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A Universal Power Bus?
mjpalm21 asks: "A friend of mine recently sent me this story on a new universal power technology that charges devices through your desk. This is a cool idea, but it seems complex. I have long wondered why there isn't a universal power bus (UPB) along the lines of universal serial bus (USB). UPB would work like this: You would buy a n port UPB hub for your desk, and then all of your electronic devices (cell phone, PDA, computer speakers, modem, phone, hubs etc.) would plug into the hub via a standard UPB cable. I would think that the device manufacturers would be all over this as it would reduce their product cost (no need to bundle a power brick), reduce their packaging cost (smaller box), increase customer satisfaction (I know I would be happier), and give them another device to sell (the UPB hub and all those cables)! Why hasn't this happened yet and what would prevent it from happening?"
You can connect your devices using these universal cables.
Different devices require different voltages.. if the device is going to have a power brick built-in to it to convert from "UPB" voltage to what they need, then your UPB is what's known as a "power strip".
-- V
Remember back to the 80s and how clunky things seemed to be? Most of that was due to the battery. Everyone used the same batteries to help bring down costs, but then the final design was around the battery.
Since formed batteries have dropped in price significantly, they can make nice sleek designs and work the battery in rather than the other way around.
Whats this have to do with your question? If everyone could use the same power source, it would mean all devices would be required to support N Volts at N Amps (or set internal resistance accordingly). This means the addition of a step up or down DC-DC transformer to all devices, and taking a step backwards on battery design as you must accommodate the lowest common demoninator again.
However, not all is lost. There is a slim possibility you could add a layer of communications with the block and request a specific voltage from it, thus placing the logistics into the power block.
Figure out how to do that in a small package, and it may simply become the AC outlet. Quite clunky to accomodate at the moment, so specific individual bricks rather than an über brick is far cheaper, smaller, and much less prone to failure.
For now, just be glad the brick isn't an integrated part of the device.
Rod Taylor
Hmmmm.... lets see here.
115V * 30A = 3450W
Monitor
150W=High 17inch usage
Computer
1100W=enermax 460W power supply
Speakers
100W=decent sized computer speakers
network hub
10W
pocket pc
35W=HP Jornada
cell
35W
laptop
200W
for a grand total of:
1645W
even with a 25% error it still is 2056W. Thats a lot of extra room for mor things on one outlet
Do not go gentle into that good night. Rage, rage against the dying of the light.
I don't think I have two objects in my house that take exactly the same voltage. It would be wasteful if something used more electricity then it needs just to fit some universal adapter.
I've hit Karma 50 and gotten a Score:5, Troll... I win!
However, things still get murky, even in a 5V standard world. You run into issues
- Over current protection of the source
- Transient protection both ways
- Accidental polarity inversion
- Ground loops
- Noise
- Devices supplying power inapropriately
The easy (cheap) way around this is to specify a standard charger that is specifically NOT interconnectable to anything else, thus resulting in the plethora of incompatible devices that frustrate you.My choices for a standard
- 5 Volts, TTL standard power with a new connector
- 13.8 Volt lighter plug, perhaps a mini version
- Standard plug/polarity/voltage sizes for barrel connectors.
- A new 5 volt, 3 phase 10Khz standard power connector
3 Phase power is cool, too bad it doesn't make it into more homes.--Mike--
What he's asking for is a very sensible idea. Airlines have already picked up on the notion that providing a low voltage power source for laptops would be quite handy by removing the need for the power brick, and have helpfully come up with multiple standards . If you think that the idea of a standard low-voltage power source in the modern household--and especially around the computer--is so wayward, just look at the growing number of USB peripherals that are learning to make do with 500mA at 5V in order to live entirely off the USB bus.
In fact I think USB will turn out to be the motivator of a revolution in standardized low power busses, because manufacturers will get used very quickly to the ubiquitous availability of a power source for their TLL logic and stepper motors without having to worry about power supplies. This has never really been the case in the past, serial and parallel devices (almost) always requiring separate power sources.
The standard could be a lot simpler than what some are suggesting. A system could consist of an under-the-table brick that plugs into a wall outlet and contains a switching power supply, with a low-voltage power strip going up to the desktop. The connectors could be simple USB-plug-like affairs with pins for ground plus 12V and 5V, satisfying the vast majority of consumer electronics devices. The standard would specify what the maximum current draw could be at each voltage level, and device manufacturers would simply design their devices towards this standard. Almost everything around your computer except for the CRT and laser printer can run off 12V and a few amps.
Face it, the 110V power system was designed for exactly the same reasons, to provide convenient and standardized power to the devices in your household. Except that that was at a time when your average consumer electronics used tubes, ran its signals at dangerously high voltages, and also doubled as space heaters. In this growingly low-power world, 110V AC just isn't all that convenient anymore. So don't be surprised if the homes of the future will indeed sprout new wall sockets.
I suppose Dell who designed my notebook's power supply with a bastardized triangular connector would sign on to this, huh? And Motorola, the company with cell phones that utilize flat connectors compatible with nothing else... and batteries that are engineered to be incompatible between models despite being the same voltage and shape and employing the same connectors and locking mechanisms? (Think StarTac vs. Nextel i1000)
I think the point here is that companies seem to like being the only source for these items. Someone decided a long time ago that being the only source for accessories increases profits and no one has thought about it since.
There are a host of real problems with current power adapters and such. First, wall warts are really pretty bad power supplies. Most are very simple and very inefficient, so even if you had to get intermediate voltages by regulating down DC to DC in some cases, it wouldn't be much worse. They are hot even when nothing is plugged in, that can't be efficient.
