What power supply...

[Your name]

What power supply should I use to test car amplifiers in my house?

Thanks.

[MOSFET]

Use a 12 volt AC to DC adaptor. You can go to any Goodwill and buy a used
one for 50 cents (like an old one that used to power a printer). Just make
sure you know which lead is positive and which lead is negative when you go
to test something otherwise you will likely fry it.

The amperage rating of the adaptor really doesn't matter (the more the
better) as the component you are testing will draw the amperage it needs.

MOSFET

"Your name" > wrote in message
news:vzR2h.78$Ue.58@trndny03...
> What power supply should I use to test car amplifiers in my house?
>
> Thanks.

[JimJ[VT]]

Astron builds, IMHO, some of the best linear 12VDC power supplies out
there.

But a good 100A constant supply won't be cheap.


--
JimJ[VT]

[MOSFET]

BTW, that is EXACTLY how I aquired my 12 volt "bench" power supply. It is a
"Sino-American" (whatever that means) and it says:

INPUT: 120VAC 60Hz 35W
OUTPUT: 12 VDC 1100 mA

It has been my power supply tester for years and has never let me down. I
bought it for 50 cents from Goodwill and just clipped off the plug on the
end.

MOSFET

"Your name" > wrote in message
news:vzR2h.78$Ue.58@trndny03...
> What power supply should I use to test car amplifiers in my house?
>
> Thanks.

[MOSFET]

I guess I was thinking about how you define "test". Obviously, if you want
to test the limits of an amplifier, you will need a hefty, expensive bench
power supply.

I was thinking more in terms of "does it turn on or not", in which case a
more simple approach could be used.

MOSFET


"JimJ[VT]" > wrote in message
...
>
> Astron builds, IMHO, some of the best linear 12VDC power supplies out
> there.
>
> But a good 100A constant supply won't be cheap.
>
>
> --
> JimJ[VT]

[Matt Ion]

MOSFET wrote:
> Use a 12 volt AC to DC adaptor. You can go to any Goodwill and buy a used
> one for 50 cents (like an old one that used to power a printer). Just make
> sure you know which lead is positive and which lead is negative when you go
> to test something otherwise you will likely fry it.
>
> The amperage rating of the adaptor really doesn't matter (the more the
> better) as the component you are testing will draw the amperage it needs.

....up to the current limit of the adapter, after which the output voltage will
start to drop, leading to the adapter itself dying, most likely from a blown
rectifier diode.

[MOSFET]

> ...up to the current limit of the adapter, after which the output voltage
will
> start to drop, leading to the adapter itself dying, most likely from a
blown
> rectifier diode.

Yes, as Dan has pointed out, in the fine tradition of RAC in pointing out
any misstep, I SHOULD have said the thing you will be testing will draw the
amps it needs, but IT OBVIOUSLY CAN'T EXCEED THE AMPERAGE RATING OF THE
ADAPTOR.

Again, I was thinking in terms of testing whether an amplifier (or any 12
volt accesory) turns on or not and can pass a signal, NOT testing the limits
of an amplifier.

If you just want to test whether an amp works or not, you do not need a
$1000 Astron bench power supply. I have been using a simple AC converter
for years as my "bench" supply and it has worked fine. If I want to test
the limits of an amp, I take it out to my car.

MOSFET

[Matt Ion]

MOSFET wrote:

> Yes, as Dan has pointed out, in the fine tradition of RAC in pointing out
> any misstep, I SHOULD have said the thing you will be testing will draw the
> amps it needs, but IT OBVIOUSLY CAN'T EXCEED THE AMPERAGE RATING OF THE
> ADAPTOR.

Obvious to us maybe, not necessarily to the original poster.

> Again, I was thinking in terms of testing whether an amplifier (or any 12
> volt accesory) turns on or not and can pass a signal, NOT testing the limits
> of an amplifier.

From your description, the OP may think any little 300mA wall wart will do...
that'll barely be enough power to start up the deck, let alone the amp. Forget
about actually getting any output from either.

[MOSFET]

> From your description, the OP may think any little 300mA wall wart will
do...
> that'll barely be enough power to start up the deck, let alone the amp.

Good point. The idle current of some amps may exceed many small AC
adaptors.

I use an AC adaptor rated for 1100 mA as my "bench" power supply and it has
been able to power up any amp or HU. And I have had no trouble getting
those amps and HU's to pass a signal (obviously I don't blast it).

So from my experience, as long as you get a 12VDC adaptor with at least 1000
mA, that should be sufficient to test (see whether it works or not) any 12
volt car audio device.

MOSFET

[Matt Ion]

MOSFET wrote:
>> From your description, the OP may think any little 300mA wall wart will
>
> do...
>
>>that'll barely be enough power to start up the deck, let alone the amp.
>
>
> Good point. The idle current of some amps may exceed many small AC
> adaptors.
>
> I use an AC adaptor rated for 1100 mA as my "bench" power supply and it has
> been able to power up any amp or HU. And I have had no trouble getting
> those amps and HU's to pass a signal (obviously I don't blast it).
>
> So from my experience, as long as you get a 12VDC adaptor with at least 1000
> mA, that should be sufficient to test (see whether it works or not) any 12
> volt car audio device.

