DC Adapter question

Discussion in 'Computer Information' started by Ann-Marie, Jun 7, 2005.

  1. Ann-Marie

    Ann-Marie Guest

    Hi,
    I just moved from the UK to the US. I brought my Wireless access
    point/router with me, but I need to get a new DC adapter for it so that it
    works on the 110V supply here.

    It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA

    Every universal adapter I find that has 7.5 as an option, seems to have a
    current rating of either below, or above the 1500mA I need. They are usually
    either about 1000mA, or 1700mA etc.

    Does anyone know if this is a required rating, or if it will automatically
    only take the current required, as long as it's set to 7.5V ?

    For example, if I get the one with only 1000mA rating, will it not work? If
    I get the 1700mA one, will it be too much and blow the wireless access
    point?

    Thanks for any help,
    Daniel
    Ann-Marie, Jun 7, 2005
    #1
    1. Advertising

  2. On Tue, 07 Jun 2005 17:25:44 GMT, "Ann-Marie"
    <> wrote:

    >For example, if I get the one with only 1000mA rating, will it not work? If
    >I get the 1700mA one, will it be too much and blow the wireless access
    >point?


    the AP will take what it needs, so the rating should be at least equal
    to what you had before.

    Was the UK supply only rated 220-240V on the input and not
    multi-voltage ?

    Getting a spare for the equivalent AP (or a whole AP) off ebay would
    be another approach.

    and don't use channels >11 :)

    Phil
    --
    spamcop.net address commissioned 18/06/04
    Come on down !
    Phil Thompson, Jun 7, 2005
    #2
    1. Advertising

  3. Ann-Marie

    Kenny Guest

    Get the higher one, it will only draw the current it needs. Check that it's
    the regulated and not unregulated type and check the polarity is correct.

    --

    Kenny Cargill


    "Ann-Marie" <> wrote in message
    news:sMkpe.2181$...
    > Hi,
    > I just moved from the UK to the US. I brought my Wireless access
    > point/router with me, but I need to get a new DC adapter for it so that it
    > works on the 110V supply here.
    >
    > It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >
    > Every universal adapter I find that has 7.5 as an option, seems to have a
    > current rating of either below, or above the 1500mA I need. They are
    > usually either about 1000mA, or 1700mA etc.
    >
    > Does anyone know if this is a required rating, or if it will automatically
    > only take the current required, as long as it's set to 7.5V ?
    >
    > For example, if I get the one with only 1000mA rating, will it not work?
    > If I get the 1700mA one, will it be too much and blow the wireless access
    > point?
    >
    > Thanks for any help,
    > Daniel
    >
    Kenny, Jun 7, 2005
    #3
  4. Ann-Marie

    Ann-Marie Guest

    Thanks for the replies.
    Next problem, the only place I've found that supplies universal adapters
    with any kind of current above about 500mA seems to be some canadian place
    called mainelectronics, but their ordering/shipping seems a bit crappy.
    Other than E-bay, any ideas on other US places that I could get more of a
    range of universal adapters? I've already tried places like radioshack, but
    they're all low current.

    Thanks again
    Daniel.


    "Ann-Marie" <> wrote in message
    news:sMkpe.2181$...
    > Hi,
    > I just moved from the UK to the US. I brought my Wireless access
    > point/router with me, but I need to get a new DC adapter for it so that it
    > works on the 110V supply here.
    >
    > It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >
    > Every universal adapter I find that has 7.5 as an option, seems to have a
    > current rating of either below, or above the 1500mA I need. They are
    > usually either about 1000mA, or 1700mA etc.
    >
    > Does anyone know if this is a required rating, or if it will automatically
    > only take the current required, as long as it's set to 7.5V ?
    >
    > For example, if I get the one with only 1000mA rating, will it not work?
    > If I get the 1700mA one, will it be too much and blow the wireless access
    > point?
    >
    > Thanks for any help,
    > Daniel
    >
    Ann-Marie, Jun 7, 2005
    #4
  5. "Ann-Marie" <> wrote:
    >Hi,
    >I just moved from the UK to the US. I brought my Wireless access
    >point/router with me, but I need to get a new DC adapter for it so that it
    >works on the 110V supply here.
    >
    >It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA


    The 7.5 VDC may (and may not, but we don't know) be important, so
    you'd best stick with something very close to that.

