Why not power peripherals off the PC power supply?

[jtr1962]

After experiencing the problems that occur when the power supply of a product is an afterthought, as it apparently was with the Microtek 4850 scanner my mom bought, it occurred to me that all peripherals should just tap into the existing PC power supply. Physically, this will mean no more outlets blocked with those stupid AC adaptors. Electronically, since the PC power supply is heavy duty and well-regulated, it should mean an end to power supply related problems.

I don't see any downside to this. Not having to include an adaptor with everything can only lower the price. The current drain on most peripherals is usually 10W or under, making supply capacity almost a non-issue. It's simply a matter of standardizing on a plug that has pins for +12V, +5v, and GND, and then putting maybe about five mating jacks on all PC power supplies. Since -5V and -12V usually can't be supplied in any great amount, these voltages can be made(if needed) inside the peripheral with an single chip such as the 7660. Usually they aren't needed anyway.

My only question is why wasn't this done years ago? It certainly seems like a no brainer. I've just about had my fill of AC adaptors. They're stupid, annoying, unreliable little things that always fall out of the socket whenever a stray breeze hits them. Sort of like a rooster that you need to have to wake you in the morning but then it just makes noise and craps the rest of the day(sorry I couldn't think of a better analogy).

 

[Mercutio]

The AT specification DID offer a plug for a monitor. 15 and 17" displays blew a LOT of PSUs.

Really, this is a matter of size - power supplies are trending to physically smaller, as anyone who has worked on a new-ish HP, emachine or Dell can attest. I don't think there's ROOM for a bunch of extra plugs. Secondly, more plugs = more strain on a part that's already dubious in its quality.

 

[Mickey]

I'd rather not have yet another long cable going from my scanner or printer to the back of the computer.

 

[blakerwry]

Honold, USB and firewire(i think) both provide external power to peripherals. Although they only offer small amounts of power, it is a great improvement and allows for lots of devices to easily conenct to a computer without the need for more AC adapters.

The problem stems from the fact that there needs to be a set limit to how much power a peripheral can draw, how many peripherals can be connected at a time, and how a PSU is set to handle the extra current draw. USB takes care of all this, although it's power specs are set pretty low. Devices with mid to high power requirements are forced to use AC adapters, this in my mind is a good thing as it decrease load on the computer and increases stability.

Digital cameras, speakers, scanners, tablets, and flash memory media are all better off because of USB. An addition I'd like to see would be external hard drives and printers being powered soley off USB.

Hard drives (especially laptop drives) I would think would be easily possible, printers however might not be because of their sudden/choppy and probably high power requirements.

 

[jtr1962]

Monitors really wasn't what I had in mind since they have a regular small plug, not an AC adaptor, and they take a rather large amount of power. Ditto for laser printers. Rather, I was thinking of the small, fairly low power peripherals like scanners, ink-jet printers, speakers, tape drives, and external drives, all of which almost always seem to have adaptors instead of regular plugs. These are things that in total might use under 100W. I'd rather just have a somewhat bigger supply in the PC. Besides the simpler cabling and less need for outlets, everthing goes off with one switch. You can have the power supply soft start the external power jacks one at a time after the PC is running to lessen the strain. Maybe all this will add $10 to $20 to the cost of an average power supply but you will save more than that on the AC adaptors for the peripherals.

Of course, if peripheral makers want to go back to making the needed voltages in the peripherals rather than in the adaptor, most of the problem is solved. I'm just getting tired of having 7 outlet strips where I can only fit three or four adaptors. :x Sure, USB is solving the problem somewhat but not everything can be powered within it's limits.

 

[blakerwry]

Monitors really wasn't what I had in mind since they have a regular small plug, not an AC adaptor, and they take a rather large amount of power. Ditto for laser printers. Rather, I was thinking of the small, fairly low power peripherals like scanners, ink-jet printers, speakers, tape drives, and external drives, all of which almost always seem to have adaptors instead of regular plugs. These are things that in total might use under 100W. I'd rather just have a somewhat bigger supply in the PC. Besides the simpler cabling and less need for outlets, everthing goes off with one switch. You can have the power supply soft start the external power jacks one at a time after the PC is running to lessen the strain. Maybe all this will add $10 to $20 to the cost of an average power supply but you will save more than that on the AC adaptors for the peripherals.

Of course, if peripheral makers want to go back to making the needed voltages in the peripherals rather than in the adaptor, most of the problem is solved. I'm just getting tired of having 7 outlet strips where I can only fit three or four adaptors. :x Sure, USB is solving the problem somewhat but not everything can be powered within it's limits.

why don't you get a power strip made for transformers?

