
Dart: The World's Smallest Laptop Adapter - stoev
https://www.kickstarter.com/projects/215201435/dart-the-worlds-smallest-laptop-adapter?ref=search
======
beambot
Best way to get me to buy one... Let Ken Shirriff do a teardown. He's done
some _amazing_ work analyzing various AC-DC adaptors [1-2].

[1] [http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-
ap...](http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-
is.html)

[2] [http://www.righto.com/2012/05/apple-iphone-charger-
teardown-...](http://www.righto.com/2012/05/apple-iphone-charger-teardown-
quality.html)

~~~
gcb0
couldn't agree more.

But besides efficiency, i'd also like to see RF interference measurements on
this one. There is a reason good power converters are fixed in one voltage
output and use transformers...

~~~
drakaal
High. VHF AC to DC conversion isn't in many devices because it is actually
hard to get it to not cause issues with everything else on the same
transformer (not even breaker).

Also you notice they use a lighter wire than most laptop power supplies would
and no ferro loop at the end to reduce the noise to the device.

Maybe I missed it, but I don't think I saw a UL approval on the device. I also
don't think there is enough room in the case to have a thermal cut out, and a
fuse/breaker. Which you really need on a power supply.

I'd love to be wrong on all this. I hate carrying a brick (though mine is
about the size of half a deck of cards).

~~~
snops
Thermal fuses are actually pretty small, this one (which is pretty
representative): [http://uk.farnell.com/nte-electronics/nte8065/fuse-
thermal-c...](http://uk.farnell.com/nte-electronics/nte8065/fuse-thermal-
cutoff-10a-250v-axial/dp/2192420) is about the size of a 1/4W resistor at 12mm
long. A fuse isn't too big either, this 0402 fuse: [http://uk.farnell.com/te-
connectivity-raychem/dp/1843788](http://uk.farnell.com/te-connectivity-
raychem/dp/1843788) is rated at 4A and is only 1mm long!

The real thing for size is the transformer and other magnetics, which decrease
with frequency, hence why this uses VHF frequencies. Output filters can also
be made smaller at higher frequencies, and Ken Shirriff's iPhone charger
teardown above shows a small ferrite ring _inside_ the charger case for high
frequencies.

UL Approval is probably under on the "Production Timeline" (2/3rds down) under
"Submit for initial regulatory certification (4 months)", which is set to
begin now (Apr-May).

As for the wire thickness, it doesn't seem that much thinner than my Macbook
Charger, which is also 65W. The production timeline on the kickstarter leaves
them time to change to a thicker one.

The big question of course, is the feasibility of the VHF AC-DC conversion.
FINsix have a paper
([http://finsix.com/assets/files/FINsix_Tech.pdf](http://finsix.com/assets/files/FINsix_Tech.pdf))
but its not very long or detailed, and I don't know enough to criticise it if
it was.

------
slg
One word of warning, the product timeline says you should expect your product
in 7-11 months. That is a long time when you are talking about device
compatibility. All Kickstarters have risks, but buying an accessory for a
device that may not even exist yet is a larger than normal gamble. There were
plenty of Kickstarters for iPhone accessories that didn't arrive until after
they were already obsoleted by the lightning cable.

Will this work on your next laptop? Probably. Can the Dart team guarantee that
the device will "work with all major PC brands" manufactured in the next year?
Probably not. Is that risk worth the extra money you save on a pre-order? That
is up to you to decide.

~~~
userbinator
Unless some radical change happens to laptop power supplies in the next few
months - a change from designs that have remained the same for over a decade -
it's very likely this adapter will work with the newest (normal) laptops
available when it comes out.

Also, laptops have very flexible power input circuits that will accept a wide
range of DC input: they'll start running from ~12V (the voltage of an almost-
dead battery), and go as high as the voltage specs on the input components
allows - 25V (filter caps) is the usual absolute upper limit. Higher voltage
means lower I^2R losses but manufacturers like to leave some safety margin,
which is why 20V is somewhat of a de-facto standard given the parts available.
The general power distribution circuits in a laptop are like this: there's a
main power rail, whose voltage varies with battery voltage when running on
battery, and is the DC-IN voltage with the adapter plugged in. The voltages
for the CPU, GPU, chipset, etc. are all generated by DC-DC converters supplied
from this main rail. There's a set of diodes/MOSFETs that wire-OR together the
battery and DC-IN to the main rail, preventing current flow in the wrong
direction. It also powers the battery charger.

