[Tobiah]

I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power supplies.
I recently got 3 usb chargers off ebay from two different vendors that were rated
at 2.1 amps, but would only deliver 300-500ma. I know that there are many
name brand counterfeits on ebay for batteries and power supplies. There were
many auctions that called out my exact interface: "Power supply for M-Audio
Fast Track Ultra". Then I'd zoom into the photo and see that the supply was
rated at 500ma, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device ratings
will be accurate.

Thanks,

Toby

[gareth magennis]

You don't say where you live, so I assume you are in the USA.


http://www.newark.com/webapp/wcs/sto...8531,811353662



Cheers,


Gareth.




"Tobiah" wrote in message ...

I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power supplies.
I recently got 3 usb chargers off ebay from two different vendors that were
rated
at 2.1 amps, but would only deliver 300-500ma. I know that there are many
name brand counterfeits on ebay for batteries and power supplies. There
were
many auctions that called out my exact interface: "Power supply for M-Audio
Fast Track Ultra". Then I'd zoom into the photo and see that the supply was
rated at 500ma, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device
ratings
will be accurate.

Thanks,

Toby

[Roy W. Rising[_2_]]

Tobiah wrote:
I got an audio interface off of ebay that didn't come with a power
supply. The manual says it's a 5V 2A DC output. I started looking for a
replacement and didn't find much out there. I see hundreds on ebay, but
my experience is that ebay is a very poor source for memory, batteries
and power supplies. I recently got 3 usb chargers off ebay from two
different vendors that were rated at 2.1 amps, but would only deliver
300-500ma. I know that there are many name brand counterfeits on ebay
for batteries and power supplies. There were many auctions that called
out my exact interface: "Power supply for M-Audio Fast Track Ultra".
Then I'd zoom into the photo and see that the supply was rated at 500ma,
or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device
ratings will be accurate.

Thanks,

Toby

How did you determine that the 2.1A supply could only deliver 300-500ma?
Could it be that is all the interface device draws? Or, did you load the
supply with a resistor decade box and reduce the load until the current
curve flattened out? [2.1A x 5V = 10.5W in 2.38 ohms. Most decade boxes
don't use 10W resistors]

--
~ Roy
"If you notice the sound, it's wrong!"

[William Sommerwerck]

"Tobiah" wrote in message ...

I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power supplies.
I recently got 3 usb chargers off ebay from two different vendors that were
rated
at 2.1 amps, but would only deliver 300-500mA. I know that there are many
name brand counterfeits on ebay for batteries and power supplies. There were
many auctions that called out my exact interface: "Power supply for M-Audio
Fast Track Ultra". Then I'd zoom into the photo and see that the supply was
rated at 500mA, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device ratings
will be accurate.

---------------------------------------------------
It's amazing that none of the suppliers for a power supply for this unit get
the voltage or current correct! You're right -- they're all 5V 500mA! Duh.

I searched for "5V 2A adapter", and got almost 4000 responses. They're fairly
cheap, so you can probably take a chance -- the only issue being the plug's
dimensions and polarity. (Many 5V supplies have narrow plugs. You might ask M
Audio if a 6V adapter is acceptable.)

[Jay Ts[_4_]]

On Tue, 01 Jul 2014, Tobiah wrote:
I got an audio interface off of ebay that didn't come with a power
supply.
The manual says it's a 5V 2A DC output.

That is not enough information. You also need to know the size of the
plug and check the polarity (usually, it's center positive).

The connector is usually a barrel style, with an outside diameter and an
inside diameter for the center connector. Common sizes for the center pin
are 2.5, 2.1 and 1.7 mm. It is easy to confuse 2.5 and 2.1 mm sizes, so
be careful.

I started looking for a
replacement and didn't find much out there. I see hundreds on ebay, but
my experience is that ebay is a very poor source for memory, batteries
and power supplies.

Yes. Many non-OEM power supplies from China are not even safe. I've heard
stories of how they design a circuit to pass the FCC, then ship the
product with components missing, no longer within FCC specs, just to save
some money. Bad power supplies can put common mode high frequency noise
on the outputs, and ... who knows what else?

Fortunately, there are also good brands, and if you work through an OEM
or reputable distributer, they will filter off the bad stuff for you.

