Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

(dont ask how much they are).

Well if they were dangerous, they should come with a warning, but if they
start blowing up phones, even at the price you would probably have a claim
against the shop if there was no warning.
Brian

--
From the Bed of Brian Gaff.
The email is valid as
Blind user.
"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned
lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

(dont ask how much they are).

P Jameson wrote:

Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

USB ports on laptops generally only provide 0.5A, divide that 0.5A
between five devices and it wouldn't go far, so presumably it has five
different types of connector and you pick the one that fits the phone?

Modern phones will take up to 1 or 2A, so charging will be slow, some
phones won't stoop that low and will refuse to charge at all.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

Provided the phone wants 5V (which is what USB provides) the supply is
regulated for the innards of the laptop anyway.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

No, it'll be regulated from the car's nominal 12v down to 5V.

On Monday, May 5, 2014 3:59:14 PM UTC+1, P Jameson wrote:
Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

The laptop would be damaged by voltage spikes too - so yes.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

I doubt it, but this is *slightly* more dodgy. It depends on your car
electrics. High quality adaptors would have plenty of smoothing to remove
any spikes.

(dont ask how much they are).
.... but you probably don't get high quality for £1

P Jameson scribbled...


Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

(dont ask how much they are).


There's not enough power for them to work on many laptops. I've had one
connected to my pc for a couple of years, never had a problem with it.

"Martin Bonner" wrote in message
...
On Monday, May 5, 2014 3:59:14 PM UTC+1, P Jameson wrote:
Poundland are doing a little cable with USB at one end and five
connections
the other end to connect to a variety of different Smart Phones. So you
can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

The laptop would be damaged by voltage spikes too - so yes.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned
lead.

Would the cigarette socket also be likely to 'spike' and damage the
phone?

I doubt it, but this is *slightly* more dodgy. It depends on your car
electrics. High quality adaptors would have plenty of smoothing to remove
any spikes.

i had a cheap garmin usb car charger let it's magic smoke out once.... the
second day of use in my new car (both the charger and the car)
Not a nice thing to happen as your driving, luckily we were in town, but got
some funny looks when a smoking charger was chucked out the window into the
gutter,

i then got one of those tomtom branded fag lighter extensions with 2 usb
sockets on the side, one usb socket is a 1 or 1.5 amp 'fast charge' socket,
and it allows me to plug in the charger for the brodit phone mount due to
the fag lighter socket pass through.

but for those cable jobbies with a USB A socket on one end, and a selection
of mini, micro and those awkward ******* phones that still use proprietry
charging jacks, they usually have no electronics in them at all, so it'll be
upto the devise providing the power to keep to the usb voltage and current
standard,

On Monday, May 5, 2014 3:59:14 PM UTC+1, P Jameson wrote:

Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.
Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

never a problem

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.
Would the cigarette socket also be likely to 'spike' and damage the phone?
(dont ask how much they are).

this is less certain. There are electronics out there that dont survive or protect against the transients that are sommomnish in vehicles. I've no idea about poundland's specs.


NT

"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned
lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

(dont ask how much they are).

The multi-connector is just a splitter - if you get any spikes, they're
coming from the laptop.

The specification is pretty tight: 5V @ 500mA - reasonable to assume you can
only charge one gadget ar a time.

The car adaptor obviously has some kind of voltage regulator to drop the 12V
down to 5V - at £1 you can afford to break one open and describe to us
what's in it so we can give better informed advice about any potential risk.

On Mon, 5 May 2014 15:59:14 +0100, "P Jameson"
wrote:

Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

I have no personal experience of this, however....

Charging a Smartphone from a USB socket on a PC or Mac is completely
normal. There should be no voltage spikes as the power output from the
USB socket is designed to power external devices. The real question here
is whether a single USB socket can supply enough current to charge five
Smartphones at once in a reasonable time.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

No. The adapter will contain electronics to reduce the voltage to what
is needed by the phone and will regulate it.

The cigarette lighter socket plug on the connector for charging my
non-smart Nokia mobile has on the label:

Inoput: DC 12V/24V
Output: 5.7V 800 mA

The mains adpater for charging that phone has an output of 5.3V DC.

