AC adapter size

Why do AC adapters have to be so big?  Can't they be designed more compact to say, 1/4 their size, or about the size of a regular outlet but with more height/depth rather than socket stealing width? 

Probably has something to do with durability, the materials can only withstand so much force, and if you make them smaller they will likely fall apart.

I have one here that supplies 18VDC and is all height and depth, so you could easily have two plugged in right next to each other.  As far as most AC adapters being big, companies usually go for the cheapest adapter that they can, a noisy switching supply, and make it big so its cheaper to assemble.  On the other hand, it could be big for a reason.  It may be able to supply a lot of current, so a larger design allows the heat to dissipate properly.  It could be a linear power supply, which regulates the power differently resulting in cleaner power.  These are used in medical machinery or high end audio where noise in the power supply could cause problems.

I'd say cheapness too. I wish someone would come up with a single standard for connectors. Then you could just have a bank of low-voltage DC connectors on a power strip or something, and connect various devices for charging or power using standard leads.

AC adapters typicaly use a step down transoformer, followed by a bridge rectifier and a big capacitor. The weight comes from the honking block of iron wrapped in yard upon yard of copper wire transformer. There are less noisy, lighter weight, smaller adapters that don't use a typical transformer. These also usually run upwards of $50 for a cheap one. And they still can get in the way because you have a high voltage circuit attached to wall outlet prongs. The real solution of course is to put the adapter somewhere a couple feet down the cord from the plug. But this too can get annoying.

I dunno, I rather like being able to plug AC adapters into more than just the end slot of a power strip. Mid plug transformers are the win.

Powerpoints should have inbuilt universal tranformers, then we can do away with adaptors

>>5
Wal-Mart was selling a compact switching universl power supply for like $20 a while back...good for one amp at any of the supported voltages. I bought one to run my Casio keyboard (CTK-611, not the Casiotone crap they used to make), since I lost the transformer I originally got for it way back in 1998-1999 or so.

>>7
My point exactly. Mains voltages are only needed these days for high power devices (fridges, kettles, televisions, etc). There ought to be a standard for DC (say, 12v) for our ever-increasing number of low-voltage devices. I've got a power strip with separate adapters plugged in for my mobile phone, my MP3 player, my GBA SP, and my PDA. If all these could be standardised to one type of power source, we could do away with those ugly wall-warts and just have two standard power point form factors - the current one for high AC voltage, and a newer one for lower DC voltage. Then device manufacturers could just use these as standard (you could even have multiple voltages - say, 3v, 5v, 9v and 12v in the same lead, and manufacturers just have the appropriate pins connected in the socket on the device to select the right voltage to power the device).

AC is used in homes because of the huge amount of power loss that would occur if a low voltage DC was supplied.  Even compared to a 120VDC line, a 3VDC line would cause 1600 times the power loss.  AC is also a lot easier to use because you can raise the voltage for transmission and lower it again for home use without using complicated methods.  The current power system is as good as its going to get right now, providing any sort of low DC voltage for home use would be impossible.

>>10
Duh, it's converted IN the home, most easily by just having individual transformers behind the power sockets (tidy and out of sight, with several DC sockets to one transformer). I'm not suggesting having low voltage DC lines running from each substation, for pete's sake!

>>11
Even that would result in a large amount of power loss. Not that the power companys would care because they get to bill you for all the power drain inside your building. I don't know about you, but I'm too poor for that. On an amusing side note about AC in the home, 60 Hz is about where the resistance of human skin is the lowest, making it the most dangerous frequency.

Plus, if you were converting to DC within your home, which then went to outlets, that means you would be running the AC/DC Converter 24/7, and you would have to pay for all the power lost as heat.  Not only that, but the DC lines would pick up interference from everything in the house.  Anything that needs pretty clean power, like audio equipment, would sound like shit unless you got a special power supply, which defeats the whole purpose of DC lines running through the house anyway.

What, you're going to get more power loss from a small transformer behind a socket than you are from a small transformer plugged into a socket (as current wall-warts are)? Read my post again; I wasn't suggesting you run DC lines all over the house, just convert it at the sockets where it's wanted. And you wouldn't need to run them 24/7 either - just have a switch there to turn the DC sockets on and off (by isolating the transformer). It would be tidier and more convenient that having a dozen different and incompatible wall warts lying around in drawers and hanging from sockets, and just have a single DC connector standard instead. Of course, it's all just idle speculation - it's never going to actually happen... :(

that would be a big bloody waste of time. Unless you had a veriac, installed on each socket...*exspensive* youd have to switch your voltage and ampres by hand, every time you wanted something new. Or else wire in a whole lot of tranformers from the gitgo. any way you go, very exspensive, time consumeing, and bulky.

>>15
You're STILL not reading my earlier post - I suggested having multiple pins in the standard connector for multiple voltages (just four or five voltages and common ground), and device manufacturers just connect the appropriate pins in the charging/power socket on their device to select the voltage(s) required for the application. If there was a standard for low-power DC power connectors, device manufacturers would design their stuff to comply with it. It wouldn't cost any more per socket than a handful of the current AC adapters we all have cluttering our homes, and you'd only need a few (one per room). But, like I say, just a pipe-dream (or would that be a wire-dream?).

They house a transformer to step the voltage down from mains (120/240V) to a more manageable 12V or less. That's why they get hot when you leave them plugged in even when there's nothing connected to them.

The factor being overlooked is amperage.  The voltage and current drawn by the DC appliance dictate the power requirements for the AC adaptor.  The adaptor has to be made of components capable of delivering without melting or shorting.

The solution I like, when it can't be made small enough, is inline bricks like most notebook computers use.

>>16
That would be the most pointless thing ever.  There would have to be a switch for each one individual one, because you would be wasting lots of power if nothing was plugged in.  Even with something plugged in, it would be wasting power because it would be supplying all of the different DC voltage sockets.  If you wanted it to handle something like a laptop, looking at my laptop's adapter it needs 20V/4.5A.  So, this thing would need to have enough DC voltages that, if all put in series, they would at least be 20V.  It would also need to be capable of providing the 4.5A.  Each of these things would cost hundreds if not thousands of dollars, and they wouldn't be accessible because they would be behind the wall, at least until the thing gets so hot that it burns a hole through the drywall.  I think its a little more practical just to use wallwarts for now...

>>19
No, you'd just have a single switch to turn all the sockets off when none of them are being used. And I wouldn't class a modern laptop as a "low power DC device", considering they draw as much or more power than a TV set or incandescent light (mine guzzles a whopping 90 watts). Mobile phones, MP3 players, PDAs and the like *are* low power devices, consuming mere milliamps, usually at lower voltages (3-12v), so supplying that amount of power is a trifle.