There were many auctions that called out my exact interface:
"Power supply for M-Audio Fast Track Ultra". Then I'd zoom into the
photo and see that the supply was rated at 500ma, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool,
where can I go to get such a power supply where I can trust that the
device ratings will be accurate.

Here are URLs you can use as starting points for searches at Mouser and
Digi-Key, two of the largest electronic component distributors in the USA:

http://www.mouser.com/Power/Power-Su...-Adapters/_/N-
brvy9Zscv7?P=1yxt7euZ1yxt794Z1yxt7bd&Keyword=power
+adapter&FS=True&Ns=Pricing|0

http://www.digikey.com/product-searc...04a%2C4f80059%
2C11800192&mnonly=0&newproducts=0&ColumnSort=0&pag e=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25

Mouser is closer to me and I'm a lot more familiar with them, but many on
the Internet swear by Digi-Key. They are both good. I see a Triad
Magnetics WSU050-2000 adapter at Mouser for $8.99. I've had good
experiences with Triad so far.

You should look at the product datasheets to check that the plug is the
size and polarity you need. Sometimes the specifications listed on the
item's page are incorrect, so always check the datasheet before
committing to a purchase. To continue the example:

http://www.mouser.com/ds/2/410/WSU-S...eet%20%282012%
29-310878.pdf

At the bottom, you can see in the diagram that it is for a 2.1mm center
pin. If you need one for 2.5mm, you will have to look at a different
model.

[Tobiah]

On 07/01/2014 10:18 AM, Roy W. Rising wrote:
Tobiah wrote:
I got an audio interface off of ebay that didn't come with a power
supply. The manual says it's a 5V 2A DC output. I started looking for a
replacement and didn't find much out there. I see hundreds on ebay, but
my experience is that ebay is a very poor source for memory, batteries
and power supplies. I recently got 3 usb chargers off ebay from two
different vendors that were rated at 2.1 amps, but would only deliver
300-500ma. I know that there are many name brand counterfeits on ebay
for batteries and power supplies. There were many auctions that called
out my exact interface: "Power supply for M-Audio Fast Track Ultra".
Then I'd zoom into the photo and see that the supply was rated at 500ma,
or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device
ratings will be accurate.

Thanks,

Toby

How did you determine that the 2.1A supply could only deliver 300-500ma?
Could it be that is all the interface device draws? Or, did you load the
supply with a resistor decade box and reduce the load until the current
curve flattened out? [2.1A x 5V = 10.5W in 2.38 ohms. Most decade boxes
don't use 10W resistors]


I bought a little inline usb meter when I found that my phone wasn't charging
very well. The ebay chargers delivered a half Amp or less into my phone, while my
OEM charger was doing close to 2 Amps. I also found an app for my phone that
tells what it's getting, and it agrees with the meter.

Tobiah

[Sean Conolly]

"Tobiah" wrote in message
...
I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a
replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power
supplies.
I recently got 3 usb chargers off ebay from two different vendors that
were rated
at 2.1 amps, but would only deliver 300-500ma. I know that there are many
name brand counterfeits on ebay for batteries and power supplies. There
were
many auctions that called out my exact interface: "Power supply for
M-Audio
Fast Track Ultra". Then I'd zoom into the photo and see that the supply
was
rated at 500ma, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device
ratings
will be accurate.

There's a lot of surplus supplies available out there, here's a page of 5V
supplies:
http://www.mpja.com/5-Volt-Power-Supply/products/534/

Honestly I'm a bit skeptical that the device is really going to dissipate
10W for very long. I'd hook it up to a bench supply and see what it really
draws.

Sean

[geoff]

On 2/07/2014 5:18 a.m., William Sommerwerck wrote:

will be accurate.

---------------------------------------------------
It's amazing that none of the suppliers for a power supply for this unit
get the voltage or current correct! You're right -- they're all 5V
500mA! Duh.

I searched for "5V 2A adapter", and got almost 4000 responses. They're
fairly cheap, so you can probably take a chance -- the only issue being
the plug's dimensions and polarity. (Many 5V supplies have narrow plugs.
You might ask M Audio if a 6V adapter is acceptable.)