I've read a lot of laptop schematics, and all of them use very similar power
circuitry, often with the same components. The only real concern with device
compatibility is in the ID schemes that some manufacturers use, either to
"lock out" third party adapters or encode wattage selection. The simplest ones
are nothing more than a resistor in the plug, different values for different
wattages (IBM/Lenovo is one example). More complex ones use a 1-wire interface
to an EEPROM or other storage element (Dell, Apple) ([http://www.laptop-
junction.com/toast/content/dell-ac-power-a...](http://www.laptop-
junction.com/toast/content/dell-ac-power-adapter-id-chip-died)
[http://www.righto.com/2013/06/teardown-and-exploration-of-
ma...](http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html)
). Then there's all the others that have no ID at all, just +/\- input, and
these are the most compatible.

About the Dart itself: the technology used here (VHF SMPS) has been around for
a long time in military/aerospace applications, where size/weight is more
important than reducing switching losses.

[http://www.eevblog.com/forum/crowd-funded-projects/vhf-
lapto...](http://www.eevblog.com/forum/crowd-funded-projects/vhf-laptop-power-
supply/)

~~~
sitkack
Is this a USB 3.1 supply? Because that is where everything is going.

~~~
ihuman
For small mobile device, maybe. However, this project is for laptops, and
laptops don't charge themselves over USB, nor will they any time soon.

~~~
abritishguy
That is simply not true, the USB spec now supports charging of laptops over
USB and I would be very surprised if over the next few months it didn't become
fairly common in new laptops - it adds an extra USB port to a laptop and is
very inexpensive.

~~~
userbinator
Charging via USB adds extra complexity and there is nothing wrong with the
existing system, so I don't think it will have as much adoption as you
predict. OEMs rely on manufacturers like TI to provide ICs and reference
designs, and for the moment it doesn't look like there's a highly-integrated
solution for USB-PD.

~~~
vidarh
> and there is nothing wrong with the existing system

Yes, there is: it causes massive electronic waste because of incompatible
chargers. Expect the new EU regulation that covers phones etc. (that replaced
"voluntary" measures) to be expanded to cover laptops too, or at least for
manufacturers to get threatened with changes to th regulation, if
manufacturers don't voluntarily switch to USB once suitable chargers start
being widely available.

~~~
userbinator
There is nothing _electrically_ wrong, and while I agree that there have been
many different connectors used and having one standard would be great,
manufacturers do tend to settle on one of relatively few standard connectors
(the majority being barrel plugs of various sizes.)

However, the solution is _not_ a grossly overcomplicated standard like USB. It
is a 20V barrel plug. Maybe if you want to get really fancy, include a
resistor on a third pin for wattage encoding. Standardise on that instead - or
pick an existing size - there are enough to choose from already (
[http://en.wikipedia.org/wiki/Coaxial_power_connector#Standar...](http://en.wikipedia.org/wiki/Coaxial_power_connector#Standards)
).

~~~
hippoman
This is a somewhat uninspiring attitude. There was nothing wrong with the PS/2
mouse and keyboard plugs either, nor the 25-pin printer plugs, nor some barrel
plug for charging phones. But the problem is there were so many different
things that all needed their own plug. Now there's no mouse plug or phone plug
or printer plug since they all use USB. Laptops with a standard non-USB plug
will still add to the duplication and inconvenience just like those old
keyboards did. You won't be able to charge your phone with your standard
barrel plug laptop charger, so you'll still have to carry two adapters when
you travel.

~~~
userbinator
_There was nothing wrong with the PS /2 mouse and keyboard plugs either, nor
the 25-pin printer plugs, nor some barrel plug for charging phones._

With the exception of the phone charging example, I would agree. The PS/2
protocol is vastly less complex than USB, and parallel ports are so simple
they can be used as GPIOs with ultra-low guaranteed latency. Phones migrated
to USB because they already needed the bulk data transfer capability along
with power, and USB made for a good fit.

