Fcobcn shared his simple and efficient 12V to 5v converter. It’s based around the TL2575 buck IC, and can output 1 amp of current.
I’m using a TL2575 from ti, wich has a max efficiency of 88%, 1A, works quite well, previously were using a 7805 wich needed heat sinking. There’s apparently no heat coming out from the TL2575 circuit.
It’s a lot better than a basic linear, but it’s an LM2575 second-source part, and it uses an NPN switch which saturates at 1.2V/1A. For battery projects, one should probably use a newer part that uses FETs and a higher switching speed for smaller coils. At load, this drops at least 1.2+0.5=1.7V. The 88% max efficiency is, I think, mainly in the datasheet for use as a salesman talking point.
Eh, wrong topology ;-). V(switch)+V(coil) drop.
You can get such modules in ebay for less than 2$. Look here for example.
The TL2575 is an interesting part to replace basic linears. But when I played a bit with the part I get a lot of problems with the EMI.
The switching regulator caused EMI in the range of UKW (in Germany: reserved for radio broadcasting and police/fire service/…). That’s a problem…