Annoyingly my PSU gave up the ghost yesterday meaning the new Logitech
wireless mouse won't be much use until I fit a replacement. It appears
the multi-voltage Maplin unit wasn't quite up to the job of running both
the Beagle itself and my small hub.
At least it'll give me the opportunity to rectify a small design flaw as
the PSU which I had integrated into the case, was giving off more heat
than I would've liked. Allowing it to remain plugged in 24/7 probably
didn't help either.

-- patric

In message <op.v7uemojtyrhmdj@medion-pc.fritz.box>
     patric <patric@invalid.com> wrote:

> Annoyingly my PSU gave up the ghost yesterday meaning the new Logitech
> wireless mouse won't be much use until I fit a replacement. It appears
> the multi-voltage Maplin unit wasn't quite up to the job of running both
> the Beagle itself and my small hub.
> At least it'll give me the opportunity to rectify a small design flaw as
> the PSU which I had integrated into the case, was giving off more heat
> than I would've liked. Allowing it to remain plugged in 24/7 probably
> didn't help either.

That's a surprise. I bought one (I think after seeing you post about it).
It's rated at 4Amps whereas I thought I read that the Beagleboard is
supposed to limited to 3amps.

-- 
Fred

In message <op.v7uemojtyrhmdj@medion-pc.fritz.box>
          patric <patric@invalid.com> wrote:

> Annoyingly my PSU gave up the ghost yesterday meaning the new Logitech
> wireless mouse won't be much use until I fit a replacement. It appears
> the multi-voltage Maplin unit wasn't quite up to the job of running both
> the Beagle itself and my small hub.
> At least it'll give me the opportunity to rectify a small design flaw as
> the PSU which I had integrated into the case, was giving off more heat
> than I would've liked. Allowing it to remain plugged in 24/7 probably
> didn't help either.

I power my B/board XM directly from a usb powered hub.

JV

In message <mpro.lxlaz200001b100w1@ypical.nospam.invalid>
          Fred Bambrough <fred@[127.0.0.1]> wrote:

> In message <op.v7uemojtyrhmdj@medion-pc.fritz.box>
>      patric <patric@invalid.com> wrote:

>> Annoyingly my PSU gave up the ghost yesterday meaning the new Logitech
>> wireless mouse won't be much use until I fit a replacement. It appears
>> the multi-voltage Maplin unit wasn't quite up to the job of running both
>> the Beagle itself and my small hub.
>> At least it'll give me the opportunity to rectify a small design flaw as
>> the PSU which I had integrated into the case, was giving off more heat
>> than I would've liked. Allowing it to remain plugged in 24/7 probably
>> didn't help either.

> That's a surprise. I bought one (I think after seeing you post about it).
> It's rated at 4Amps whereas I thought I read that the Beagleboard is
> supposed to limited to 3amps.

Don't forget that a USB hub is allowed to supply 0.5 amps from each 
port, so a 7-port hub can need 3.5 amps in addition to the power used 
to run the hub itself.

While it's unlikely to need all that, connecting a hard drive will 
make quite a difference.


-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

In article <mpro.lxlaz200001b100w1@ypical.nospam.invalid>,
   Fred Bambrough <fred@[127.0.0.1]> wrote:
> That's a surprise. I bought one (I think after seeing you post about it).
> It's rated at 4Amps whereas I thought I read that the Beagleboard is
> supposed to limited to 3amps.

Regardless of rating or load, electronic gismos are guaranteed to fail at
some point.

Statistical analysis produces something called "the bathtub curve" which
shows that a large number of devices fail at or within a very short time
of switch on. The failure rate decrease with increasing time and levels
out till the devices begin to reach the end of their life, when the
failure rate increases again.