--
Peter Duncanson
(in uk.tech.digital-tv)

On 05/05/2014 15:59, P Jameson wrote:
Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

It's only a dumb cable - the voltage comes from the laptop. The laptop's
USB output should be regulated to 5v - so it won't damage the phone.
Just mightn't charge it as fast as a dedicated charger 'cos the laptop's
USB will likely only supply 500mA.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?


No, it will be a regulated DC to DC converter to produce 5v from the
car's 12+ volts. Very likely the same innards as those sold by the likes
of Maplin at several times the price.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"Peter Duncanson" wrote in message
...
On Mon, 5 May 2014 15:59:14 +0100, "P Jameson"
wrote:

Poundland are doing a little cable with USB at one end and five
connections
the other end to connect to a variety of different Smart Phones. So you
can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

I have no personal experience of this, however....

Charging a Smartphone from a USB socket on a PC or Mac is completely
normal. There should be no voltage spikes as the power output from the
USB socket is designed to power external devices. The real question here
is whether a single USB socket can supply enough current to charge five
Smartphones at once in a reasonable time.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned
lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

No. The adapter will contain electronics to reduce the voltage to what
is needed by the phone and will regulate it.

I think the point is whether a £1 charge adapter is safe to use on say; a
£100 smartphone for instance.

If it uses a series pass transistor in the regulator, there's always a
possibility the transistor could fail short-circuit and dump the full 12V on
the USB connector.

If the target device uses a lithium battery, a fault condition of 12V on the
USB connector could overwhelm the charge control chip and cause
overcharging - overcharged lithium cells tend to get thermal runaway and
vent with flaming gas!

How many corners did they cut to get it on the shelves at that price?!

On 05/05/2014 16:15, Martin Bonner wrote:

High quality adaptors would have plenty of smoothing to remove
any spikes.


They probably do not. Some of the "quality" branded 12V/5V adapters for
the car are so small there is no room for anything large.

It will be a switched mode converter using a commonly available chip
that cost pence.

As already stated the current available from a USB lead connected to a
computer/laptop will be limited and the capability will be charging one
phone at a time. Even from a 12V/5V converter for the car probably it
will be limited to charging only one or two devices at the same time.


--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

I bought a poundland (actually it was a 99p shop) USB hub

it was CFU

tim

On Mon, 05 May 2014 17:50:22 +0100, Peter Duncanson
wrote:

On Mon, 5 May 2014 15:59:14 +0100, "P Jameson"
wrote:

Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

I have no personal experience of this, however....

Charging a Smartphone from a USB socket on a PC or Mac is completely
normal. There should be no voltage spikes as the power output from the
USB socket is designed to power external devices. The real question here
is whether a single USB socket can supply enough current to charge five
Smartphones at once in a reasonable time.

I suspect that is not its intended purpose. As another poster has
commented, it is more likely to be designed to allow connectivity with
different devices.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

No. The adapter will contain electronics to reduce the voltage to what
is needed by the phone and will regulate it.

I'm sure that's true but I think the point of the question is whether
a device that costs £1 will be up to the job.

On Mon, 05 May 2014 17:52:43 +0100, Roger Mills
wrote:

[snip]

No, it will be a regulated DC to DC converter to produce 5v from the
car's 12+ volts. Very likely the same innards as those sold by the likes
of Maplin at several times the price.

I think you have analysed the question correctly but not extended this
analysis into your answer :-)

On Mon, 5 May 2014 19:11:19 +0200, "tim....."
wrote:



"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

I bought a poundland (actually it was a 99p shop) USB hub

it was CFU

tim


I bought a USB SD card reader from Pound World but it failed after a
few weeks. I bought another one but that failed too.
I think if you plug and unplug the whole thing from the computer it is
OK but it doesn't like the card being inserted or removed when the
reader is powered.

CBA buying another one to investigate further.

--

Graham.

%Profound_observation%

On 05/05/14 15:59, P Jameson wrote:
Poundland are doing a little cable with USB at one end and five connections
the other end to connect to a variety of different Smart Phones. So you can
charge your phone from your laptop.


Had a look a couple of weeks ago, they also sell USB phone chargers that
plug into the mains. Of course these are safe. Only a quid.



So I spent a while in the shop thinking I'd buy one to take to bits out
of morbid curiosity, but then I spotted a bag of 'spicy crackers' that
probably rates higher in the morbidity for a pound sweepstake. So I
bought that...



