In most other parts of the computer the worst that can happen in most cases is that you damage the computer, the power supply is different, there you also have a good chance of getting shocked.
So, to add another advice, be sure that you have a ground fault circuit interrupter or residual-current device and test it regularly.
If you receive a shock, if can affect the rhythm of your heart and cause problems later. We’re taught to go and get an ECG after receiving a shock. Like jump in the car and go to the doctor or hospital and have someone else drive you.
If you’ve received a shock - go get checked out.
Your heart muscle is controlled by a tiny voltage. Suddenly forcing it to follow 50/60Hz of a huge voltage isn't precisely natural, and something that can leave lasting damage even if your heart seems to work just fine immidiately after.
There is a reason in electrics a lot is done just to prevent electrical shocks (e.g. RCDs), because you know: it kills people.
I am legally allowed to connect houses to the electrical grid in Germany.
That was an electrical shock that in my naive opinion does not pose a cardiac risk.
I imagine that there is some judgement call to make about what is "electrical shock", and when does it pose a cardiac risk.
If all is going well, shocks are rare, and so I could imagine as a rule "if you felt a shock, go to the doctor". But in some [yes, of course, unfortunate, avoidable, and unacceptable] contexts, a rule like that might not be followed. That is why I was wondering about what guidance electrician's unions provide.
"basic respect for human life" and "unions" can have a lot in common, especially in such a country.
That's common in the way shark bites and lightening strikes are common. Dropping dead hours after a minor electrical shock is so rare you shouldn't even be worrying about it.
>You should always see a cardiologist even if you feel completely fine.
It was included in your training so the company could cover its ass. By including a comically over the top warning and recommendation like that they are ensuring that statistically nobody will follow the training and the company will have leverage if you get hurt on their watch and sue.
It's a really shame that this kind of disingenuous ass covering behavior gets picked up and parroted by people as though it were honest advice because it moves the overton window and leads to a world where everyone acts like step-stools are a serious threat to public health.
Everybody follows the training, because you get fired if you don't, or your manager gets fired. I don't know where you live, but here we have unions that make sure workers are as safe as reasonably possible.
A very good summary article is here: https://www.bmj.com/content/357/bmj.j1418 .
Take home points:
-- Arrhythmias (superventricular and ventricular) are common
-- Exposure to high voltage can cause asystole directly
-- Delayed [life threatening!] ventricular arrhythmias have been reported for up to 12 hours post incident, both with high and low voltage shocks
-- Delayed, serious bradycardia can result months or years after the accident
-- The SA nodes are particularly vulnerable; patients may effectively give themselves an SA node ablation
-- Direct myocardial injury may occur without chest pain (due to nerve damage)
-- MI may also occur via coronary spasm or thrombus.
That neglects the rest of the body -- where the effects can also be significant.
Electricity in large amounts is bad for you – c.f. the electric chair!
Yep. This is what defibrillation is. When you use a defibrillator, you're shocking the heart into asystole in the hopes that it will restart itself. Shocking an already "flatlined" heart will not restart it, contrary to what many movies would have you believe.
> The SA nodes are particularly vulnerable; patients may effectively give themselves an SA node ablation
This I did not know. Wow!
For normal household circuits I’d just say learn from your mistake.
Think of it as an inverse lottery you really really don't want to lose. The outcome, not the odds is what matters in this case.
The Alanis Morissette method; I've got one hand in my pocket, and the other's probing a live circuit.
I mean, we're talking about an organ that runs off of millivolts. Surely the heart is close enough to the middle when we're talking about running 120 or 240 volts of AC through it?
IIRC they were rated at 600v, and would leave black indents in the skin.
Kids are effing stupid…
You'll get a nice, painful reminder to respect electricity that'll last a few days, and not be in any actual danger.
(I also did the exact same thing as a teenager)
Seriously thought electrolytic capacitors need to be respected but not feared.
Knowing that they could deliver a nasty shock, I discharged one once by shorting the terminals with a screw driver.
The sound of the spark, and the scorch mark left on the PCB and screw driver left me fearful of them.
Or was that caused by the knowledge that I had a friend who said he put one of those capacitors in a highlighter, thereby making a makeshift, single-use, "shelf-unstable" taser?
it's also interesting to witness a bit glass thing acting like a capacitor
ps: for long I wanted to make a discharge rod but never finished it
The very first capacitors were glass jars:
In a power supply, you'd also have to worry about shorting and shocking other ICs with steel wool, but not with a big capacitor.