    The 1500mA is a minimum. Which means that the unit you describe below
    as 1700mA is just fine. The only catch with the current is that if
    it says some specific voltage at a specific current, as the actual current
    drawn goes down the actual voltage delivered will go up. Hence you don't
    want to use something able to supply twice the required current simply
    because it will be so under loaded that the voltage will be significantly
    higher than what it would be with a full load.

    However, as noted, the voltage doesn't always make any real difference
    either! Lots of units are powered with "switching" power supplies, and
    the voltage chosen is merely a convenient one. "Convenient" may be the
    best deal they can get on purchasing bulk orders, or may be related to
    a size that is commonly available.

    One example that has been discussed in detail in this newsgroup is the
    power supply for Linksys WRT54G routers. They come with a 12 VDC 1A
    supply. The unit will work off a supply of less than 5 volts to more
    than 20 volts though. The actual power used stays about the same, so
    as the voltage goes down the current goes up. Using a 6 VDC supply
    it would be a good idea to have one rated at 2 Amps. An 18 VDC supply
    would probably do fine if rated at 750 mA.

    As Jeff Liebermann originally pointed out, with the WRT54G the upper
    voltage is probably limited by when the capacitors blow up (literally).

    >Every universal adapter I find that has 7.5 as an option, seems to have a
    >current rating of either below, or above the 1500mA I need. They are usually
    >either about 1000mA, or 1700mA etc.


    The 1700 mA unit is perfect.

    >Does anyone know if this is a required rating, or if it will automatically
    >only take the current required, as long as it's set to 7.5V ?
    >
    >For example, if I get the one with only 1000mA rating, will it not work? If
    >I get the 1700mA one, will it be too much and blow the wireless access
    >point?


    The 1000 mA unit would almost certainly work. The question merely how
    long before it failed. Not if, just how long. At that difference in
    rated current, it might fail within minutes. It might take months.
    You'll have the 1700 mA one stuffed in a box on a shelf, just in case,
    long after the device it powers has been tossed into the trash.

    --
    Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
    Ukpeagvik (Barrow, Alaska)
    Floyd L. Davidson, Jun 7, 2005
    #5
  6. Ann-Marie

    Kenny Guest

    Another solution is to get a 110V to 240V AC transformer, then you can use
    your existing adapter.

    --

    Kenny Cargill


    "Ann-Marie" <> wrote in message
    news:WDlpe.2193$...
    > Thanks for the replies.
    > Next problem, the only place I've found that supplies universal adapters
    > with any kind of current above about 500mA seems to be some canadian place
    > called mainelectronics, but their ordering/shipping seems a bit crappy.
    > Other than E-bay, any ideas on other US places that I could get more of a
    > range of universal adapters? I've already tried places like radioshack,
    > but they're all low current.
    >
    > Thanks again
    > Daniel.
    >
    >
    > "Ann-Marie" <> wrote in message
    > news:sMkpe.2181$...
    >> Hi,
    >> I just moved from the UK to the US. I brought my Wireless access
    >> point/router with me, but I need to get a new DC adapter for it so that
    >> it works on the 110V supply here.
    >>
    >> It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >>
    >> Every universal adapter I find that has 7.5 as an option, seems to have a
    >> current rating of either below, or above the 1500mA I need. They are
    >> usually either about 1000mA, or 1700mA etc.
    >>
    >> Does anyone know if this is a required rating, or if it will
    >> automatically only take the current required, as long as it's set to 7.5V
    >> ?
    >>
    >> For example, if I get the one with only 1000mA rating, will it not work?
    >> If I get the 1700mA one, will it be too much and blow the wireless access
    >> point?
    >>
    >> Thanks for any help,
    >> Daniel
    >>

    >
    >
    Kenny, Jun 7, 2005
    #6
  7. Ann-Marie

    Phil Weldon Guest

    A power supply current rating is the maximum available current. Any
    equipment connected to it will draw no more current that the equipment
    rating. Your wireless access point/router will draw no more current than
    the rating of the wireless access point/router (which should be printed on
    the unit.)

