During lunch, I went to my local electrical distributor store today to see if they have any new+silly+expensive LED lighting, and I stumble upon a kit set of 12VAC 50W electronic transformer halogen set for approx AU$8. It can't be real... the kit consist of an 240v>12v electronic transformer that complies with electrical safety AS/NZ standards, a white two piece diecast aluminium fixture and a 50W halogen bulb. Well it was no brainer, the power supply was very small I wanted to see what's in it so I bought it and waited impatiently to knock off and get home.
I just renovated my 20 yr old home, and I have standard coil transformer for my halogen downlights. I want to see how these cheap power supply works and to my surprise, quite well. I wired it up and hooked up a kill-a-watt, with the standard 50W bulb, the kill-a-watt reports 53W. On the true rms Fluke is telling me output 12.0xxVAC which is very nice voltage regulation. Then I tried a bi-pin 20W bulb, the kill-a-watt says 23W.
Two high power TO-220 NPN for switching and a TO-92 NPN all I can see, and some caps and resistors, 7 diodes, lots of magnetics. 12V output is fully isolated via a toroid winding. I'll post some pictures of the internal tomorrow.