But that didn't stop him from encouraging me to experiment while taking precautions. As a teenager I destroyed two ATX PSUs trying to add 110vac compatibility to an 12vdc RC battery charger. Third time was the charm.
Even after that, I continued to do dumb things around electricity. I'm not all that smart.
Additionally there are typically bleed resistors to drain capacitors to safe levels, but they can also go open.
They're inexpensive for desktop/gaming machines and if there's a fault its either in warranty or its time to purchase a new one.
i repeat danger
There are components in there that can exceed mains voltage when probed the wrong way.
When you start getting into the higher voltages, the body’s resistance is much lower. It only takes a few milliamps to stop the heart.
Not in a normal power supply.
Sure it's peak rather than RMS, but a warning that something "exceeds mains voltage" to me sounds like a description of a significantly bigger danger than that.
Is it to discharge that capacitors?
- Always ground yourself to an actual building rod or a rod planted at least six feet deep.
- Lock out, tag out everything. Our tools were metal, go work on ONE truck with a battery array without an extension and you will almost certainly arc something.
- Voltage isn't what kills. It takes an insanely low amount of amperage to stop a heart.
- Always have another person nearby with a wood or rubberized object to disconnect the circuit. Being stuck being electrocuted is a surprisingly slow death that you will be entirely conscious for.
Personally I would probably not want to mess around inside a AXT supply.
But dielectric soakage runs in reverse, too. So even if you short out the capacitor once, it can recover some voltage after days to months left open again. (The energy comes from the molecules in the dielectric relaxing, very slowly.)
This isn't a problem if the designer has put in a bleeder resistor across the capacitor. But some designers are cheap, and don't want to pay the extra few cents to make their products non-lethal to technicians. Some are just stupid (yes, dumbfuck "senior engineer" coworker, I am thinking of you here, you colossal waste of oxygen).
What you want to do is short it out, with a screwdriver or otherwise, then keep it shorted with a gator cable or even resistor. Then you'll be safe even if you set the project aside for a week. Or three months.
I wired up an unwisely huge bank out of them for some fun HV experiments. They were in a shed outside and could self charge to useful levels in the course of a windy day. Dont recall the actual numbers but it could vaporize dimes handily.
Mains filter caps will be lucky to recover a few dozen volts, which isn't going to do much (and inside a PSU, if the voltage is high enough it will try to run and quickly discharge them anyway.)
Maybe I'm just salty about having had this argument too often recently. But I strongly believe that every mains voltage or higher system needs bleeders across its capacitors. If you don't want to pay for the resistor, fine... but leave the footprint for it.
This goes 10x stronger if the thing is open-frame, sits on a bench, and is regularly being probed by engineers. Just put the goddamn resistors in there before someone gets hurt.
Ahem. Apologies for the intermission.
Check for voltage - If not present / marginal, Then shorten, Else discharge through resistor and GoTo Check. A "capacitor discharge tool" automates this cycle.
1. Electrolytic capacitors: Only Japanese brands can be trusted (this sounds racist or something, but it's an actual requirement). They all should be de-rated for reliability (have 2x the voltage rating). Only exception is the main bulk filter capacitors, where your only reasonable choice is 450V, but these should be 105C. Tantalum capacitors: not allowed.
2. Main switch MOSFETs: only Infineon can be trusted. Single active clamp / single switch topology is a no-no due to bad experience. (I think the one in the article uses a diode clamp, so should be OK).
3. Standby supply needs its own fuse. The problem is that the main fuse is too big for the standby supply. If there is a standby supply fault, you will fill the machine room with smoke and your brand will be mentioned in the news when machine room is shut down. This destroys shareholder value.
The current limit for any exposed 12V rail is only 20A or something line that (240VA UL limit), so you must not have exposed 12V when the server cover is open.
There was basically a 100 page requirements document all along these lines.
Although even putting this aside, capacitors don't seem to age well - anybody interested in 80s/90s electronics and gaming, will be aware that they should check boards before plugging them in, and if in doubt, but a 're-capping' kit
https://jianghai-europe.com/wp-content/uploads/Jianghai-Euro... (page 9)
That's because A: It's my PC sound, so, I uh, need it. and B: It sounds better when it's good and warm, which takes a bit if it's powered off.
Of course it's solid state and not tube
Old-timey capacitors with organic electrolytes are still available for applications that need reliability more than the best ESR or highest density, but they're kinda rare and expensive.
Edit: then there is “RIFA plague”, which shows that you can get same issue even with better engineered encapsulation material.
