Our wholesalers are selling a half euro module USB charger socket. You could fit it along with a 2 way switch for the lights into a 1 gang plate next to your bed. 
Mains USB Charger
- Thread starter ellal
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Our wholesalers are selling a half euro module USB charger socket. You could fit it along with a 2 way switch for the lights into a 1 gang plate next to your bed.
heh, yeah, but I've got to feed the laptop, amplifier, TV, and so on..
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If a USB socket supply is unable to maintain the voltage due to the device being plugged in wanting too much current it can do one of three things.
1) Let the voltage drop below 5 volt.
2) Auto switch off.
3) Permanently fail.
Having something on charge where the voltage is either low or pulsed on and off is likely to upset the charge monitoring within the device which could both result in under or over charging. So having a universal USB able to supply maximum amps for USB and maintain the 5 volts can be used with all devices needing a USB charger but taking a USB charger from a device which requires a low current and using it with a device needing a high current is clearly a problem.
There is also more than just voltage supplied by a USB socket and I have a external powered USB hub and some items will continue to charge when the computer is powered down others stop charging once the computer powers down even though there is still power at the hub. Yet the items still charge from a USB charger clearly something tells the device to do this other than just having 5 volt available.
I have found the USB socket on my hi-fi, car radio, and even the replacement computer power supply rated at 12A will not charge my Iphone but will charge my Nokia phone clearly some vital hand shaking missing.
Phones can be rather strange one of my Nokia phones decided it would only charge when switched off and I now charge the batteries on a stand alone charger not in the phone which has both 100 - 240 volt ac/dc input and a 5v USB input and will charge the battery off all USB sockets I have tried. Yet the phone will often not charge from them.
Phones in particular seem very picky in what they will charge from one reason why my Iphone with non removable battery is not used as a phone. Great display unit and games console but useless phone. For a phone one wants good reception and a reliable power source have a spare battery in my wallet means my old Nokia is far better as a phone than the Iphone. Finding a suitable USB outlet not easy with Iphone and unlike other phone can't simply swap battery.
As a result there is no easy answer to the USB charger question. With a simple battery charger be it to charge AA, AAA batteries or special flat batteries as used in phone swapping the USB chargers around does not SEEM to be a problem. However where the battery is an integral part of a piece of equipment it is apparent that one does have to be selective as to which USB outlet one uses.
1) Let the voltage drop below 5 volt.
2) Auto switch off.
3) Permanently fail.
Having something on charge where the voltage is either low or pulsed on and off is likely to upset the charge monitoring within the device which could both result in under or over charging. So having a universal USB able to supply maximum amps for USB and maintain the 5 volts can be used with all devices needing a USB charger but taking a USB charger from a device which requires a low current and using it with a device needing a high current is clearly a problem.
There is also more than just voltage supplied by a USB socket and I have a external powered USB hub and some items will continue to charge when the computer is powered down others stop charging once the computer powers down even though there is still power at the hub. Yet the items still charge from a USB charger clearly something tells the device to do this other than just having 5 volt available.
I have found the USB socket on my hi-fi, car radio, and even the replacement computer power supply rated at 12A will not charge my Iphone but will charge my Nokia phone clearly some vital hand shaking missing.
Phones can be rather strange one of my Nokia phones decided it would only charge when switched off and I now charge the batteries on a stand alone charger not in the phone which has both 100 - 240 volt ac/dc input and a 5v USB input and will charge the battery off all USB sockets I have tried. Yet the phone will often not charge from them.
Phones in particular seem very picky in what they will charge from one reason why my Iphone with non removable battery is not used as a phone. Great display unit and games console but useless phone. For a phone one wants good reception and a reliable power source have a spare battery in my wallet means my old Nokia is far better as a phone than the Iphone. Finding a suitable USB outlet not easy with Iphone and unlike other phone can't simply swap battery.
As a result there is no easy answer to the USB charger question. With a simple battery charger be it to charge AA, AAA batteries or special flat batteries as used in phone swapping the USB chargers around does not SEEM to be a problem. However where the battery is an integral part of a piece of equipment it is apparent that one does have to be selective as to which USB outlet one uses.
My phone will charge from its charger, a Kindle one, a Bluetooth headset one, and a general purpose one that plugs into a car fag lighter socket.
Plug it into my PC and it thinks I want to start transferring data.
Plug it into my PC and it thinks I want to start transferring data.
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Short version: newer stuff is mostly compatible, older stuff may or may not be.
Long version:
While it's always been possible to charge stuff over USB there was originally no provision for dumb chargers. A device that followed the USB specs could only start to charge at any significant rate after it's request to use the full 500ma had been granted.
In theory one could build a charger with sufficient electronics to act as a USB host and perform the enumeration but I don't think anyone ever actually did that (it would have been a fairly expensive option).
Vendors who wanted to charge over USB did one of two things.
1: Just assume 500ma will be available. It's a violation of the USB spec but many manufactures don't give a f*ck about actually following the USB spec and virtually no hosts enforce that devices only take the power they have agreed to take.
2: Indicate the dumb charger to the device in some vendor specific way. Usually involving a resistor network between the DATA and power lines of the USB socket on the charger
Some time later the "USB battery charging specification" came along. This stated (among other things) that a dumb charger should indicate itself by shorting the data lines to each other and if overloaded should go into a current limit mode where it drops the voltage.
Long version:
While it's always been possible to charge stuff over USB there was originally no provision for dumb chargers. A device that followed the USB specs could only start to charge at any significant rate after it's request to use the full 500ma had been granted.
In theory one could build a charger with sufficient electronics to act as a USB host and perform the enumeration but I don't think anyone ever actually did that (it would have been a fairly expensive option).
Vendors who wanted to charge over USB did one of two things.
1: Just assume 500ma will be available. It's a violation of the USB spec but many manufactures don't give a f*ck about actually following the USB spec and virtually no hosts enforce that devices only take the power they have agreed to take.
2: Indicate the dumb charger to the device in some vendor specific way. Usually involving a resistor network between the DATA and power lines of the USB socket on the charger
Some time later the "USB battery charging specification" came along. This stated (among other things) that a dumb charger should indicate itself by shorting the data lines to each other and if overloaded should go into a current limit mode where it drops the voltage.
Have done a practical test, given the fear of damage has been assuaged...
All devices (2x smart phones, tablet, kobo reader, 2x cameras) charge off all but the kobo USB adaptor...
It seems then that the output of that one is lower, but can someone tell me what the amperage output of a PC USB slot is, as charging by that method is slower on all the devices than their respective adaptors, bar the kobo.
All devices (2x smart phones, tablet, kobo reader, 2x cameras) charge off all but the kobo USB adaptor...
It seems then that the output of that one is lower, but can someone tell me what the amperage output of a PC USB slot is, as charging by that method is slower on all the devices than their respective adaptors, bar the kobo.
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A device is supposed to draw no more than 100mA, or 500mA if it can be negotiated during enumeration from a standard downstream port. A device with a flat battery which can't get started on USB otherwise, is allowed to draw 500mA for up to 2 minutes without negotiation.
There is generally more available, but it would be against the rules to draw it. On USB 3.0 the limits are higher, but most existing devices would not take advantage of this.
There is generally more available, but it would be against the rules to draw it. On USB 3.0 the limits are higher, but most existing devices would not take advantage of this.
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When I wrote 'many people', I suspect I probably should have written 'most people' - I, too, am also guilty
Kind Regards, John
Slowly raises hand...
To be honest, I do unplug them and tell off my other half for leaving them in all the time. After all, it's my name the lectric bill is on!
All money which stays in my pocket and out of the energy companies and the government, is worth it to me.
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