6V will NOT be ok. The internals likely require 5V, and if original
supply is 5V that is what it needs.

You might get away with a (significantly, say 9V) charger if there was
an internal regulator, but as original the original requires 5V it is
relying on the external supply being that regulated 5V already.

Oh, and 5V 2A PSU - go to almost any small appliance or electronic hobby
store. Here at least ...


geoff

[gareth magennis]

"Sean Conolly" wrote in message ...

"Tobiah" wrote in message
...
I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a
replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power
supplies.
I recently got 3 usb chargers off ebay from two different vendors that
were rated
at 2.1 amps, but would only deliver 300-500ma. I know that there are many
name brand counterfeits on ebay for batteries and power supplies. There
were
many auctions that called out my exact interface: "Power supply for
M-Audio
Fast Track Ultra". Then I'd zoom into the photo and see that the supply
was
rated at 500ma, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device
ratings
will be accurate.

There's a lot of surplus supplies available out there, here's a page of 5V
supplies:
http://www.mpja.com/5-Volt-Power-Supply/products/534/





I thought the whole point of this post was to circumvent probably shonky
goods, such as you have just pointed to.

Go with the big distributers - Newark, DigiKey, Mouser etc and you will NOT
be sold a piece of crap.

Probably.



Gareth.

[William Sommerwerck]

"geoff" wrote in message ...

6V will NOT be ok.

And you know that... how? Many Sony products come with power supplies whose
rated voltage is well-above the nominal battery voltage.

[gareth magennis]

"geoff" wrote in message
...

On 2/07/2014 5:18 a.m., William Sommerwerck wrote:

will be accurate.

---------------------------------------------------
It's amazing that none of the suppliers for a power supply for this unit
get the voltage or current correct! You're right -- they're all 5V
500mA! Duh.

I searched for "5V 2A adapter", and got almost 4000 responses. They're
fairly cheap, so you can probably take a chance -- the only issue being
the plug's dimensions and polarity. (Many 5V supplies have narrow plugs.
You might ask M Audio if a 6V adapter is acceptable.)

6V will NOT be ok. The internals likely require 5V, and if original
supply is 5V that is what it needs.

You might get away with a (significantly, say 9V) charger if there was
an internal regulator, but as original the original requires 5V it is
relying on the external supply being that regulated 5V already.

Oh, and 5V 2A PSU - go to almost any small appliance or electronic hobby
store. Here at least ...





I suspect that any device requiring a 5v power supply does not rely on the
fact that it will receive a 5v regulated supply to run properly.

More likely that this device regulates this 5v supply internally to provide
3.3v to the associated digital stuff inside, and/or generates other voltages
as required.



Gareth.

[Scott Dorsey]

In article , Tobiah wrote:
I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power supplies.

Go to digi-key. Get the paper catalogue, don't fight with the horrible web
page interface. They have three or four different wall-wart vendors, with
pictures. Pick the current, the voltage, the degree of regulation, and
the correct connector.

I recently got 3 usb chargers off ebay from two different vendors that were rated
at 2.1 amps, but would only deliver 300-500ma.

Okay, USB devices are a different thing altogether, because USB is supposed
to be limited to about 500mA until the device specially requests more current
over the USB interface. You can't just chop the connector off a USB charger
and put a coaxial connector on and expect it to deliver more than 500mA.

Also note that most USB chargers are pretty damn noisy. You're much better
off with a linear supply.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device ratings
will be accurate.

If you buy from a legitimate supplier like Digi-Key or Mouser, you can expect
that the device will meet specifications. You need to look carefully at the
specifications, though.

Was the original supply a linear "line lump" type that was heavy, or was it
a light switching supply wall wart?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Dave Plowman (News)]

In article ,
William Sommerwerck wrote:
"geoff" wrote in message ...

6V will NOT be ok.

And you know that... how? Many Sony products come with power supplies
whose rated voltage is well-above the nominal battery voltage.

If it needs a five volt supply it doesn't sound like it was designed with
batteries in mind?

--
*Procrastination is the art of keeping up with yesterday.

Dave Plowman London SW
To e-mail, change noise into sound.

