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.
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'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.
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.
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.
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.
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.
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...
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.
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.
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.