw some Marconi Hf auto tune,intresting thing was auto tuning always got lower I P, s inter modulation products! Than l could get on manuel tuning! On H f tx! Also uhf txs 500ml w to25w, l once saw the result of standding wave on mistuned 10kw hf tx that set fire to AE patch panel,that happen whilst l was in middle of manuel tuning, and main supply failed,and as usual despite d o e resting standby generator every month, as usual it failed to get up to speed to produce 240v so l had to go outside to generator adjust speed regulator! so by time l got back in tx hall, only2mins tx had come back on line,in mistuned state and standing wave just happened to meet @AE patch panel plug setting on fire! There was a b.e.r.s site on island, British eastern relay svs l got to pay visit to they had mega w tx,they show me result of mistuned tx,feeder to AE size of large drain pipe 2ft dia,it had melted/blown hole in aluminium feeder! This bit you'll well understand, they had2 very large paxman generators, can't remember power!must have been meg watts for such high power HF tx. Sombody had really bad day when running up standby gen and getting the phase out of alinment with on line gen,as in for change over,there was friging humus bang, alternator stalled engine,which promtelly blew engine up,very big deisel engine, that then despatched it's self thro roof of building, engine size of around 2double decker buses, really bad day for BBC facility shut down for repair for some time,theyve moved now from island to mainland Arabia. Short distance across sea.

Look! A Chinese product with character. Now that's refreshing!

amazing content as always big guy

They also make almost identical two other configuration: 5V 6A, and 4V 1.5A. Just some different configuration of some resistors, capacitors and transformer probably, and maybe some diodes. Same PCB exactly. It actually can work down to 100V AC, and 141-746V DC.

Nice one Clive, that PSU has certainly had some thought put into it, what with the creepage slots and the resisters in series, I am impressed for a chinese built PSU.

Thanks Clive!

A very long time ago I was contracting at a company that made the drop towers for quartz fiber optic cable. There was a new induction oven for larger billets which was water cooled on the outside and took 100A per phase. It needed such a high water pressure it was unreal but we didn't have the pump yet and one of the bosses wanted it tested so a water tank was put on the roof of the gantry tower as that was six stories. The hoses were fitted and a wide drain pipe fitted and the tank was filled. The water flow valve was opened up and the electricity turned on. Then all hall broke loose. The high pressure supply came off spraying water like a fire hose, and the supervisor dived in (almost literally with that much water) trying to push it back on to the fitting shouting "Oh no, oh no, oh no in a Brummie accent which somehow made it funnier. There was an almost perfect 180 degree fan of water with about a 3 meter radius. The owner of the company came down to see what the havoc was and just pissed himself laughing. The induction oven got so hot it turned to slag and scorched the concrete. That was after the power was off. There was a huge amount of latent heat (I'm going from memory of about 25 years ago). The boss checked everyone was uninjured and then just pissed himself laughing all over again. The supervisor was sent home as he was a bit shaken and told to come in the next morning. The boss the next morning took one look at him and started laughing all over again. Nobody got any kind of formal reprimand and there was an open meeting on the shop floor held by the top boss focusing on how we could stop this happening again. The only thing that happened was the supervisor got the wooden spoon at the Christmas party. It was one of those companies that had awards for the trainee who made the biggest advance in ability etc. Pity there are so few companies about like this any more. Anyway that's my story about the only time I ever worked with 3 phase.

This isn't a full 3-phase unit though, and there's one advantage of having a full 3-phase because then you can use a 3-phase rectifier and get a smoother current. But common mode suppression is more complicated on 3-phase.

It is nice to see that EBAY is selling some "deathtaps" (Play on words.) I usually go through automation direct for my 240 and 480VAC to DC power supplies at the best price with certifications. But a quality non certified unit is always handy in a pinch.

Hmm, I've been long keeping my eye out for a 208volt 2-phase power supply like this... I've never even thought that eBay might have something like this. I'll have to take a look

I think your fingers weren't listening properly at 23:05 when you *said* "×2 gives 3,000" and *wrote* "×3" 😼

I very much appreciate you reverse engineering the circuit and describing its operation. Thanks so much for sharing. 😉👌🏼

My coincidence I've had videos of rotary converters used in the New York subway recommended to me recently. It's not clear in the videos if these 115 year old machines are still in use, but the ones they have are fully operational. One thing that came up in discussion was how 3-phase rectification gives less ripple, albeit at a higher frequency. IME w/ linear amplifiers having liner power supplies, single phase ripple can be tamed easily enough, and any remaining ripple is barely audible at 50/60 Hz, where 150/180 would be more obvious. I don't know if switchers need to be careful about ripple, as it's sliced and diced in the next step.

Ebay seller: why is everyone buying this? We need to raise the price.

