Not sure what adapter to use

[Mike S.]

I have three sets of computer speakers that have no adapters. I'm
trying to determine what kind of adapter I can use as I'm sure I have
some old ones that would work. The problem is that I cannot determine
the polarity of the little power jacks on the back of the speakers.
There's no information on this anywhere.

I'm still confused about what adapter to use. Two speakers indicate
that they're 9V, but that's all the information there is.

One speaker is 12V 0.5A and there's a symbol that indicates rectified
AC (one long dash over three short dashes). However it also indicates
to use an adapter that is 230V. So, if I use 120V adapters (for the
U.S.) would that be ok?

When choosing an adapter, do watts matter? And what about mA and
unregulated adapters?

Here are some of the adapters I have (I'm not going to include the
polarity):
Input:120v AC 60 Hz 10.1w Output: 9V DC 600 mA
Input:120v AC 60 Hz 12w Output: 9.0V DC 500 mA
Input:120v AC 60 Hz Output: 9.0V DC 1200 mA
Input:120v AC 60 Hz 14w Output: 12V DC 500 mA
Input:120v AC 60 Hz 9.5w Output: 12V DC 500 mA

 

[krw@att.bizzzzzzzzzzzz]

On Thu, 25 Aug 2011 12:26:29 -0700 (PDT), "Mike S." <littleboyblu87@yahoo.com>
wrote:

I have three sets of computer speakers that have no adapters. I'm
trying to determine what kind of adapter I can use as I'm sure I have
some old ones that would work. The problem is that I cannot determine
the polarity of the little power jacks on the back of the speakers.
There's no information on this anywhere.

Look up the model numbers on the web? More than 90% of these things are
Center-Pin-Positive (CPP). If you have to guess that's the way I'd go.

I'm still confused about what adapter to use. Two speakers indicate
that they're 9V, but that's all the information there is.

One speaker is 12V 0.5A and there's a symbol that indicates rectified
AC (one long dash over three short dashes). However it also indicates
to use an adapter that is 230V. So, if I use 120V adapters (for the
U.S.) would that be ok?

That's strange. Sure, the unit doesn't care what the voltage on the other
side of the power supply is.

When choosing an adapter, do watts matter? And what about mA and
unregulated adapters?

More is better. If the supply can't supply the current you'll likely notice
distortion before you have too much fire. ;-) Make sure nothing gets hot.

Here are some of the adapters I have (I'm not going to include the
polarity):
Input:120v AC 60 Hz 10.1w Output: 9V DC 600 mA
Input:120v AC 60 Hz 12w Output: 9.0V DC 500 mA
Input:120v AC 60 Hz Output: 9.0V DC 1200 mA
Input:120v AC 60 Hz 14w Output: 12V DC 500 mA
Input:120v AC 60 Hz 9.5w Output: 12V DC 500 mA

As with many things, the size of the connector matters, also. Many look the
same but there are many "standard" sizes of these things.

 

[Globemaker]

On Aug 25, 3:26 pm, "Mike S." <littleboybl...@yahoo.com> wrote:

I have three sets of computer speakers that have no adapters. I'm
trying to determine what kind of adapter I can use as I'm sure I have
some old ones that would work. The problem is that I cannot determine
the polarity of the little power jacks on the back of the speakers.
There's no information on this anywhere.

I'm still confused about what adapter to use. Two speakers indicate
that they're 9V, but that's all the information there is.

One speaker is 12V 0.5A and there's a symbol that indicates rectified
AC (one long dash over three short dashes). However it also indicates
to use an adapter that is 230V. So, if I use 120V adapters (for the
U.S.) would that be ok?

When choosing an adapter, do watts matter? And what about mA and
unregulated adapters?

Here are some of the adapters I have (I'm not going to include the
polarity):
Input:120v AC 60 Hz 10.1w Output: 9V DC 600 mA
Input:120v AC 60 Hz 12w Output: 9.0V DC 500 mA
Input:120v AC 60 Hz Output: 9.0V DC 1200 mA
Input:120v AC 60 Hz 14w Output: 12V DC 500 mA
Input:120v AC 60 Hz 9.5w Output: 12V DC 500 mA

Use a fuse . Do experiments while a diode and a resistor limit the
power. Ring may be GND, tip is +12v.
Sneak up on it . Start with 100 ohms in series. Then 33 ohms. If it
makes sounds, decrease the protection. Experiment. The series
protections of fuse, diodes and R will save your bacon. Enjoy the
experimental progress until success is yours.