Yeah, a full amp (ampere, not amplifier) should be sufficient for a simple bench
tester. If you need more, look into a 10-15A unit typically sold for CB base
station use.

[Captain_Howdy]

Being you just out right sucks.

In article >, "MOSFET"
> wrote:
>> From your description, the OP may think any little 300mA wall wart will
>do...
>> that'll barely be enough power to start up the deck, let alone the amp.
>
>Good point. The idle current of some amps may exceed many small AC
>adaptors.
>
>I use an AC adaptor rated for 1100 mA as my "bench" power supply and it has
>been able to power up any amp or HU. And I have had no trouble getting
>those amps and HU's to pass a signal (obviously I don't blast it).
>
>So from my experience, as long as you get a 12VDC adaptor with at least 1000
>mA, that should be sufficient to test (see whether it works or not) any 12
>volt car audio device.
>
>MOSFET
>
>

[GregS]

In article >, "MOSFET" > wrote:
>I guess I was thinking about how you define "test". Obviously, if you want
>to test the limits of an amplifier, you will need a hefty, expensive bench
>power supply.
>
>I was thinking more in terms of "does it turn on or not", in which case a
>more simple approach could be used.
>

That cheap supply could have its benefits too.
I would want at least 10-15 amp and with meters and adjustable
voltage. The really nice thing is adjustable current limiting. If
your playing around replacing parts, a current limit is great.
i use current limiting when working on home amps. A light bulb.

greg

>
>"JimJ[VT]" > wrote in message
...
>>
>> Astron builds, IMHO, some of the best linear 12VDC power supplies out
>> there.
>>
>> But a good 100A constant supply won't be cheap.
>>
>>
>> --
>> JimJ[VT]
>
>

[Chad Wahls]

I use 3 supplies.

The first is a bipolar 24V adjustable voltage/currnet (0-4A) supply. So I
can do very low current testing on the power supply AND go into bipolar mode
to power up the amp without the internal switcher.

The second is an acopian lab grade 22A supply

The third is a sky's the limit (limited to 200A by me) 6 golf cart batteries
and a solar/pulse charger for testing the big stuff and putting stress on
it.

I have a 4th supply but it doesn't count for car audio BUT it's 0-600V, 0-
(-150)V 6.3V, 12.6V, 0-120VAC. Guess what I use it for? :)

I can't stress the importance of a bipolar supply if you want to tinker with
amps.

Chad

"GregS" > wrote in message
...
> In article >, "MOSFET"
> > wrote:
>>I guess I was thinking about how you define "test". Obviously, if you
>>want
>>to test the limits of an amplifier, you will need a hefty, expensive bench
>>power supply.
>>
>>I was thinking more in terms of "does it turn on or not", in which case a
>>more simple approach could be used.
>>
>
> That cheap supply could have its benefits too.
> I would want at least 10-15 amp and with meters and adjustable
> voltage. The really nice thing is adjustable current limiting. If
> your playing around replacing parts, a current limit is great.
> i use current limiting when working on home amps. A light bulb.
>
> greg
>
>>
>>"JimJ[VT]" > wrote in message
...
>>>
>>> Astron builds, IMHO, some of the best linear 12VDC power supplies out
>>> there.
>>>
>>> But a good 100A constant supply won't be cheap.
>>>
>>>
>>> --
>>> JimJ[VT]
>>
>>

[GregS]

In article >, "Chad Wahls" > wrote:
>I use 3 supplies.
>
>The first is a bipolar 24V adjustable voltage/currnet (0-4A) supply. So I
>can do very low current testing on the power supply AND go into bipolar mode
>to power up the amp without the internal switcher.

Thats a bit more than I get into right now. Sounds like a good idea if you
are really doing a lot of amps. I would rather not do car amps though.
I have made suggestions to perhaps make some manufacturers consider converting
their car voltage switchers into 120 VAC switchers and use the same amps
fopr home or mobile installations.

greg

[Chad Wahls]

It don't work that way, sure would be nice though :)

A lot of Ham Radio places sell great power supplies that are switchers and
high ish current. Shall I send you some links?

Chad

"GregS" > wrote in message
...
> In article >, "Chad Wahls" >
> wrote:
>>I use 3 supplies.
>>
>>The first is a bipolar 24V adjustable voltage/currnet (0-4A) supply. So I
>>can do very low current testing on the power supply AND go into bipolar
>>mode
>>to power up the amp without the internal switcher.
>
> Thats a bit more than I get into right now. Sounds like a good idea if you
> are really doing a lot of amps. I would rather not do car amps though.
> I have made suggestions to perhaps make some manufacturers consider
> converting
> their car voltage switchers into 120 VAC switchers and use the same amps
> fopr home or mobile installations.
>
> greg

[MOSFET]

> (-150)V 6.3V, 12.6V, 0-120VAC. Guess what I use it for? :)
>
Your own home-made electric-chair? I don't know, what.

