Submitted by brad on Tue, 2009-11-10 14:57.
Recently I wrote about the desire to provide power in every sort of cable in particular the video cable. And while we’ll be using the existing video cables (VGA and DVI/HDMI) for some time to come, I think it’s time to investigate new thinking in sending video to monitors. The video cable has generally been the highest bandwidth cable going out of a computer though the fairly rare 10 gigabit ethernet is around the speed of HDMI 1.3 and DisplayPort, and 100gb ethernet will be yet faster.
Even though digital video methods are so fast, the standard DVI cable is not able to drive my 4 megapixel monitor — this requires dual-link DVI, which as the name suggests, runs 2 sets of DVI wires (in the same cable and plug) to double the bandwidth. The expensive 8 megapixel monitors need two dual-link DVI cables.
Now we want enough bandwidth to completely redraw a screen at a suitable refresh (100hz) if we can get it. But we may want to consider how we can get that, and what to do if we can’t get it, either because our equipment is older than our display, or because it is too small to have the right connector, or must send the data over a medium that can’t deliver the bandwidth (like wireless, or long wires.)
Today all video is delivered in “frames” which are an update of the complete display. This was the only way to do things with analog rasterized (scan line) displays. Earlier displays actually were vector based, and the computer sent the display a series of lines (start at x,y then draw to w,z) to draw to make the images. There was still a non-fixed refresh interval as the phosphors would persist for a limited time and any line had to be redrawn again quickly. However, the background of the display was never drawn — you only sent what was white.
Today, the world has changed. Displays are made of pixels but they all have, or can cheaply add, a “frame buffer” — memory containing the current image. Refresh of pixels that are not changing need not be done on any particular schedule. We usually want to be able to change only some pixels very quickly. Even in video we only rarely change all the pixels at once.
This approach to sending video was common in the early remote terminals that worked over ethernet, such as X windows. In X, the program sends more complex commands to draw things on the screen, rather than sending a complete frame 60 times every second. X can be very efficient when sending things like text, as the letters themselves are sent, not the bitmaps. There are also a number of protocols used to map screens over much slower networks, like the internet. The VNC protocol is popular — it works with frames but calculates the difference and only transmits what changes on a fairly basic level.
We’re also changing how we generate video. Only video captured by cameras has an inherent frame rate any more. Computer screens, and even computer generated animation are expressed as a series of changes and movements of screen objects though sometimes they are rendered to frames for historical reasons. Finally, many applications, notably games, do not even work in terms of pixels any more, but express what they want to display as polygons. Even videos are now all delivered compressed by compressors that break up the scene into rarely updated backgrounds, new draws of changing objects and moves and transformations of existing ones.
So I propose two distinct things:
- A unification of our high speed data protocols so that all of them (external disks, SAN, high speed networking, peripheral connectors such as USB and video) benefit together from improvements, and one family of cables can support all of them.
- A new protocol for displays which, in addition to being able to send frames, sends video as changes to segments of the screen, with timestamps as to when they should happen.
The case for approach #2 is obvious. You can have an old-school timed-frame protocol within a more complex protocol able to work with subsets of the screen. The main issue is how much complexity you want to demand in the protocol. You can’t demand too much or you make the equipment too expensive to make and too hard to modify. Indeed, you want to be able to support many different levels, but not insist on support for all of them. Levels can include:
- Full frames (ie. what we do today)
- Rastered updates to specific rectangles, with ability to scale them.
- More arbitrary shapes (alpha) and ability to move the shapes with any timebase
- VNC level abilities
- X windows level abilities
- Graphics card (polygon) level abilities
- In the unlikely extreme, the abilities of high level languages like display postscript.