 _You won 't be able to charge your phone with your standard barrel plug
laptop charger, so you'll still have to carry two adapters when you travel._

The Dart has both USB and a barrel plug, which is the same as many other
aftermarket adapters. (They could've made this more obvious in the marketing
material, e.g. by showing USB devices plugged into it and not just laptops
most of the time.)

I'll choose a laptop with a big robust barrel plug, and one that can be
powered from anything outputting 12-24VDC, over one with a USB socket and
requiring complex negotiation protocols to even start consuming power. It's
the KISS principle. Standards that try to do everything don't tend to do any
one thing particularly well, and introduce unnecessary complexity.

------
dotBen
To get around the Apple patent, they should have made the device compatible
with a cigaratte lighter socket or the old-school plane power socket, which
would enable customers to buy the official Apple Travel Adapter. This is how
HyperJuice has done it.

Additionally, If you have a MacBook Air it doesn't seem significantly enough
smaller than the 45W MBA power brick - not to justify the higher price,
anyway.

UPDATE: meant 45W, not 65W, corrected

~~~
rcthompson
Which Apple patent is this? The Magsafe thing for the end that attaches to the
computer?

~~~
userbinator
Yes, their magnetic power connector is patented. US7311526. (Not that it ever
stopped the Chinese who have had magnetic power connectors on their electric
kettles and skillets for years before Macbooks even existed from cloning it,
but that's a different story...)

~~~
stormbrew
Deep fryers sold in the US also have magnetic power adapters.

Apparently the thing with this (as magnetic power connectors have existed for
a _long_ time) is that there are, at the very least, claims in Apple's patents
that differ from previous examples and patents[1].

So basically the novel thing isn't magnetic power adapters.

[1] [http://patents.stackexchange.com/questions/200/prior-art-
for...](http://patents.stackexchange.com/questions/200/prior-art-for-apples-
magsafe)

~~~
pbhjpbhj
Looking quickly through the claims they don't appear to cover having a
circular magnetic connector - instead it's specified (eg in claim 1) that the
connector has 2-fold symmetry and in other claims that the 3 connections are
arranged linearly.

The other point you might "attack" the claims on (ie in designing around them)
appears to be the inclusion of "bias". Mind you it's not entirely clear¹ what
is meant (without referring to the description) by "biased" here: claim 6
suggests it means sprung in some way.

Edit: looking at a couple of pieces of the prior art
[http://www.google.com/patents/us7311526#backward-
citations](http://www.google.com/patents/us7311526#backward-citations) it
seems the main innovation in the Apple claims is probably the symmetry /
reversible nature of the connector. There were already circular connectors, eg
the cited US3808577, so Apple's claims may have had to work around those -
hence the construction including the symmetry clauses. Seems a magnetic
connector is well doable even without any need for invention, just based on
expired patent disclosures.

------
gamache
I am left wondering what's novel/patent-worthy about a VHF power converter. It
sounds like an incremental improvement on current systems (which typically
operate in the 100kHz-1MHz range), and the link in the Kickstarter doesn't
have much substance to it. Anyone know what I am missing?

~~~
goldbeck
According to the company's website, their tech gets them up to the 30-300MHz
range.

[http://finsix.com/power-platform/#section-frequency-
innovati...](http://finsix.com/power-platform/#section-frequency-innovation)

------
beggi
This looks legit backed by MIT patents and grad students, but I wonder why a
group making this "breakthrough" is going directly to Kickstarter to raise
hundreds of thousands of dollars, instead of selling the technology directly
to companies like Apple or Samsung and make tens of millions of dollars.

~~~
dragonwriter
Because Kickstarter is used to get the resource to accelerate the business
which they may well eventually sell to Apple or Samsung for far more than they
raise from kickstarter. (See, e.g., Oculus Rift.)

~~~
probably_wrong
That's a fairly cynical and negative point of view that goes against the core
ideas on which Kickstarter was created.

And yet, there's a high chance that you are 100% right.

I find it sad that we'll have to always consider that particular scenario from
now on. Stupid Facebook.