It may just be bad luck

-- 
Stuart Winsor

Only plain text for emails
http://www.asciiribbon.org

In message <af027d4f52.Alan.Adams@laptop.adamshome.org.uk>
     Alan Adams <alan@adamshome.org.uk> wrote:

> In message <mpro.lxlaz200001b100w1@ypical.nospam.invalid>
>           Fred Bambrough <fred@[127.0.0.1]> wrote:
> 
> > In message <op.v7uemojtyrhmdj@medion-pc.fritz.box>
> >      patric <patric@invalid.com> wrote:
> 
> >> Annoyingly my PSU gave up the ghost yesterday meaning the new Logitech
> >> wireless mouse won't be much use until I fit a replacement. It appears
> >> the multi-voltage Maplin unit wasn't quite up to the job of running
both
> >> the Beagle itself and my small hub.
> >> At least it'll give me the opportunity to rectify a small design flaw
as
> >> the PSU which I had integrated into the case, was giving off more heat
> >> than I would've liked. Allowing it to remain plugged in 24/7 probably
> >> didn't help either.
> 
> > That's a surprise. I bought one (I think after seeing you post about
it).
> > It's rated at 4Amps whereas I thought I read that the Beagleboard is
> > supposed to limited to 3amps.
> 
> Don't forget that a USB hub is allowed to supply 0.5 amps from each 
> port, so a 7-port hub can need 3.5 amps in addition to the power used 
> to run the hub itself.
> 
> While it's unlikely to need all that, connecting a hard drive will 
> make quite a difference.

But (speaking from ignorance, I hasten to warn) would the Beagleboard allow
that uptake? Assuming the hub isn't being supplied separately.

-- 
Fred

In message <524f8212f4Spambin@argonet.co.uk>
     Stuart <Spambin@argonet.co.uk> wrote:

> In article <mpro.lxlaz200001b100w1@ypical.nospam.invalid>,
>    Fred Bambrough <fred@[127.0.0.1]> wrote:
> > That's a surprise. I bought one (I think after seeing you post about
it).
> > It's rated at 4Amps whereas I thought I read that the Beagleboard is
> > supposed to limited to 3amps.
> 
> Regardless of rating or load, electronic gismos are guaranteed to fail at
> some point.
> 
[snip]
> 
> It may just be bad luck

I think Patric said he'd been using it for a year, so yes.

-- 
Fred

On Tue, 10 Jan 2012 23:46:49 +0100,  wrote:

> In message <524f8212f4Spambin@argonet.co.uk>
>      Stuart <Spambin@argonet.co.uk> wrote:
>
>> In article <mpro.lxlaz200001b100w1@ypical.nospam.invalid>,
>>    Fred Bambrough <fred@[127.0.0.1]> wrote:
>> > That's a surprise. I bought one (I think after seeing you post about
> it).
>> > It's rated at 4Amps whereas I thought I read that the Beagleboard is
>> > supposed to limited to 3amps.
>>
>> Regardless of rating or load, electronic gismos are guaranteed to fail  
>> at
>> some point.
>>
> [snip]
>>
>> It may just be bad luck
>
> I think Patric said he'd been using it for a year, so yes.
>

It came as quite a surprise to me too. My usual setup and power  
requirements
are the BB itself, a USB2PS/2 converter and a small hub rated at 2A. The
usb hdd goes into the hub (can't be more than 500mA) and even though PS/2
keyboards tend to be less frugal than modern ones I'd rate it @250mA. Add a
mouse to that ~80mA and the odd USB pen drive. Shouldn't exceed 4A at all!
Perhaps I should have disconnected it when not in use but my bet is on the
"bad luck" theory.
Going to replace it with a fixed voltage 5A brick (15 quid off ebay!).

Actually it was less than a year as I hadn't used my Beagleboard for
several months. :-(

Patric

In article <524f8212f4Spambin@argonet.co.uk>,
   Stuart <Spambin@argonet.co.uk> wrote:
> Statistical analysis produces something called "the bathtub curve" which
> shows that a large number of devices fail at or within a very short time
> of switch on. The failure rate decrease with increasing time and levels
> out till the devices begin to reach the end of their life, when the
> failure rate increases again.