Hmmm, WiFi doesn't permeate too well here 6 feet down. Am I getting out?


--
Not Me

P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of
ways those things signal how much current they need so its not
very likely that an el cheapo cable thing will be able to do that
correctly with all the phone connectors, so it wont necessarily
charge the phone as quickly as possible, or at all in the worst cases.

They also do an adapter to plug into the car cigarette socket with a USB
femail socket built in. This will then accomodate the first mentioned
lead.

Would the cigarette socket also be likely to 'spike' and damage the phone?

That’s certainly much more likely.

(dont ask how much they are).

"Adrian C" wrote in message
...
On 05/05/14 15:59, P Jameson wrote:
Poundland are doing a little cable with USB at one end and five
connections
the other end to connect to a variety of different Smart Phones. So you
can
charge your phone from your laptop.


Had a look a couple of weeks ago, they also sell USB phone chargers that
plug into the mains. Of course these are safe. Only a quid.



So I spent a while in the shop thinking I'd buy one to take to bits out of
morbid curiosity,

There's various gadgets in Poundland that I'd like to pull apart out of
curiosity - but all those £'s mount up.

"Rod Speed" wrote in message
...
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of
ways those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually available
by default.

A common scheme is "Polyfuse" protection - its a PTC thermistor that can
heat up with the current flowing through it, at a certain current it heats
enough to increase in resistance enough to practically stop current flow.

When the overload is removed it cools and returns to low resistance, so its
self resetting.

In article , Ian Field
wrote:


"Rod Speed" wrote in message
...
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

A common scheme is "Polyfuse" protection - its a PTC thermistor that can
heat up with the current flowing through it, at a certain current it
heats enough to increase in resistance enough to practically stop
current flow.

When the overload is removed it cools and returns to low resistance, so
its self resetting.

That could well explain why my "Nokia Smart Phone" refused to charge from a
cheap car USB adaptor.

--
From KT24

Using a RISC OS computer running v5.18

"charles" wrote in message
...
In article , Ian Field
wrote:


"Rod Speed" wrote in message
...
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

A common scheme is "Polyfuse" protection - its a PTC thermistor that can
heat up with the current flowing through it, at a certain current it
heats enough to increase in resistance enough to practically stop
current flow.

When the overload is removed it cools and returns to low resistance, so
its self resetting.

That could well explain why my "Nokia Smart Phone" refused to charge from
a
cheap car USB adaptor.

In any computer, the 5V rail the USB supply comes from is capable of at
least several amps, without short circuit protection, a mishap could result
in melted copper tracks on the motherboard.

The arrangement in a car adapter is a little different - and there's various
ways of going about it depending how cheap they want to make it.

Possibly the best way is with a switch-mode chip like the industry standard
MC34063 - whether you'll get that for a £ is another matter.

Next time I go into town, I might punt a £ for one just to break open and
see what's in it.

Ian Field wrote
Rod Speed wrote
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone with
'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

That’s a different issue to the current situation where plenty of
phones will happily charge at a lot higher current than 500mA
when that current is available. That would be particularly relevant
with the car fag adapter rather than the use on the laptop. It
is obviously very desirable to have the phone charge as quickly
as possible, particularly when you are charging it in the car after
you have discovered that you forgot to charge it overnight etc.

And needless to say, there are a variety of ways various phones
use to signal that they are can charge at the multiple amps rates.

A common scheme is "Polyfuse" protection - its a PTC thermistor that can
heat up with the current flowing through it, at a certain current it heats
enough to increase in resistance enough to practically stop current flow.

When the overload is removed it cools and returns to low resistance, so
its self resetting.

Just had a technoklutz manage to trigger the protection
in a Toshiba laptop USB port by shoving a 3.5mm jack in
there without looking at where he was putting the jack.

In that case it was actually a laptop reboot that reset
the USB port. I haven't managed to remember to get
the model number from him to check what the Toshiba
maintenance manual actually says about that.

charles wrote
Ian Field wrote
Rod Speed wrote
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different
Smart Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety
of ways those things signal how much current they need

In the original USB specification it was 100mA unless the target
device signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the
full 500mA is usually available by default.

A common scheme is "Polyfuse" protection - its a PTC thermistor
that can heat up with the current flowing through it, at a certain
current it heats enough to increase in resistance enough to
practically stop current flow.