[Jay Ts[_4_]]

On Tue, 01 Jul 2014, Gareth Magennis wrote:
"geoff" and

William Sommerwerck wrote:

6V will NOT be ok. The internals likely require 5V, and if original
supply is 5V that is what it needs.

You might get away with a (significantly, say 9V) charger if there was
an internal regulator, but as original the original requires 5V it is
relying on the external supply being that regulated 5V already.



I suspect that any device requiring a 5v power supply does not rely on
the fact that it will receive a 5v regulated supply to run properly.

More likely that this device regulates this 5v supply internally to
provide 3.3v to the associated digital stuff inside, and/or generates
other voltages as required.

This is getting into the ugly realities of power adapters.

Most I've seen are unregulated, so the rating listed on it really means
more like "at least 5 volts DC at a current of 2000 mA."

For an unregulated adapter, if you measure the voltage when the adapter
is not plugged into the device, you often read 2 more more volts above
what is printed on it. If the circuit does not need *any* regulation,
then the ripple voltage typically will increase as the circuit draws more
power, but it shouldn't matter. I expect this is *not* the case for the
OP's audio adapter.

For a circuit that requires regulated voltage (most audio circuits),
voltage regulators typically allow the input voltage from the power
adapter to be far higher than the regulated output. In the case if a
common 78xx regulator, up to 37 volts.

But the same regulator won't work right if the input voltage is too low,
and it needs to be 1.5-2 volts above the regulated voltage. So you might
get away with a 6v adapter rather than the 5v OEM one, but to be careful,
it's not a good idea. The 6v adapter may provide 10 volts and who knows,
that might be too much for the specific circuit. I'm just saying it's
best to be careful.

There are also regulated power adapters, and if the circuit needs that
(because it lacks internal regulation, and depends on the power adapter),
then you need one! If you use an unregulated adapter instead, you may be
operating at the wrong voltage (that is, outside of the intended design),
plus you may get bad effects (hum) from the ripple in the power supply.

One common example of this is found with guitar effects pedals. The most
common require 9 volts DC, *regulated*, with center *negative*. An
unregulated 9v DC adapter may, depending on the pedal, produce large
amounts of hum, which might be confused with grounding (ground loop)
problems.

However, most other audio products (including all I've seen) have voltage
regulation inside the circuit, so an unregulated power adapter is fine.
(It's better engineering to do the regulation on the internal circuit
board rather than in the power adapter, because then either a regulated
or unregulated adapter will work. Also, I think it's generally less
expensive.)

[William Sommerwerck]

"Dave Plowman (News)" wrote in message ...

In article ,
William Sommerwerck wrote:
"geoff" wrote in message
...

6V will NOT be ok.

And you know that... how? Many Sony products come with power
supplies whose rated voltage is well-above the nominal battery voltage.

If it needs a five volt supply it doesn't sound like it was designed
with batteries in mind?

Find concrete wall. Bang head against it.

Sony manufactured millions of Discmans powered by two AA cells, but come with
a 4.5V power adapter. That a product is designed for a particular voltage
doesn't mean it will be damaged by a slightly higher voltage.

[Mike Rivers[_2_]]

On 7/1/2014 3:13 PM, Tobiah wrote:
I bought a little inline usb meter when I found that my phone wasn't
charging
very well. The ebay chargers delivered a half Amp or less into my
phone, while my
OEM charger was doing close to 2 Amps. I also found an app for my phone
that
tells what it's getting, and it agrees with the meter.

Geez, what will they think of next? I wanted to find the peak current
load presented to the USB port by the TASCAM US-122 after discovering
that when switching on the phantom power, one of my computers couldn't
handle the initial load and caused the interface to disconnect. I cut a
USB cable in the middle, soldered a 1 ohm resistor in series with the
power leads, and connected an oscilloscope across it.

Who makes the USB meter you used? I'd be interested to see one, or at
least see what it's actually measuring.


--
For a good time, visit http://mikeriversaudio.wordpress.com

[Mike Rivers[_2_]]

On 7/1/2014 6:39 PM, Jay Ts wrote:
This is getting into the ugly realities of power adapters.

Most I've seen are unregulated, so the rating listed on it really means
more like "at least 5 volts DC at a current of 2000 mA."