I’m not sure the last layers are good to standardize in hardware, but let’s consider the first few levels. When I bought my 4 megapixel (2560x1600) monitor, it was annoying to learn that none of my computers could actually display on it, even at a low frame rate. Technically single DVI has the bandwidth to do it at 30hz but this is not a desirable option if it’s all you ever get to do. While I did indeed want to get a card able to make full use, the reality is that 99.9% of what I do on it could be done over the DVI bandwith with just the ability to update and move rectangles, or to do so at a slower speed. The whole screen never is completely replaced in a situation where waiting 1/30th of a second would not be an issue. But the ability to paint a small window at 120hz on displays that can do this might well be very handy. Adoption of a system like this would allow even a device with a very slow output (such as USB 2 at 400mhz) to still use all the resolution for typical activities of a computer desktop. While you might think that video would be impossible over such a slow bus, if the rectangles could scale, the 400 megabit bus could still do things like paying DVDs. While I do not suggest every monitor be able to decode our latest video compression schemes in hardware, the ability to use the post-compression primatives (drawing subsections and doing basic transforms on them) might well be enough to feed quite a bit of video through a small cable.
One could imagine even use of wireless video protocols for devices like cell phones. One could connect a cell phone with an HDTV screen (as found in a hotel) and have it reasonably use the entire screen, even though it would not have the gigabit bandwidths needed to display 1080p framed video.
Sending in changes to a screen with timestamps of when they should change also allows the potential for super-smooth movement on screens that have very low latency display elements. For example, commands to the display might involve describing a foreground object, and updating just that object hundreds of times a second. Very fast displays would show those updates and present completely smooth motion. Slower displays would discard the intermediate steps (or just ask that they not be sent.) Animations could also be sent as instructions to move (and perhaps rotate) a rectangle and do it as smoothly as possible from A to B. This would allow the display to decide what rate this should be done at. (Though I think the display and video generator should work together on this in most cases.)
Note that this approach also delivers something I asked for in 2004 — that it be easy to make any LCD act as a wireless digital picture frame.
It should be noted that HDMI supports a small amount of power (5 volts at 50ma) and in newer forms both it and DisplayPort have stopped acting like digitized versions of analog signals and more like highly specialized digital buses. Too bad they didn’t go all the way.
As noted, it is key the basic levels be simple to promote universal adoption. As such, the elements in such a protocol would start simple. All commands could specify a time they are to be executed if it is not immediate.
- Paint line or rectangle with specified values, or gradient fill.
- Move object, and move entire screen
- Adjust brightness of rectangle (fade)
- Load pre-buffered rectangle. (Fonts, standard shapes, quick transitions)
- Display pre-buffered rectangle
However, lessons learned from other protocols might expand this list slightly.
This, in theory allows the creation of a single connector (or compatible family of connectors) for lots of data and lots of power. It can’t be just one connector though, because some devices need very small connectors which can’t handle the number of wires others need, or deliver the amount of power some devices need. Most devices would probably get by with a single data wire, and ideally technology would keep pushing just how much data can go down that wire, but any design should allow for simply increasing the number of wires when more bandwidth than a single wire can do is needed. (Presumably a year later, the same device would start being able to use a single wire as the bandwidth increases.) We may, of course, not be able to figure out how to do connectors for tomorrow’s high bandwidth single wires, so you also want a way to design an upwards compatible connector with blank spaces — or expansion ability — for the pins of the future, which might well be optical.
There is also a security implication to all of this. While a single wire that brings you power, a link to a video monitor, LAN and local peripherals would be fabulous, caution is required. You don’t want to be able to plug into a video projector in a new conference room and have it pretend to be a keyboard that takes over your computer. As this is a problem with USB in general, it is worth solving regardless of this. One approach would be to have every device use a unique ID (possibly a certified ID) so that you can declare trust for all your devices at home, and perhaps everything plugged into your home hubs, but be notified when a never seen device that needs trust (like a keyboard or drive) is connected.
To some extent having different connectors helps this problem a little bit, in that if you plug an ethernet cable into the dedicated ethernet jack, it is clear what you are doing, and that you probably want to trust the LAN you are connecting to. The implicit LAN coming down a universal cable needs a more explicit approval.
Final rough description
Here’s a more refined rough set of features of the universal connector:
- Shielded twisted pair with ability to have varying lengths of shield to add more pins or different types of pins.
- Asserts briefly a low voltage on pin 1, highly current limited, to power negotiator circuit in unpowered devices
- Negotiator circuits work out actual power transfer, at what voltages and currents and on what pins, and initial data negotiation about what pins, what protocols and what data rates.
- If no response is given to negotiation (ie. no negotiator circuit) then measure resistance on various pins and provide specified power based on that, but abort if current goes too high initially.