MTBF for a type of SFP fibre optic transmitter from Avaya (data division
was Nortel) is quoted, in hours, as being in excess of 99 years. There must
be some heavy stats analysis and curve prediction involved there.
As you say most failures occur at the beginning and end of the curve and
anyone getting a quick failure tends to label it as "a Friday job"

-- 

Steve Pampling

In article <op.v7uemojtyrhmdj@medion-pc.fritz.box>,
   patric <patric@invalid.com> wrote:
> Annoyingly my PSU gave up the ghost yesterday meaning the new Logitech
> wireless mouse won't be much use until I fit a replacement. It appears
> the multi-voltage Maplin unit wasn't quite up to the job of running both
> the Beagle itself and my small hub.
> At least it'll give me the opportunity to rectify a small design flaw as
> the PSU which I had integrated into the case, was giving off more heat
> than I would've liked. Allowing it to remain plugged in 24/7 probably
> didn't help either.

The problem is that these power supplies need a free flow of air around
them so shouldn't be put into another case as well unless there is a fan
in it. If it's the same one that I got (Maplin L11BQ) it should give 5A at
6V but even at low current it does get hot. I assume that Maplin have
exchanged it for another one.

Alan

-- 
alan.dawes@argonet.co.uk
alan.dawes@riscos.org
Using an Acorn RiscPC

In message <524fd7ec10alan.dawes@argonet.co.uk>
     Alan Dawes <alan.dawes@argonet.co.uk> wrote:

> If it's the same one that I got (Maplin L11BQ) it should give 5A at
> 6V but even at low current it does get hot. I assume that Maplin have
> exchanged it for another one.

One's joy with that would seem to depend on the branch's manager. I bought a
Zippy mini keyboard to go with my Beagleboard. It wouldn't work with BB nor
RPC nor Mac. I took it back to my local store who refused an exchange
because it worked with their PC. I took it to another store who exchanged it
without question. The replacement (same model) works well.

-- 
Fred

In message <mpro.lxn3mh00001eg0054@ypical.nospam.invalid>
          Fred Bambrough <fred@[127.0.0.1]> wrote:

> In message <524fd7ec10alan.dawes@argonet.co.uk>
>      Alan Dawes <alan.dawes@argonet.co.uk> wrote:

>> If it's the same one that I got (Maplin L11BQ) it should give 5A at
>> 6V but even at low current it does get hot. I assume that Maplin have
>> exchanged it for another one.

> One's joy with that would seem to depend on the branch's manager. I bought a
> Zippy mini keyboard to go with my Beagleboard. It wouldn't work with BB nor
> RPC nor Mac. I took it back to my local store who refused an exchange
> because it worked with their PC. I took it to another store who exchanged it
> without question. The replacement (same model) works well.

New PSU, unbranded China export, arrived on Monday and after getting 
my act together everything seems to be up and running again. As Alan 
mentioned the Maplin PSU was actually rated at 5A for 5-12V (4A @ 
13.5-15V) and runs rather hot. The replacement looks similar to 
"Voltcraft" products and runs noticably cooler, hardly warm actually

In article <59547f5352.gmx@albutat.gmx.de>,
   Patric Albutat <albutat@gmx.de> wrote:
>  The replacement looks similar to 
> "Voltcraft" products and runs noticably cooler, hardly warm actually

That is always good.

-- 
Stuart Winsor

Only plain text for emails
http://www.asciiribbon.org

In message <525394558cSpambin@argonet.co.uk>
          Stuart <Spambin@argonet.co.uk> wrote:

> In article <59547f5352.gmx@albutat.gmx.de>,
>    Patric Albutat <albutat@gmx.de> wrote:
>>  The replacement looks similar to
>> "Voltcraft" products and runs noticably cooler, hardly warm actually

> That is always good.

Interestingly had some problems cold booting this time. The board 
remained unlit exept for the red overvoltage LED. Multimeter reads 
5.45V which doesn't sound excessive to me. Disconnecting from mains 
seems to have done the trick but is the Beagleboard really *that* 
picky? Should I use a resistor or something?

patric

In message <baf7a15352.gmx@albutat.gmx.de>
          Patric@invalid.com wrote:

> In message <525394558cSpambin@argonet.co.uk>
>           Stuart <Spambin@argonet.co.uk> wrote:

>> In article <59547f5352.gmx@albutat.gmx.de>,
>>    Patric Albutat <albutat@gmx.de> wrote:
>>>  The replacement looks similar to
>>> "Voltcraft" products and runs noticably cooler, hardly warm actually

>> That is always good.