    I suggest you check the Wireless access point/router label for the DC power
    consumption. The rating of the 220 VAC adapter you have has a rating that
    seems to me to be very high, much higher than the two 120 VAC adapters used
    by the two wireless access point/router units I own (12 VDC @ 300 MA and 12
    VDC @ 500 MA.) Your adapter supplies up to 11.5 Watts, as compared to 3.6
    Watts and 6 Watts for the two I have.

    One thing to consider is the flood of very inexpensive wireless access
    point/router units in stores like CompUSA and Office Depot. If you are
    willing to wait for a mail-in-rebate, the price can be as low as $8 US for a
    802.11g Motorola wireless access point/router (my $8 US Motorola is Model
    WR850G.) This price is less than half the price of a 7.5 VDC @ 1500 mA
    adapter; RadioShack, for example, charges $39.95 US for a 3 to 12 VDC @ 1000
    mA multi-voltage adapter, and $34.95 for a 40 Watt 120 ACV to 220 VAC
    transformer with US type AC plug and UK/European AC socket.)

    Phil Weldon

    "Ann-Marie" <> wrote in message
    news:sMkpe.2181$...
    > Hi,
    > I just moved from the UK to the US. I brought my Wireless access
    > point/router with me, but I need to get a new DC adapter for it so that it
    > works on the 110V supply here.
    >
    > It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >
    > Every universal adapter I find that has 7.5 as an option, seems to have a
    > current rating of either below, or above the 1500mA I need. They are
    > usually either about 1000mA, or 1700mA etc.
    >
    > Does anyone know if this is a required rating, or if it will automatically
    > only take the current required, as long as it's set to 7.5V ?
    >
    > For example, if I get the one with only 1000mA rating, will it not work?
    > If I get the 1700mA one, will it be too much and blow the wireless access
    > point?
    >
    > Thanks for any help,
    > Daniel
    >
    Phil Weldon, Jun 7, 2005
    #7
  8. Ann-Marie

    Phil Weldon Guest

    Sorry, I left out the POINT of checking the power requirement level on the
    wireless access point/router. You need only get an AC adapter with the
    correct voltage and sufficient current rating to meed the requirements on
    the label, and not the current rating on your 220 VAC adapter. A lower
    current adapter will be much easier to find, and much cheaper.

    Phil Weldon

    "Phil Weldon" <> wrote in message
    news:Clnpe.676$...
    >A power supply current rating is the maximum available current. Any
    >equipment connected to it will draw no more current that the equipment
    >rating. Your wireless access point/router ....
    Phil Weldon, Jun 7, 2005
    #8
  9. Ann-Marie

    Peter Pan Guest

    Depending on who made it, I just get the power supplies from the
    manufacturer site. Some even have dual voltage supplies for use both here
    (at 120) and elsewhere at 240.

    Ann-Marie wrote:
    > Thanks for the replies.
    > Next problem, the only place I've found that supplies universal
    > adapters with any kind of current above about 500mA seems to be some
    > canadian place called mainelectronics, but their ordering/shipping
    > seems a bit crappy. Other than E-bay, any ideas on other US places
    > that I could get more of a range of universal adapters? I've already
    > tried places like radioshack, but they're all low current.
    >
    > Thanks again
    > Daniel.
    >
    >
    > "Ann-Marie" <> wrote in message
    > news:sMkpe.2181$...
    >> Hi,
    >> I just moved from the UK to the US. I brought my Wireless access
    >> point/router with me, but I need to get a new DC adapter for it so
    >> that it works on the 110V supply here.
    >>
    >> It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >>
    >> Every universal adapter I find that has 7.5 as an option, seems to
    >> have a current rating of either below, or above the 1500mA I need.
    >> They are usually either about 1000mA, or 1700mA etc.
    >>
    >> Does anyone know if this is a required rating, or if it will
    >> automatically only take the current required, as long as it's set to
    >> 7.5V ? For example, if I get the one with only 1000mA rating, will it not
    >> work? If I get the 1700mA one, will it be too much and blow the
    >> wireless access point?
    >>
    >> Thanks for any help,
    >> Daniel
    Peter Pan, Jun 7, 2005
    #9
  10. Ann-Marie