- Full power is applied, unpowered devices boot up and perform more advanced negotiation of what data goes on what pins.
- When full data handshake is obtained, negotiate further functions (hubs, video, network, storage, peripherals etc.)
Submitted by brad on Fri, 2009-10-23 17:54.
I’ve written a lot about how to do better power connectors for all our devices, and the quest for universal DC and AC power plugs that negotiate the power delivered with a digital protocol.
While I’ve mostly been interested in some way of standardizing power plugs (at least within a given current range, and possibly even beyond) today I was thinking we might want to go further, and make it possible for almost every connector we use to also deliver or receive power.
I came to this realization plugging my laptop into a projector which we generally do with a VGA or DVI cable these days. While there are some rare battery powered ones, almost all projectors are high power devices with plenty of power available. Yet I need to plug my laptop into its own power supply while I am doing the video. Why not allow the projector to send power to me down the video cable? Indeed, why not allow any desktop display to power a laptop plugged into it?
As you may know, a Power-over-ethernet (PoE) standard exists to provide up to 13 watts over an ordinary ethernet connector, and is commonly used to power switches, wireless access points and VoIP phones.
In all the systems I have described, all but the simplest devices would connect and one or both would provide an initial very low current +5vdc offering that is enough to power only the power negotiation chip. The two ends would then negotiate the real power offering — what voltage, how many amps, how many watt-hours are needed or available etc. And what wires to send the power on for special connectors.
An important part of the negotiation would be to understand the needs of devices and their batteries. In many cases, a power source may only offer enough power to run a device but not charge its battery. Many laptops will run on only 10 watts, normally, and less with the screen off, but their power supplies will be much larger in order to deal with the laptop under full load and the charging of a fully discharged battery. A device’s charging system will have to know to not charge the battery at all in low power situations, or to just offer it minimal power for very slow charging. An ethernet cable offering 13 watts might well tell the laptop that it will need to go to its own battery if the CPU goes into high usage mode. A laptop drawing an average of 13 watts (not including battery charging) could run forever with the battery providing for peaks and absorbing valleys.
Now a VGA or DVI cable, though it has thin wires, has many of them, and at 48 volts could actually deliver plenty of power to a laptop. And thus no need to power the laptop when on a projector or monitor. Indeed, one could imagine a laptop that uses this as its primary power jack, with the power plug having a VGA male and female on it to power the laptop.
I think it is important that these protocols go both directions. There will be times when the situation is reversed, when it would be very nice to be able to power low power displays over the video cable and avoid having to plug them in. With the negotiation system, the components could report when this will work and when it won’t. (If the display can do a low power mode it can display a message about needing more juice.) Tiny portable projectors could also get their power this way if a laptop will offer it.
Of course, this approach can apply everywhere, not just video cables and ethernet cables, though they are prime candidates. USB of course is already power+data, though it has an official master/slave hierarchy and thus does not go both directions. It’s not out of the question to even see a power protocol on headphone cables, RF cables, speaker cables and more. (Though there is an argument that for headphones and microphones there should just be a switch to USB and its cousins.)
Laptops have tried to amalgamate their cables before, through the use of docking stations. The problem was these stations were all custom to the laptop, and often priced quite expensively. As a result, many prefer the simple USB docking station, which can provide USB, wired ethernet, keyboard, mouse, and even slowish video through one wire — all standardized and usable with any laptop. However, it doesn’t provide power because of the way USB works. Today our video cables are our highest bandwidth connector on most devices, and as such they can’t be easily replaced by lower bandwidth ones, so throwing power through them makes sense, and even throwing a USB data bus for everything else might well make a lot of sense too. This would bring us back to having just a single connector to plug in. (It creates a security problem, however, as you should not just a randomly plugged in device to act as an input such as a keyboard or drive, as such a device could take over your computer if somebody has hacked it to do so.)
Submitted by brad on Wed, 2009-07-01 18:49.
