240 Volt AC To 12 Volt DC

[Dave.H]

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.

 

[Tim Wescott]

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

 

[Brendan Gillatt]

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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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[Dave.H]

On Dec 8, 5:12 am, Brendan Gillatt
<brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote:

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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
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I'll have a look at Dick Smith Electronics.