> Interestingly had some problems cold booting this time. The board
> remained unlit exept for the red overvoltage LED. Multimeter reads
> 5.45V which doesn't sound excessive to me. Disconnecting from mains
> seems to have done the trick but is the Beagleboard really *that*
> picky? Should I use a resistor or something?

5.4 volts is well outside the tolerance for most 5 volt logic. +/- 0.2 
volts would be closer I would think.

It may be there isn't enough load to pull the output down to spec. Was 
the supply advertised as 5 volt regulated, or just 5 volt? If the 
latter it could easily be delivering 9 volts on light loads, which 
would cause significant damage. A regulated PSU should produce the 
rated output from no load to full, with only a few percent change 
across the range.

Alan

> patric



-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

> Interestingly had some problems cold booting this time. The board
> remained unlit exept for the red overvoltage LED. Multimeter reads
> 5.45V which doesn't sound excessive to me. Disconnecting from mains
  ^^^^^
> seems to have done the trick but is the Beagleboard really *that*
> picky? Should I use a resistor or something?

> patric

Google came up with this:

Gerald�Coley�<ger...@...>�wrote:
>�You�need�to�measure�the�voltage�and�not�read�the�label.�The�maximum�voltage
>�is�5.25V.�I�do�not�think�Linux�can�cause�an�over�voltage�condition.�This�is
>�all�HW�and�only�triggers�if�the�voltage�is�too�high,�which�it�triggers�at
>�5.4V.

Any suggestions how to get rid of 0.3V?

patric

In message <56f1a95352.Alan.Adams@laptop.adamshome.org.uk>
          Alan Adams <alan@adamshome.org.uk> wrote:

> In message <baf7a15352.gmx@albutat.gmx.de>
>           Patric@invalid.com wrote:

>> In message <525394558cSpambin@argonet.co.uk>
>>           Stuart <Spambin@argonet.co.uk> wrote:

>>> In article <59547f5352.gmx@albutat.gmx.de>,
>>>    Patric Albutat <albutat@gmx.de> wrote:
>>>>  The replacement looks similar to
>>>> "Voltcraft" products and runs noticably cooler, hardly warm actually

>>> That is always good.

>> Interestingly had some problems cold booting this time. The board
>> remained unlit exept for the red overvoltage LED. Multimeter reads
>> 5.45V which doesn't sound excessive to me. Disconnecting from mains
>> seems to have done the trick but is the Beagleboard really *that*
>> picky? Should I use a resistor or something?

> 5.4 volts is well outside the tolerance for most 5 volt logic. +/- 0.2
> volts would be closer I would think.

> It may be there isn't enough load to pull the output down to spec. Was
> the supply advertised as 5 volt regulated, or just 5 volt? If the
> latter it could easily be delivering 9 volts on light loads, which
> would cause significant damage. A regulated PSU should produce the
> rated output from no load to full, with only a few percent change
> across the range.

It was advertised as:

Tabletop power supply
5V regulated
25 Watt
100~245V�
47~63Hz
<0.7mA/230VAC
�0.5%
max.�5 Ampere
overload protection�110~130%
overvoltage protection�115~135%
Isolation�I/P-OP:3KVAC/1min
temperature -10 ~ +50�C ; 20%~90%RH (non condensing)
storage temperature -20�C ~+85�C, 20~95%RH (non condensing)
CE, CCC-SAE

Power runs through a glass fuse, on/off rocker switch and chock block 
to which both the board itself as well as a 4-port USB hub connect. 
Harddrive plugged into hub but there doesn't seem to be sufficient 
voltage drop although I didn't measure under load and I'm hardly using 
a pro multimeter.

patric

In message <8a27aa5352.gmx@albutat.gmx.de>
          Patric@invalid.com wrote:

>> Interestingly had some problems cold booting this time. The board
>> remained unlit exept for the red overvoltage LED. Multimeter reads
>> 5.45V which doesn't sound excessive to me. Disconnecting from mains
>   ^^^^^
>> seems to have done the trick but is the Beagleboard really *that*
>> picky? Should I use a resistor or something?

