1 amp

[Max]

If a device specifies that it requires power input of 1 amp, is it bad to
use an adaptor that supplies 2 amps?

 

[Computer Nerd Kev]

Max <max@val.morgan> wrote:

If a device specifies that it requires power input of 1 amp, is it bad to
use an adaptor that supplies 2 amps?

No, as long as it is the right Voltage and polarity. Although I should
just tell you to type it into a search engine.

--
__ __
#_ < |\| |< _#

 

[Sylvia Else]

On 23/07/2016 10:38 AM, Max wrote:

If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

Not only is it not bad, it's a good idea. Manufacturers frequently
overstate the current that their adapters can supply while maintaining
regulation.

Sylvia.

 

[Trevor Wilson]

On 23/07/2016 10:38 AM, Max wrote:

If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[Phil Allison]

Trevor Wilson wrote:

If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.

** Unregulated DC supplies are no longer available due to MEPS regulations introduced a few years ago. So only SMPS and simple AC transformer ones are left on sale.

Typical SMPSs have a current limit circuit that kicks in when the threshold current is reached - dropping the output voltage instantly - while unregulated 1 amp nominal supplies have no limiting circuit and can deliver short bursts of current several times the continuous rating by virtue of a 4,700uF filter electro.

This can make a big difference with devices that have a DC motors and /or solenoids.


..... Phil

 

[Computer Nerd Kev]

Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Phil Allison" <pallison49@gmail.com> wrote in message
Trevor Wilson wrote:

If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.

** Unregulated DC supplies are no longer available due to MEPS regulations
introduced a few years ago. So only SMPS and simple AC transformer ones
are left on sale.

Typical SMPSs have a current limit circuit that kicks in when the
threshold current is reached - dropping the output voltage instantly -
while unregulated 1 amp nominal supplies have no limiting circuit and can
deliver short bursts of current several times the continuous rating by
virtue of a 4,700uF filter electro.

This can make a big difference with devices that have a DC motors and /or
solenoids.

You could've explained that better - the old ones with iron cored
transformers have lousy regulation, so a 12V unit may even put out more than
20V off load. As you stated; the internal electro charges up to the high
level and dumps into whatever load gets connected.

That alone is a good enough reason to dump any old type and use the SMPSU
variety which usually have pretty good regulation.

No it isn't. It means that if a device is designed to use the higher surge
current capability of a transformer-based plugpack, a plugpack with a
current rating less than this surge current can be used, with a
corresponding cost saving.

The fact that the voltage output of the plugpack when the load of a relay,
motor, etc. is initially powered on may be much higher than specified is
not particularly important, because the relay or motor can be specified
to suit this condition, and in many cases it won't cause damage even if
their standard operation voltage is the same as the plugpack's stated
voltage.

Of course the one thing that is required in a device to be used
with a transformer plugpack is some sort of voltage regulator for
any circuitry which requires a regulated voltage. Because the
voltage regulator may be designed to operate with the higher than
specified voltage output of a tansformer plugpack, some devices
designed for use with transformer plugpacks may not work with switch
mode types of the same voltage rating. Similarly, devices designed
for use with switch mode plugpacks may not have internal voltage
regulating circuitry where regulated voltage is required, hence
a transformer based plugpack of the same voltage rating may not
be suitable, or may even cause damage.

For this reason, switch mode and transformer based plugpacks may not
be interchangable in some circumstances. In the above case of surge
currents being required from transformer based types, even different
models of transformer based plugpacks with the same rating may have
different characteristics which could affect operation of the powered
device when these current pulses have to be delivered. When a switch
mode type is used in this instance, it's current limiting circuitry
could well turn off the device altogether.

--
__ __
#_ < |\| |< _#

 

[Ian Field]

"Phil Allison" <pallison49@gmail.com> wrote in message
news:bc51314b-5ceb-405d-b271-678c41a01f29@googlegroups.com...

Trevor Wilson wrote:


If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.


** Unregulated DC supplies are no longer available due to MEPS regulations
introduced a few years ago. So only SMPS and simple AC transformer ones
are left on sale.

Typical SMPSs have a current limit circuit that kicks in when the
threshold current is reached - dropping the output voltage instantly -
while unregulated 1 amp nominal supplies have no limiting circuit and can
deliver short bursts of current several times the continuous rating by
virtue of a 4,700uF filter electro.

This can make a big difference with devices that have a DC motors and /or
solenoids.

You could've explained that better - the old ones with iron cored
transformers have lousy regulation, so a 12V unit may even put out more than
20V off load. As you stated; the internal electro charges up to the high
level and dumps into whatever load gets connected.

That alone is a good enough reason to dump any old type and use the SMPSU
variety which usually have pretty good regulation.

 

[Phil Allison]

Computer Nerd Kev wrote:

Ian Field

"Phil Allison" wrote in message
Trevor Wilson wrote:

If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.

