US appliance + local power supply

[Beetle]

hello,

i have an appliance imported from the US, a small piece of computer
audio hardware. it uses a fully external 'wall wart' power supply and i
was told by the company that i will be able to use it fine locally with
an equivalent power supply. i just have a few questions, as it's a
pretty expensive piece of equipment so i don't want to damage it

the full stats of the 'wall wart' it comes with as listed on the actual
power supply are:

AC Adapter
Class 2 Transformer
INPUT: 120VAC 60Hz 12W
OUTPUT: 9VAC 1000mA

now am i right in thinking that i only need to buy a power supply that
has the same OUTPUT? or are there other things to consider.

any information greatly appreciated. thanks

 

[Phil Allison]

"Beetle"

hello,

i have an appliance imported from the US, a small piece of computer
audio hardware. it uses a fully external 'wall wart' power supply and i
was told by the company that i will be able to use it fine locally with
an equivalent power supply. i just have a few questions, as it's a
pretty expensive piece of equipment so i don't want to damage it

the full stats of the 'wall wart' it comes with as listed on the actual
power supply are:

AC Adapter
Class 2 Transformer
INPUT: 120VAC 60Hz 12W
OUTPUT: 9VAC 1000mA

now am i right in thinking that i only need to buy a power supply that
has the same OUTPUT? or are there other things to consider.

** Yes - you need a unit with 9 volts AC at 1000mA.

Plus the right connector of course.

Polarity is irrelevant .



.............. Phil

 

[Beetle]

** Yes - you need a unit with 9 volts AC at 1000mA.

Plus the right connector of course.

Polarity is irrelevant .

thanks a lot, phil.

 

[Gregory Toomey]

Phil Allison wrote:

Polarity is irrelevant .

Where did you get that idea. For most equipment connected to these small
transformers, polarity (+ve centre or -ve centre) is VERY important.

gtoomey

 

[swanny]

Phil Allison wrote:




Where did you get that idea. For most equipment connected to these small
transformers, polarity (+ve centre or -ve centre) is VERY important.

gtoomey

It's AC. This stands for 'alternating' current ...

 

[Phil Allison]

"Gregory Toomey"

Where did you get that idea. For most equipment connected to these small
transformers, polarity (+ve centre or -ve centre) is VERY important.

gtoomey

** Quote from OP : " OUTPUT: 9VAC 1000mA "

VAC stands for " Volts Alternating Current ".

One moment the polarity is centre +, next it is centre -, center +,
centre - ...........

Might have to reverse that plus a lot and often.





.............. Phil

 

[Bushy]

Bingo!

With the following disclaimer:

60 Hertz designed operating frequency may give slightly different results
when operated on the 50 Hertz frequency of the mains in good old Aus. Being
a piece of audio equipment it may be more sensitive to noise at 50 Hertz as
any filtering may have been designed to operate at 60 Hertz. This would show
up as a low frequency hum, and if present and checked with a spectrum
analyser may show some harmonic frequencies as well like 100, 150, 200,
250,,,,,,,.

I would also assume the audio equipment has it's own internal power supply
to turn the low voltage AC to either a straight DC voltage, or a spilt DC
voltage. This power supply that is part of the equipment and is generally
not user serviceable, but in all of the gear I have ever worked on I have
never seen a problem.

If you get a supply with different output ratings, then it could cause
problems.

Hope this helps,
Peter

 

[Beetle]

well, i'm having some difficulty locating a 9VAC 1000mA adapter. i've
been to a few dick smiths and a tandy and no go. i even had one guy at
dick smith first try and sell me a multi-voltage adapter that didn't
include a 9V setting, and then one that had 9V but was DC output. anyone
have any recommendations for where i might find one of these adapters?
seems like it's a kind of rare configuration. i've checked all the
adapters we have in the house and we don't have any suitable.

thanks.

 

[Phil Allison]

"Beetle"

well, i'm having some difficulty locating a 9VAC 1000mA adapter. i've
been to a few dick smiths and a tandy and no go. i even had one guy at
dick smith first try and sell me a multi-voltage adapter that didn't
include a 9V setting, and then one that had 9V but was DC output. anyone
have any recommendations for where i might find one of these adapters?
seems like it's a kind of rare configuration. i've checked all the
adapters we have in the house and we don't have any suitable.

** DSE sell the ** exact** one you need - the M 9635 for $ 24.98

http://www.dse.com.au/cgi-bin/dse.storefront/415d333e0acecc5c273fc0a87f9c06e
5/Product/View/M9653


Some of the 'staff' are not exactly your Rocket Scientist types ..... ;-)

Tell 'em the cat. number - watch things happen !!!




