I want to build http://www.hobby-hour.com/electronics/lm2576hv-adj-buck-regulator-schematic.png From http://www.hobby-hour.com/electronics/lm2576-step-down-switching-regulator.php I might not be able to source exactly the same parts. I assume I have to use the same IC, but could I use a, say, 200uH inductor instead of a 100uH? Or slightly different types of capacitors, with different capacitances? How about that Zener diode? If I'm stepping down 24 to 3V and drawing up to 400mA, I'll probably still want to attach a heatsink, no? edit: the output voltage will be running a small 3V gear-motor system needing to lift a small amount of weight (half to a couple of kilos) vertically in a reasonable amount of time.