    Will-Lee-Cue Guest

    This place has them.

    http://www.altex.com/

    William Lee



    "Ann-Marie" <> wrote in message
    news:WDlpe.2193$...
    > Thanks for the replies.
    > Next problem, the only place I've found that supplies universal adapters
    > with any kind of current above about 500mA seems to be some canadian place
    > called mainelectronics, but their ordering/shipping seems a bit crappy.
    > Other than E-bay, any ideas on other US places that I could get more of a
    > range of universal adapters? I've already tried places like radioshack,
    > but they're all low current.
    >
    > Thanks again
    > Daniel.
    >
    >
    > "Ann-Marie" <> wrote in message
    > news:sMkpe.2181$...
    >> Hi,
    >> I just moved from the UK to the US. I brought my Wireless access
    >> point/router with me, but I need to get a new DC adapter for it so that
    >> it works on the 110V supply here.
    >>
    >> It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >>
    >> Every universal adapter I find that has 7.5 as an option, seems to have a
    >> current rating of either below, or above the 1500mA I need. They are
    >> usually either about 1000mA, or 1700mA etc.
    >>
    >> Does anyone know if this is a required rating, or if it will
    >> automatically only take the current required, as long as it's set to 7.5V
    >> ?
    >>
    >> For example, if I get the one with only 1000mA rating, will it not work?
    >> If I get the 1700mA one, will it be too much and blow the wireless access
    >> point?
    >>
    >> Thanks for any help,
    >> Daniel
    >>

    >
    >
    Will-Lee-Cue, Jun 7, 2005
    #10
  11. On Tue, 07 Jun 2005 17:25:44 GMT, "Ann-Marie"
    <> wrote:

    >I just moved from the UK to the US. I brought my Wireless access
    >point/router with me, but I need to get a new DC adapter for it so that it
    >works on the 110V supply here.


    You could just get a 117VAC to 220VAC stepup transformer. You
    probably have other devices that run off 220VAC.
    http://www.starkelectronic.com/st500.htm

    >It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA


    It would also be helpful if you would disclose the maker and model
    number of your wireless access point and router. The problem is that
    the sticker label is NOT what the unit draws. The voltage is probably
    correct, but the current drain of the router may be considerably less
    than the current rating on the transformer. It would be easy enough
    to measure the current drain of the router with an amps-guesser and
    size the power supply accordingly.

    >Every universal adapter I find that has 7.5 as an option, seems to have a
    >current rating of either below, or above the 1500mA I need. They are usually
    >either about 1000mA, or 1700mA etc.


    I don't like the universal adapters (the ones with a switch from zero
    volts to more than enough to blow up anything if you goof). I've
    confiscated those from customers before they blow up their laptops and
    electonic devices. Actually, the usual problem is not the voltage but
    the polarity of the connector. Getting it backwards is all too easy.
    About 3-4 times per year, someone drifts into my shop with a blown
    something and a universal replacement adapter. Not recommended unless
    you glue the switch and plug adapter in place.

    >Does anyone know if this is a required rating, or if it will automatically
    >only take the current required, as long as it's set to 7.5V ?


    More current is always a safer bet. If it says 1500ma on the adapter,
    then 1500ma or larger will do just fine.

    >For example, if I get the one with only 1000mA rating, will it not work?


    1000ma might work if the access point draws less power. The typical
    access point (no router or switch section) burns about 8 watts. At
    7.5VDC that's about 1000ma. However, without measuring the current
    drain, this is pure speculation on my part.

    Another problem is that if it actually does work at 1000ma, it might
    be running at near its maximum rating. That's a problem because the
    limit is set by iron core saturation which results in gross
    inefficiency, heating, and a small fire if left alone. This is
    another reason why underrated power supplies are a bad idea.

    >If
    >I get the 1700mA one, will it be too much and blow the wireless access
    >point?


    No. Only excessive voltage or reverse polarity can do any damage.
    The access point will draw only whatever it decides to draw in
    current. Having excess current capability will have no effect on how
    much the access point draws.