When the overload is removed it cools and
returns to low resistance, so its self resetting.

That could well explain why my "Nokia Smart Phone"
refused to charge from a cheap car USB adaptor.

No, that is due to what I said previously. The various smartphones
use different ways of signalling that they can charge with more
than 500mA and some of them just refuse to charge at all if they
don’t see the signal from the USB that they are looking for.

The signalling is done by different fixed voltage
levels etc on the USB data lines in that connector.

"Rod Speed" wrote in message
...
Ian Field wrote
Rod Speed wrote
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

That’s a different issue to the current situation where plenty of
phones will happily charge at a lot higher current than 500mA
when that current is available. That would be particularly relevant
with the car fag adapter

That's part of what the OP was asking, a badly designed/cheap car adapter
might waste an awful lot of power as heat - an still not quite make the
500mA spec.

A very cheaply made linear regulator could suffer excessive heating at full
load - if the series pass transistor fails, it will fail short-circuit and
dump the full 12V on the load.

A step down switch mode regulator will be a buck-regulator - which also has
a series transistor which will dump the full 12V if it fails, but the
transistor generates much less heat and is far less likely to fail.

Regulation is usually a lot more accurate with a switcher too.

"Ian Field" wrote in message
...
That’s a different issue to the current situation where plenty of
phones will happily charge at a lot higher current than 500mA
when that current is available. That would be particularly relevant
with the car fag adapter

Do car 12V - 5V adaptors have an over-current cutout which will cut the
power to the phone if it tries to draw too much current? My wife has a
tablet PC which will charge happily from some car chargers but not others.
Even in the latter case, it still gives a "charging" indication, rather than
reporting that the charger has been disconnected, but the battery charge
never increases (indeed it falls gradually if the tablet is turned on). The
chargers that fail to charge it still charge other devices OK.

I could understand an over-current cutout, but I'm puzzled that if it comes
into effect the device doesn't report that charging has stopped.

"NY" wrote in message
o.uk...
"Ian Field" wrote in message
...
That’s a different issue to the current situation where plenty of
phones will happily charge at a lot higher current than 500mA
when that current is available. That would be particularly relevant
with the car fag adapter

Do car 12V - 5V adaptors have an over-current cutout which will cut the
power to the phone if it tries to draw too much current?

That question goes to the root of what the OP asked - it all depends what
you get for your £ in Poundland.

A common switch mode regulator chip used in this type of application is the
MC34063 - it has a pin to include a current sensing resistor, whether the
manufacturer of the adapter bothered to use it is another matter.

On Mon, 5 May 2014 21:07:39 +0100, "Ian Field"
wrote:



"charles" wrote in message
. ..
In article , Ian Field
wrote:


"Rod Speed" wrote in message
...
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

A common scheme is "Polyfuse" protection - its a PTC thermistor that can
heat up with the current flowing through it, at a certain current it
heats enough to increase in resistance enough to practically stop
current flow.

When the overload is removed it cools and returns to low resistance, so
its self resetting.

That could well explain why my "Nokia Smart Phone" refused to charge from
a
cheap car USB adaptor.

In any computer, the 5V rail the USB supply comes from is capable of at
least several amps, without short circuit protection, a mishap could result
in melted copper tracks on the motherboard.

Not just any computer MoBo, only PC Chips MoBos ime. Even here they
do add a safety fuse in the form of either a very thin circuit trace
or an smd inductor, not items you'd normally class as a fuse but, at 5
volts, good enough to stop a conflagration.

However, the downside of this one shot fusing protection is that all
the USB and PS/2 sockets lose their 5v rail (keyboard and mouse stop
working). I should know 'cos I've bridged a few burnt out
inductors/cct traces with a 3 amp polyfuse on these ****e MoBos (after
clearing the short cicrcuit, usually a vandalisedd USB socket from
which I've snipped the offending pin).

With every other brand of MoBo I've seen, the standard practice is to
completely forego the USB negotiation for current protocols and simply
wire the +5v pins to a common bus protected by a 3 or 4 amp polyfuse.
IOW, your 2 or 3 amp usb charger is unlikely to be kept short of juice
when plugged into a desktop PC.

A laptop, otoh, probably does include the full power control protocol
to minimise excessive demand from its battery (but, even here, this
may not always be the case).