I've replaced the electrolytic caps in two different stereo recievers and one amplifier, all from the 1977-1980 era. Only one of the three had noticable difference in sound quality, but it was the one that had clearly been abused over the years (failing power switch that arced and sputtered, absolutely filthy and blown bulbs when I got it)
Some industrial espionage went wrong and a bad electrolyte formula was stolen, and of that's of course what manufacturers who were trying to save a buck (all of them for the most part) got.
Nothing like "we're spending this whole month dealing with bulging or otherwise faulty capacitors" to raise eyebrows. As I recall it was a rolling wave of work done to mitigate multiple supply chain failures. "Just" because of capacitors.
The author makes a point that there's a clear division between the AC line side and the DC side. That's required for UL approval, but power supplies do show up without it. The power transformer that crosses the boundary should also have a split bobbin, so the AC line side coil and the output side coil are separated by a barrier, not wound on the same bobbin.
There are worse power supplies.
One of the constructors attacked them and lost.
Separate bobbin is not required for robust isolation.
For example, just right now on my bench there is a medical separation transformer. No separate bobbin (hint: it is toroidal).
Most PCBs with large, heavy through-hole components are still manufactured by hand, by the way.
The originator of that website landed a dream job doing R&D for Corsair. The owner of the domain (not Johnny, as far as I can tell) simply decided to let it expire.
I'm using a Corsair RM1000x basically because it got full marks on his review.
And even older PC power supplies also provided a -5V voltage, the corresponding pin on the ATX connector is now (according to Wikipedia) a reserved pin.
This progression also shows in the expansion slot standards: the ISA slot had pins for -5V and -12V; the PCI slot removed the -5V pin; and the PCIe slot finally removed the -12V pin. That is, a motherboard without any ISA or PCI slot, and without a RS232 socket or header, has no use for the -12V voltage.
And there's already a newer power supply standard, called ATX12VO, which simplifies the power supply by providing only 12V (and a separate standby 12V). There's already at least one motherboard built for that standard: https://www.anandtech.com/show/15763/first-atx12vo-consumer-...
What prevents one from just wiring mobo.5v to port.gnd and mobo.gnd to port.-5v? That would effectively create a -5v potential between port.gnd and port.-5v
I don't know what -5 V was used for. Maybe some analog circuits somewhere, very early MOS logic also often had awkward supply voltages (charge-pumps made this obsolete too, just like high-voltage supplies for EEPROMs).
However usually there is. For example, the device might need +5V or +3.3V as well.
Well you can't supply +5V and PSU ground as separate leads, because almost always multiple ground connections are internally connected in a device.
Thus that would mean the +5V rail gets shorted to (PSU) ground by the device.
It'd be nice to have power monitoring on that side of the mainboard's power regulators and caps, to pick up marginal issues before they get filtered out, and the power supplies these days will have a little ucontroller with all that information anyway without the mainboard having to duplicate that monitoring circuitry in the right place.
For what's such an important piece of a computer there's so little introspection for data while in use that has to be being collected regardless. Yeah, you can always hook up a oscope or what have you, but catching it in the act of being marginal early on would have saved me more hours in my life than I'd like to admit.
I don't really have enough data to outright blame the power supply. I don't think I connected all of the 12V lines to the motherboard (power supply didn't come with enough cables), and I can't be sure that the motherboard was designed properly for a mildly-overclocked 6950X (VRM banks, capacitors near the CPU, etc.)
It was all enough of a pain that I will never buy another Corsair power supply. My current best practices involve only buying Seasonic power supplies, and connecting every possible "optional" power connector to the motherboard. If the PSU doesn't come with enough cables to do that, buy them separately. My current Threadripper motherboard has a 6-pin and 2 4-pin ATX12V connectors, and a Molex connector. Many are marked "optional" in the motherboard's instruction manual, but I have them connected anyway. Probably overkill. Great stability. Without having designed the system or the test scenario, skipping optional things sounds like the sort of thing that's going to cost you a lot of time at some random point in the future. Best to avoid, even if you look like an idiot to the EE that designed the board.
Here is my output from lm-sensors
Adapter: HID adapter
v_in: 230.00 V
v_out +12v: 12.00 V
v_out +5v: 5.00 V
v_out +3.3v: 3.00 V
psu fan: 0 RPM
vrm temp: +49.0°C
case temp: +40.0°C
power total: 96.00 W
power +12v: 80.00 W
power +5v: 16.00 W
power +3.3v: 8.00 W
curr in: N/A
curr +12v: 6.00 A
curr +5v: 3.00 A
curr +3.3v: 2.00 A
After quick searching is looks there are people reading this info with a MCU . But I think it would be hard to find such PSU in ATX form factor.