    >Thanks for any help,
    >Daniel


    Reminder... Since you're now in the colonies, kindly reset your
    firmware to US regulations and standards. If it's not possible, see
    if there is a replacement flash firmware from the unspecified
    manufactory web pile.


    --
    # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
    # 831.336.2558 voice http://www.LearnByDestroying.com
    # -cruz.ca.us
    # AE6KS
    Jeff Liebermann, Jun 8, 2005
    #11
  12. Ann-Marie

    Ann-Marie Guest

    Hi,
    It's a D-link DSL-604+, it has built in modem, router, switch, WAP, so I
    guess thats why it takes quite a lot of power.

    I looked in the manual, and it says the power consumption is 12W max, which,
    I worked out to be 1.6A at 7.5V - would that be right?

    If I get this 1700mA adapter, and run it at 7.5V, is there a risk of fire or
    anything? or is that only if I got a lower rated one.


    "Jeff Liebermann" <-cruz.ca.us> wrote in message
    news:...
    > On Tue, 07 Jun 2005 17:25:44 GMT, "Ann-Marie"
    > <> wrote:
    >
    >>I just moved from the UK to the US. I brought my Wireless access
    >>point/router with me, but I need to get a new DC adapter for it so that it
    >>works on the 110V supply here.

    >
    > You could just get a 117VAC to 220VAC stepup transformer. You
    > probably have other devices that run off 220VAC.
    > http://www.starkelectronic.com/st500.htm
    >
    >>It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA

    >
    > It would also be helpful if you would disclose the maker and model
    > number of your wireless access point and router. The problem is that
    > the sticker label is NOT what the unit draws. The voltage is probably
    > correct, but the current drain of the router may be considerably less
    > than the current rating on the transformer. It would be easy enough
    > to measure the current drain of the router with an amps-guesser and
    > size the power supply accordingly.
    >
    >>Every universal adapter I find that has 7.5 as an option, seems to have a
    >>current rating of either below, or above the 1500mA I need. They are
    >>usually
    >>either about 1000mA, or 1700mA etc.

    >
    > I don't like the universal adapters (the ones with a switch from zero
    > volts to more than enough to blow up anything if you goof). I've
    > confiscated those from customers before they blow up their laptops and
    > electonic devices. Actually, the usual problem is not the voltage but
    > the polarity of the connector. Getting it backwards is all too easy.
    > About 3-4 times per year, someone drifts into my shop with a blown
    > something and a universal replacement adapter. Not recommended unless
    > you glue the switch and plug adapter in place.
    >
    >>Does anyone know if this is a required rating, or if it will automatically
    >>only take the current required, as long as it's set to 7.5V ?

    >
    > More current is always a safer bet. If it says 1500ma on the adapter,
    > then 1500ma or larger will do just fine.
    >
    >>For example, if I get the one with only 1000mA rating, will it not work?

    >
    > 1000ma might work if the access point draws less power. The typical
    > access point (no router or switch section) burns about 8 watts. At
    > 7.5VDC that's about 1000ma. However, without measuring the current
    > drain, this is pure speculation on my part.
    >
    > Another problem is that if it actually does work at 1000ma, it might
    > be running at near its maximum rating. That's a problem because the
    > limit is set by iron core saturation which results in gross
    > inefficiency, heating, and a small fire if left alone. This is
    > another reason why underrated power supplies are a bad idea.
    >
    >>If
    >>I get the 1700mA one, will it be too much and blow the wireless access
    >>point?

    >
    > No. Only excessive voltage or reverse polarity can do any damage.
    > The access point will draw only whatever it decides to draw in
    > current. Having excess current capability will have no effect on how
    > much the access point draws.
    >
    >>Thanks for any help,
    >>Daniel

    >
    > Reminder... Since you're now in the colonies, kindly reset your
    > firmware to US regulations and standards. If it's not possible, see
    > if there is a replacement flash firmware from the unspecified
    > manufactory web pile.
    >
    >
    > --
    > # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
    > # 831.336.2558 voice http://www.LearnByDestroying.com
    > # -cruz.ca.us
    > # AE6KS
    Ann-Marie, Jun 8, 2005
    #12
  13. On Wed, 08 Jun 2005 00:12:09 GMT, "Ann-Marie"
    <> wrote:

    >It's a D-link DSL-604+, it has built in modem, router, switch, WAP, so I
    >guess thats why it takes quite a lot of power.


