240 Volt AC To 12 Volt DC

Discussion in 'Electronic Basics' started by Dave.H, Dec 7, 2007.

  1. Dave.H

    Dave.H Guest

    I was wondering if it was possible to build a power supply that steps
    the 240 Volts AC mains to 12 volt DC 200 mA. I know I could use a
    wall transformer, but that would be to bulky for my little Tunecast II
    FM Transmitter.
    Dave.H, Dec 7, 2007
    #1
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  2. Dave.H

    Tim Wescott Guest

    On Fri, 07 Dec 2007 04:09:01 -0800, Dave.H wrote:

    > I was wondering if it was possible to build a power supply that steps
    > the 240 Volts AC mains to 12 volt DC 200 mA. I know I could use a wall
    > transformer, but that would be to bulky for my little Tunecast II FM
    > Transmitter.


    You basically have the choice of using a transformer-rectifier-regulator
    supply, which will pretty much be a wall wart, or using an off-line
    switcher. In the US the wall warts have all gotten smaller because
    they're off-line switchers now -- has this not happened in the 240VAC
    countries?

    --
    Tim Wescott
    Control systems and communications consulting
    http://www.wescottdesign.com

    Need to learn how to apply control theory in your embedded system?
    "Applied Control Theory for Embedded Systems" by Tim Wescott
    Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
    Tim Wescott, Dec 7, 2007
    #2
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  3. -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA1

    Tim Wescott wrote:
    > On Fri, 07 Dec 2007 04:09:01 -0800, Dave.H wrote:
    >
    >> I was wondering if it was possible to build a power supply that steps
    >> the 240 Volts AC mains to 12 volt DC 200 mA. I know I could use a wall
    >> transformer, but that would be to bulky for my little Tunecast II FM
    >> Transmitter.

    >
    > You basically have the choice of using a transformer-rectifier-regulator
    > supply, which will pretty much be a wall wart, or using an off-line
    > switcher. In the US the wall warts have all gotten smaller because
    > they're off-line switchers now -- has this not happened in the 240VAC
    > countries?
    >


    I'd say about half of the wall warts I have in the UK are switchers. It's
    only the _really_ cheap stuff that still has a transformer in.

    My advice to the OP is to get a phone charger that outputs 9v DC - that
    little gizmo will happily run from it. They're cheap enough and nearly
    all are switchers.

    - --
    Brendan Gillatt
    brendan {at} brendangillatt {dot} co {dot} uk
    http://www.brendangillatt.co.uk
    PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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    Brendan Gillatt, Dec 7, 2007
    #3
  4. Dave.H

    Dave.H Guest

    On Dec 8, 5:12 am, Brendan Gillatt
    <> wrote:
    > -----BEGIN PGP SIGNED MESSAGE-----
    > Hash: SHA1
    >
    > Tim Wescott wrote:
    > > On Fri, 07 Dec 2007 04:09:01 -0800, Dave.H wrote:

    >
    > >> I was wondering if it was possible to build a power supply that steps
    > >> the 240 Volts AC mains to 12 volt DC 200 mA. I know I could use a wall
    > >> transformer, but that would be to bulky for my little Tunecast II FM
    > >> Transmitter.

    >
    > > You basically have the choice of using a transformer-rectifier-regulator
    > > supply, which will pretty much be a wall wart, or using an off-line
    > > switcher. In the US the wall warts have all gotten smaller because
    > > they're off-line switchers now -- has this not happened in the 240VAC
    > > countries?

    >
    > I'd say about half of the wall warts I have in the UK are switchers. It's
    > only the _really_ cheap stuff that still has a transformer in.
    >
    > My advice to the OP is to get a phone charger that outputs 9v DC - that
    > little gizmo will happily run from it. They're cheap enough and nearly
    > all are switchers.
    >
    > - --
    > Brendan Gillatt
    > brendan {at} brendangillatt {dot} co {dot} ukhttp://www.brendangillatt.co.uk
    > PGP Key:http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
    > -----BEGIN PGP SIGNATURE-----
    > Version: GnuPG v1.4.3 (MingW32)
    >
    > iD8DBQFHWYz+kA9dCbrNdDMRAskoAJ93kv9Rbw++m9cTL3CQGAN4/ApSFgCfQSH9
    > ZxkaJSiYROhkP9eqlryldIQ=
    > =P/PT
    > -----END PGP SIGNATURE-----


    I'll have a look at Dick Smith Electronics.
    Dave.H, Dec 7, 2007
    #4
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