The power clients (mainboard, GPUs, disk drives, etc) normally know they're getting pretty bad power from a PSU and filter it heavily to smooth it out. It'd be nice to know if the voltage is occasionally dropping and it's just being covered up by downstream caps that are over provisioned to just smooth out not fully rectified AC.
You don't need a CPU core to do this, and the older, cheaper parts do not necessarily have a CPU in them. There are even (iirc, very uncommon) designs with no digital logic save the switching.
The entry-level and lower-priced ones don't, AFAIK.
But they don't last forever, and my old file server's 10-year-old PSU finally started causing random errors about a couple of months ago - recognized when a sustained hard disk operation dimmed the power LED. I had spares, but it's time for me to think about building something new. Whether it's more computing power for the same electrical input, or the same for less, I can do better.
Even quality brands have crappy models.
They are not necessarily the cheapest ones, it is possible that the 400w is fine, the 550w is crap, and the 600w is fine again, even if they are in the same series.
They can also change the specs over time, without any indication on the packaging.
You have to look for reviews where they actually disassemble and check the insides of the psu to determine if it is a good buy.
There is a forum local to my language where they keep track of the small number of truly recommended models, there must be an English equivalent.
I just knew which video is linked without clicking. ElectroBOOM is a treasure.
And yet I learned something. In nearly 50 years of playing with electronics I've never seen such a beautiful LER (light emitting resistor).
Edit: I am disappointed in his hooking up his oscilloscope ground to some random point of the circuit. Did he really do that? It sure looked convincing on the video.
It's something that everyone using scopes learns not to do very early on. It can't be good for the wiring in the scope.
Though probably not due to current, likely someone took a torch to it to try to make it easier to remove, and then took a picture. Then again those connections are vastly undersized for the cables...
Honestly, I can't tell if this is a good thing or a bad thing.
On the plus side, power supplies will be much simpler to design and test, with potentially better efficiencies.
On the other hand, all those additional DC-DC converters will take up quite a bit of space on the already crammed boards, and now you got more heat to manage.
No heavy loads are connected to the 5 V / 3.3 V rails. Those are all supplied through the 12 V rail.
Yeah, not only is 3.3V not guaranteed to be there, the latest rev of the SATA power spec reused (at least one) of those pins as a signal to inhibit spin-up; used for power sequencing in large disk arrays, with the fun side effect that if you've got a PSU old enough to have 3.3v on sata power, and you use a hard drive new enough to support spin-up inhibiting, you need to either tape the pin, or cut the orange wire, or you can't use your disks.
Though you do have a good point, nobody misses -12V and -5V.
Some of us (masochists) actually like RS-232!
A modern supply would use the same principles, but would probably have mostly surface mount components, a single controller IC, and probably separate switching supplies for each different supplied voltage.
Obviously some components in a power supply still need to be through hole for mechanical reasons, but it isn't many.
Great generic current mode control circuit good for lots of things, not just supplies. Still in active use today. Datasheet is like a textbook.
For example, Here's a (very packed!) modern 1600 watt (!) powersupply from Corsair: https://cdn.cplonline.com.au/media/description/POW-COR-AX160...
You can definitely see that SMT is used for the distribution side, but you can see single-layer boards used closer to the A/C side as well.
Surface mount components exist in some cases that are very compact but you pay a large premium.
If you continue further on to the motherboard, the CPU has a multiphase SMPS (sometimes exceeding 20 phases!) that drops the voltage further to core and IO voltages (usally ~1.8V or less for the former) but still has to generate lots of Watts (think about a Xeon or Ryzen at 3+ GHz).
What's really neat IMHO is how Apple changed the <5W adapter market by moving to dense SMP in such a brilliant form factor. It can take 120/240 because it is a buck converter and doesn't care about the input voltage.
I've wondered, if the SMPS circuit in the 5W apple adapters be scaled up to 600~800W would they be enormous and/or less efficient? Because it seems like the circuits in this board are either designed for higher power so big honkin' coils & caps are necessary, or are they that big (and inefficient) in order to save money?
All power supplies of a few hundred watts will look broadly the same as this one. The rare exceptions are very expensive AC/DC modules, and linear power supplies used mostly in higher-end audio and test equipment.