>> patric

> Google came up with this:

> Gerald�Coley�<ger...@...>�wrote:
>>�You�need�to�measure�the�voltage�and�not�read�the�label.�The�maximum�voltage
>>�is�5.25V.�I�do�not�think�Linux�can�cause�an�over�voltage�condition.�This�is
>>�all�HW�and�only�triggers�if�the�voltage�is�too�high,�which�it�triggers�at
>>�5.4V.

> Any suggestions how to get rid of 0.3V?

> patric

I'd be inclined to try a series diode. A non-Shottky one will drop 0.6 
to 0.7 volts giving 4.75 to 4.85. You will need one capable of 
handling 5 amps or more.

A Shottky diode should drop about 0.3 volts. They will probably be a 
bit more expensive.


-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

In article <56e7ad5352.gmx@albutat.gmx.de>,
   <Patric@invalid.com> wrote:

> It was advertised as:

> Tabletop power supply
> 5V regulated
> 25 Watt

If you can lay your hands on an accurate multimeter, somewhere on the
board there will be a means of setting the output voltage accurately. It
may be via a pot or resistor chain but, unfortunately, not knowing this
particular supply I am unable to advise.

I suggest contacting your supplier or manufacturer to see if they can
advise, or replace it if it is out of tolerance (which it seems to be).

A fixed series resistor will not help as the voltage drop will depend on
the instantaneous load drawn. A Schottky diode such as the SB530 (Digikey)
might be a better option, as it will drop about half a volt, so you would
be just under 5V and the board may be happier with this situation

-- 
Stuart Winsor

Only plain text for emails
http://www.asciiribbon.org

In article <8a27aa5352.gmx@albutat.gmx.de>,
   <Patric@invalid.com> wrote:
> > Interestingly had some problems cold booting this time. The board
> > remained unlit exept for the red overvoltage LED. Multimeter reads
> > 5.45V which doesn't sound excessive to me. Disconnecting from mains
>   ^^^^^
> > seems to have done the trick but is the Beagleboard really *that*
> > picky? Should I use a resistor or something?

> > patric

> Google came up with this:

> Gerald Coley <ger...@...> wrote:
> > You need to measure the voltage and not read the label. The maximum
> > voltage is 5.25V. I do not think Linux can cause an over voltage
> > condition. This is all HW and only triggers if the voltage is too high,
> > which it triggers at 5.4V.

> Any suggestions how to get rid of 0.3V?

Yes take it back to Maplins - it is faulty. It is advertised as giving a
regulated 5V supply which it does not do.

Alan

-- 
alan.dawes@argonet.co.uk
alan.dawes@riscos.org
Using an Acorn RiscPC

On Thu, 19 Jan 2012 19:13:58 +0100, Alan Dawes <alan.dawes@argonet.co.uk>  
wrote:

> In article <8a27aa5352.gmx@albutat.gmx.de>,
>    <Patric@invalid.com> wrote:
>> > Interestingly had some problems cold booting this time. The board
>> > remained unlit exept for the red overvoltage LED. Multimeter reads
>> > 5.45V which doesn't sound excessive to me. Disconnecting from mains
>>   ^^^^^
>> > seems to have done the trick but is the Beagleboard really *that*
>> > picky? Should I use a resistor or something?
>
>> > patric
>
>> Google came up with this:
>
>> Gerald Coley <ger...@...> wrote:
>> > You need to measure the voltage and not read the label. The maximum
>> > voltage is 5.25V. I do not think Linux can cause an over voltage
>> > condition. This is all HW and only triggers if the voltage is too  
>> high,
>> > which it triggers at 5.4V.
>
>> Any suggestions how to get rid of 0.3V?
>
> Yes take it back to Maplins - it is faulty. It is advertised as giving a
> regulated 5V supply which it does not do.
>
> Alan
>

Yeah, contacted the seller. I hope he'll exchange it for a working one
instead of just taking it back.