Really impressive, when you consider the very genesis of the creative innovation along with the brainchild of the mere thought process into a schematic, and onto the planning the data of what's needed in size shape, input and output and then create materials needed, and making , or finding mass amounts,..anyway, I digress, .. it really is interesting. Good videos Clive.👍

That looks like a good design.

GREAT Lesson Clive. Now I think I under stand SMPS. Could U1 be PWM Controller like On Semi NCP1251?

Another possible application for these SMPS's is electric cars. The main battery voltage is in the 500v range. Yet they also use 12v electrical accessories like lights and other electronics, probably because these are off the shelf for building of cars and at least the Tesla still has a standard 12v battery in addition to the high voltage propulsion battery.

that circuit / board design is at a high standard for such a low cost , not often found these days - good one

Excellently explained. I'd like to see a DC power supply that takes it's supply from all three phases and how that works.

ST it's the mark of the beast. I recently repaired and parcially reverce ing. the control unit of my condensing boiler by viessmann. It's full of ST ic and for some reasons finding the datasheets for this brand was a royal pain in the... you know, the easter bunny think.

A friend of mine tried turning down the supply to a computer power supply, it worked with a small load down to below 20v, all the output voltages were correct, so i think your psu should work too, just at a lower max current maybe.

I'm always intrigued with 3 phase circuitry, thanks! Btw, Did you leave the foam up? You sound muffled...

Hi Clive, i have a amp that works but the LCD is dead, i read about dry solder and cold solder joints and looking at the board, this seems the only feasible possibility, i don't know if you have discussed this in your videos or demonstrated fixing this type of issue, but maybe it is an idea for a video as it is pretty relevant, i would like to repair it myself, but i want to be prepared before i attempt such a task, long time fan of your work and i highly respect your knowledge.

Nice lesson my friend

@bigclivedotcom please revisit this power supply later and upgrade the output circuit to support an adjustable power supply. Maybe 0 to 40V would be a good target?

Seems a lot of gubbins and effort, nicely done, I tend to just take off 240v from one of the phases for my control, contactors, relays etc. for invertors for motor drive.....

Nice vid mate

They do make 3p power supplies to 24vdc din mounted. However I just use 1 leg of a 3p power supply to a 1p power supply.

"And it's going to positive... Pretty sure it's going to positive", he says, while having his pen pointing at "V-" marking on the PCB.

Clive can sleeve my output windings...

Some newer viewers of Clive might think on first glance that Clive has a rather low production value for his videos, but the truth is he spends all of his production value on ink cartridges so he can print out full color photos of PCBs on massive canvases!

Nice reverse engineering & explanation vid! How long would you estimate this design would last compared to a design that uses a large transformer instead of a SMPS? You paid 8.85£ for the PS, how much would a comparable PS cost that uses a large transformer? Thanks for sharing!

Is this from China? If so China making some stuff not cheeping out and actually doing some circuits right? Ok joking aside I know not everything out of China is made quick and cheaply. It was fun to watch how excited Clive got when the circuit board was done right. Well except the one solder spot but other then that was a glowing review of this circuitry. :)

Good to see my favorite YT channel hasn't been deleted without notice.

I see big capacitors. This video is going to be interesting. Hopefully with lots of explosions and circuitry catching fire.

I'd love to see this kind of reverse engineering done for a contemporary desktop PC power-supply.

I know I'm a year late, but it appears our 33RC3 is actually a NCP1251 by On Semiconductor

3 Phase industrial power supplies dont usually have a Neutral. But most of them have a ground and a metal casing.

really good video

Great video. Thanks bigclive for sharing. What is the purpose of the link just south of C5 @24:30 that seems to goes nowhere?

How does the optoisolator feedback work? Is it pulsed on for 'overvoltage' so the control chip can reduce it's PWM duty cycle? They've got a 14V reference. Do they use the potential divider network to get a 12V reference and then compare the output voltage to that?

Interested to hear your thoughts on cheaper lab type power supplies.

I'm 100% convinced BigClive and Jim Browning must be from the same town. They sound , soo much alike

I miss videos on more complex circuits like this.

Well done.

My understanding is you also put resistors across series capacitors because even if they don't have any leakage, typical capacitors have a tolerance of 10%-20%. If one is 20% low and the other hi, you can easily exceed the voltage rating of the low capacitance one (assuming each is rated for half the rail voltage). Isn't that why all the resistors across the high voltage ones?

Hi Clive, really enjoy your videos. Probably crazy simple but do you know how a ring doorbell works with origional doorbell chimes while taking power to keep charged at the same time? Cant get my mind round how it can replace a simple switch (door bell) controlling power to the origional chime. Using the supplied power to power itself without triggering the origional chime since surly it needs to close the circuit in turn powering the chime in series in order to get power itself? Couldn't find an answer online and thought I bet Clive knows the answer ;-)

What kind of fuses are those? I'm asking because I'm just starting to learn the basics and wanted to search them on the net to take a closer look. Thx

Surprisingly well made for $5.