Universal laptop power supplies for desks, conference tables


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.


I've always thought that someone could make a bundle renting out different flavors of power supplies for laptops around university campuses, although you'd have to figure a way to gaurd against people simply renting and stealing them. Heck, you might even be able to sell them at retail and make a bundle (students frequently end up in a bind an go to great lengths to find a power supply to borrow... sometimes the right supply can't be found for borrow).

the selectable tip is just a way to convey information to the power supply. A better way would be to keep the selection of tips we have now and put a tiny amount of smarts into new devices, so that they will talk (say) 5V signals to negotiate the power required, then use the same cable (and tip) to get that power. Of course, you'd still need manual override for dumb devices, and since this would cost the manufacturers money at both ends, it's unlikely to happen. Accessory power supplies are a lucrative sideline for laptop (etc) companies, and if they accept a generic supply suddenly there's competition where there never used to be.

Interestingly, some devices are very input-tolerant, especially anything that accepts alkaline batteries (which discharge from over 1.8V to under 1V). So you can power via the battery connectors using just about anything. Many digital cameras are like this - the "4.8V DC in" actually means 3-12V, with the limit often being your 15V CMOS one. I've run my Canon off a "fake battery" that had 8 AA NiMH cells in it... instead of 200 shots from the LiI battery I was getting 500+, but it was pushing 9.6V into a nominal 7.4V input.

You probably didn't follow the link to my earlier post that I referencesd which is about this. That is the long term goal.

I was proposing a shorter term goal, so that you can plug in most any laptop at any corporate desk or conference table without having to bring a power supply, or anything else special, on existing laptops.

I work in a State University where we have laptop carts with up to 24 laptops aboard. Installing the power bricks into the laptop carts and then removing them for use when the laptops need to be used with the AC supply during long sessions, is a real pain. It would be nice to have a central power supply with enough cables to route through the laptop cart to allow charging of the batteries when they are stored. Of course, it would be nice to have a universally used power supply end to do this but, with Propietory companies such as Sony and Dell, getting them to conform will be the most difficult becuase they want to charge premium prices for equipment that they soley want to sell.

If I were a Electonic Technician, I would love to build such a device and I am sure they would sell as there are many many laptop carts in the education market.

If they could build different models with different amounts of cables, this wouuld also be helpful in conference rooms, cubicles where multi users are just accross the walls from each other could all plug in.

Just a thought.

I'd like to see something like that designed for conference tables.

The biggest stalling point is of course the manufacturers, selling replacement power supplies is acutally fairly lucrative, hence in manuals they strongly advise against 'inferior generic power supplies' (remind you of ink catridges?) citing all sorts of rubbish reasons. Having anything generic means better competition for sales of that generic product, hence the price is driven down, which is great for us, but poor for manufacturers.

There is of course the argument that with most manufacturers having the generic connection that the 'odd one out' would lose sales and be forced to join the mainstream connector, the problem will be convincing the majority of manufacturers to change to this connector in order to make it the standard.

The interum measure you have suggested is sound, it would be a convenient way for consumers to connect, but I can't see it forcing manufacturers to adopt the new standard long term, as long as we can adapt to whatever they are using there is no incentive to change

As a side thought, I would prefer long term for it to be taken one step further and a generic docking station implemented. That way peripherals are also easily connected. It would have to suit various sizes, but as it is essentially just a platform with plugs at the back, it shouldnt be too hard.

I used to be an Optima repair agent, and the Stands they provided to schools used a single connector to a power board that then had fixed plugs at the back of the unit, so that you could easily charge them on stand and keep the normal power supplies on the desks.

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