On Thu, 19 Jan 2012 20:03:40 +0100, patric <patric@invalid.com> wrote:

> On Thu, 19 Jan 2012 19:13:58 +0100, Alan Dawes  
> <alan.dawes@argonet.co.uk> wrote:
>
>>
>> Yes take it back to Maplins - it is faulty. It is advertised as giving a
>> regulated 5V supply which it does not do.
>>
>> Alan
>>
>
> Yeah, contacted the seller. I hope he'll exchange it for a working one
> instead of just taking it back.

I've been told my unit only regulates under load. Since the BB however  
refuses to
start with 5.4V while the USB hub seems happy enough I guess there's  
actually to
little load when switching on.

patric

On Fri, 20 Jan 2012 14:40:31 +0100, Patric <patric@invalid.de> wrote:

> On Thu, 19 Jan 2012 20:03:40 +0100, patric <patric@invalid.com> wrote:
>
>> On Thu, 19 Jan 2012 19:13:58 +0100, Alan Dawes  
>> <alan.dawes@argonet.co.uk> wrote:
>>
>>>
>>> Yes take it back to Maplins - it is faulty. It is advertised as giving  
>>> a
>>> regulated 5V supply which it does not do.
>>>
>>> Alan
>>>
>>
>> Yeah, contacted the seller. I hope he'll exchange it for a working one
>> instead of just taking it back.
>
> I've been told my unit only regulates under load. Since the BB however  
> refuses to
> start with 5.4V while the USB hub seems happy enough I guess there's  
> actually to
> little load when switching on.
>
> patric

Okay had another go. I had previously plugged in two pen drives but as they
draw very little power they failed to increase the load. Same obviously
goes for my hdd or they need to be initialised by the Beagleboard before  
drawing
power. Bit of a circular reference. Connected my mobile phone instead and  
although
RISC OS won't recognise it, it does recharge from USB (probably asking for  
all
the 500mA it can get).
Voltage down to 5.1-5.2 which is spot on. Even hot booting working now with
no change in voltage.

While this seems to work I'll have to come up with a more sophisticated  
solution!

patric

In article <op.v8dyihwaeksv19@aristide.fritz.box>,
   Patric <patric@invalid.de> wrote:

> While this seems to work I'll have to come up with a more sophisticated  
> solution!

Why not include an extra 3-pin 5 volt regulator - see

        http://cds.linear.com/docs/Datasheet/lt0123.pdf

You could mount it in a little box with its two capacitors and an input
socket and output plug.

It would actually only be doing anything for a short while whilst your load
was established.

Assuming, of course, that isn't what's already doing the regulating!

John

-- 
John Williams, Brittany, Northern France - no attachments to these addresses!
Non-RISC OS posters change user to johnrwilliams or put 'risc' in subject!
Who is John Williams? http://petit.four.free.fr/picindex/author/

In message <52548cc82fUCEbin@tiscali.co.uk>
          "John Williams (News)" <UCEbin@tiscali.co.uk> wrote:

> In article <op.v8dyihwaeksv19@aristide.fritz.box>,
>    Patric <patric@invalid.de> wrote:

>> While this seems to work I'll have to come up with a more sophisticated
>> solution!

> Why not include an extra 3-pin 5 volt regulator - see

>         http://cds.linear.com/docs/Datasheet/lt0123.pdf

> You could mount it in a little box with its two capacitors and an input
> socket and output plug.

> It would actually only be doing anything for a short while whilst your load
> was established.

> Assuming, of course, that isn't what's already doing the regulating!

> John

It won't work. According to the data sheet, to maintain 5 volts output 
the input has to be between 7.5 and 15 volts. Once it drops below 7.5, 
the output will drop below 5 volts. With your 5.4 volts in, I'd be 
surprised to get more than 2.5 volts out.

The only regulator which would work is a shunt regulator, and if I was 
stuck with this PSu, that is what I would build. They're not usually 
off-the-shelf items.