I’ve written before about both the desire for universal dc power and more simply universal laptop power at meeting room desks. This week saw the announcement that all the companies selling cell phones in Europe will standardize on a single charging connector, based on micro-USB. (A large number of devices today use the now deprecated Mini-USB plug, and it was close to becoming a standard by default.) As most devices are including a USB plug for data, this is not a big leap, though it turned out a number of devices would not charge from other people’s chargers, either from stupidity or malice. (My Motorola RAZR will not charge from a generic USB charger or even an ordinary PC. It needs a special charger with the data pins shorted, or if it plugs into a PC, it insists on a dialog with the Motorola phone tools driver before it will accept a charge. Many suspect this was to just sell chargers and the software.) The new agreement is essentially just a vow to make sure everybody’s chargers work with everybody’s devices. It’s actually a win for the vendors who can now not bother to ship a charger with the phone, presuming you have one or will buy one. It is not required they have the plug — supplying an adapter is sufficient, as Apple is likely to do. Mp3 player vendors have not yet signed on.
USB isn’t a great choice since it only delivers 500ma at 5 volts officially, though many devices are putting 1 amp through it. That’s not enough to quickly charge or even power some devices. USB 3.0 officially raised the limit to 900ma, or 4.5 watts.
USB is a data connector with some power provided which has been suborned for charging and power. What about a design for a universal plug aimed at doing power, with data being the secondary goal? Not that it would suck at data, since it’s now pretty easy to feed a gigabit over 2 twisted pairs with cheap circuits. Let’s look at the constraints
The world’s new power connector should be smart. It should offer 5 volts at low current to start, to power the electronics that will negotiate how much voltage and current will actually go through the connector. It should also support dumb plugs, which offer only a resistance value on the data pins, with each resistance value specifying a commonly used voltage and current level.
Real current would never flow until connection (and ground if needed) has been assured. As such, there is minimal risk of arcing or electric shock through the plug. The source can offer the sorts of power it can deliver (AC, DC, what voltages, what currents) and the sink (power using device) can pick what it wants from that menu. Sinks should be liberal in what they take though (as they all have become of late) so they can be plugged into existing dumb outlets through simple adapters.
Style of pins
We want low current plugs to be small, and heavy current plugs to be big. I suggest a triangular pin shape, something like what is shown here. In this design, two main pins can only go in one way. The lower triangle is an optional ground — but see notes on grounding below. read more »
Submitted by brad on Thu, 2008-07-31 18:26.
I often rant here about the need for better universal power supply technology. And there is some progress. On a recent trip to Europe, I was astounded how much we took in the way of power supply gear. I am curious at what the record is for readers here. I suggested we have a contest at a recent gathering. I had six supplies, and did not win.
Here’s what the two of us had on the German trip in terms of devices. There were slightly fewer supplies, due to the fact several devices charged from USB, which could be generated by laptops or dedicated wall-warts.
- My laptop, with power supply. (Universal, able to run from plane, car or any voltage)
- Her laptop, with power supply.
- My unlocked GSM phone, which though mini-USB needs its dedicated charger, so that was brought
- My CDMA phone, functioning has a PDA, charges from mini-USB
- Her unlocked GSM phone, plus motorola charger
- Her CDMA Treo, as a PDA, with dedicated charger
- My Logger GPS, charges from mini-USB
- My old bluetooth GPS, because I had just bought the logger, charges from mini-USB
- My Canon EOS 40D, with plug in battery charger. 4 batteries.
- Her Canon mini camera, with different plug in battery charger. 2 batteries.
- Canon flash units, with NiMH AA batteries, with charger and power supply for charger.
- Special device, with 12v power supply.
- MP3 player and charger
- Bluetooth headset, charges from same Motorola charger. Today we would have two!
- External laptop battery for 12 hour flight, charges from laptop charger
- Electric shaver — did not bring charger as battery will last trip.
- 4 adapters for Euro plugs, and one 3-way extension cord. One adapter has USB power out!
- An additional USB wall-wart, for a total of 3 USB wall-warts, plus the computers.
- Cigarette lighter to USB adapter to power devices in car.
That’s the gear that will plug into a wall. There was more electronic gear, including USB memory sticks, flash cards, external wi-fi antennal, headsets and I’ve probably forgotten a few things. read more »
Submitted by brad on Tue, 2008-02-19 21:11.