The arrangement in a car adapter is a little different - and there's various
ways of going about it depending how cheap they want to make it.

Possibly the best way is with a switch-mode chip like the industry standard
MC34063 - whether you'll get that for a £ is another matter.

Next time I go into town, I might punt a £ for one just to break open and
see what's in it.

With a limit of just half an amp output, the chinese manufacturer
will be able to get away with mounting the chip straight onto the
circuit board with a blob of protective epoxy to stick it down to the
board (just like those cheap USB flash memory card adapters).

They only have to survive 6 to 12 months before atmospheric pollution
poisons the chip and the punter has to...well, punt another quid their
way. Most Pound shop customers wouldn't bother invoking SOGA over a
one pound item. The Pound shop management rely on this factor but
aren't stupid enough to open this can of worms so will cheerfully
accept any warranty returns with good grace.

If the chip turns out to be under a blob of epoxy on the circuit
board, I'd be a little leary of such a product in this case.
--
Regards, J B Good

Ian Field wrote
Rod Speed wrote
Ian Field wrote
Rod Speed wrote
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

That’s a different issue to the current situation where plenty of phones
will happily charge at a lot higher current than 500mA when that current
is available. That would be particularly relevant with the car fag
adapter

That's part of what the OP was asking,

No.

a badly designed/cheap car adapter might waste an awful lot of power as
heat - an still not quite make the 500mA spec.

That cheap cable will be entirely passive, just a splitter
and maybe some attempt to signal what the cable can
deliver current wise to the smartphones, but the problem
is that the signalling methods that are used don’t allow
any way for them all to signal properly without some
form of switching which I bet it doesn’t have.

There won't be any waste as heat with the cable and
there is very unlikely to be with the fag plug charger
either, just because its not even possible to get rid
of enough heat in one of those and cheaper to use
a switcher anyway.

A very cheaply made linear regulator could suffer excessive heating at
full load

But there is no way to get rid of that heat in a
fag plug adapter, so a switcher would be used
instead and that would be cheaper anyway.

- if the series pass transistor fails, it will fail short-circuit and dump
the full 12V on the load.

But the smartphone may be designed to handle that situation.

A step down switch mode regulator will be a buck-regulator - which also
has a series transistor which will dump the full 12V if it fails, but the
transistor generates much less heat and is far less likely to fail.

Regulation is usually a lot more accurate with a switcher too.

The real problem isnt how it fails, the real problem
is the way the different smartphones signal that they
can use more current and with most of them refusing
to charge at all when they don’t see the type of
signalling they expect to see. They do that
because they choose to fail safe in that situation.

NY wrote
Rod Speed wrote

That’s a different issue to the current situation where plenty of
phones will happily charge at a lot higher current than 500mA
when that current is available. That would be particularly relevant
with the car fag adapter

Do car 12V - 5V adaptors have an over-current cutout which will cut the
power to the phone if it tries to draw too much current?

The best of them do, but its far from clear what those very cheap ones do on
that.

Presumably if the ic used has that capability, the better designs
would use that, but there must be some of the most incompetent
designers that don’t even bother to implement that even when
the ic can do it without any added cost.

My wife has a tablet PC which will charge happily from some car chargers
but not others.

And that is because there is more than one way to
signal that it can use the higher charging currents fine.

Even in the latter case, it still gives a "charging" indication, rather
than reporting that the charger has been disconnected,

That varys with the tablet and smartphone. Some of the better
designs do indicate when they are refusing to charge even when
the 5V is available.

but the battery charge never increases (indeed it falls gradually if the
tablet is turned on).

Yeah, that's not uncommon, because of the different signalling methods used.

The chargers that fail to charge it still charge other devices OK.

Because they use a different signalling detail to the one that refuses to
charge.

I could understand an over-current cutout, but I'm puzzled that if it
comes into effect the device doesn't report that charging has stopped.

It doesn’t because that isnt a cutout. It doesn’t cut out, so
the 5V is still there and so the charging indication is still there.

The signalling is there so the charger can decide that its not a fault
in what is being charged, its just using amps to charge quicker.

On Mon, 05 May 2014 18:35:03 +0100, Graham. wrote:

On Mon, 5 May 2014 19:11:19 +0200, "tim....."
wrote:



"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

I bought a poundland (actually it was a 99p shop) USB hub

it was CFU

tim


I bought a USB SD card reader from Pound World but it failed after a
few weeks. I bought another one but that failed too.
I think if you plug and unplug the whole thing from the computer it is
OK but it doesn't like the card being inserted or removed when the
reader is powered.

