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Re: where can I find a universal *linear* laptop power supply?

From mike <spamme9@gmail.com>
Newsgroups comp.sys.laptops
Subject Re: where can I find a universal *linear* laptop power supply?
Date 2012-01-27 01:44 -0800
Organization A noiseless patient Spider
Message-ID <jftrov$ljc$1@dont-email.me> (permalink)
References <jfs0hr$evo$1@dont-email.me> <jfsdpf$v6q$1@dont-email.me>

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On 1/26/2012 12:42 PM, cameo wrote:
> On 1/26/2012 8:55 AM, Harry Brown wrote:
>> Looking for a reasonable cost, universal linear (NOT switching) laptop
>> power supply. Where might I find one?
>
> That reminds me: what is really the difference between the two and what
> is being "switched" and why?
>
A linear power supply needs several things.
A big/heavy transformer that runs at 50/60 Hz. line frequency.
A big heat sink and or fan to dissipate the heat.
You have to adjust the voltage so that at low line and maximum
load, the trough voltage is higher than the output voltage by the
headroom required by the regulator transistor.  That means at high line
you dissipate significant power in the pass transistor.

The switcher uses high frequency, so the transformer and output filter
can be MUCH smaller/lighter.  The loss in the switching transistor is
way less than in a linear circuit, so you don't need the big heatsink/fan.

And since you can easily build a supply that runs from 90VAC to 260VAC,
you need only one part number for worldwide application.

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Thread

where can I find a universal *linear* laptop power supply? "Harry Brown" <harrybrown@harrybrown.net> - 2012-01-26 11:55 -0500
  Re: where can I find a universal *linear* laptop power supply? mike <spamme9@gmail.com> - 2012-01-26 10:05 -0800
    Re: where can I find a universal *linear* laptop power supply? "Harry Brown" <harrybrown@harrybrown.net> - 2012-01-27 00:54 -0500
      Re: where can I find a universal *linear* laptop power supply? AaronJ <12465no-mail@no-mail.com> - 2012-01-27 00:55 -0700
      Re: where can I find a universal *linear* laptop power supply? mike <spamme9@gmail.com> - 2012-01-27 02:00 -0800
      Re: where can I find a universal *linear* laptop power supply? Salvador Freemanson <no@spam.com> - 2012-01-29 14:13 +0100
  Re: where can I find a universal *linear* laptop power supply? cameo <cameo@unreal.invalid> - 2012-01-26 12:42 -0800
    Re: where can I find a universal *linear* laptop power supply? mike <spamme9@gmail.com> - 2012-01-27 01:44 -0800
      Re: where can I find a universal *linear* laptop power supply? cameo <cameo@unreal.invalid> - 2012-01-27 10:12 -0800
        Re: where can I find a universal *linear* laptop power supply? mike <spamme9@gmail.com> - 2012-01-27 23:00 -0800
          Re: where can I find a universal *linear* laptop power supply? "BillW50" <BillW50@aol.kom> - 2012-01-28 08:01 -0600
          Re: where can I find a universal *linear* laptop power supply? Sjouke Burry <s@b> - 2012-01-28 17:19 +0000
            Re: where can I find a universal *linear* laptop power supply? Bob_Villa <pheeh.zero@gmail.com> - 2012-01-28 10:26 -0800
          Re: where can I find a universal *linear* laptop power supply? cameo <cameo@unreal.invalid> - 2012-01-28 19:28 -0800
        Re: where can I find a universal *linear* laptop power supply? Michael Black <et472@ncf.ca> - 2012-01-28 21:13 -0500
          Re: where can I find a universal *linear* laptop power supply? AaronJ <12333465no-mail@no-mail.com> - 2012-01-28 20:40 -0700
            Re: where can I find a universal *linear* laptop power supply? Bob_Villa <pheeh.zero@gmail.com> - 2012-01-28 20:34 -0800
              Re: where can I find a universal *linear* laptop power supply? mike <spamme9@gmail.com> - 2012-01-29 00:36 -0800
              Re: where can I find a universal *linear* laptop power supply? AaronJ <12333465no-mail@no-mail.com> - 2012-01-29 10:25 -0700
            Re: where can I find a universal *linear* laptop power supply? Michael Black <et472@ncf.ca> - 2012-01-29 10:25 -0500
              Re: where can I find a universal *linear* laptop power supply? AaronJ <12333465no-mail@no-mail.com> - 2012-01-29 10:03 -0700
        Re: where can I find a universal *linear* laptop power supply? davy <davy.573q95@no.email.invalid> - 2012-01-28 04:34 -0600

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