~~~
cdash
Whatever kickstarter was meant to be it is clearly being used for nothing more
than preorders far in advance and you don't even have a guarantee you will
ever get the product you preorder. In exchange for that risk and tieing up
your money for such a long time before the product is available you possibly
get a product that might not otherwise exist. The truth is you don't really
know if it wouldn't have existed without kickstarter or not.

~~~
ansible
Yeah, this particular product is nice, but maybe I'm suffering from
kickstarter-fatigue too. This is nice, but not unique enough to warrant
special effort (and waiting months) to get it though.

------
ytjohn
This looks very much like the Rommoss car charger. I have one for my laptop.
This gets its source from 12V DC instead of AC, but the rest works the same.
Usb port and automatic voltage sensing circuitry. You just need a specific
cable for whatever you're charging. Plug in a standard usb cable to charge
your phone, you get 5V. Plug in an adapter cable for your Dell laptop, get the
desired 19V (or whatever your laptop needs).

[http://www.amazon.com/Universal-Portable-Charger-Charging-
La...](http://www.amazon.com/Universal-Portable-Charger-Charging-
Latitude/dp/B008QV0AF0)

------
raverbashing
Good they're thinking about the regulatory needs

But I doubt they'll make do without the ferrite core.

The smaller the device is, it usually means more interference being generated,
and the higher frequencies make it more complicated.

~~~
nraynaud
there are 2 things made of ferrite in an adapter, for different reasons. There
is a ferrite ring around the input cable so that EMI don't go upstream in the
socket, and this one they will probably keep. The other one is the core of the
transformer and they say they don't need it at that frequency.

------
AceJohnny2
This looks like a great and promising product.

At the headline, I had the kneejerk doubt that they could fit laptop-level
power in such a small adapter, but they claim that's exactly why their product
is interesting.

Nevertheless, I'm going to wait for the first wave to prove itself and for
them to iron the kinks out (there are always kinks in a first-gen HW product).
As such, I hope this is a true "kickstarter" that starts company momentum and
isn't, like too many others, a one-shot deal.

~~~
robobro
It's a bit pricey, too.

------
kubiiii
Very nice product. I have an (fairly) old compaq laptop with a built in
adapter and even though its heavier than it should be, pluging the cable is a
delight.

I use the HN facebook feed (yes I do) and there is no direct link on it, just
the video (maybe specific to KS?). Also the music in the video is distracting.
It is way overcompressed.

------
tdicola
Very polished kickstarter but I'm left wondering, do I really need an $80-$200
charger? The MacBook air charger is already pretty small and my phone lasts
all day without the need to recharge. Although the tech inside it might be
novel and interesting I really don't see the cost vs benefit as a consumer.

~~~
mschuster91
My Acer netbook comes with a lightweight but still bulky-as-fxxk charger...

------
zan2434
This looks like a funded, experienced, hardware team with an already finished
product. Are they only using Kickstarter for exposure? If they're looking for
validation/upfront manufacturing costs they should be doing pre-orders instead
of "crowdfunding"

~~~
SoftwareMaven
Please define the difference in this context, especially looking at the
funding rewards.

~~~
Xylakant
Pre-Order gives you a right to obtain the product or at least get some money
back in case the company folds and there are assets left, usually even before
the investors see any money. You're a customer. Kickstarter gives you "you're
a backer" and in case the company folds you get nothing.

~~~
jessaustin
That might be an argument against Kickstarter in general, but it isn't a good
criticism of any particular use of Kickstarter, especially of one like this
which appears highly likely to succeed in producing the promised product.

~~~
Xylakant
I think it's even a better criticism of this particular case: If this
kickstarter really has such a low risk of failure, why don't the investors
bear that risk and go for preorders?

~~~
jessaustin
As a consumer I would rather the investors expose me to a tiny risk than a
huge risk. Would you really prefer the converse?

------
stoev
I've been thinking about the overweight (and overpriced) laptop adapters for a
while and reading about this project made me very happy. Could anyone suggest
some scientific reading on their claimed very high frequency power conversion
(or any similar technology)?

~~~
sp332
It's pretty recent. This is a good overview (especially page 2)
[http://www.powerpulse.net/powerViews.php?pv_id=48&page=1](http://www.powerpulse.net/powerViews.php?pv_id=48&page=1)

~~~
stoev
Thanks. I read that, but was hoping that I could get more detailed information
somewhere.