 

[Tom Biasi]

On Thu, 25 Aug 2011 12:26:29 -0700 (PDT), "Mike S."
<littleboyblu87@yahoo.com> wrote:

I
It doesn't matter what the input is as long as you get the correct

output.
If your device needs 12 volts @ 500 ma. (.5 A) then your adaptor that
supplies that will be OK. (You need the correct plariity.)
Maybe the symbol (O) with a + at the O is there, this indicates that
the center is possitive.
You were not too clear on the other requirements.

Tom

 

[Roberto Waltman]

Mike S. wrote:

... The problem is that I cannot determine
the polarity of the little power jacks on the back of the speakers.

As mentioned already, for most "cylinder/coaxial" type adapters, the
center is positive. If you can open the speakers and check the
circuitry, you may find a hint from a polarized electrolytic cap, the
way an LED is wired, etc.
--
Roberto Waltman

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[Michael Black]

On Fri, 26 Aug 2011, Roberto Waltman wrote:

Mike S. wrote:
... The problem is that I cannot determine
the polarity of the little power jacks on the back of the speakers.

As mentioned already, for most "cylinder/coaxial" type adapters, the
center is positive. If you can open the speakers and check the
circuitry, you may find a hint from a polarized electrolytic cap, the
way an LED is wired, etc.

I don't know where this "most" comes from, someone else said it too. I
certainly wouldn't trust it. I'm getting the impression from recent
comments (elsewhere) that maybe there was an attempt in recent years to
"standardize" but that sure isn't the case from the past. Which means you
never know.

I sure wouldn't trust something without verifying. Just a couple of weeks
ago I bought an ipaq PDA at a garage sale, with the docking station but no
ac adapter. I had no qualms about assuming the adapter was 5v (at the
very least, if I was wrong it would be because I guessed a too low
voltage, which won't hurt something) but a search didn't show anything
that I'd trust. So I used the usb connector in the base to find which of
the ac adapter pins was ground, and thus verified what the search results
said.

It is pretty easy once the speaker is open. On the other hand, some of
those computer speakers seem quite difficult to open. I just smashed one
open a few weeks ago, though in that case I merely wanted the small
amplifier for something else rather than a working speaker.

Michael

 

[krw@att.bizzzzzzzzzzzz]

On Fri, 26 Aug 2011 22:41:19 -0400, Michael Black <et472@ncf.ca> wrote:

On Fri, 26 Aug 2011, Roberto Waltman wrote:

Mike S. wrote:
... The problem is that I cannot determine
the polarity of the little power jacks on the back of the speakers.

As mentioned already, for most "cylinder/coaxial" type adapters, the
center is positive. If you can open the speakers and check the
circuitry, you may find a hint from a polarized electrolytic cap, the
way an LED is wired, etc.

I don't know where this "most" comes from, someone else said it too. I
certainly wouldn't trust it. I'm getting the impression from recent
comments (elsewhere) that maybe there was an attempt in recent years to
"standardize" but that sure isn't the case from the past. Which means you
never know.

Certainly not all DC barrel connectors are CPP but easily 90% (add another
nine) are.

I sure wouldn't trust something without verifying. Just a couple of weeks
ago I bought an ipaq PDA at a garage sale, with the docking station but no
ac adapter. I had no qualms about assuming the adapter was 5v (at the
very least, if I was wrong it would be because I guessed a too low
voltage, which won't hurt something) but a search didn't show anything
that I'd trust. So I used the usb connector in the base to find which of
the ac adapter pins was ground, and thus verified what the search results
said.

It is pretty easy once the speaker is open. On the other hand, some of
those computer speakers seem quite difficult to open. I just smashed one
open a few weeks ago, though in that case I merely wanted the small
amplifier for something else rather than a working speaker.

If one knew what they were doing, an ohm meter might tell the positive
terminal, too. I'd want to play with it before telling someone unfamiliar
with such circuits what was what.