That's not a card reader, it's a flash to USB pen drive converter.
The idea is that you load an appropriate memory card into the slot
then plug it in. When it comes to ejecting it, you have to treat the
whole thing the same as you would a usb pen drive, that is, you use
the 'safely eject hardware' applet in the systray before unplugging it
from the USB slot.
--
Regards, J B Good

Yes, but if my life depended on an item I'd certainly not buy it from a
pound shop. Luckily none of them sell parachutes..... yet.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Rod Speed" wrote in message
...
Ian Field wrote
Rod Speed wrote
Ian Field wrote
Rod Speed wrote
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

That’s a different issue to the current situation where plenty of phones
will happily charge at a lot higher current than 500mA when that current
is available. That would be particularly relevant with the car fag
adapter

That's part of what the OP was asking,

No.

a badly designed/cheap car adapter might waste an awful lot of power as
heat - an still not quite make the 500mA spec.

That cheap cable will be entirely passive, just a splitter
and maybe some attempt to signal what the cable can
deliver current wise to the smartphones, but the problem
is that the signalling methods that are used don’t allow
any way for them all to signal properly without some
form of switching which I bet it doesn’t have.

There won't be any waste as heat with the cable and
there is very unlikely to be with the fag plug charger
either, just because its not even possible to get rid
of enough heat in one of those and cheaper to use
a switcher anyway.

A very cheaply made linear regulator could suffer excessive heating at
full load

But there is no way to get rid of that heat in a
fag plug adapter, so a switcher would be used
instead and that would be cheaper anyway.

- if the series pass transistor fails, it will fail short-circuit and
dump the full 12V on the load.

But the smartphone may be designed to handle that situation.

A step down switch mode regulator will be a buck-regulator - which also
has a series transistor which will dump the full 12V if it fails, but the
transistor generates much less heat and is far less likely to fail.

Regulation is usually a lot more accurate with a switcher too.

The real problem isnt how it fails, the real problem
is the way the different smartphones signal that they
can use more current and with most of them refusing
to charge at all when they don’t see the type of
signalling they expect to see. They do that
because they choose to fail safe in that situation.

On 05/05/2014 21:07, Ian Field wrote:

In any computer, the 5V rail the USB supply comes from is capable of at
least several amps, without short circuit protection, a mishap could
result in melted copper tracks on the motherboard.

In any computer with proper USB you can short it out for as long as you
like and nothing will break. The USB chips include such protection and
even power management so the OS can limit the power being drawn.

If you are silly enough to wire a USB header to the 5V power rail there
will be a big bang and things will melt when shorted. (seen that done)

On 05/05/2014 22:42, Johny B Good wrote:

With a limit of just half an amp output, the chinese manufacturer
will be able to get away with mounting the chip straight onto the
circuit board with a blob of protective epoxy to stick it down to the
board (just like those cheap USB flash memory card adapters).

There are good reasons why some electronics are like that.. its more
reliable and is used in telecoms and military applications.
Its only a problem if its done incorrectly.

On Monday, 5 May 2014 15:59:14 UTC+1, P Jameson wrote:
Poundland are doing a little cable with USB at one end and five connections

(dont ask how much they are).

I'm not going get ripped off by poundland I'm waiting till the 99p shop gets them in

On Tue, 06 May 2014 00:23:03 +0100, Johny B Good
wrote:

On Mon, 05 May 2014 18:35:03 +0100, Graham. wrote:

On Mon, 5 May 2014 19:11:19 +0200, "tim....."
wrote:



"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

I bought a poundland (actually it was a 99p shop) USB hub

it was CFU

tim


I bought a USB SD card reader from Pound World but it failed after a
few weeks. I bought another one but that failed too.
I think if you plug and unplug the whole thing from the computer it is
OK but it doesn't like the card being inserted or removed when the
reader is powered.

That's not a card reader, it's a flash to USB pen drive converter.
The idea is that you load an appropriate memory card into the slot
then plug it in. When it comes to ejecting it, you have to treat the
whole thing the same as you would a usb pen drive, that is, you use
the 'safely eject hardware' applet in the systray before unplugging it
from the USB slot.