.............. Phil

 

[Beetle]

** DSE sell the ** exact** one you need - the M 9635 for $ 24.98

http://www.dse.com.au/cgi-bin/dse.storefront/415d333e0acecc5c273fc0a87f9c06e
5/Product/View/M9653

hey phil,

i saw that one but ignored it because it says 9.3v. i take it from your
recommendation that the extra .3 is harmless then?

thanks.

 

[Bushy]

the extra .3 is harmless then?

It will be within expected range of input voltage the circuit should have
been designed for!

Peter

 

[TonyP]

i saw that one but ignored it because it says 9.3v. i take it from your
recommendation that the extra .3 is harmless then?

If the output voltage is within 0.3V anyway, I'll be surprised. 3% would be
a good figure and depends on actual load.
I also wouldn't be surprised if your device actually runs on 5V DC and has
it's own regulator anyway.

TonyP.

 

[Chas]

well, i'm having some difficulty locating a 9VAC 1000mA adapter. i've
been to a few dick smiths and a tandy and no go. i even had one guy at
dick smith first try and sell me a multi-voltage adapter that didn't
include a 9V setting, and then one that had 9V but was DC output. anyone
have any recommendations for where i might find one of these adapters?
seems like it's a kind of rare configuration. i've checked all the
adapters we have in the house and we don't have any suitable.

thanks.

Oatley Electronics in Sydney sell a 9V 1A AC plugpack, product code PP16,
price $9. There is also a 9V 1A plugpack product code K023CP at $6
available for the Garage Door Controller Kit in this month's Silicon Chip,
but it might be the same unit at a discount as part of the kit.
http://oatleyelectronics.com/ Hope this helps.

Regards, Chas.


To Email, replace 'xxx' with tango papa golf.

 

[Beetle]

i actually found one that seems to be exactly right at jaycar:

http://tinyurl.com/5gf7h

thanks for all the replies. fingers crossed i don't blow up my $400 toy

 

[Howard Latham]

hello,

i have an appliance imported from the US, a small piece of computer
audio hardware. it uses a fully external 'wall wart' power supply and i
was told by the company that i will be able to use it fine locally with
an equivalent power supply. i just have a few questions, as it's a
pretty expensive piece of equipment so i don't want to damage it

the full stats of the 'wall wart' it comes with as listed on the actual
power supply are:

AC Adapter
Class 2 Transformer
INPUT: 120VAC 60Hz 12W
OUTPUT: 9VAC 1000mA

Its a very low chance of this , but if its a tone generator, it just might
require 60hz AC.

It wont hurt it to use it at 50hz, its frequency might be off..

 

[Beetle]

well, this is becoming really quite irritating.

the original US supply the unit came with was rated 9VAC 1A. the manual
stated that it came with a '500mA' supply, so i did some research and
found out that it should only draw what it needed, hence the 1A supply.
so i figured i'd be ok just buying a local 9VAC 1A supply. i guess not

i bought that one i listed from jaycar, and it has an interesting
sticker on the front:

WARNING: UNREGULATED
output voltage will be higher if your appliance draws less than the
rated current

so i guess if the unit only draws 500mA from this 1A supply it's going
to blow, eh? sigh. it'd have been nice if it was advertised as
'unregulated' on their website.

 

[Beetle]

for the record, the appliance itself only has '9VAC' on it. no amp
listing. it only says it 'comes with' a 500mA adapter in the manual.

 

[Phil Allison]

"Beetle"

well, this is becoming really quite irritating.

** The only irritating thing is your attitude.

the original US supply the unit came with was rated 9VAC 1A. the manual
stated that it came with a '500mA' supply, so i did some research and
found out that it should only draw what it needed, hence the 1A supply.
so i figured i'd be ok just buying a local 9VAC 1A supply. i guess not

i bought that one i listed from jaycar, and it has an interesting
sticker on the front:

WARNING: UNREGULATED
output voltage will be higher if your appliance draws less than the
rated current

so i guess if the unit only draws 500mA from this 1A supply it's going
to blow, eh? sigh. it'd have been nice if it was advertised as
'unregulated' on their website.

** ALL** AC adaptors are unregulated.

The smaller they are - the worse the regulation.

You are inventing problems.



............ Phil

 

[Beetle]

** ALL** AC adaptors are unregulated.

The smaller they are - the worse the regulation.

You are inventing problems.

if i am, it's only because i (obviously) know next to nothing about
electronics and can't afford to ruin this piece of equipment.

sorry for the bother, and thanks for your help.