Wikipedia:Reference desk/Archives/Computing/2013 July 26

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July 26

Rechargeable MP3 player

I have a rechargeable MP3 player (that is, a player that does not use batteries, it is simply pluged to the socket plug, and it gets recharged). I have noticed lately that, no matter how much time I left it recharging, it always run out of energy in a very short time. What can cause this? Is there a fix? Cambalachero (talk) 01:44, 26 July 2013 (UTC)

I think it's very unlikely that it "doesn't use batteries". Most likely, the battery is built in and is not replaceable by the consumer. My guess is that it's a lithium-ion battery. See lithium-ion battery#Battery life for the effect you're describing.

Unfortunately the only obvious fix is to buy another player; you might look for one that lets you change the battery. I wouldn't be shocked if there's some DIY way of cutting open the case and replacing the battery — you might look on YouTube with the precise model of player you have in mind. --Trovatore (talk) 01:52, 26 July 2013 (UTC)

My iPhone did the same, but a suggestion that the battery be allowed to get below 20% before it was recharged solved the problem.85.211.204.94 (talk) 03:25, 26 July 2013 (UTC)

If you've recharged your MP3 player more than a thousand times, then the Li-ion battery is probably past its best, so a replacement battery, or running the player from one of those small switch-mode rechargers that use a normal cell (battery) as power source might be a solution. I have a couple of MP3 players that run quite happily from these when their internal battery is exhausted. Dbfirs 13:17, 26 July 2013 (UTC)

Hey, nice idea! Hadn't thought of that. --Trovatore (talk) 16:07, 26 July 2013 (UTC)

Yeah it's probably just an old battery - as noted above, after they've been charged a lot they tend to lose their capacity; especially in cheaply made devices (I once had an aftermarket games device which claimed 10 hours fully charged. I never saw it hold more than four and it discharged so quickly just sitting on my desk that I had to charge it a couple hours in advance if I knew I was going to be using it!) It may be possible to find a replacement battery, but a simpler solution would be to either replace the mp3 player (if it's old and needed replacing sooner or later anyway) or try what Dbfirs suggested. --Yellow1996 (talk) 16:48, 26 July 2013 (UTC)

In a lot of these devices, finding a replacement battery is only half the battle — the batteries are not designed to be replaced. You'd have to jimmy open the case and maybe solder something; not really sure what would be involved. When you were finished, it would almost certainly be visually obvious that you'd done something to the gadget. But it might be doable. --Trovatore (talk) 17:17, 26 July 2013 (UTC)

I remember in my case (the aftermarket device I described) it required you to install the battery yourself when you first get it! Though it was quite easy (just had to unscrew a hatch at the back, put the battery in, screw the battery in, then screw the hatch back on) I guess that contests to how cheaply made it was; either that or the manufacturers didn't care about people servicing their own devices. Finding a replacement battery for something more mainstream (like an mp3 player) would probably be doable, but if the device is older then it's probably a better idea to just replace it. Getting the case open probably wouldn't be too much of a hassle, but (in non-cheaply made devices) soldering would almost surely be involved - and I know first-hand that one should not attempt soldering unless you know what you're doing! --Yellow1996 (talk) 17:25, 26 July 2013 (UTC)

USB stick backup to computer program

Is there any program out there that backups our USB stick /external hard disk to PC HDD as soon it enters our USB port and preferably using delta compression so it will go on much faster? DeltaCopy is too hard to use 140.0.229.26 (talk) 14:09, 26 July 2013 (UTC)

Check out this page, which reviews a program called USBFlashCopy. Hope this helps, --Yellow1996 (talk) 16:52, 26 July 2013 (UTC)

I think the speed will be a problem. In my experience it can take hours to backup a large USB stick. So, unless the files on the USB stick are tiny, you will need a lot of patience. StuRat (talk) 01:04, 27 July 2013 (UTC)

Outputting Binary with MS Batch

Is it still possible to output ms binaries now PE files with batch programming? ( I remember that there were some programs wrote only using ASCII so you can output the program contents and run it. it was something like Echo %binaryInfo%>executable.com (Now .exe) (like [1] or [2])), I wonder if you can still manage to create a (Win 32bit)program using only a batch file, or perhaps it's not possible anymore?

Thanks for your help 190.60.93.218 (talk) 14:23, 26 July 2013 (UTC)

Windows PowerShell, a standard feature of Windows from version 7 onward, has proper binary datatypes and real binary file I/O, so with it there's no need to resort to escaping and encoding to persuade echo to work as you'd want. PowerShell can be called directly from the cmd.exe command line (and thus from batch files) - so a little script to write a binary file might look like

  powershell -command "[IO.File]::WriteAllBytes('foo.bin', (0,2,4,7,8,10,12,15,21,39))"

where 0,2,4,7,8, etc. will be encoded as bytes. By default some of the scripting features of PowerShell are disabled for security reasons, so I'm not 100% that this will work on an out-of-the-box Windows 7 or 8 system (it may be necessary to change the ExecutionPolicy to allow that). Naturally running untrustworthy PowerShell code (which usually takes the .PS1 file extension) on your machine is an entirely dangerous thing to do, just as for untrustworthy .BAT, .COM, .EXE files. -- Finlay McWalterჷTalk 16:00, 26 July 2013 (UTC)

I was asking (preferably) for a *batch* only version, of course your method does work, but as you know batch and powershell scripting are not the only languages either, you can also use 'vbs', maybe output the file with JScript or VBScript, may have a higuer chance of working on most computers.. Well, it works for me I guess, thanks! 181.50.178.92 (talk) 23:28, 26 July 2013 (UTC)

The EICAR test file is an example of an executable file containing only printable ASCII characters. It's an MS-DOS COM file (which also works in non-64-bit Windows). You can't create a Win32 executable this way because there are some required field values that aren't printable ASCII. -- BenRG (talk) 17:38, 27 July 2013 (UTC)

If LEDs can capture light ....

Then can the LEDs of a computer or of a TV screen be a kind of camera? OsmanRF34 (talk) 19:14, 26 July 2013 (UTC)

You won't have a camera. You'll be only able to know it there are light in the room or not. See LEDs_as_Photodiode_Light_Sensors. 2A02:8422:1191:6E00:56E6:FCFF:FEDB:2BBA (talk) 19:47, 26 July 2013 (UTC)

To elaborate on that, the reason you won't have a camera is that LEDs aren't directionally sensitive to light (so they can't act as a compound eye), and there isn't a lens in front of the screen to focus an image on it (so it can't act as a conventional image sensor). --Carnildo (talk) 23:40, 26 July 2013 (UTC)

But yes, in theory if you put a lens in front of each LED you could create a very crude camera that way. Not very practical, but might make an interesting science fair project. StuRat (talk) 01:02, 27 July 2013 (UTC)

What a relief; since that's something my tinfoil hat wouldn't protect me from! ;) --Yellow1996 (talk) 01:04, 27 July 2013 (UTC)

You're not wearing it right, then! It goes in front of the idiot box, to shield you from the propaganda. ;-) --Stephan Schulz (talk) 13:33, 27 July 2013 (UTC)

Ah! *Adjusts* - there we are. Thanks, Stephan! ;) --Yellow1996 (talk) 19:15, 27 July 2013 (UTC)

A normal TV or computer monitor will use an LCD display, not LED. The backlight may be a bunch of LEDs, but it doesn't sound like that's what you're asking about. 209.131.76.183 (talk) 15:02, 29 July 2013 (UTC)