    True. The DLink DSL-604+ is not sold in the US. It does DMT ADSL so
    it will probably work with most US DSL ISP's. Check with your local
    DSL ISP to be sure.

    >I looked in the manual, and it says the power consumption is 12W max, which,
    >I worked out to be 1.6A at 7.5V - would that be right?


    That will save me the effort of looking up the specs. Yep, 1.6A is
    correct.
    12 watts / 7.5V = 1.6A

    >If I get this 1700mA adapter, and run it at 7.5V, is there a risk of fire or
    >anything? or is that only if I got a lower rated one.


    Nope. The rated current is where it will run forever without
    overheating difficulties. Only the lower current drain adapters will
    cause problems. However, just to be sure, check if the power adapter
    gets unusually warm when you first plug it in.


    --
    # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
    # 831.336.2558 voice http://www.LearnByDestroying.com
    # -cruz.ca.us
    # AE6KS
    Jeff Liebermann, Jun 8, 2005
    #13
  14. Ann-Marie

    me Guest

    "Kenny" <> wrote in message
    news:d84v3a$4t2$...
    > Another solution is to get a 110V to 240V AC transformer, then you can use
    > your existing adapter.
    >
    > -- Yup,i'm with Kenny on that one,thats what i did,works great.
    me, Jun 8, 2005
    #14
  15. Ann-Marie

    Robert Baer Guest

    Ann-Marie wrote:

    > Hi,
    > I just moved from the UK to the US. I brought my Wireless access
    > point/router with me, but I need to get a new DC adapter for it so that it
    > works on the 110V supply here.
    >
    > It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA
    >
    > Every universal adapter I find that has 7.5 as an option, seems to have a
    > current rating of either below, or above the 1500mA I need. They are usually
    > either about 1000mA, or 1700mA etc.
    >
    > Does anyone know if this is a required rating, or if it will automatically
    > only take the current required, as long as it's set to 7.5V ?
    >
    > For example, if I get the one with only 1000mA rating, will it not work? If
    > I get the 1700mA one, will it be too much and blow the wireless access
    > point?
    >
    > Thanks for any help,
    > Daniel
    >
    >

    A supply could be rated at 1000A and work no differntly than one
    rated at 1700mA.
    It is the *voltage* rating that one must be cautious about.
    Now, if there was a way you could measure the actual current drawn by
    the unit, i would expect that it would draw less than 1500mA - perhaps
    as low or lower than 1000mA.
    If that were true, then you could use the less expensive supply.
    However, in your case, it is wiser to use a supply rated at or more
    than 1500mA.
    Robert Baer, Jun 8, 2005
    #15
  16. Robert Baer, <> wrote:


    > A supply could be rated at 1000A and work no differntly than one
    > rated at 1700mA.


    BWAHAHAHAHAHAAHAHAHAHAHAHAAH! You fucking moron.

    > the actual current drawn


    There's your contradiction, you fuckwitted ****.
    Infected puffer fish snot, Jun 8, 2005
    #16
  17. Robert Baer <> wrote:
    > A supply could be rated at 1000A and work no differntly than
    >one rated at 1700mA.
    > It is the *voltage* rating that one must be cautious about.


    Almost, but not quite. If a DC supply is significantly under loaded,
    the voltage will rise. How much depends greatly on the design chosen.

    For that reason it is probably not a good idea to use a supply
    rated significantly higher than the original supply was rated
    for... *if* the voltage actually makes any difference at all.

    (But if, as is true with many wifi units, the onboard supply is
    actually a switching power supply, which is basically
    insensitive to input voltage, it simply won't make any
    difference at all.)

    > Now, if there was a way you could measure the actual current
    >drawn by the unit, i would expect that it would draw less than
    >1500mA - perhaps as low or lower than 1000mA.
    >
    > If that were true, then you could use the less expensive supply.


