Application: solar USB charger.
I have a 9V solar panel. I use a buck converter circuit to bring it down to 5V before going into the USB battery charging circuit.
This link has more information about the buck converter circuit (I think it's the same one I bought from amazon above):
I was hoping that the buck converter would also increase the output current (say, for example, from 333mA to 450 mA, for a ~75% efficiency), but after measuring it, it seems to track exactly the input current (Ioutput = Iinput). That's why I didn't simply use a 7805 regulator, which I understand dissipates extra power as heat: I was hoping that the buck converter circuit would convert more efficiently, and translate in increased output current.
Are there any alternative buck converters (PCB or a design that I could build myself) which would reduce from 9V to 5V while also increasing the current somewhat? If yes, in practice, would their efficiency be worth it? (I think that anything below ~75% efficiency might not be worth it for such low power).