Hi Dane and all,
I don't think Brian, and he can correct me of course, was asking about
getting from mains power or 12 volt power to USB. I may be wrong, but I don't
think that was what he was after because from 120-240 volts to USB is very easy
and common, such transformers are very cheap and easy to get. Apple's are quite
good, as you say, but there are tons of manufacturers and though some are
better than others, they're usually more or less usable. The same may be said
of 12-24 volts to USB, again, these are very easy to get. What isn't so easy to
get is USB out to another voltage. That is, cables making that USB 5 volt
output into something else, whether a non-USB connector or an increased
voltage. This is useful in allowing portable USB batteries, which are very
common, to power non-USB devices. As I said, I hope USB C makes this easier. I
agree with you, there is usually no issue for blind people with standard power
adapters providing USB output and if I wanted USB power, I would probably use a
dedicated supply anyhow. I would do that because many USB devices are not
tolerant of problematic power and I would want something that gives them
reasonably clean power so I don't have to worry about where the problems are
coming from. As I said, I haven't seen a really usable transformer from USB to
9/12 volts, but that has nothing to do with accessibility.
Aman
-----Original Message-----
From: all-audio@groups.io [mailto:all-audio@groups.io] On Behalf Of Dane
Trethowan
Sent: Sunday, August 11, 2019 1:13 PM
To: all-audio@groups.io
Subject: [all-audio] USB Power
Hi,
I’ve changed the subject line a little so both to avoid confusion and to
explain other devices which are available.
The same retailer in Australia sells a wide variety of USB Power supplies
including a multi voltage “Plug Pack” variety which comes with a USB plug as
well as the standard lot of plugs to power most other devices.
A blind person has to set the voltage of this “Plug Pack” to the USB setting
which its indicated on. The bottom of the unit with the voltage adjustment
screw and it can be adjusted by someone without vision counting up from 3 volts.
I also appreciate that this method does take a little time so therefor I think
one would be better off by using a straight USB power supply which are readily
available.
Apple sell a 12 watt version of this for $20 which I think is very good value.
As for charging cables/ Well again Apple have plenty of these to suit most
needs.
> On 12 Aug 2019, at 2:55 am, Aman Singer <aman.sin...@gmail.com> wrote:
>
> Hi,
>
> I'm not sure what you mean by such cables, but if you mean usb A to
> barbell connectors, they do exist
> https://www.startech.com/ca/Cables/USB-2.0/USB-Adapters/usb-5v-dc-type
> -m-pow
> er-cable-3ft~USB2TYPEM
> just for example. If you're asking about USB to 12 bolts, these also exist.
> Keep in mind, though, usb A/B is limited to 15 Wats at best.
> Therefore, when you go up to 12 volts, you will end up, assuming
> perfect conversion which you will never get, at 1.25 A. This will
> never happen, as I said, the transformers I've seen:
> http://amzn.com/B074R7FDCR
> say they'll give 0.8 A at 12 volts (9 wats). In my view, they're
> being seriously optimistic, but I haven't used one and hope I'm wrong
> about that last point. Even assuming the specs are right about the
> real world, it will be a very few devices which will run on 12 volt
> and less than 1 amp. I have hopes of USB C for this, it would be
> really nice to use a single plug for anything up to 60 wats and up to 20
> volts.
> HTH,
> Aman
>
>
>
>
> -----Original Message-----
> From: all-audio@groups.io [mailto:all-audio@groups.io] On Behalf Of
> Brian Olesen
> Sent: Sunday, August 11, 2019 8:38 AM
> To: all-audio@groups.io
> Subject: Re: [all-audio] Variable Voltage/Current Power Supply
>
> So you say that such cables exists?
>
> Brian
>
> -----Oprindelig meddelelse-----
> Fra: all-audio@groups.io <all-audio@groups.io> På vegne af Dane
> Trethowan
> Sendt: 11. august 2019 11:23
> Til: all-audio@groups.io
> Emne: Re: [all-audio] Variable Voltage/Current Power Supply
>
> No problem whatever.
>
>
> -----Original Message-----
> From: all-audio@groups.io <all-audio@groups.io> On Behalf Of Brian
> Olesen
> Sent: Sunday, 11 August 2019 6:30 PM
> To: all-audio@groups.io
> Subject: Re: [all-audio] Variable Voltage/Current Power Supply
>
> Hi Dane,
> Really really cool although I don't use such anymore stuff much these days.
> But can you find prebuild cables with plugs let's say for usb, so you
> can charge a device with 5 volts and connect other stuff with for
> example 12 volts DC? That would be really neet.
> 5 amps is a nice portion of power though. smile Brian
>
> -----Oprindelig meddelelse-----
> Fra: all-audio@groups.io <all-audio@groups.io> På vegne af Dane
> Trethowan
> Sendt: 10. august 2019 23:43
> Til: all-audio@groups.io
> Emne: [all-audio] Variable Voltage/Current Power Supply
>
> Hi everyone,
>
> I know there are a few people out there who are into Electronic and
> DIY projects of the same nature like me.
>
> Up until now I've found it very difficult to find power supply units
> that can be set accurately without vision and offering stable Yes,
> some "Plugpack" units will allow quite a bit of flexibility these days
> but let's face it, these units are of a low quality usually and don't last
> too long.
>
> Not only that they don't have the voltage or current range required
> for good testing and are subject to RF interference or contribute to
> the RF interference in the immediate environment, as if we don't have
> enough of that already.
>
> I've found a Power Supply unit which is easy to set for blind people,
> incredibly accurate and incredibly quiet as far as RF noise goes.
>
> You can see the power supply at
> https://www.jaycar.com.au/0-to-30vdc-0-to-5a-regulated-power-supply/p/
> MP3840
> ?utm_campaign=redirect
> <https://www.jaycar.com.au/0-to-30vdc-0-to-5a-regulated-power-supply/p
> /MP384 0?utm_campaign=redirect&utm_source=MP3840r&utm_medium=web>
> &utm_source=MP3840r&utm_medium=web
>
> I'm writing from Australia so residents of the US will have to do a
> bit of digging to find a similar unit though residents of the UK
> shouldn't have any trouble sourcing this supply as Jaycar also do business in
> the UK.
>
> As you can see the supply has a voltage range of 0 to 30 volts and 0
> to 5 amps so any value can be set in these ranges even fine voltage
> adjustments can be made - say 1.2 volts -.
>
> The supply has 2 jog-dials on the face to control volts and amps.
>
> These dials click when turned and push in.
>
> Suppose you wanted to adjust the voltage to 4.5 volts.
>
> After turning the supply on you would press the voltage jog-dial once
> and turn 4 clicks clockwise, press the jog-dial in to advance to the
> next unit and turn the dial clickwise 5 clicks.
>
> The beauty of this supply is that you hear a beep when you've reached
> the minimum or maximum value so you can count up or down by click from
> these points, the count doesn't wrap around so once you're say at 30
> volts the unit will beep and stay at 30 volts unless you turn the
> voltage dial anti clockwise to bring the voltage count down.
>
> The supply remembers the last settings made when the power is turned off.
>
> I have also discovered power supplies available where voltage and
> current values can be set via an IOS or Android App.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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