If you have read my articles on power you know I yearn for the days when we get smart power so we have have universal supplies that power everything. This hit home when we got a new Thinkpad Z61 model, which uses a new power adapter which provides 20 volts at 4.5 amps and uses a new, quite rare power tip which is 8mm in diameter. For almost a decade, thinkpads used 16.5 volts and used a fairly standard 5.5mm plug. It go so that some companies standardized on Thinkpads and put cheap 16 volt TP power supplies in all the conference rooms, allowing employees to just bring their laptops in with no hassle.
Lenovo pissed off their customers with this move. I have perhaps 5 older power supplies, including one each at two desks, one that stays in the laptop bag for travel, one downstairs and one running an older ThinkPad. They are no good to me on the new computer.
Lenovo says they knew this would annoy people, and did it because they needed more power in their laptops, but could not increase the current in the older plug. I’m not quite sure why they need more power — the newer processors are actually lower wattage — but they did.
Here’s something they could have done to make it better. read more »
Submitted by brad on Sat, 2008-01-12 16:33.
I’ve written before about both the desire for universal dc power and more simply universal laptop power at meeting room desks.
Today I want to report we’re getting a lot closer. A new generation of cheap “buck and boost” ICs which can handle more serious wattages with good efficiency has come to the market. This means cheap DC to DC conversion, both increasing and decreasing voltages. More and more equipment is now able to take a serious range of input voltages, and also to generate them. Being able to use any voltage is important for battery powered devices, since batteries start out with a high voltage (higher than the one they are rated for) and drop over their time to around 2/3s of that before they are viewed as depleted. (With some batteries, heavy depletion can really hurt their life. Some are more able to handle it.)
With a simple buck converter chip, at a cost of about 10-15% of the energy, you get a constant voltage out to matter what the battery is putting out. This means more reliable power and also the ability to use the full capacity of the battery, if you need it and it won’t cause too much damage. These same chips are in universal laptop supplies. Most of these supplies use special magic tips which fit the device they are powering and also tell the supply what voltage and current it needs. read more »
Submitted by brad on Tue, 2007-11-13 13:20.
Ok, I haven't had a new laptop in a while so perhaps this already happens, but I'm now carrying more devices that can charge off the USB power, including my cell phone. It's only 2.5 watts, but it's good enough for many purposes.
However, my laptops, and desktops, do not provide USB power when in standby or off. So how about a physical or soft switch to enable that? Or even a smart mode in the US that lets you list what devices you want to keep powered and which ones you don't? (This would probably keep all devices powered if any one such device is connected, unless you had individual power control for each plug.)
This would only be when on AC power of course, not on battery unless explicitly asked for as an emergency need.
To get really smart a protocol could be developed where the computer can ask the USB device if it needs power. A fully charged device that plans to sleep would say no. A device needing charge could say yes.
Of course, you only want to do this if the power supply can efficiently generate 5 volts. Some PC power supplies are not efficient at low loads and so may not be a good choice for this, and smaller power supplies should be used.
Submitted by brad on Sat, 2006-10-28 15:59.
In furtherance of my prior ideas on smart power, I wanted to add another one — the concept of backup power.
As I wrote before, I want power plugs and jacks to be smart, so they can negotiate how much power the device needs and how much the supply can provide, and then deliver it.
However, sometimes, what the supply can provide changes. The most obvious example is a grid power failure. It would not be hard, in the event of a grid power failure, to have a smaller, low capacity backup system in place, possibly just from batteries. In the event of failure of the main power, the backup system would send messages to indicate just how much power it can deliver. Heavy power devices would just shut off, but might ask for a few milliwatts to maintain internal state. (Ie. your microwave oven clock would not need an internal battery to retain the time of day and its memory.) Lower power devices might be given their full power, or they might even offer a set of power modes they could switch to, and the main supply could decide how much power to give to each device.
Of course, devices not speaking this protocol, would just shut off. But things like emergency lights need not be their own system — though there are reasons from still having that in a number of cases, since one emergency might involve the power system being destroyed. However, battery backup units could easily be distributed around a building.
In effect, one could have a master UPS, for example, that keeps your clocks, small DC devices and even computers running in a power failure, but shuts down ovens and incandescent bulbs and the like, or puts devices into power-saving modes.
