less current consuming circuit for led lamp

i am working on a project called less current consuming led lamp,and
the major idea of this project is less consumtion of current and
compact in size.so i have planned to take out transformer ,which
consume lot more space,so i want a help from u guys how to isolate the
current from 230v/50hz supply to 12v dc supply with out
transformer.were i am using a dimmer circuit but the current
consumstion is more.the spefication of led is 12v/3watt.

so i hope u help me out

 

[terryc]

On Wed, 02 Jul 2008 03:25:22 -0700, sg858585 wrote:

so i hope u help me out

Err, buck converters / switching mode power supplies are basically what
you should be looking at.

what voltage are your leds?

Try fiddling with and old PC power supply.

AIUI, to get better efficency than the trnasformer route, you need to
customise the SMPS to closely match load.

 

[Bob Monsen]

<sg858585@gmail.com> wrote in message
news:1cfdf4e6-1cad-49a6-83d8-64af9e7fc504@m73g2000hsh.googlegroups.com...

i am working on a project called less current consuming led lamp,and
the major idea of this project is less consumtion of current and
compact in size.so i have planned to take out transformer ,which
consume lot more space,so i want a help from u guys how to isolate the
current from 230v/50hz supply to 12v dc supply with out
transformer.were i am using a dimmer circuit but the current
consumstion is more.the spefication of led is 12v/3watt.

so i hope u help me out

take out transformer, put in capacitor. use flameproof resistor.

View in courier font.

500V flameproof 1W diode
LINE ----- 10uF ---- 1R ------o---->|----o-- 12V
- |
zener ^ 5W 12V 3.3mF
| |
NEUTRAL-----------------------o----------0-- GND

You can get 250mA at 12V out of it.

If you need a more regulated supply, use a 15V zener
and regulate the output with a 7812

Not sure this is cheaper than a transformer, though,
since the cap and zener are fairly expensive.

Regards,
Bob Monsen