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Sony NW-A45 Walkman & Sony Noise-Cancelling headphones


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#1 stuub27

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Posted 24 June 2018 - 02:56 PM

I recently bought one of these: https://www.sony.com...n/nw-a40-series

 

and am looking at buying either these: https://www.sony.com...phones/wh-h900n

 

or these: https://www.sony.com...ones/wh-1000xm2

 

Of course, they all require charging. Via USB. Either desktop or laptop. I only have a desktop.

Which is fine when I'm at home, obviously.

 

But I want to know if I can charge them using the wall adapter that I use for my phone?

Or even better, can I use the power bank I carry with me?

 

Now, I did ask Sony first. But they gave me the helpful answer of, basically- you can, but we don't recommend it. But they didn't say why. And I certainly don't know enough about electronics to understand.

 

Can anyone at least enlighten me as  to why it would be a bad idea?

 

Thanks

 



#2 Rybags

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Posted 24 June 2018 - 04:16 PM

OK, it's sort of something like this (I think BigCliveDotCom on YouTube explains it somewhere).

 

USB (forget 3.x here) uses 4 lines, + - and the data lines.  + - carry the power.

A device can identify whether there's a computer at the other end or just a "dumb" power supply by fact that the data lines should be grounded if it's a power supply (or the other way).

But bottom line is that a device can identify what's at the other end and e.g. request more than 500 mA from a computer, or take more from a power supply.

 

The recommended thing for L-Ion type batteries is something like test extra amperage @ charging voltage until the wanted maximum is found provided no great voltage drop occurs.

Then charge at high amps until almost full.  Then trickle for the remaining few %

 

Anyway - something like that.  Some devices have good smarts and can just regulate what's coming in and cope with a meaty 2.5 Amp 5 Volt external battery.

Others are lesser equipped (maybe like headphones) and might only want 800 mA at 5 Volts max for the entire duration.

 

I suppose there's ways you could do a bodge - like make a dongle with current limiting resistors so a 2 Amp supply is reduced somewhat.  Of course if you use a single resistor you're probably going to have heat issues.



#3 stuub27

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Posted 24 June 2018 - 04:30 PM

OK, it's sort of something like this (I think BigCliveDotCom on YouTube explains it somewhere).

 

USB (forget 3.x here) uses 4 lines, + - and the data lines.  + - carry the power.

A device can identify whether there's a computer at the other end or just a "dumb" power supply by fact that the data lines should be grounded if it's a power supply (or the other way).

But bottom line is that a device can identify what's at the other end and e.g. request more than 500 mA from a computer, or take more from a power supply.

 

The recommended thing for L-Ion type batteries is something like test extra amperage @ charging voltage until the wanted maximum is found provided no great voltage drop occurs.

Then charge at high amps until almost full.  Then trickle for the remaining few %

 

Anyway - something like that.  Some devices have good smarts and can just regulate what's coming in and cope with a meaty 2.5 Amp 5 Volt external battery.

Others are lesser equipped (maybe like headphones) and might only want 800 mA at 5 Volts max for the entire duration.

 

I suppose there's ways you could do a bodge - like make a dongle with current limiting resistors so a 2 Amp supply is reduced somewhat.  Of course if you use a single resistor you're probably going to have heat issues.

Well, thanks heaps for that. Appreciated :)

 

I don't understand some of the technical stuff, but I get the general idea now, I think.



#4 Rybags

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Posted 24 June 2018 - 04:54 PM

It's one of those times a USB power meter can come in handy - they're all over eBay for about 3-4 bucks each.



#5 stuub27

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Posted 24 June 2018 - 05:01 PM

It's one of those times a USB power meter can come in handy - they're all over eBay for about 3-4 bucks each.

I'll look into that






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