We could go much further than this, and consider a real-time power availability negotiation, when we have a power supply or a wire with a current limit. For example, a device might normally draw 100mw, but want to burst to 5w on occasion. If it has absolutely zero control over the bursts, we may have to give it a full 5w power supply at all times. However, it might be able to control the burst, and ask the power source if it can please have 5w. The source could then accept that and provide the power, or perhaps indicate the power may be available later. The source might even ask other devices if they could briefly reduce their own power usage to provide capacity to the bursting device.
For example, a computer that only uses a lot of power when it’s in heavy CPU utilization might well be convinced to briefly pause a high-intensity non-interactive task to free up power for something else. In return, it could ask for more power when it needs it. A clothes-dryer or oven our furnace or other such items could readily take short pauses in their high power drain activities — anything that uses a cycle rather than 100% on can do this.
This is also useful for items with motors. A classic problem in electrical design is that things like motors and incandescent lightbulbs draw a real spike of high current when they first turn on. This requires fuses and circuit breakers to be “slow blow” because the current is often briefly more than the circuit should sustain. Smart devices could arrange to “load balance” their peaks. You would know that the air conditioner compressor would simply never start at the same time as the fridge or a light bulb, resulting in safer circuits even though they have lower ratings. Not that overprovisioning for safety is necessarily a bad thing.
This also would be useful in alternative energy, where the amount of power available changes during the day.
Of course, this also applies to when the price of power changes during the day, which is one application we already see in the world. Many power buyers have time-based pricing of their power, and have timers to move when they use the power. In many cases whole companies agree their power can be cut off during brown-outs in order to get a cheaper price when it’s on. With smart power and real-time management, this could happen on a device by device basis.
These ideas also make sense in power over ethernet (which is rapidly dropping in price) which is one of the 1st generation smart power technologies. There the amount of power you can draw over the thin wires is very low, and management like this can make sense.
Submitted by brad on Sun, 2006-07-02 16:57.
Those who travel on trips through many countries face the problem of how to plug in their laptops and gear. Many stores sell collections of adapters, but they are often bulky, and having multiple adapters for multiple gear can be really bulky. (Usually you get one adapter and then use a 3-way splitter or cord for your type of plug.)
Today, however, almost all my travel gear is 2-prong, not 3-prong. It’s mostly my laptop and various chargers for cameras, phones etc. And all of it runs on every voltage and hz found in the world.
It seems if you’re willing to break the rules on rigidity of plugs, one could make a very small adapter by using independent pins, perhaps with a flexible rubber strip handle between them to keep them together and make it safer, but still allowing the pins to bend and have different spacing.
If you do this, there are really just a few types of pins you need. Thin blades, thick blades, thin round pins and in a few places fat round pins. The blades come at different angles — parallel in North America, slanted in Australia, colinear for thick blades in UK. With pins it’s more a question of spacing than angles. A single plug with a way to adjust the spacing could also work. (Israel has a strange pin I haven’t used, I don’t know if other pins or blades could be adapted to it.)
Generally this would not be suitable for plugging a wall-wart into a wall, you would want to plug in a short extension cord with multiple sockets of “your” type. And it might be hard to sell a product like this due to safety standards, since they don’t want to trust the user to know what they are doing, know that they are only plugging in equipment that takes any voltage and doesn’t care what pin is live and which is neutral, doesn’t need ground and doesn’t draw lots of current in any event. But it would be very compact.
Submitted by brad on Sun, 2006-04-02 22:47.
I’ve blogged several times before about my desire for universal DC power — ideally with smart power, but even standardized power supplies would be a start.
However, here’s a way to get partyway, cheap. PC power supplies are really cheap, fairly good, and very, very powerful. They put out lots of voltages. Most of the power is at +5v, +12v and now +3.3v. Some of the power is also available at -5v and -12v in many of them. The positive voltages above can be available as much as 30 to 40 amps! The -5 and -12 are typically lower power, 300 to 500ma, but sometimes more.
So what I want somebody to build is a cheap adapter kit (or a series of them) that plug into the standard molex of PC power supplies, and then split out into banks at various voltages, using the simple dual-pin found in Radio Shack’s universal power supplies with changeable tips. USB jacks at +5 volts, with power but no data, would also be available because that’s becoming the closest thing we have to a universal power plug.