What I did was to use an extention cord with power taps along the length of the cord.. I think it has like 8 outlets on it and since it's 2 prong only it works great for transformers... It's origninal use was for indor christmas lighting(has a 5A fuse) so it works well for my 2 sets of speakers, Scanner, KVM, network hub, etc...

 

[Piyono]

jtr, quick lesson -- in the place from whence I come, "power adapters" are lovingly and fittingly reffered to as "Wall Warts". As apt a description as possible. These suck.
A more highly evolved relative of the wall wart is the slighly more tolerable, albeit unfortunately much harder to find transformer, the "line lump". The line lump's superiority lies in its one major advancement -- a second line portruding from the other end of the box terminated with a wall plug, hence giving the line lump it's distinct appearance and well-suited moniker.


That's all.


Piyono

 

[blakerwry]

jtr, quick lesson -- in the place from whence I come, "power adapters" are lovingly and fittingly reffered to as "Wall Warts". As apt a description as possible. These suck.
A more highly evolved relative of the wall wart is the slighly more tolerable, albeit unfortunately much harder to find transformer, the "line lump". The line lump's superiority lies in its one major advancement -- a second line portruding from the other end of the box terminated with a wall plug, hence giving the line lump it's distinct appearance and well-suited moniker.


That's all.


Piyono

Line lumps are ok.. but they're only better than wall warts in some situations.

...basically the equivalent of putting wall warts on an extention cord.

 

[Fushigi]

jtr, check out the Canon LiDE20 or 30 scanners: they are powered by the USB port so there's only the one small cable. I've been waiting for the LiDE50 to come out but Canon might not release it in the US.

- Fushigi

 

[Mercutio]

One of the resellers I deal with sells 1-foot-long power cables. First time I saw one I didn't get it. They turn wall warts into line lumps.

 

[honold]

Honold

invoking my name for confusion effect?

 

[blakerwry]

Honold

invoking my name for confusion effect?

yes!

 

[Platform]

The reason we are stuck with external DC and AC power supplies ("wall warts" etc.) -- more than ever, I might add -- is because this is a less expensive and quicker method of getting a device UL Certified (USA) and the equivalent in electrical certification wherever else in the world a device is sold. A single device can be mated up to any one of 3 or 4 external power supplies and sold worldwide. Using an external power supply that has already been electrically certified can get a product to market quickly and without much testing.

Honold, USB and firewire(i think) both provide external power to peripherals...

Of these 3, only USB and Firewire provide external power to peripherals, unless Honold wears wool sweaters and leather shoes.

Even then, USB and Firewire can only provide just so much current over the channel.

The AT specification DID offer a plug for a monitor. 15 and 17" displays blew a LOT of PSUs...

The monitor power plug on the old AT power supplies was simply an AC loop-through connection.

 

[Fushigi]

The reason we are stuck with external DC and AC power supplies ("wall warts" etc.) -- more than ever, I might add -- is because this is a less expensive and quicker method of getting a device UL Certified (USA) and the equivalent in electrical certification wherever else in the world a device is sold. A single device can be mated up to any one of 3 or 4 external power supplies and sold worldwide. Using an external power supply that has already been electrically certified can get a product to market quickly and without much testing.

Still, the same effect could be achieved if the power adapter brick was at the device end and a normal plug was utilized.

Or, like most notebooks, in the middle. Use a universal external PSU with a varies-by-country stubby cable to hit the wall outlet. Same concept as the 1 foot power cords Merc mentioned.

Even my cel phone charger is a brick. While on the small side as far as the bricks go, it is still large enough to block the other plug in a normal outlet.

You know, at a minimum they should put in a pass-through plug like Christmas tree lights provide.

- Fushigi

 

[mubs]

Honold, USB and firewire(i think) both provide external power to peripherals...

Of these 3, only USB and Firewire provide external power to peripherals, unless Honold wears wool sweaters and leather shoes.

Shocking, I say! Absolutely shocking!

 

[honold]

 

[Jan Kivar]

Even then, USB and Firewire can only provide just so much current over the channel.

True, especially if the ports are integrated to the motherboard (=no add-on cards) the current has to go through the motherboard. I think that the max. ratings are 0.5A for both USB and FireWire port. If You have (and use) more than one USB port, the max. power is shared. (maybe there is 0.5A per USB controller/hub)

Cheers,

Jan