** Unregulated DC supplies are no longer available due to MEPS regulations
introduced a few years ago. So only SMPS and simple AC transformer ones
are left on sale.

Typical SMPSs have a current limit circuit that kicks in when the
threshold current is reached - dropping the output voltage instantly -
while unregulated 1 amp nominal supplies have no limiting circuit and can
deliver short bursts of current several times the continuous rating by
virtue of a 4,700uF filter electro.

This can make a big difference with devices that have a DC motors and /or
solenoids.

You could've explained that better - the old ones with iron cored
transformers have lousy regulation, so a 12V unit may even put out more than
20V off load. As you stated; the internal electro charges up to the high
level and dumps into whatever load gets connected.

That alone is a good enough reason to dump any old type and use the SMPSU
variety which usually have pretty good regulation.

No it isn't. It means that if a device is designed to use the higher surge
current capability of a transformer-based plugpack, a plugpack with a
current rating less than this surge current can be used, with a
corresponding cost saving.

The fact that the voltage output of the plugpack when the load of a relay,
motor, etc. is initially powered on may be much higher than specified is
not particularly important, because the relay or motor can be specified
to suit this condition, and in many cases it won't cause damage even if
their standard operation voltage is the same as the plugpack's stated
voltage.

Of course the one thing that is required in a device to be used
with a transformer plugpack is some sort of voltage regulator for
any circuitry which requires a regulated voltage. Because the
voltage regulator may be designed to operate with the higher than
specified voltage output of a tansformer plugpack, some devices
designed for use with transformer plugpacks may not work with switch
mode types of the same voltage rating. Similarly, devices designed
for use with switch mode plugpacks may not have internal voltage
regulating circuitry where regulated voltage is required, hence
a transformer based plugpack of the same voltage rating may not
be suitable, or may even cause damage.

For this reason, switch mode and transformer based plugpacks may not
be interchangable in some circumstances. In the above case of surge
currents being required from transformer based types, even different
models of transformer based plugpacks with the same rating may have
different characteristics which could affect operation of the powered
device when these current pulses have to be delivered. When a switch
mode type is used in this instance, it's current limiting circuitry
could well turn off the device altogether.

** Sounds like Kev has *seen* some of the problems that arise when playing musical chairs with DC plug paks.

Equipment makers have long warned owners to use ONLY the supplied DC adaptor as using other types can result in malfunction and/or damage. This warning needs to be taken seriously.

At one time, stores like DSE and even Woollies were selling "universal" DC adaptors with switchable voltages and swappable polarity. Since not many devices are designed to tolerate reverse or overvoltage supplies these units could destroy nearly any device you tried them with - and Murphy's Law says that sooner or later they will.

Recently, I saw a SMPS DC adaptor that was being marketed to guitarists for use with effects pedals that usually run on a 9V battery. The unit claimed to have very low noise and so was especially suited to the job. Only problem was that it carried a 3 amp current rating.


..... Phil

 

[Chris Jones]

On 23/07/2016 16:25, Phil Allison wrote:

Trevor Wilson wrote:


If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.


** Unregulated DC supplies are no longer available due to MEPS regulations introduced a few years ago. So only SMPS and simple AC transformer ones are left on sale.

I recently bought something (at a retail store) that came with a
DC-output plugpack that by the weight of it (and the acoustic hum it
produces) must contain a 50Hz transformer. I guess the efficiency rules
are not always enforced, as I doubt the manufacturer would have
developed an extremely efficient 50Hz transformer for this low-cost product.

Sometimes I want a non-SMPS plugpack, e.g. if I don't want a y-capacitor
from my circuit to the mains, or if I don't want RFI (e.g. to power a
radio), or if I want the plug pack to be reliable for more than a couple
of years. In my experience some of the SMPS ones are quite prone to
failure whereas I can't recall a 50Hz one ever failing unless
overloaded. At least afaik the AC-output plugpacks are still allowed,
and should be the most reliable as there is no electrolytic cap being
kept too warm inside it.

 

[Computer Nerd Kev]

Chris Jones <lugnut808@spam.yahoo.com> wrote:

On 23/07/2016 16:25, Phil Allison wrote:
Trevor Wilson wrote:


If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.


** Unregulated DC supplies are no longer available due to MEPS regulations
introduced a few years ago. So only SMPS and simple AC transformer ones
are left on sale.

I recently bought something (at a retail store) that came with a
DC-output plugpack that by the weight of it (and the acoustic hum it
produces) must contain a 50Hz transformer. I guess the efficiency rules
are not always enforced, as I doubt the manufacturer would have
developed an extremely efficient 50Hz transformer for this low-cost product.