~~~
sp332
Well, there's always the patent itself :)
[http://patents.justia.com/patent/8542509](http://patents.justia.com/patent/8542509)

------
chx
Right now the smallest laptop adapter; also has no AC cord; is the
[http://www.fsplifestyle.com/product.php?LID=1&PSN=771](http://www.fsplifestyle.com/product.php?LID=1&PSN=771)
FSP Twinkle. It's the same 19V 65W adapter this one claims to be. It's made by
a reputable power supply maker. While I applaud smaller and lighter adapters I
would be extremely wary of an unknown startup meddling with power supplies.
Also, regulatory approval is _hell_ and while they do mention it among the
risks I am also wary of that. I will pass this Kickstarter...

------
IvyMike
As someone who's travelled a lot, this looks like a cool upgrade.

But man, what I wouldn't give for an adapter that make it easy to pack by
having some clever and clean way to wrap the cord. It doesn't look like this
one does.

------
jebblue
Good idea but the implementation is gravity challenged which will wear the
plugs and the sockets used over time. It would be better to reduce the length
and get it closer to the socket.

------
neil_s
Wait so what's the advantage of this over the free adapter your laptop came
with? It says its smaller, and yes it does look marginally smaller (not enough
to make a difference to me personally), but is that it? You can charge another
USB device with it, but my Surface Pro charger offers that too. Am I missing
some other USP that would make it worth buying this as an upgrade? I can see
this being useful when licensed to laptop manufacturers, but not as an
aftermarket upgrade.

~~~
witty_username
Me too. I see that it has some new technology; but the benefits don't seem
that much. Can the downvoters explain?

------
nouveaux
I know this is Hacker News and we love startups, but I think this would have
been a better licensing play. It just doesn't seem like its a good business
model to try and create all these adapters for old and new laptops. That
compatibility list looks really annoying from a consumer standpoint. Its just
not something I want to look up every time I'm in the market for a new laptop.

~~~
rhizome
That's just for now. From the looks of the laptop connection they're angling
for a buyout/license from iGo, who already makes a zillion nub-ends just like
theirs.

------
colindean
I saw this at CES and it was one of the very few products I saw the entire
event that made me say, "I want to invest in this company." I wanted to take
one home!

Coverage I helped write: [http://www.thinkcomputers.org/finsix-shrinks-laptop-
power-br...](http://www.thinkcomputers.org/finsix-shrinks-laptop-power-bricks-
to-pocket-size/)

------
brianbreslin
Sadly this isn't directly Apple compatible. It says the mac version they buy
an off the shelf apple power adapter and then connect them for you or
something. I guess the magsafe connector is patented?

I would hope Apple was working on a smaller power brick, its kind of silly
when my power adapter is almost as heavy as my Macbook Air 13". yeah, i know
#firstworldproblems

~~~
megablast
Not sure what adapter you are using, but the one that ships with the 2012 or
2013 air is tiny and very light.

------
somid3
I've know this team for some time (also an MIT grad). I'm so happy they have
pushed their product and have moved to the Bay Area.

The Dart might look like a small device but its an incredible feat --
specially since it needs to safely work with all laptops and devices. Very
excited about the future of the product.

------
AndrewDucker
I'm looking forward to seeing what improvements happen once there's a laptop
charging standard:

[http://www.theinquirer.net/inquirer/news/2319855/eu-
pushes-f...](http://www.theinquirer.net/inquirer/news/2319855/eu-pushes-for-a-
single-laptop-charger-standard)

------
zobzu
not sure how using a better switching regulator is "patentable" but then
again...

main reason for chargers to be bulky is costs (nobody "cares" when they buy
the laptop, they only realize later..), not technology.

other than that it's dearly needed for many.

------
derengel
Its funny how they show it most of the time without the cable.

------
macco
I don't get it. Do they really solve a problem? I have a pretty nice laptop
adapter, that is light and about twice the size of Dart.

I is perfectly fine for me.

------
balladeer
I am not sure it's just me, or few more, or many more, but after Oculus VR I
doubt I'll crowd-fund almost anything other than charity.

------
Khao
Shouldn't a power adapter like that be grounded?