Years ago I was given a USB cup-heater as a conference freebee - that 
would solve your problem - just unplug it once the disc drive starts 
up.


-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

In message <op.v8dxlufbeksv19@aristide.fritz.box>
          Patric <patric@invalid.de> wrote:

> On Thu, 19 Jan 2012 20:03:40 +0100, patric <patric@invalid.com> wrote:
> 
> > On Thu, 19 Jan 2012 19:13:58 +0100, Alan Dawes  
> > <alan.dawes@argonet.co.uk> wrote:
> >
> >>
> >> Yes take it back to Maplins - it is faulty. It is advertised as giving a
> >> regulated 5V supply which it does not do.
> >>
> >> Alan
> >>
> >
> > Yeah, contacted the seller. I hope he'll exchange it for a working one
> > instead of just taking it back.
> 
> I've been told my unit only regulates under load. Since the BB however  
> refuses to
> start with 5.4V while the USB hub seems happy enough I guess there's  
> actually to
> little load when switching on.
> 
> patric

That's a particularly shabby response even from Maplin. 5.4v dropping
to 5.00v on unspecified load is hardly regulation. Usually switched
mode PSUs don't /rise/ to their regulated output without a little load
- I'm using an A7000 one, and the 5v usb hub is a quite sufficient
load to prod the 5v into life at 5.04v

Get forceful with them :-)

-- 
Mark J 
 

In message <0817a95452.News@poppy-land.fslife.co.uk>
          Mark <mark@poppyland.plu$.com.invalid> wrote:

> In message <op.v8dxlufbeksv19@aristide.fritz.box>
>           Patric <patric@invalid.de> wrote:

>> On Thu, 19 Jan 2012 20:03:40 +0100, patric <patric@invalid.com> wrote:
>> 
>>> On Thu, 19 Jan 2012 19:13:58 +0100, Alan Dawes
>>> <alan.dawes@argonet.co.uk> wrote:
>>>
>>>>
>>>> Yes take it back to Maplins - it is faulty. It is advertised as giving a
>>>> regulated 5V supply which it does not do.
>>>>
>>>> Alan
>>>>
>>>
>>> Yeah, contacted the seller. I hope he'll exchange it for a working one
>>> instead of just taking it back.
>> 
>> I've been told my unit only regulates under load. Since the BB however
>> refuses to
>> start with 5.4V while the USB hub seems happy enough I guess there's
>> actually to
>> little load when switching on.
>> 
>> patric

> That's a particularly shabby response even from Maplin. 5.4v dropping
> to 5.00v on unspecified load is hardly regulation. Usually switched
> mode PSUs don't /rise/ to their regulated output without a little load
> - I'm using an A7000 one, and the 5v usb hub is a quite sufficient
> load to prod the 5v into life at 5.04v

> Get forceful with them :-)

The PSU came off ebay, haven't got an axe to grind with Maplin. Matter 
of fact I've found them quite helpful in the past :)
RO-friendly missle launchers aside, how about a USB media device? HD 
playback in the same box! Okay, none of them would interface in any 
way with RISC OS I reckon but couldn't this be an interesting path 
around the media shortcomings of RISC OS? Like a custom chip?
Then again, there's the Raspberry Pi which supports a bunch of 
codices, requires 5V and I've now got some empty space in my BB case 
where the original PSU used to live.

patric

In message <0817a95452.News@poppy-land.fslife.co.uk>
          Mark <mark@poppyland.plu$.com.invalid> wrote:

> In message <op.v8dxlufbeksv19@aristide.fritz.box>
>           Patric <patric@invalid.de> wrote:
> 
> > I've been told my unit only regulates under load. Since the BB however  
> > refuses to
> > start with 5.4V while the USB hub seems happy enough I guess there's  
> > actually to
> > little load when switching on.
> > 
> > patric
> 
> That's a particularly shabby response even from Maplin. 5.4v dropping
> to 5.00v on unspecified load is hardly regulation. Usually switched
> mode PSUs don't /rise/ to their regulated output without a little load
> - I'm using an A7000 one, and the 5v usb hub is a quite sufficient
> load to prod the 5v into life at 5.04v

No, Mark.  It is common for a single-output power supply to have
an output voltage that is too high when given too little load.
There should be a specification somewhere for the range of load
currents over which the output voltage specification applies.  I
have seen power supplies that require a minimum of 25% of full
load.  The minimum load is very variable between designs of power
supply.

