If you've been purchasing consumer electronics in the past few years,
you'll have noticed that 3.3V is becoming a popular regulated output
voltage as well. That's part of the problem: You'd really need to give
people adjustable power supplies from at least 2.5V-18V -- if not
0V-48V -- and get everyone to agree on the "programming" standard that
sets that output voltage.
No-one knows more about the exact power requirements of a product than the
people who build it, so for special needs they can add internal regulation.
This is usually done anyway. There's not much difference between 3.3 and
5V, just a little extra heat dissipation in the regulator when fed by 5V.
I don't agree about the adjustable type. The point of standards is to try
to remove the need for that, just as Joerg and others seek to remove the
need for a product to be shipped with preset pots in it. Good design to
established standards will reduce waste energy.
Another problem you have is... who's responsible if a product dies due
to being fried?
Ideally, its maker. The mains supplier isn't responsible for repairing a
110V unit plugged to 240V. Same logic applies. Also, up to a point, the
user should be responsible. If a unit intended for a 5V buss is regulated
with thermal or overvoltage protection, then plugging it to a 12V buss
would make it shut off periodically and annoyingly, or perhaps do something
more appropriate to warn the user to plug to a lower volt buss. Users would
generally know that if in doubt, plug to the low-volt buss first.
Connectors should be different for each buss, eliminating this risk.
If you've been around awhile you're familiar with the old Tektronix
TM-500 series mainframes -- a large part of the attraction was the
single power supply being shared by all the plug-in cards. Why did
TM-500 go away? One significant reason was that the power supply
started becoming a smaller and smaller cost of the product -- these
days you can get a 40W Chinese import switcher for <$10 in quantity.
This cheapness of SMPSU's allows devices to have their own regulators in.
Unlike linear types, it might not even matter which low-volt buss it's
plugged to, or even if it's AC or DC, if it has rectification and smoothing
built in. As this is no more than the effort and cost put into most warts,
this ought to be doable. (I'd suggest a DC buss system though, things
needing AC specifically are rarer and might best use their own
arrangements).
The electronics world is full of successful standardizations like
mains voltages, plug shapes
[Cough!] Done much world-traveling lately? I'm thankful that most
switching power supplies are now universal input (90-240VAC).
Not much.
This universal input thing IS a big step in the right
direction, for sure. It will make it increasing painless to adapt to common
standards in the future. If products needing low-volt DC input also had
more of this, the standard low-volt buss becomes more feasible too.
Yeah, you have a point, but I think that "solving" the problem is
significantly harder from a political point of view than you might
think.
Yes. Which is why I'm saying this to engineers not politicians. If the
politicians end up enforcing unenforcibles because the industry can't reign
in its conflict-induced waste, things will be worse, not better.
There are -- or at least were -- small businesses that cater to RVers
and truckers that make their livings modifying equipment for 12V
operation. I have a suspicion that many of them have gone out of
business due to the proponderence of cheap 12V-->120V inverters,
though (you can get something like a 300W inverter for <$20, and while
it's utter junk, in many cases it works just fine).
As a business like that is answering a need, it proves the need exists. I
could rest my case right there, but that would be boring. >
Going out of business as you describe means the need just got answered
differently. All that's happening is conversion to ANY standard buss, at
whatever cost. That's not just a need, it's a roaring demand! So there's a
new motive, profit. If that doesn't make the industry sit up and watch, and
think, what will?! They're small businesses, so I guess that's why. Most
big things start small though. If the thing were addressed so it's easy for
most people to get, it would grow enormously.
Most people are utterly clueless about this sort of thing.
Only because no thoughtful, simple standard exists. If the industry isn't
willing to at least try, you can't blame the end consumer. Judging by the
number and type of inquiries that clog the queues of Maplin and Radio Shack
type stores, the consumer is really trying to find a way, and they are NOT
being helped adequately. Maybe it's time they were given a simpler choice
when they need to find sensible power supply and connector arrangements.
It doesn't really... cars are 12V, yes, but other vehicles are 24V,
48V... the IEEE wants cars to transition to 42V... older vehicles were
6V... so there are always going to be more "standards" than you might
prefer.
Agreed, but if the product has its own regulation for anything other than
standard 5V and 12V (the most commonly used in domestic locations), and
protection against plugging to a higher voltage, then it will work.
The question is which volts to standardise, and how many voltages. I'd
suggest a maximum of three (24V, 12V, 5V), ideally just two (12V and 5V),
because the biggest demand for clean DC voltages between 12V and 24V are
for analog IC's. These are usually small-signal devices, or have their own
mains supplies built in, and in either case, benefit from additional local
supply cleaning anyway, so a tiny power converter running off a 12V buss is
fine.
Almost all things of 5V and lower can run off 5V, with linear regulation or
power converter on very small scale. Many things are designed to run on 5V,
so it's extremely easy to adapt to. Same applies to 12V, hence my choice.
6V and 9V are common, but 9 is easy, regulate off 12V. 6 is a tad harder,
some things might need the 12V and waste a bit, most might be able to run
on 5V well enough.
Higher voltages like 48V are worth making a special case for, but it's just
a variant on the same idea. In small cluttered places like homes and
offices, few things demand voltages that high, and those that do either
have their own mains inputs or can be made to work on 12V with a small
power converter built in. As a wound transformer might cost more, it's
worth doing. It's more efficient too.
To a certain extent I think this problem slowly is fixing itself, no
government intervention needed -- people do seem to have a preference
for power supplies that don't block adjacent ports on a power strip,
and I believe a significant number will buy the product with the small
switcher (that doesn't block the next port) over one with a
traditional (linear) wall-wart.
I'd hope that no government intervention will happen at all. But with the
current pressures being put on industry, can you imagine they won't?
They're already wreaking havok with CO2 emissions controls, and the sudden-
ness of the demand to phase out the use of lead. The problem is fixing
itself because it must.
I'm only pointing out that trying to accomodate wall warts on a purely
physical basis is the wrong way of looking at the problem. Most switchers
for public consumption seem to be 5V or 12V output, unless you buy for
something specific. This is good, it's as you say, part of the self-fixing
effort the industry is making. All I'm saying is, why not go further, make
more powerful ones, standardise connectors per voltage, NOT on some
arbitrary way to make firm A's wart useless for B's product. That way the
end user buys one per room, and anything in that room will plug into it.
There are better ways to bring heads together than waiting for government
to bang them together.