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The problem is, I've realized I know basically naught about electronics. What I know could probably have been learned in a 3 day course.
QuoteThe problem is, I've realized I know basically naught about electronics. What I know could probably have been learned in a 3 day course. Thomas, give us some more info, particularly current requirement?Will you want to over-build it for any future project?There is lots of stuff like Paul Price mentions, but you should give more info of your requirements.
Easier than you think . You friend is the 34063 IC, which is easy to obtain online. All of the maths is laid out for you in step-order in the datasheet and the external parts are not that complicated.
IMHO I'd grab an LM2596 module off of eBay and reverse engineer that.You start with a known working designYou can follow the design guide in the data sheet and grind the maths to see if you come up with the same answersYou get insight to availability of cheap and plentiful parts.It's a massive drag to get something like an inductor choice wrong and need to wait for new parts before you can try your next iteration of a design. This way you can still learn, but as your starting point already works, you gain some early satisfaction!
There is a calculator software on Sourceforge for MC34063 and similar chips : http://sourceforge.net/projects/mc34063uc/ ... but even without software, you can use formulas in datasheet to figure out the parts.You need to use Schottky diodes and a suitable inductor (pay attention to peak currents and other parameters)LM2596 boards on eBay are cheap and pretty reliable but you don't learn much about it that way... they don't "optimize" those circuits so the components often won't match with what the datasheet formulas say. Some also use some fake chips or some clones of LM2596 or LM25**. You can get the parts from Digikey or Mouser, they have good filtering mechanisms on their sites.
12v input10% tolerance5v output1A max output current50mv ripple0.4v diode voltage drop (based on 1N5822 diode @2a peak current)1.1v step down saturation voltage75kHz operating frequency10k ohm R1