UK 3-pin sockets and two USB ports
Whats the 3 pronged symbol below the USB on the first pic?
What is the meaning of this crappy sentence:
"It fits any backbox up to a depth of 35mm and USB ports are limited to
2 Amps, meaning only the required power is delivered to the devices"
How does a limit of 2 A mean anything of the sort?
And USB 3.1 has already overtaken the 2 A capacity...
The USB 3.1 standard is backward compatible with USB 3.0 and USB 2.0.
Using three power profiles of those defined in the USB Power Delivery
Specification, it lets devices with larger energy demands request higher
currents and supply voltages from compliant hosts – up to 2 A at 5 V
(for a power consumption of up to 10 W), and optionally up to 5 A at
either 12 V (60 W) or 20 V (100 W).
I'd be hacked off to have fitted a houseful of these sockets and then
find that they are inadequate for newer devices.
I would not. Every 2 years I buy a new generic charger. Last time, 1A.
This time 2A. The standard is too unstable to be bothered fitting into
Hindsight is easy - but wouldn't it have been nice if USB had chosen 24V
instead of 5V for the power line (data lines could still be low). 1/5th
of the current more or less for the same power.
Handy for modern high-power USB devices but not very convenient when USB
was developed in the mid-90s. Back then +5V was the most common logic
supply voltage so a USB controller would already have a +5V rail to source
the power and a low-power USB client device would be able to directly use
a +5V supply. Using a 24V supply would have increased the cost significantly
by requiring voltage converters at both ends of the link. It's unlikely that
USB would ever have become successful if it had such a cost penalty to start
with. For example there is no 24V supply in the most common USB controller -
A 5V supply was fine for the sort of low power devices originally
envisaged for being USB-powered, like keyboards and mice. It's
only because USB could start up cheaply that it had the opportunity
to grow to the point of offering 5A at 20V in the latest specification.
Thank you and Andrew too. I had not noticed voltage switching had
arrived. 20V? Interesting.
Does this mean that "bad code" now had the potential to blow stuff up?
 One computer from the 80's could literally fry itself if an IO port
was programmed wrong - was it an Apple II - cannot find it on google.
And I wonder if the voltage can be controlled from the computer side of
the USB chipset - or it is something the chip is hardwired to negotiate
from the USB side only?
Wonder what implications this has for dumb chargers and their cheaty
Nice. In the future* one will type in google "USB" expecting technical
goodness, and end up on the spamming bigoting ill-informed universal
site of immoral link trotting clap-trap that is reportedly the web
edition of the daily mail, but really just a money plant.
* hmmm, typing in google seems it has already happened..
Has Russ Andrews thought about on-site advertising with them?
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