Where a supply's voltage is /low/ under no or low load and /rises/
as the load is increased: that is only the case for a non-primary
output when the load on /other/ outputs is increased.

Dave

In article <op.v8dxlufbeksv19@aristide.fritz.box>,
   Patric <patric@invalid.de> wrote:

> I've been told my unit only regulates under load. Since the BB however
> refuses to start with 5.4V while the USB hub seems happy enough I guess
> there's actually to little load when switching on.

Did they specify what the minimum load needs to be?

-- 
Stuart Winsor

Only plain text for emails
http://www.asciiribbon.org

On 18 Jan,  
     Patric Albutat <albutat@gmx.de> wrote:

> New PSU, unbranded China export, arrived on Monday and after getting 
> my act together everything seems to be up and running again. As Alan 
> mentioned the Maplin PSU was actually rated at 5A for 5-12V (4A @ 
> 13.5-15V) and runs rather hot. The replacement looks similar to 
> "Voltcraft" products and runs noticably cooler, hardly warm actually

Sounds like the one I bought for my SDR radio. It started playing up and no
longer works. For that pupose I now use a modified scrap pc psu. Much more
reliable. 

Is the china one fixed voltage, or will it deliver 5-15 volts? if so have you
any details for a replacement for my maplins one? I need about 13.5 volts,
ideally 13.8.

-- 
Brian D 
VirtualRPC-AdjustSA
Change lycos to yahoo to reply.

On Fri, 20 Jan 2012 15:00:07 +0100, Patric <patric@invalid.de> wrote:

> While this seems to work I'll have to come up with a more 
sophisticated

Kill two birds with one stone. You can buy USB gadgets that keep your 
tea mug warm. Take off three USB plug and hook it directly to the 
power supply. Then use the regulated volts to power the Beagle...

;-)

Best wishes,

Rick.

In message <5254BF5A27%brian13434@lycos.co.uk>
          <me9@privacy.net> wrote:

> On 18 Jan,
>      Patric Albutat <albutat@gmx.de> wrote:

>> New PSU, unbranded China export, arrived on Monday and after getting
>> my act together everything seems to be up and running again. As Alan
>> mentioned the Maplin PSU was actually rated at 5A for 5-12V (4A @
>> 13.5-15V) and runs rather hot. The replacement looks similar to
>> "Voltcraft" products and runs noticably cooler, hardly warm actually

> Sounds like the one I bought for my SDR radio. It started playing up and no
> longer works. For that pupose I now use a modified scrap pc psu. Much more
> reliable.

> Is the china one fixed voltage, or will it deliver 5-15 volts? if so have you
> any details for a replacement for my maplins one? I need about 13.5 volts,
> ideally 13.8.

Unfortunately not, the one I use now is fixed voltage and delivers 5V 
only.

patric

In message <almarsoft.7511050503149695510@news.orange.fr>
          Rick Murray <heyrickmail-usenet@yahoo.co.uk> wrote:

> On Fri, 20 Jan 2012 15:00:07 +0100, Patric <patric@invalid.de> wrote:

>> While this seems to work I'll have to come up with a more
> sophisticated

> Kill two birds with one stone. You can buy USB gadgets that keep your
> tea mug warm. Take off three USB plug and hook it directly to the
> power supply. Then use the regulated volts to power the Beagle...

> ;-)

> Best wishes,

> Rick.

At first I dismissed your idea for being in conflict with the first 
law of thermodynamics (which btw is strictly enforced over here though 
probably not in France) but anyways: I use a tea light for that!
Got to check if my old and unused USB CD-ROM runs off 5V. That would 
be ideal and quite at swim two birds :)

patric