My idea is that you could have a well designed switching supply that could take in a range of AC or DC voltages (say 12-270), and put out what you need. The smart portion could be a pretty standard chip that could be used in a wide variety of supply capacities and voltage sets. I'm thinking about alternative power situations too, peddle power, solar cells, fuel cells, wall power around the world.
You just plug it into whatever you got and it senses it and configures itself to whatever is there. Integrating a storage device might be nice too, and the controller would properly take care of battery maintanance as well so you get the longest possible battery life for the technology. It might be complex to design, but it wouldn't need a very powerful processor so the controller chip could be cheap once it is designed.
"Well, that may be, but wait until it's ubiquitous, then they can stop including the conventional power supply."
This is true to some degree, but there are plenty of situations where it would be inconvenient to require a power hub. Sometimes you only have one DC-powered device in an outlet or a given area. In fact, I would say the majoriry of the time this is the case. Certainly, most people could think of a situation where they have more than two wall-warts, but outside of the computer room these cases become more rare. And your whole argument is based on ubiquity, that everything would use this universal standard. I don't think that's necessarily practical. You may be tempted to imagine a range of power hubs, so that you can choose a "lite" version for just these situations. I submit that the wall-wart is exactly this, and that trying to sell as a seperate device that which has always been included (at a higher price, no doubt) is just asking for customer dissatisfaction.
"But surely, as the ueber-nerd that I am, it would eliminate a big mess?"
It would help, no doubt. But really, does it buy you that much? Every device still has a power cord. Yes, you would not have to deal with a number of smaller "power bricks", but you still have to deal with one rather large power brick. Don't expect this device to be small and slim like your network hubs. Instead envision something along the lines of a computer power supply. So you save some weight, and some volume, but in the end all that you're really getting is not worrying about how to make all those wall-warts fit onto power strips. And again, the people to whom this will be most useful (those with a number of devices) will likely already have a large number of power strips, since they're power users anyway. For the more modest installation of one or two devices it's nearly as bulky and doesn't gain you much.
There's also the issue of whether such a device is even practical to build. It would obviously have to support a number of output voltages, which complicates things a great deal. On top of that, since this is a general device, you cannot make assumptions about the relative output strengths required. On a computer power supply, you optimize the design for the 3.3V and 5V outputs since those provide a great deal more current than -12V and -5V supplies, which are mere trickles in comparison. For your "power hub" you can really make no such assumption -- remember that the point is to be able to run anything and everything from this device. And that's the real kicker, it will have to be rather beefy, since it runs everything. Things like modems may not draw much, but things like speakers certainly can. Yes, you could make these things in a range of varying output levels. But again, if you're going to have a "lightweight" version for only a couple of devices, you're better off from a marketing and price standpoint to just continue using wall-warts. So much for ubiquity...
Let's not even get started on the issues of who makes the standards, since after all, every consumer electronics manufacturer has to agree on a standard (and then follow through on it) to make this useful.
So, to summarize:
Nontrivial engineering to provide arbitrary outputs
Only really benefits a minority of "power users" (ugh! bad pun) yet requires universal acceptance
Implies industry-wide cooperation and adherance to a standard (yeah right)
Does not lower product cost (in fact it increases total cost significantly for those who adopt it)
In the best case, reduces clutter marginally
I'm sorry, it's a nice idea but I don't think it's realistic.
The parts for a USB interface (with data) are probably still more expensive than a wall-wart type power supply. I think the cheapest wall-warts are around US$1. USB interfaces are 2 or 3 times as much.
If the USB connector is just used for power, then it's the cost of the connector, which is well under $1.
USB prices will continue to drop, so no other low power bus is likely to be cheaper for the next few years.
If USB becomes more popular, it will probably develope a higher wattage version (or it may have already).
They change the connectors/pinouts on every rev of a phone for a reason, BTW. There's no way they would have gone in for a plan to adopt a standard connector. They may have done something like make a cable that has the UPB end and the proprietary phone end, however. But I doubt it.
-B
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I tried something like this, and it failed dismally. Ground loops and interference made the device useless. I eventually gave up and went back to plug packs (or "wall warts" if you prefer).
Technically, he's correct. Unfortunately, since device manufacturers also specify all characteristics of the power supply, some are planned around very specific voltage/current profiles, in other words, actually planning on a certain voltage drop at a certain current draw. This is most common with rechargers, wherein at the start of the charge cycle, the device relies on the power supply sagging under the load to prevent charging the battery too fast. Give it a more robust supply, and you overheat the battery.
This, however, is only an excuse, and applies to only very simple and inexpensive devices, and not even many of them, any more. The real reason is forced incompatibility. Batteries and power supplies commonly have elaborately-keyed connectors, both physically and electrically. Even though the device reqires only some minimum current capability within some voltage range, in some cases the connector actually has to provide power and ground on some undocumented combination of the pins, and has to turn on and off some pins based on power sense in others, provided by the device. This is just to prevent aftermarket replacements. Did anyone ever try to buy a replacement dongle for an ethernet or modem PC card? It's commonly barely cheaper than to purchase a complete replacement for the device. open up one of those automotive power adapters for a cell phone, and see what it is. I've never seen one yet that did any voltage or current modification. THe phone just lives with whatever voltage it gets, as long as it's not too little to run on, or too much to handle. The cost is in the needlessly-complicated and fragile connector. Power to portable consumer devices is still largely closed-source.