Using a mini-USB connector to power things from a PS seems to be quite common these days for things like phones, Tom-Tom, etc. Presumably only using some of the 'pins' on the connector as there is no data being transferred. Are they universal? Assuming the PS supplies enough current will any one work with another, as it were?
The data pins may be shorted, or have a known resistance across them to act as a secret handshake for certain devices to take more current.
iThings seem to be different to most other things.
Dave Plowman (News) wrote
In my experience - no. I have a Hudl, I attempted to charge it with the wrong charger that had an identical (or so I thought) USB cable connection, it failed and I thought the Hudl had a problem, until I used the correct charger and cable.
Not quite. But close enough that I use mine pretty much interchangeably.
Some USB3 are capable of supplying nearly 900mA whereas the standard USB2 ones are only good for 600mA and weedy PSUs might not manage that.
Smart devices wanting more power are supposed to negotiate with their host to get it, but some things just go gimmee gimmee gimmee.
The general rule of thumb is that they mostly work interchangeably but it may take a longer to recharge a power hungry device from a weedy USB PSU. It is the assumption that all can supply the correct current that might be an issue. Some power hungry peripherals have a pair of USB connectors on them so that they can take current from two USB sockets.
It is a *HUGE* improvement from the early era of mobile phones when every manufacturer and model seemed to require a different charger, voltage and physical connector with ever more peculiar shapes!
Shame that laptops are still not fully standardised. I have collection of old PSU blocks for them in a drawer ranging from 14v up to 19v. Mostly centre positive but you can't take it for granted!
Regards, Martin Brown
I'd agree with Martin that supplies and devices are *mostly* interchangeable - but I don't have anything from Apple, which probably helps!
I've successfully charged phones, satnavs, e-readers etc, from each others supplies, and from desk PC's and (esp. away from home) a netbook.
One very good thing about the USB standard is that the voltage concerned is always 5 volts at a specified polarity, irrespective of current availability and odd resistor "fiddles", so it's reasonable to assume that even if a device isn't properly charged from a particular supply - no harm will be done.
Charles F
Thanks for that - gives me confidence to try it. If there's no chance of magic smoke.
One gotcha, is car chargers. I use my Nokia 620 as a satnav, and noticed that when it was "charging" from the 12V USB adapter, it slowly lost charge until dying.
Swapping chargers with my wifes phone (which was marked "1A", whereas the orginal was unmarked) fixed the problem, and now I can satnav all day
*and* charge the phone.
The only risk of magic smoke is if you plug something impolite about taking maximum permitted current without bothering to ask into a USB socket on something smart that is weedy and unable to comply.
Most times the worst that will happen is that the USB charger will be slower than it should be because it can't source the same current as the units proper charger. It helps now that cars have USB sockets.
Given the short battery life of smartphones you can't afford to be too picky about where you charge them...
Regards, Martin Brown
Unlikely, as the chipset on the output side *should* limit the available current independently of any negotiation, so even a dead short across the power lines won't cause damage. Similarly, the chipset on the input side will limit itself to what it can take safely.
True.
One reason I like Nokias, as they tend to have better battery life.
I agree that it shouldn't happen in well designed circuits, but I have my suspicions about some cheap budget stuff cutting silly corners.
There is a chance that some high draw devices like satnavs might continue to discharge their own battery if the PSU is inadequate.
Me too. I kept a 6303 going until last year when I discovered the hard way that it doesn't like being dunked in a bucket of water. The battery life was phenomenally good nearly two weeks running on a single charge.
Some folk I know have to recharge their smartphones at lunchtime... I suspect CandyCrush Saga is a battery thief!
Regards, Martin Brown
As they all seem to use the same chipsets, I'd expect it to be rare, as long as the makers use the reference design, which seems to be a single chip on a PCB, with a tiny coil and couple of other bits with some suppression components if you're lucky. All the current limiting and control logic is on the chip, with everything preset and no adjustments for the manufacturer to get wrong.
Just don't ask how *I* know this....
Even the Lumia 520 I bought recently lasts me a couple of days, but I'm a light user.
Not to mention all the other games that phone home to download the adverts that pay for them.
Not meaning to pick you up too much on a very reasonable generalisation. My Nokia 925 was the absolute worst phone on the planet when running any navigation app. I managed to flatten in under an hour despite being plugged in to an external battery pack as well. My Nokia 1520 is pretty damned good almost whatever you run on it.
Actually, I disagree. I think micro-USB is very common on phones, mini-USB less so. Other devices vary somewhat unpredictably.
Some info on 'pin' protocol, and also a vid of a teardown of a chinese 'extremely dangerous' USB charger, and the difference to a true Apple charger - very high spec... and price, of course.
Think it's micro I'm talking about. The handbook for the camera says 'mini' but it's the same one as on my phone and Tom Tom. Unless there's yet another even smaller.
It seemed to go from weird and wondeful to mini uSB to micro USB. I was told that it has recently been decided to standardise on micro USB for all devices using a USB connnection for power and data.
Until theybuggrem change their minds again...
(Apple are of course excluded from this generalisation)
The one I'm talking about measures 6.8 x 3 mm
The wonderful things about standards is that there are so many to choose from.
Shows the shape differences fairly well but is not to scale micro B is slightly narrower than mini B and about half the thickness.
In contradistinction to toy animals:
But the most wonderful thing about tiggers is I'm the only one
In message , at 13:32:42 on Fri, 1 Aug
2014, Martin Brown remarked:
Really? I've got a couple of dozen that range from perhaps 6v to 24v, with semi-random centre-polarity.
This is nothing new, I wrote an article about it for Computer Shopper about 20 years ago (my monthly column was for mobile/portable computing).
Another common theme was "never buy anything that uses AAA batteries, if there's any alternative that accepts AA").
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