    Bad idea. The supply has to be able to provide current at
    *peak* usage. Trying to measure that can be very difficult, if
    not impossible for most people. With a wireless radio, for example,
    the peaks happen when the unit is transmitting and may be for very
    short bursts. If you simply measure the current while the unit
    is idle, what you measure is a totally misleading value.

    > However, in your case, it is wiser to use a supply rated at
    >or more than 1500mA.


    Ah, you got that one pegged.

    --
    Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
    Ukpeagvik (Barrow, Alaska)
    Floyd L. Davidson, Jun 8, 2005
    #17
  18. Ann-Marie

    Not Me Guest

    "Kenny" <> wrote in message
    news:d84v3a$4t2$...
    | Another solution is to get a 110V to 240V AC transformer, then you can use
    | your existing adapter.


    Transformers are recipical devices so a US adaptor (240 to 110) can supply
    240 from 110 by reversing the connections just make sure you have a
    transformer and not a ballast reduction. In this case likely won't hurt
    anything it just won't work.
    Not Me, Jun 8, 2005
    #18
  19. Ann-Marie

    JANA Guest

    The router will draw the current that is correct. You need to match the
    voltage to within about 1 Volt. The rating of the adaptor is the maximum
    safe load it can handle. You can use the 1700 ma one, as long as the voltage
    is correct.

    If you were to read up on ohm's law and understand it, you would understand
    the answer to this.

    A simple explanation, is that your AC outlet in the average home (In North
    America) can supply 15 Amps at 120 Volts. Very few of your devices use more
    than 1 or 2 Amps. The only exceptions are the air conditioner, toaster,
    microwave oven, and the electric kettle, just to mention a few.

    --

    JANA
    _____


    "Ann-Marie" <> wrote in message
    news:sMkpe.2181$...
    Hi,
    I just moved from the UK to the US. I brought my Wireless access
    point/router with me, but I need to get a new DC adapter for it so that it
    works on the 110V supply here.

    It says on my UK adapter that the output is: 7.5V DC 1500mA 11.25VA

    Every universal adapter I find that has 7.5 as an option, seems to have a
    current rating of either below, or above the 1500mA I need. They are usually
    either about 1000mA, or 1700mA etc.

    Does anyone know if this is a required rating, or if it will automatically
    only take the current required, as long as it's set to 7.5V ?

    For example, if I get the one with only 1000mA rating, will it not work? If
    I get the 1700mA one, will it be too much and blow the wireless access
    point?

    Thanks for any help,
    Daniel
    JANA, Jun 8, 2005
    #19
  20. Floyd L. Davidson wrote:

    > Robert Baer <> wrote:
    >
    >> A supply could be rated at 1000A and work no differntly than
    >>one rated at 1700mA.
    >> It is the *voltage* rating that one must be cautious about.

    >
    >
    > Almost, but not quite. If a DC supply is significantly under loaded,
    > the voltage will rise.


    That's true if it's unregulated but the voltage change with a regulated
    supply is negligible.

    > How much depends greatly on the design chosen.
    >
    > For that reason it is probably not a good idea to use a supply
    > rated significantly higher than the original supply was rated
    > for... *if* the voltage actually makes any difference at all.
    >
    > (But if, as is true with many wifi units, the onboard supply is
    > actually a switching power supply, which is basically
    > insensitive to input voltage, it simply won't make any
    > difference at all.)
    >
    >
    >> Now, if there was a way you could measure the actual current
    >>drawn by the unit, i would expect that it would draw less than
    >>1500mA - perhaps as low or lower than 1000mA.
    >>
    >> If that were true, then you could use the less expensive supply.

    >
    >
    > Bad idea. The supply has to be able to provide current at
    > *peak* usage. Trying to measure that can be very difficult, if
    > not impossible for most people. With a wireless radio, for example,
    > the peaks happen when the unit is transmitting and may be for very
    > short bursts. If you simply measure the current while the unit
    > is idle, what you measure is a totally misleading value.
    >
    >
    >> However, in your case, it is wiser to use a supply rated at
    >>or more than 1500mA.

    >
    >
    > Ah, you got that one pegged.
    >
    David Maynard, Jun 8, 2005
    #20
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