There would be two forms of this kit. One form would be meant to be plugged into a running PC, and have a thick wire running out a hole or slot to a power console. This would allow powering devices that you don’t mind (or even desire) turning off when the PC is off. Network hubs, USB hubs, perhaps even phones and battery chargers etc. It would not have access to the +3.3v directly, as the hard drive molex connector normally just gives the +5 and 12 with plenty of power.
A second form of the kit would be intended to get its own power supply. It might have a box. These supplies are cheap, and anybody with an old PC has one lying around free, too. Ideally one with a variable speed fan since you’re not going to use even a fraction of the capacity of this supply and so won’t get it that hot. You might even be able to kill the fan to keep it quiet with low use. This kit would have a switch to turn the PS on, of course, as modern ones only go on under simple motherboard control.
Now with the full set of voltages, it should be noted you can also get +7v (from 5 to 12), 8.7v (call it 9) from 3.3 to 12, 1.7v (probably not that useful), and at lower currents, 10v (-5 to +5), 17v (too bad that’s low current as a lot of laptops like this), 24v, 8.3v, and 15.3v.
On top of that, you can use voltage regulators to produce the other popular voltages, in particular 6v from 7, and 9v from 12 and so on. Special tips would be sold to do this. This is a little bit wasteful but super-cheap and quite common.
Anyway, point is, you would get a single box and you could plug almost all your DC devices into it, and it would be cheap-cheap-cheap, because of the low price of PC supplies. About the only popular thing you can’t plug in are the 16v and 22v laptops which require 4 amps or so. 12v laptops of course would do fine. At the main popular voltages you would have more current than you could ever use, in fact fuses might be in order. Ideally you could have splitters, so if you have a small array of boxes close together you can get simple wiring.
Finally, somebody should just sell nice boxes with all this together, since the parts for PC power supplies are dirt cheap, the boxes would be easy to make, and replace almost all your power supplies. Get tips for common cell phone chargers (voltage regulators can do the job here as currents are so small) as well as battery chargers available with the kit. (These are already commonly available, in many cases from the USB jack which should be provided.) And throw in special plugs for external USB hard drives (which want 12v and 5v just like the internal drives.)
There is a downside. If the power supply fails, everything is off. You may want to keep the old supplies in storage. Some day I envision that devices just don’t come with power supplies, you are expected to have a box like this unless the power need is very odd. If you start drawing serious amperage the fan will need to go on and you might hear it, but it should be pretty quiet in the better power supplies.
Submitted by brad on Mon, 2006-01-02 14:14.
I’ve written before about the desire for a new universal dc power standard. Now I want to rethink our systems of household and office power.
These systems range from 100v to 240v, typically at 50 or 60hz. But very little that we plug in these days inherently wants that sort of power. Most of them quickly convert it to something else. DC devices use linear and switched mode power supplies to generate lower voltage DC. Flourescent lights convert to high voltage AC. Incandescent bulbs and heating elements use the voltage directly, but can be designed for any voltage and care little about the frequency. There are a dwindling number of direct 60hz AC motors in use in the home. In the old days clocks counted the cycles but that’s very rare now.
On top of that, most of what we plug in uses only modest power. The most commonly plugged in things in my house are small power supplies using a few watts. Most consumer electronics are using in the 50-200w range. A few items, such as power tools, major appliances, cooking appliances, heatters, vacuum cleaners and hairdryers use the full 1000 to 1800 watts a plug can provide.
So with this in mind, how might we redesign household and office power… read more »
Submitted by brad on Sat, 2005-08-20 01:30.
I’ve called before for a system of Universal DC Power and I still want it, but there is a partial step we could take.
I have a laptop power supply that comes with a variety of tips. The tips tell (through something as simple as a resistor) the power supply how much voltage and current to supply for the laptop they are designed for. I bought mine for use in an airplane, others are sold that do both 12v and AC power.
I would like to see one designed for the corporate market, rather than the carry-around market. Ones to be left in offices and under conference tables, so that when somebody visits with a laptop, they can plug it in. No need to get out their own supply or eventually no need to bring it.
Unlike the carry-around where you pick your tip and leave the rest, this would have an array of tips, possibly rotating on a click-wheel, or all connected to a switch where one can dial the voltage/polarity/etc.