Most of the power supplies for audio gear that I've encountered in the
past couple of years have been switching supplies that are extremely
well regulated and have much lower ripple than the old
transformer-diode-capacitor-goodluck wall warts.

Radio Shack has one that will do nicely, switchable from 3 to 7.5v, 2.5A
maximum current.
http://www.radioshack.com/product/in...ductId=3875410

--
For a good time, visit http://mikeriversaudio.wordpress.com

[Jay Ts[_4_]]

On Tue, 01 Jul 2014, Dave Plowman (News) wrote:

If it needs a five volt supply it doesn't sound like it was designed
with batteries in mind?

Five volts has been used since the 1970s as a positive supply for digital
circuitry, and parts that require 3.3 volts or lower can get it from
additional voltage regulators in the circuit. Since the unit in question
is a USB audio adapter, it may need 5 volts for that. (Caveat: I have
never designed USB interface circuitry.

[Jay Ts[_4_]]

On Tue, 01 Jul 2014, Scott Dorsey wrote:

Also note that most USB chargers are pretty damn noisy. You're much
better off with a linear supply.

Yes, but ...

Was the original supply a linear "line lump" type that was heavy, or was
it a light switching supply wall wart?

He might not be able to get a linear supply anymore.

Some years ago, I got some Dunlop effects pedal power adapters, and they
were the traditional linear kind. But a year later I decided to get some
more, and from 2 different vendors, even though they showed photos of the
old style, I received smaller, lighter switching power supplies.

I was not happy about that, but started using them.

I had 3 of the switching supplies plugged in 24/7 for about 2.5 years, at
which time they were all failing, adding audible high frequency noise to
the sound of the pedals. I took one apart and found the cheapest circuit,
parts and construction imaginable, and I threw them all in the trash.

So I thought I should ask retailers of Dunlop products (Swee****er,
Musician's Friend, and some of the usual names) to see if they had any of
the linear style to sell me, and I could not find any. Most were still
showing photos of the linear style. Swee****er updated their image after
I pointed out the issue.

I was wondering what was going on, and I'm no legal expert, but found
some things in the federal act that banned 100 watt lightbulbs that
applied to power adapters. I think maybe the linear style was effectively
banned by that due to their lower efficiency.

If anyone knows more about that, I'm happy to hear from them.

[Tobiah]

On 7/1/2014 10:02 AM, Gareth Magennis wrote:
You don't say where you live, so I assume you are in the USA.

I'm just curious as to whether you assume I'm in the USA because
of some facet of my post, or whether the glaring omission of that
distinction was absent from it. A notable side affect of my
ingrained geocentricity (not a real word I gather) I'm sure.

Tobiah


---
This email is free from viruses and malware because avast! Antivirus protection is active.
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[Tobiah]

Okay, USB devices are a different thing altogether, because USB is supposed
to be limited to about 500mA until the device specially requests more current
over the USB interface. You can't just chop the connector off a USB charger
and put a coaxial connector on and expect it to deliver more than 500mA.

I should have mentioned that my phone is USB 3.0. It has that funky
wide double connector. I'm not looking it up right now, but I'm pretty
sure that 3.0 allows for a larger current at the get go.

Thanks,

Toby

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This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

[Tobiah]

Who makes the USB meter you used? I'd be interested to see one, or at
least see what it's actually measuring.


It was somewhere around $6, and it probably came from the
same lame source as the chargers I was measuring. Still,
global conspiracy aside, it agreed with other sources and
measured my OEM charger where it should have been.

Look on ebay if you like. It's this little Wrigley's sized
charger in blue plastic. It alternately flashes current and
volts.

Thanks,

Tobiah




---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

[Sean Conolly]

"Gareth Magennis" wrote in message
...


"Sean Conolly" wrote in message ...

"Tobiah" wrote in message
...
I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a
replacement
and didn't find much out there. I see hundreds on ebay, but my
experience
is that ebay is a very poor source for memory, batteries and power
supplies.
I recently got 3 usb chargers off ebay from two different vendors that
were rated
at 2.1 amps, but would only deliver 300-500ma. I know that there are
many
name brand counterfeits on ebay for batteries and power supplies. There
were
many auctions that called out my exact interface: "Power supply for
M-Audio
Fast Track Ultra". Then I'd zoom into the photo and see that the supply
was
rated at 500ma, or 4 volts, etc.