~~~
Xylakant
Apple power adapters are not grounded if you use the short plug (the cable is
grounded) and they supply up to 85W. You sometimes get the slight tingly
feeling when touching the case.

------
cordite
> Dart for MacBook costs us an additional $79

Apple sure doesn't like to make it easy for third parties to be physically
compatible with them.

------
xexers
I wonder about vampire power usage. If I leave it plugged in to the wall, but
not into my laptop, how much power does it consume.

------
graywh
I'd love to be able to send in my old Macbook power adapters with frayed cords
to save $79 on the connector.

------
wtracy
I would like to see exact dimensions of this thing. All I see on the page is
"2.5 cubic inches".

------
pacofvf
But.. but.. Canada and Mexico use the same socket/voltage, we have to buy the
global edition anyway?

------
Theodores
I can't see many British people queuing up to pay for this - it has the wrong
plug on it!

------
cliveowen
Looks like it'll only work on US outlets, so it's unfit for most of the world.

~~~
Jtsummers
> Global Dart: You live abroad and you want a Dart. This reward is for you.
> _The Dart will work internationally, but you 'll need a plug to match your
> outlet. This reward includes the Dart PLUS a plug adapter for your region._
> Your Dart, your color holds for this offer. Choose your favorite from among
> our signature Kickstarter colors. Please note the later estimated delivery
> date. Not MacBook compatible. Shipping is included.

(Emphasis added)

It seems this is in fact fit for most of the world.

~~~
cliveowen
If you have to resort to an adapter you lose the main proposition (the small
form factor), so the point remains.

~~~
joezydeco
A plug adapter doesn't have to be as large as a transformer.

[http://ep.yimg.com/ca/I/theshorelinemarket_2310_643977735](http://ep.yimg.com/ca/I/theshorelinemarket_2310_643977735)

Inelegant? Sure. Large? No.

~~~
kijin
That only works in continental Europe, South Korea, and a handful of other
countries that use the CEE7 (Europlug) standard.

In the UK, the plug adapter is going to be twice as big as Dart:

[https://www.google.com/search?q=uk%20plug&tbm=isch](https://www.google.com/search?q=uk%20plug&tbm=isch)

~~~
chx
This adapter [http://www.dx.com/p/mini-worldwide-power-plug-
adapter-2238](http://www.dx.com/p/mini-worldwide-power-plug-adapter-2238)
[http://www.amazon.com/Kikkerland-UL03-A-Universal-Travel-
Ada...](http://www.amazon.com/Kikkerland-UL03-A-Universal-Travel-
Adapter/dp/B00210MRGC) will fold itself into a UK plug while still being flat
and all that. Once upon a time even APC sold a version of this.

------
ajb
Sticks a long way out of the wall. How much, lest's see: the size is given in
cubic inches, how useful - not.

It's also only 50% of the size of my current adapter, not a quarter, although
to be fair, that one is only 33W. Does have a UK plug though! Dart plus plug
adapter is probably no smaller.

------
Dorian-Marie
200$ for "Global Dart for MacBook", that's a lot for a charger

------
51Cards
US Only. Insert my sad face here. Canada gets no love... sigh.

~~~
ama729
It actually does, check the FAQ at the bottom, it was a mistake on their end.

~~~
51Cards
Wonderful, thanks! Off to spend some money.

------
hippich
Too bad my laptop requires 240W power adapter :)

~~~
TheLoneWolfling
240W?

How much battery life do you get? Half an hour?

~~~
hippich
with normal usage - 4.5 hours. But if I run something in dGPU - I can burn
through battery in like an hour.

Under windows they told it will get better battery life mostly because of
better drivers support. But I never tested it.

This is Dell Precision M6600. This one and most other Precisions will consume
similar amount of power from PSU. Not sure why all the downvotes. Even MacBook
Pro I have requires 85W

------
pud
Give it a retractable cord and I'm sold.

------
yoamro
Great product. Cant help but feel this will be extremely losable, if consumers
are anything like me..

------
sp332
Wow, that got to market quickly!

~~~
stoev
Not yet, apparently they will start shipping in about six months.