Sometimes I want a non-SMPS plugpack, e.g. if I don't want a y-capacitor
from my circuit to the mains, or if I don't want RFI (e.g. to power a
radio), or if I want the plug pack to be reliable for more than a couple
of years. In my experience some of the SMPS ones are quite prone to
failure whereas I can't recall a 50Hz one ever failing unless
overloaded. At least afaik the AC-output plugpacks are still allowed,
and should be the most reliable as there is no electrolytic cap being
kept too warm inside it.

Some of the smaller electronic components suppliers still sell transformer
DC plugpacks. Oatley Electronics and Rockby Electronics are two, with the
latter having quite a few last time I looked. Whether it's strictly legal
for them to be sold now, I'm not sure.

I collect plugpacks whenever I find them at garage sales and Op-Shops,
usually for $1 or less each. Because of this I've got a good range to
select from when I want to power a device I've built, or find a replacement
for something. They usually come from before the Switch Mode era, so most
are transformer types, and in practice I usually have a preference for the
transformer ones because one doesn't have to trust in the regulation,
current limiting, or noise characteristics.

--
__ __
#_ < |\| |< _#

 

[Ian Field]

"Phil Allison" <pallison49@gmail.com> wrote in message
news:3c32508a-d366-495f-bb17-1047060c12dd@googlegroups.com...

Computer Nerd Kev wrote:

Ian Field

"Phil Allison" wrote in message
Trevor Wilson wrote:

If a device specifies that it requires power input of 1 amp, is it
bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.

** Unregulated DC supplies are no longer available due to MEPS
regulations
introduced a few years ago. So only SMPS and simple AC transformer
ones
are left on sale.

Typical SMPSs have a current limit circuit that kicks in when the
threshold current is reached - dropping the output voltage
nstantly -
while unregulated 1 amp nominal supplies have no limiting circuit and
can
deliver short bursts of current several times the continuous rating by
virtue of a 4,700uF filter electro.

This can make a big difference with devices that have a DC motors and
/or
solenoids.

You could've explained that better - the old ones with iron cored
transformers have lousy regulation, so a 12V unit may even put out more
than
20V off load. As you stated; the internal electro charges up to the
high
level and dumps into whatever load gets connected.

That alone is a good enough reason to dump any old type and use the
SMPSU
variety which usually have pretty good regulation.

No it isn't. It means that if a device is designed to use the higher
surge
current capability of a transformer-based plugpack, a plugpack with a
current rating less than this surge current can be used, with a
corresponding cost saving.

The fact that the voltage output of the plugpack when the load of a
relay,
motor, etc. is initially powered on may be much higher than specified is
not particularly important, because the relay or motor can be specified
to suit this condition, and in many cases it won't cause damage even if
their standard operation voltage is the same as the plugpack's stated
voltage.

Of course the one thing that is required in a device to be used
with a transformer plugpack is some sort of voltage regulator for
any circuitry which requires a regulated voltage. Because the
voltage regulator may be designed to operate with the higher than
specified voltage output of a tansformer plugpack, some devices
designed for use with transformer plugpacks may not work with switch
mode types of the same voltage rating. Similarly, devices designed
for use with switch mode plugpacks may not have internal voltage
regulating circuitry where regulated voltage is required, hence
a transformer based plugpack of the same voltage rating may not
be suitable, or may even cause damage.

For this reason, switch mode and transformer based plugpacks may not
be interchangable in some circumstances. In the above case of surge
currents being required from transformer based types, even different
models of transformer based plugpacks with the same rating may have
different characteristics which could affect operation of the powered
device when these current pulses have to be delivered. When a switch
mode type is used in this instance, it's current limiting circuitry
could well turn off the device altogether.



** Sounds like Kev has *seen* some of the problems that arise when playing
musical chairs with DC plug paks.

Equipment makers have long warned owners to use ONLY the supplied DC
adaptor as using other types can result in malfunction and/or damage. This
warning needs to be taken seriously.

At one time, stores like DSE and even Woollies were selling "universal" DC
adaptors with switchable voltages and swappable polarity. Since not many
devices are designed to tolerate reverse or overvoltage supplies these
units could destroy nearly any device you tried them with - and Murphy's
Law says that sooner or later they will.

I've seen one or two that had a LM317 and switched resistor chain, those had
more or less acceptable regulation - the vast majority just have a tapped
secondary and no regulation.

 

[Phil Allison]

Computer Nerd Kev wrote:

Some of the smaller electronic components suppliers still sell transformer
DC plugpacks. Oatley Electronics and Rockby Electronics are two, with the
latter having quite a few last time I looked. Whether it's strictly legal
for them to be sold now, I'm not sure.

** There is an exemption for external power supplies from MEPS if the unit is for replacement purposes. AC transformer supplies are also exempt so manufacturers can use them and put the rectifier and filter cap inside the equipment.

Making a small, iron core transformer that complies with MEPS is sometimes possible, but few have bothered as it significantly increases the size and cost.