So the question is, aside from finding an OEM, which would be cool, where
can I go to get such a power supply where I can trust that the device
ratings
will be accurate.

There's a lot of surplus supplies available out there, here's a page of 5V
supplies:
http://www.mpja.com/5-Volt-Power-Supply/products/534/





I thought the whole point of this post was to circumvent probably shonky
goods, such as you have just pointed to.

Go with the big distributers - Newark, DigiKey, Mouser etc and you will
NOT be sold a piece of crap.

Probably.

Just cause it's surplus doesn't mean it's junk - it can be a simple as made
for an EOL'd product, which I suspect is the case for the Cisco supply on
that page.

Sean

[geoff]

On 2/07/2014 9:32 a.m., William Sommerwerck wrote:
"geoff" wrote in message
...

6V will NOT be ok.
And you know that... how?


I fix them .

Many Sony products come with power supplies
whose rated voltage is well-above the nominal battery voltage.

In which case there is likely an internal regulator in the device itself.


geoff

[geoff]

On 2/07/2014 10:50 a.m., William Sommerwerck wrote:
"Dave Plowman (News)" wrote in message
...

In article ,
William Sommerwerck wrote:
"geoff" wrote in message
...

6V will NOT be ok.

And you know that... how? Many Sony products come with power
supplies whose rated voltage is well-above the nominal battery voltage.

If it needs a five volt supply it doesn't sound like it was designed
with batteries in mind?

Find concrete wall. Bang head against it.

Sony manufactured millions of Discmans powered by two AA cells, but come
with a 4.5V power adapter. That a product is designed for a particular
voltage doesn't mean it will be damaged by a slightly higher voltage.


I a computer interface type device needs a 5V supply, then highly likely
it has internal chips that operate at 5V.

If a battery-powered device had a PSU the same voltage as it's
batteries, rechargables would likely not charge properly.

geoff

[geoff]

On 2/07/2014 9:47 a.m., Gareth Magennis wrote:


"geoff" wrote in message
...

On 2/07/2014 5:18 a.m., William Sommerwerck wrote:

will be accurate.

---------------------------------------------------
It's amazing that none of the suppliers for a power supply for this unit
get the voltage or current correct! You're right -- they're all 5V
500mA! Duh.

I searched for "5V 2A adapter", and got almost 4000 responses. They're
fairly cheap, so you can probably take a chance -- the only issue being
the plug's dimensions and polarity. (Many 5V supplies have narrow plugs.
You might ask M Audio if a 6V adapter is acceptable.)

6V will NOT be ok. The internals likely require 5V, and if original
supply is 5V that is what it needs.

You might get away with a (significantly, say 9V) charger if there was
an internal regulator, but as original the original requires 5V it is
relying on the external supply being that regulated 5V already.

Oh, and 5V 2A PSU - go to almost any small appliance or electronic hobby
store. Here at least ...





I suspect that any device requiring a 5v power supply does not rely on
the fact that it will receive a 5v regulated supply to run properly.

More likely that this device regulates this 5v supply internally to
provide 3.3v to the associated digital stuff inside, and/or generates
other voltages as required.

Possibly - but easiest to have the correct voltage regulated SMPS in the
first place. 1.5v is marginal or inadequate differential for a linear
3.3V regulator - but could be an internal SMPS or buck-boost circuit.

Still best to use the recommended PSU though, IMO. Especially if little
effort to find one - and 5V is very standard.

geoff

[geoff]

On 2/07/2014 4:21 a.m., Tobiah wrote:
I got an audio interface off of ebay that didn't come with a power supply.
The manual says it's a 5V 2A DC output. I started looking for a
replacement
and didn't find much out there. I see hundreds on ebay, but my experience
is that ebay is a very poor source for memory, batteries and power
supplies.
I recently got 3 usb chargers off ebay from two different vendors that
were rated
at 2.1 amps, but would only deliver 300-500ma.

Maybe that was all the charging device was DRAWING.

The capacity of a PSU is the maximium available current (supposedly) -
that doesn't mean devices have to draw that current in any particular
situation.

geoff

[geoff]

On 2/07/2014 2:02 p.m., Jay Ts wrote:
On Tue, 01 Jul 2014, Scott Dorsey wrote:


If anyone knows more about that, I'm happy to hear from them.


