Laptop computer power supplies

[mshields]

Someone told me recently, that you could put 120, 208 single phase or 240V into a typical computer power supply and still get the 20V dc output. He claimed that diodes in the power supply regulated this nearly perfectly.

This is a person who is often wrong but never in doubt.

Any input on this?

 

[petersonra]

most computer power supplies are indeed rated for an input of 100-240V, 50-60Hz. that way they can be used anywhere in the world simply by changing the power supply cord.

 

[LawnGuyLandSparky]

most computer power supplies are indeed rated for an input of 100-240V, 50-60Hz. that way they can be used anywhere in the world simply by changing the power supply cord.

Yep, that's exactly what the in-line power supplly reads on my Dell. AC 100-240v 50-60hz. Output DC19.5v.

 

[zbang]

Just to avoid confusion: typical laptop supply- yes. Desktop supplies usually have a voltage switch.

 

[spsnyder]

The advent of Switch Mode Power supplies has revolutionized the size and performance of power supplies. They now have feed-back that allows for very large ranges of input voltage. Unfortunately I think he is right. Just tell him that even a blind squirrel gets a nut some days.

Regards

 

[LarryFine]

Anyone notice that the newer electronic ballasts have the same input characteristics? Not a coincidence.

 

[infinity]

Seems as though power supply manufacturers make the input cord removable so they can install any input configuration that's out there. The guts of the supply and the low voltage cord/connector are always the same just the input cord with the 100-240 volt plug on the end needs to change for various voltage systems.

 

[iwire]

Just to avoid confusion: typical laptop supply- yes. Desktop supplies usually have a voltage switch.

No switch on newer desktops, just change the cord set and plug it in.

 

[brian john]

Omron manufacture time relays with multiple functions, time delay settings and they operate over a wide range of voltages.

Our control guys use to carry a variety of relays to accomplish all the options this one relay can offer.

 

[kbsparky]

We traveled to Easter Europe last fall, and all we needed was a dual pin plug adapter to power up the laptop. I measured the voltage at various places that we stayed, and found a range of 220-240. Frequency measured 49.9 to 50.3.

Came back home, and removed the dual pin adapter, the computer still works fine on 120.

 

[brian john]

One thought comes to mind...NAME PLATE DATA. 100-250 VAC 50-60 HZ Toshiba Laptop

 

[tallgirl]

The design of most computer power supplies allows them to work over an extremely wide range of input voltages, frequencies and even waveform shapes. I went looking for something I could point y'all at, but this article is out of date and still talks about input voltage switches. This article is more accurate, but also longer and more technical is nature.

The simplified answer is that the power supply contains parts that very rapidly turn on and off the input from the line, as needed to maintain the appropriate voltages under varying load conditions. The slices of the input sine wave are then used to charge banks of capacitors in order to provide a more constant source of power, and those banks then feed a variety of regulators which provide the final output.

 

[dereckbc]

It is all in the magic of Switch Mode Rectifiers. The old technology of Linear Power Supplies is all but gone. With Linear PS the line is connected directly to a input transformer, stepped down to say 24 VAC, rectified to DC, and then regulated to say something like 20 VDC. So in the case of a linear PS the input voltages was a small window or range of voltages of something like 110 to 130 VAC.

Switch Mode is a completely different animal. AC line voltage is immediately rectified to DC, eliminating the 50/60 Hz stepdown transformer. The line DC voltage is converted to a high frequency AC usually above 60 Khz, fed to a step down transformer, and then rectified again to a usable DC voltage.

Why you ask? B/c it is much more effeicient in operation, and high frequency transformers are much smaller, lighter and cheaper then their 50/60 cousins.

 

[RRelec]

True, I believe that the PS's operate at 100-240V, but that the 240V is at 50HZ (little switch). From what I have seen and Installed regarding 240V is L to N, Not L to L, A lot of equipment is designed to run at 240/380, like 120/240.

Are you refering to 240 @ 50Hz or 240 @ 60HZ? Two different animals I believe. I don't think the PS's internal components are rated for 240V 60HZ. then again, I could be wrong.

R

 

[zbang]

My whole point is that while most laptop supplies of any age are any-voltage, there are quite a few desktop (and server) supplies out that are not. Desktops built in the last year or so are probably any-voltage, but many older than that aren't. The servers I installed last year have a voltage switch, and the couple-year-old Dell desktop sitting here has one. In the installed base, voltage switches are still quite common.

 

[dbuckley]

Until recently we had a lot of problems with desktop PC voltage selectors in school computers; kids would switch them from 230V to 110V, and the PSU would expire, as we've got 230V power. Bar stewards. Glad to see the introdution of universal supplies for desktops.