Some companies take more drastic steps. At Google for example, I notice they have standardized on thinkpads, and so all desks and conference tables have think pad supplies. Everybody is able to roam the building and be sure of laptop power. These supplies, while a bit more expensive, could solve the same problem.
An alternate would be to standardize the special tip that describes the power needed. Everybody could get a tip or pigtail for their laptop and carry just that around. Conference rooms could in fact have single supplies that let you plug in several of the pigtail. Of course that is halfway to my original proposal.
Now it turns out a considerable majority of laptops take either 16 volts or 19 volts. The main rebel is Dell, which uses funny plugs and often over 20v. Some need more current than others, I don’t know if any need current limiting or if simply making the PS capable of 100w would do the trick. Anyway, in this case, we could develop a standard 16v plug (the thinkpad one) and a different standard 19v plug (probably an HP one), in two different shapes and colours, and people with laptops could carry a cheap converter to plug their laptop into it. Over time, laptops might come directly able to use this, if they aren’t already — on our path to a smarter power bus. Then people could say, “Oh, you have the orange plug. Great, I can plug my laptop into that.” Vendors who make laptops that won’t plug into one of these two will probably think about switching.
Submitted by brad on Mon, 2004-09-13 11:53.
We all would love solar power to work better, but it's hard to have it make economic sense yet, at least if you're near the grid. A solar panel takes 4 years just to give back the energy it took to build it, and it never pays back the money put in if you compare it to putting the money into the stock market. And that's with full utilization. If you use panels and batteries, any time your batteries are near full the power is being discarded, and you also have to replace your batteries every so often and dispose of the old lead-filled ones. Yuk. A grid-tie can use all the power of a panel but that's an expensive, whole-house thing.
But here's a start -- a solar-using PC power supply. My PCs, like many folks', are on all day, including the peak-demand heat of the day. Desktops draw anywhere from 50 to 200 watts even when idling.
So make a PC power supply that has 3 external connections. One for the wall plug. And two optional ones, one for a 12v solar panel and one for a battery. Then sell it with a 50w or 100w solar panel -- most importantly, the panel should not ever generate more power than the PC uses.
Because of that, during the bright part of the day, the panel will be providing most, or just barely all, of the power for the PC. The wall plug will provide the rest. At night, the wall plug would provide all the power. It's a grid-tie but it doesn't feed power back to the grid, it just reduces demand on it. The 100w panel takes 100w off the grid load during the peak demand times. And we use every watt the panel generates, we never throw any away. read more »
Submitted by brad on Mon, 2004-01-26 10:23.
I went around and counted that we seem to have around 30 birick and wall-wart DC power supplies plugged in around the house, and many more that are not plugged in which charge or power various devices. More and more of what we buy is getting to be more efficient and lower power, which is good.
But it's time for standardization in DC power and battery charging. In fact, I would like to move to a world where DC devices don't come with a power supply by default, because you are expected to be able to power them at one of the standard voltage/current settings.
One early experiment is on airplanes. I have an adapter that takes the 12v from the airplane, and has many tips which put out different voltages for different laptops. These are expensive right now, but on the right track.
Our other early venture is USB, which provides up to 500ma at 5 volts. Many small devices now use USB for power if that's all they need. There are devices that plug in to USB only for power, they don't use the data lines. Some come with a small cigarette lighter plug that has a USB socket on it for car use. This includes cellular chargers, lights etc.
I think a good goal would be a standardized data+power bus with a small number of standard plugs. One would be very tiny for small devices and only provide minimal USB-level power, a couple of watts. Another would handle mid-level devices, up to a couple of amps. A third would be large and handle heavy duty devices up to say 20 amps, replacing our wall plugs eventually. There might be a 4th for industrial use.
In full form, the data bus would be used for the components to exchange just what power they want and have. Years ago that would have been ridiculous overkill, today such parts are cheap. However, to make it simple there would be a basic passive system -- perhaps as simple as a finely tuned resistor in place of the data components -- to make it easy and cheap to adapt today's components.
A fully smart component would plug into the smart power and get a small "carrier" voltage designed to run the power electronics only. A protocol would establish what power the supply can provide and what the component wants, and then that power would be provided. read more »