Now you tell me! ;-)



--

Graham.

%Profound_observation%

"Johny B Good" wrote in message
...
On Mon, 05 May 2014 18:35:03 +0100, Graham. wrote:

On Mon, 5 May 2014 19:11:19 +0200, "tim....."
wrote:



"P Jameson" wrote in message
...
Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

I bought a poundland (actually it was a 99p shop) USB hub

it was CFU

tim


I bought a USB SD card reader from Pound World but it failed after a
few weeks. I bought another one but that failed too.
I think if you plug and unplug the whole thing from the computer it is
OK but it doesn't like the card being inserted or removed when the
reader is powered.

That's not a card reader, it's a flash to USB pen drive converter.
The idea is that you load an appropriate memory card into the slot
then plug it in. When it comes to ejecting it, you have to treat the
whole thing the same as you would a usb pen drive, that is, you use
the 'safely eject hardware' applet in the systray before unplugging it
from the USB slot.

I've bought multi-card readers from various suppliers and paid considerably
more than £1 for them - without exception, any camera has refused to
recognise a card formatted by one of these card readers.

"Johny B Good" wrote in message
...
On Mon, 5 May 2014 21:07:39 +0100, "Ian Field"
wrote:



"charles" wrote in message
.. .
In article , Ian Field
wrote:


"Rod Speed" wrote in message
...
P Jameson wrote

Poundland are doing a little cable with USB at one end and five
connections the other end to connect to a variety of different Smart
Phones. So you can charge your phone from your laptop.

Would the voltage likely be *steady* enough not to damage the phone
with 'spikes' ?

Yes. The voltage is determined by the laptop, not that cable thing.

The very fundamental problem tho is that there are a variety of ways
those things signal how much current they need

In the original USB specification it was 100mA unless the target device
signalled otherwise, then a max 500mA was available.

AFAIK that has largely been dropped and the full 500mA is usually
available by default.

A common scheme is "Polyfuse" protection - its a PTC thermistor that
can
heat up with the current flowing through it, at a certain current it
heats enough to increase in resistance enough to practically stop
current flow.

When the overload is removed it cools and returns to low resistance, so
its self resetting.

That could well explain why my "Nokia Smart Phone" refused to charge
from
a
cheap car USB adaptor.

In any computer, the 5V rail the USB supply comes from is capable of at
least several amps, without short circuit protection, a mishap could
result
in melted copper tracks on the motherboard.

Not just any computer MoBo, only PC Chips MoBos ime. Even here they
do add a safety fuse in the form of either a very thin circuit trace
or an smd inductor, not items you'd normally class as a fuse but, at 5
volts, good enough to stop a conflagration.

However, the downside of this one shot fusing protection is that all
the USB and PS/2 sockets lose their 5v rail (keyboard and mouse stop
working). I should know 'cos I've bridged a few burnt out
inductors/cct traces with a 3 amp polyfuse on these ****e MoBos (after
clearing the short cicrcuit, usually a vandalisedd USB socket from
which I've snipped the offending pin).

You'll probably find an increasing number of MOBOs have a polyfuse from the
outset.

"dennis@home" wrote in message
eb.com...
On 05/05/2014 21:07, Ian Field wrote:

In any computer, the 5V rail the USB supply comes from is capable of at
least several amps, without short circuit protection, a mishap could
result in melted copper tracks on the motherboard.

In any computer with proper USB you can short it out for as long as you
like and nothing will break. The USB chips include such protection and
even power management so the OS can limit the power being drawn.

AFAIK - available current negotiation is falling by the wayside - nowadays
many just give you 500mA by default and use a polyfuse for protection.

"Rod Speed" wrote in message
...
NY wrote
Rod Speed wrote

That’s a different issue to the current situation where plenty of
phones will happily charge at a lot higher current than 500mA
when that current is available. That would be particularly relevant
with the car fag adapter

Do car 12V - 5V adaptors have an over-current cutout which will cut the
power to the phone if it tries to draw too much current?

The best of them do, but its far from clear what those very cheap ones do
on that.

Just been in Poundland - but they were out of stock.

Town center is off the beaten track for me, but eventually they might have
them in stock when I go there - by the time I get one to crack open and
investigate the innards, this thread will probably be long forgotten.