There are a number of factors that influence the designs that are practical for different power outputs but a big one is the gate charge of the switching transistor. Bigger output power requires a bigger switching transistor which stores more charge in its gate. This requires more energy from the controller to charge and discharge the gate and more concern about the ohmic losses in the transistor as its transitioning from being on to being off. This limits the switching frequency you can practically use. Lower switching frequency means larger transformer; you need more iron to take the magnetic field so it doesn't saturate on the larger slower pulses.
Note also that with more power almost every component needs to be larger. Also note that standard PC supplies need to supply many voltage rails while the classic Apple 5W adapter only needs one. With newer standards like ATX12VO the supply only supplies 12V and 12V standby.
Isn't that a lot of power?! A modern PC can easily draw 500W or more. Does that mean there's some enormous magnetic field in my power supply? Why doesn't that pose a problem for the things around it?
(I cheerfully admit to being very very good at manipulating bits, CPU opcodes, and TCP/IP packets and knowing next to nothing about electrical engineering.)
Also almost nothing in your computer is affected much by moderate magnetic fields. Go ahead, stick magnets all over the motherboard!
Also, the energy of an electromagnetic wave grows as the 4th power of its frequently, IIRC. This is why old power supplies which directly used the 60Hz frequency from the socket were so bulky, while modern power supplies, which convert the mains electricity to high-frequency AC, can use physically small and lightweight transformers.
It's much more roundabout than that.
A transformer has a magnetizing inductance (you can measure this with an LCR meter by leaving all other windings open). This is generally a pretty big inductance (several henries for mains transformers). When you supply a waveform, that inductance will cause a small current to flow. That's the magnetizing current. The problem is saturation - if the voltage over time gets too large [=the magnetic field in the core], the transformer's core will saturate (that's also why transformers cannot handle DC; any DC offset will accumulate over time and cause saturation). This causes the magnetizing inductance to drop to approx. zero. When that happens, the magnetizing current becomes huge, basically a short circuit.
This means that you need to avoid saturation. Note that the strength of the field depends on the number of turns - each turn reduces the impressed field. So you want as many turns to avoid saturation as necessary, but as few turns as you can get away with (each turn adds resistance, and needs space inside the transformer).
And this is why mains transformers are so big. Because the frequency is low, voltagetime is large. So they need many, many turns (a few hundred to thousands) in order to prevent their steel cores from saturating. So the primary winding is a very long wire, which has a lot of resistance. So you need to increase the size of the core to fit a thicker wire, in order to avoid resistive losses. Now that bunch of wire doesn't fit any more through your transformer, so you need to use a bigger core, but wrapping N turns around that needs even more wire and so on. So you end up with a big, heavy transformer.
For a high-frequency switch mode power supply, the frequency is high, so voltagetime is orders of magnitude lower (e.g. 100 kHz vs. 50 Hz = 2000x lower), so they need far fewer turns. So their primary winding's wire is short, so it can be a) a little bit thinner and b) takes up much less space! So you get a small, light transformer.
But the core, it doesn't really care about power, like at all. It's all about not driving it into saturation, and having windings that can carry your current. Those two factors make the cores of mains transformers so big.
Saturation for mains transformers is not usually an issue but there are a fair number of electronics that could be made smaller with materials supporting higher magnetization.
How Does a Computer Power Supply Work (ATX): https://www.youtube.com/watch?v=Cur3nQjjyyo
How To Repair a Computer Power Supply (or other switching power supply): https://www.youtube.com/watch?v=HcYFbCqM61g
I know the Apple I was a kit and came with no power supply but every one I've ever seen the hobbyist has added a clunky linear power supply with a monster transformer and giant electrolytics.
It's almost like the two computers stood so near but just across from one another on two sides of some threshhold.
From https://www.electronics-tutorials.ws/power/switch-mode-power... "The Buck Switching Regulator" looks like an arrangement with a diode, inductor and capacitor is enough. Interesting.
A transformer converts electrical energy into a magnetic field and back into electrical energy. All the energy from a single 'sine wave' must be stored in the magnetic field inside the transformer briefly before coming out of the output. The transformer core is made of steel usually. For a given weight of steel, there is a maximum amount of magnetic energy it can store.
That means that at low frequencies like 50/60Hz, transformers end up very bulky.
The motivation would be to try to eliminate the full bridge rectifier and the high-voltage capacitors.
I'm not an EE, but I would guess the simple answer is it's because you can't pass a AC through a transistor, since a transistor not only switches but also acts like a diode.
I think you could work around that (build a circuit that switches AC with transistors), but there must be a reason why you wouldn't want to. Perhaps it's because it's simpler to just go ahead and rectify, or perhaps there's an advantage to having capacitors on the high-voltage side.
