Power Supplies

[fell8]

I'm thinking about tinkering around with some LEDs for lighting purposes. So far as power supplies that are inexpensive and readily available I have two choices: transformers and switching PSs. Prices are about the same for comparable capacity so the overriding factor is efficiency.

1) So far as I know, switching PSs are more efficent than transformers. Is this correct?

2) How much more efficient is one than the other? (not really important, just curious)

Thanks a lot, guys.

P.S.
My choices are this and this, for those curious.

 

[f95toli]

1) Yes
2) It varies, but generally speaking switching power supplies are a LOT more efficient than conventional types; if you need e.g. 12.00V DC regardless of load a conventional supply will waste a lot of power.

 

[Calin]

If your transformer is set up for a certain task (like the big transformers on power lines are), they are pretty efficient (99+%). This holds true also if you use a transformer to power a load in alternative current. What is problematic is giving continous and stable current, mostly in more than one voltage.
A switching power supply will keep the output voltage constant by varying the time slices during which it receives power from the power socket. A conventional AC to DC converter will simply throw away extra power (using a resistence). This resistence is needed to keep the output voltage stable during low loadout