It's called MEPS :

http://en.wikipedia.org/wiki/Minimum...mance_standard

The idea is that that devices when turned off "soft" still draw power
is transformer-based. SMPSs draw much much less in an idle state.

However there are some transformer-based PSU that are design to comply
with MEPS . Cost possibly becomes a factor there....

geoff

[John Williamson]

On 02/07/2014 08:47, geoff wrote:
On 2/07/2014 4:21 a.m., Tobiah wrote:
I got an audio interface off of ebay that didn't come with a power
supply.
The manual says it's a 5V 2A DC output. I started looking for a
replacement
and didn't find much out there. I see hundreds on ebay, but my
experience
is that ebay is a very poor source for memory, batteries and power
supplies.
I recently got 3 usb chargers off ebay from two different vendors that
were rated
at 2.1 amps, but would only deliver 300-500ma.

Maybe that was all the charging device was DRAWING.

The capacity of a PSU is the maximium available current (supposedly) -
that doesn't mean devices have to draw that current in any particular
situation.

Also, drawing more than the standard amount of current from a USB port
requires negotiation between the port and the device. There are a few
mutually incompatible ways of doing this in use.


--
Tciao for Now!

John.

[geoff]

On 2/07/2014 2:12 p.m., Tobiah wrote:

Okay, USB devices are a different thing altogether, because USB is
supposed
to be limited to about 500mA until the device specially requests more
current
over the USB interface. You can't just chop the connector off a USB
charger
and put a coaxial connector on and expect it to deliver more than 500mA.

I should have mentioned that my phone is USB 3.0. It has that funky
wide double connector. I'm not looking it up right now, but I'm pretty
sure that 3.0 allows for a larger current at the get go.

The phone still won't necessarily suck more current than it actually
wants. Heat is a major factor.

I just can't imagine a 2A going into a cellphone !

geoff

[Trevor]

"Jay Ts" wrote in message
...
Yes. Many non-OEM power supplies from China are not even safe.

You got that right, a woman was killed here last week by a cheap USB
charger!

Trevor.

[Trevor]

"geoff" wrote in message
...
6V will NOT be ok. The internals likely require 5V, and if original supply
is 5V that is what it needs.

You might get away with a (significantly, say 9V) charger if there was an
internal regulator, but as original the original requires 5V it is
relying on the external supply being that regulated 5V already.

Oh, and 5V 2A PSU - go to almost any small appliance or electronic hobby
store. Here at least ...

And you will find most of them are not regulated, so be careful if that is
what is needed.

Trevor.

[Trevor]

"Dave Plowman (News)" wrote in message
...
In article ,
William Sommerwerck wrote:
"geoff" wrote in message
...

6V will NOT be ok.

And you know that... how? Many Sony products come with power supplies
whose rated voltage is well-above the nominal battery voltage.

If it needs a five volt supply it doesn't sound like it was designed with
batteries in mind?

If it requires 2 Amps, then it's probably a safe bet it wasn't!

Trevor.

[Dave Plowman (News)]

In article ,
Jay Ts wrote:
On Tue, 01 Jul 2014, Dave Plowman (News) wrote:

If it needs a five volt supply it doesn't sound like it was designed
with batteries in mind?

Five volts has been used since the 1970s as a positive supply for
digital circuitry, and parts that require 3.3 volts or lower can get it
from additional voltage regulators in the circuit. Since the unit in
question is a USB audio adapter, it may need 5 volts for that. (Caveat:
I have never designed USB interface circuitry.


Quite. And of course it's now the standard for mobile phones too.

My point was that all the 5 volt supplies I've come across are regulated.
Ones which aren't - designed for use with older equipment which was also
powered by alkaline cells - were more usually marked as a multiple of
1.5v. Even when non regulated.

--
*Save the whale - I'll have it for my supper*

Dave Plowman London SW
To e-mail, change noise into sound.

[Dave Plowman (News)]

In article ,
geoff wrote:
Many Sony products come with power supplies
whose rated voltage is well-above the nominal battery voltage.

In which case there is likely an internal regulator in the device itself.