There are two stages: power factor correction, and the forward converter. The forward converter uses a transformer mainly for isolation. The power factor corrector exists because the transformer is an inductive load. If you have too much of an inductive or capacitive load on a distribution network you affect is performance.
You can make the power factor corrector, which does the rectification, out of active components that switch in time with the AC signal. This eliminates the voltage drop of the diodes which can be a few percentage points of efficiency and a fair bit of heat.
If you didn't need to isolate the power supply you could chop mains directly but you need to manage the radiated noise. The current designs try to maximize safety and then economy and then efficiency. Coincidentally, the power factor correction, done correctly, also helps reduce radiated noise by keeping the system synchronized with the incoming power. (This is not precisely accurate but is an interesting way to think of it.)
4.1.1 A-c power. The a-c power system shall be a 3-phase, 4-wire “Y” system, having a nominal voltage of 115/200 and a nominal frequency of 400 cps. The neutral point of the source of power is connected to ground (see 3.2), and the ground is considered the fourth conductor.
5.1.5 Steady-state frequency. The a-c power systems frequency shall be maintained at 400 ± 20 cps for steady-state operation.
They are easy to build, much less complex than switching power supplies. But as others say, less efficient and I'd guess more expensive, these days, unless you have some spare toroid transformer and high capacity low voltage capacitors laying around, already.
Just the toroidal transformer for the 800W power supply would weigh like 8kg or so. :)
Saved me from buying one and kept the power supply from ending up getting throwed out.
"Win-win", as my annoying ex-boss would say.
Which can result from releasing some magic smoke if you are lucky, to a call with your insurance company.
I like Seasonic's fanless series, but wouldn't mind getting a bit more power out of the same size PSU.
The main components with losses:
* The input capacitors are non-ideal and have some resistance. That resistance causes heat every time current flows in or out of them.
* The MOSFET switch has an 'on resistance' which means it wastes energy when current flows through it.
* The MOSFET takes a certain time to turn on or off. During that time it is partially on, which wastes a bunch of energy each switch.
* The transformer has resistance in the coils.
* The transformer has iron core hysteresis, which makes the steel of the transformer get warm as magnetic fields change in it.
* The diode on the output side has voltage drop across it.
* The capacitor on the output side has resistance.
There are also supply chain and security considerations, though. You can buy magic PSU chips but what if you can't?
And I'm not up to date on modern electrical design, but a satellite-view on industry innovations & trends would be interesting.
I'll make a Hackaday page. So far I've got:
I just started putting myself out there. I have material queued up that I need to edit and I need to pick out the good parts for blog posts. I've started acquiring components for the prototypes. Sadly it's slow going, HW prototyping is kind of expensive for me right now. My design progress is way ahead of what I've actually documented and I need to start documenting so it looks better.
That said, most supplies for sale are based on old, fossilized designs created ~10 years ago, hovering at around 80%. If you spend more you can get the gold, titanium, etc. But then, even those tend to be below the maximum you can get, which is closer to 98% if you have information about your load. You can also design the system to have better efficiency at various loads. Typically half, but could be worth tracking newer CPU/mobo/GPU developments.
The 170W power supply for my old ThinkPad W520 measures about 17cm x 8cm x 3cm and weighs about 580g.
The 170W supply for my new X1 Extreme measures about 14cm x 8cm x 2cm and weighs about 320g.
Does anyone know what technology let them make the power supply so much smaller and lighter?
(Note that Lenovo itself almost certainly doesn't design nor produce them -- if there's a UL registration number or similar, you may be able to find the actual OEM/ODM.)
 You can see something similar in the marketing specs for cars vs. trucks - a performance car may have a 2L engine rated for 300HP, while you can find a truck with a 9L engine also rated at 300HP. The former is unlikely to last for long putting out its rated power.
Electronic speed controllers for brushless motors are one area you can really see this too - they are amazingly compact, efficient, and high power now.
Although called a magnetic amplifier; this application really
uses an inductive element as a controlled switch. A mag
amp is a coil of wire wound on a core with a relatively
square B-H characteristic. This gives the coil too operating
modes: when unsaturated, the core causes the coil to act
as a high inductance capable of supporting a large voltage
with little or no current flow. When the core saturates, the
impedance of the coil drops to near zero, allowing current
to flow with negligible voltage drop. Thus a mag amp
comes the closest yet to a true "ideal switch" with significant benefits to switching regulators."