MOSFET

[Chad Wahls]

"MOSFET" > wrote in message
m...
>
>> (-150)V 6.3V, 12.6V, 0-120VAC. Guess what I use it for? :)
>>
> Your own home-made electric-chair? I don't know, what.
>
> MOSFET
>
>

Prototyping and repairing tube amps :)

Plate voltage, bias voltage (the negative number) and filament voltage. The
little variac inside gets used rarely in lieu of the big stancor on the
bench.

Chad

[MOSFET]

> Plate voltage, bias voltage (the negative number) and filament voltage.
The
> little variac inside gets used rarely in lieu of the big stancor on the
> bench.
>
> Chad

OK, thanks. That's what I get for asking. I don't know what a "variac" and
a "stancor" are. But I appreciate the answer. ;)

MOSFET

[Matt Ion]

MOSFET wrote:
>>Plate voltage, bias voltage (the negative number) and filament voltage.
>
> The
>
>>little variac inside gets used rarely in lieu of the big stancor on the
>>bench.
>>
>>Chad
>
>
> OK, thanks. That's what I get for asking. I don't know what a "variac" and
> a "stancor" are. But I appreciate the answer. ;)

http://en.wikipedia.org/wiki/Variac :)

Stancor is a company that makes transformers and assorted other power-control
products: http://www.stancor.com/

[GregS]

In article <liz4h.280943$5R2.186492@pd7urf3no>, Matt Ion > wrote:
>MOSFET wrote:
>>>Plate voltage, bias voltage (the negative number) and filament voltage.
>>
>> The
>>
>>>little variac inside gets used rarely in lieu of the big stancor on the
>>>bench.
>>>
>>>Chad
>>
>>
>> OK, thanks. That's what I get for asking. I don't know what a "variac" and
>> a "stancor" are. But I appreciate the answer. ;)
>
>http://en.wikipedia.org/wiki/Variac :)
>
>Stancor is a company that makes transformers and assorted other power-control
>products: http://www.stancor.com/

Wikipedia does not come out and say what it is. A variable transformer, and
it doesn't have to be an auto transformer.

I have use of a Stancor with big voltage an current meters, and
I also installed another transformer inside to perform
the isolation trick. I can use the isolated output or the standard
autotransformer output.

greg

[Chad Wahls]

"Matt Ion" > wrote in message
news:liz4h.280943$5R2.186492@pd7urf3no...
> MOSFET wrote:
>>>Plate voltage, bias voltage (the negative number) and filament voltage.
>>
>> The
>>
>>>little variac inside gets used rarely in lieu of the big stancor on the
>>>bench.
>>>
>>>Chad
>>
>>
>> OK, thanks. That's what I get for asking. I don't know what a "variac"
>> and
>> a "stancor" are. But I appreciate the answer. ;)
>
> http://en.wikipedia.org/wiki/Variac :)
>
> Stancor is a company that makes transformers and assorted other
> power-control products: http://www.stancor.com/

My Variac is not on that site, Hmmmm, it WAS built in the 60's though! A
variac allows me to bring something up REALLY slow by adjusting the voltage
from 0V to 140V. It allows full current though (20A).

For example if an amp has blown finals I can bring it up without doing more
damage, although I prefer current limiting for this. I'm more likely to
bring it up on the variac after it's complete to make sure it's not going to
take off again. Variacs are also good for re-forming caps in tube stuff to
at least get it going to see if it's worth a re-furb. A 500V cap that's sat
for a while doesn't really like to be hit with 500V right away, it wants to
be eased into the situation.

For car stuff you really only need a variable voltage/current bipolar supply
(or two) and a 12V (13.8) that will supply enough current to do unloaded
testing or testing under light load/low power to make sure the drivers are
good. If you have an open driver circuit the amp will make a darn purdy
waveform under no load but will collapse when load is applied. The 20A
supply does good for this and even for mild burn in. Then it goes over to
the mutha of supplies for final cooking and torture to make sure I won't see
it again until someone does something stupid again.

Contrary to consumer popular belief 99.9% of all major repairs of amplifiers
are due to ignorance on the consumer's/Installer's part. RARELY do I find
failed power supplies/blown finals in amps that are "driven on Sundays by
grandmas" :) Low impedance driving and overzealous use of the loudness,
bass bost, and bass control onthe head unit at once are the primary causes.
As in "What! You mean I can't bridge this amp at 2 ohms?"

Another 2 common problems are burnt protection resistors (acting as fuses)
on the signal ground path from improper installation or loss of amplifier
ground. And the ominous cold solder joints. Most of these problems can be
sussed out in triage and the amp can be repaired and returned to the
customer on the spot as long as the bench is clear. So... Woofer boxes
don't make good mounting surfaces :)

Chad