I can remember a walkman which had regulation for only some of the
electronics. The power amp used full battery volts. So as the voltage
dropped the available clean output became less - although it continued to
function ok otherwise.

--
*Why is "abbreviated" such a long word?

Dave Plowman London SW
To e-mail, change noise into sound.

[Mike Rivers[_2_]]

On 7/1/2014 10:12 PM, Tobiah wrote:
I should have mentioned that my phone is USB 3.0. It has that funky
wide double connector. I'm not looking it up right now, but I'm pretty
sure that 3.0 allows for a larger current at the get go.

I read somewhere that the USB 3.0 power spec allows for as much as 100
watts! Since USB 2, there's been two current limits for USB power. 500
mA is the limit for powering external devices, but there's up to 900 mA
available for charging only. If the device only needs to be charged, it
can say to the computer "Shoot the juice to me, Bruce" and get the
higher current for, presumably faster charging.



--
For a good time, visit http://mikeriversaudio.wordpress.com

[Scott Dorsey]

Jay Ts wrote:

Some years ago, I got some Dunlop effects pedal power adapters, and they
were the traditional linear kind. But a year later I decided to get some
more, and from 2 different vendors, even though they showed photos of the
old style, I received smaller, lighter switching power supplies.

I was not happy about that, but started using them.

I had 3 of the switching supplies plugged in 24/7 for about 2.5 years, at
which time they were all failing, adding audible high frequency noise to
the sound of the pedals. I took one apart and found the cheapest circuit,
parts and construction imaginable, and I threw them all in the trash.

So I thought I should ask retailers of Dunlop products (Swee****er,
Musician's Friend, and some of the usual names) to see if they had any of
the linear style to sell me, and I could not find any. Most were still
showing photos of the linear style. Swee****er updated their image after
I pointed out the issue.

I was wondering what was going on, and I'm no legal expert, but found
some things in the federal act that banned 100 watt lightbulbs that
applied to power adapters. I think maybe the linear style was effectively
banned by that due to their lower efficiency.

Not that I know of.

And the thing is, linear supplies can be built to be reasonably efficient,
it's just that it costs more money to put more windings on the transformer
primary so that the no-load current drops to something reasonable, and people
out to make the cheapest possible product won't do that.

Again, I'd suggest a trip to Digi-Key for your Dunlop pedal wall-wart.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[William Sommerwerck]

"geoff" wrote in message
...
On 2/07/2014 9:32 a.m., William Sommerwerck wrote:
"geoff" wrote in message
...


6V will NOT be ok.

And you know that... how?

I fix them.

In other words... ALL devices with a marked 5V input will malfunction or be
damaged if 6V is applied to them? ALL of them?

My point was not that the user doesn't have to pay attention to the voltage of
the power supply, but that the claim of universal unsuitability was specious.


Many Sony products come with power supplies whose
rated voltage is well-above the nominal battery voltage.

In which case there is likely an internal regulator in the device itself.

Correct.

I don't know what M Audio's approach to power-supply design is, but if a
circuit needed //specific// voltages to work correctly, I would not depend on
the power supply to provide them. Regulators are cheap, and would represent a
small percentage of the cost of the product shown.

[William Sommerwerck]

"Tobiah" wrote in message ...

I should have mentioned that my phone is USB 3.0. It has that funky
wide double connector. I'm not looking it up right now, but I'm pretty
sure that 3.0 allows for a larger current at the get go.

I believe USB 3.0 is spec'd at 750mA.

[Scott Dorsey]

William Sommerwerck wrote:
"geoff" wrote in message
6V will NOT be ok.

And you know that... how?

I fix them.

In other words... ALL devices with a marked 5V input will malfunction or be
damaged if 6V is applied to them? ALL of them?

Pretty much anything that has a 5V input is going to be applying the power
directly to logic gates. That's what is magic about that specific "5V" number.
If it said 6V or 12V, I might expect it to be a lot more relaxed but, 5V is
a magic value that almost certainly indicates logic supplies.

However.... the fact that this is a USB device (which was not apparent early
in the thread) pretty much changes everything, because USB has very specific
power requirements in terms of regulation and current limiting and later USB
interfaces require a data connection in order to negotiate the power.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."