..... Phil

 

[Ian Field]

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
news:nn8rhm$2fp$1@gioia.aioe.org...

Chris Jones <lugnut808@spam.yahoo.com> wrote:
On 23/07/2016 16:25, Phil Allison wrote:
Trevor Wilson wrote:


If a device specifies that it requires power input of 1 amp, is it bad
to use an adaptor that supplies 2 amps?

**It SHOULD be OK, but you need to check a bunch of things first.

* Is the supply a DC or an AC one?
* Does it require a regulated or unregulated supply?
* If unregulated, then what limits are acceptable?
* If regulated, then there should be no problem.


** Unregulated DC supplies are no longer available due to MEPS
regulations
introduced a few years ago. So only SMPS and simple AC transformer ones
are left on sale.

I recently bought something (at a retail store) that came with a
DC-output plugpack that by the weight of it (and the acoustic hum it
produces) must contain a 50Hz transformer. I guess the efficiency rules
are not always enforced, as I doubt the manufacturer would have
developed an extremely efficient 50Hz transformer for this low-cost
product.

Sometimes I want a non-SMPS plugpack, e.g. if I don't want a y-capacitor
from my circuit to the mains, or if I don't want RFI (e.g. to power a
radio), or if I want the plug pack to be reliable for more than a couple
of years. In my experience some of the SMPS ones are quite prone to
failure whereas I can't recall a 50Hz one ever failing unless
overloaded. At least afaik the AC-output plugpacks are still allowed,
and should be the most reliable as there is no electrolytic cap being
kept too warm inside it.

Some of the smaller electronic components suppliers still sell transformer
DC plugpacks. Oatley Electronics and Rockby Electronics are two, with the
latter having quite a few last time I looked. Whether it's strictly legal
for them to be sold now, I'm not sure.

I collect plugpacks whenever I find them at garage sales and Op-Shops,
usually for $1 or less each. Because of this I've got a good range to
select from when I want to power a device I've built, or find a
replacement
for something. They usually come from before the Switch Mode era, so most
are transformer types,

When my collection outgrows its storage space, I sort through it and see how
many old type units have become surplus to requirements.

 

[Computer Nerd Kev]

Phil Allison <pallison49@gmail.com> wrote:

Computer Nerd Kev wrote:



Some of the smaller electronic components suppliers still sell transformer
DC plugpacks. Oatley Electronics and Rockby Electronics are two, with the
latter having quite a few last time I looked. Whether it's strictly legal
for them to be sold now, I'm not sure.



** There is an exemption for external power supplies from MEPS if the unit
is for replacement purposes. AC transformer supplies are also exempt so
manufacturers can use them and put the rectifier and filter cap inside the
equipment.

I just found this paragraph on a page of the Energy Ratings website:

"Any external power supplies imported into, or manufactured in Australia prior
to December 2008 and prior to 9th June 2011 in New Zealand, and held in stock,
may continue to be sold or used to provide replacements after this date,
however non complying products imported or manufactured after the MEPS start
date cannot be sold or supplied."
http://www.energyrating.gov.au/products/external-power-supplies/

This would exclude items that were made or imported before 2009, possibly
even if they've since been sold between suppliers within Australia.

Making a small, iron core transformer that complies with MEPS is sometimes
possible, but few have bothered as it significantly increases the size and
cost.

They're not included in the MEPS regulations, but it may be of interest that
the "Embertec" power saving double adapters which were handed out in Victoria,
and possibly other states, as part of a number of power saving initiatives,
use iron core transformers for their internal power.

How they stand efficiency wise compared to switch mode designs, I don't know,
but they appear to use the surge current ability that you mentioned earlier
in order to switch the internal latching relay, as this action would require
more than the rated transformer current even at minimum voltage. They
have three 1000uF caps next to the transformer (in fact so close that I hope
the transformer doesn't get very warm).

Warning: Needlessly detailed information follows.

The datasheet for the transfromer (model "BV302D09015") is on this webpage:
https://www.maritex.com.pl/en/power-15va/TRAFO-1VA5-2X9-Z-i-15600-c-400

Specs are: two windings, each 9V 83mA 0.75VA

The relay is a GRT508EC 1B-5VDC-D, and there's a datasheet for it out there
somewhere (I've got it saved, but I'm not sure where from).

5V 19.5R coil (x2, different coils energised for on/off), min 3.5V, min pulse
50ms.
Switching 250VAC 16A, single pole.


I collected them as people got rid of them at the same garage sales and
Op-Shops where I get the plugpacks. They defaulted after a power outage
to turning off your TV if you didn't use the remote within the last hour,
so most people got sick of them fairly quickly. The transformer, relay,
and current transformer are handy parts to get for $1, and one of the
cases came in handy too.

--
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#_ < |\| |< _#