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by jhogendorn 18 days ago
So a lot of this goes away if you try to stick to jlcpcb basic parts from lcsc, and you sort of develop preferred components for things. Another trick is when in a category, for example angular hall sensors, once you have the key attributes like vin, smt, etc, sort by quantity desc to see what parts get heavily stocked, that tends to indicate what is popular in industry and likely to be a good generic fit. Out of the top 10-20 pick according to stock level against price. If youre ordering from jlc, look through lcsc and you can do pcba with them, or get the parts shipped with the pcbs. Otherwise digikey, mouser (good for connectors), farnell, rs etc, roughly in that order. You will quickly learn for a lot of components there are very standard parts everyone uses. Diodes, inductors for example. To some extent if your footprint is already in the jlcpcb library, its popular and use that. Ie theres 1 smd push button that is basic on jlc and has a footprint in kicad default library. Youd be a little crazy to use anything else. Make all your resistors and caps 0603 or 0402, jlc stocks those the most, vs spotty coverage in 0805 or 1206.

But you find each time you find something in a category, a hall sensors, an encoder, a capacitance sensor, gpio expander, adc, you just file that away as kind of solved and next time you hit that part first before finding alts. Over time you have to dig about less and less. But dont bother with things like resistors, caps, etc that are basic. Even mosfets, unless you have special needs the 3 main types jlc has as basic are fine. Dont get some odd package thats technically two mosfets in one, just put down two basic mosfets. And if you do need a more 'advanced' part, look what is on jlc's promo list atm. Theres very popular stm's for example that are prettymuch constantly on promo (promo is they have the part loaded in mid term for some big customer so you might as well piggyback. Means no loading fee. Adds up)

Llm's can be useful for sifting the sand. Narrowed it to like 30 options and still dont know whats the best pick? Export search as csv and ask your favourite stochastic parrot which part would work best for your application and why. Dont ask them for part numbers though, completely pointless.

1 comments

LCSC has been my problem. It's built into EasyEDA, but most search results aren't in stock, and most of the rest have high minimum order quantities.

I needed a lot of different resistor, capacitor, etc values so each and every one needed me to go through that search.

Yes, you need to design for what jlc stocks as basic parts to retain your sanity. Dont just slap down a 1206 resistor and call it good, jlc prob has no stock in that size in that value, but they probably have it in 0603. Once you get a handle for whats basic or very common extended parts, that sort of thing gets a lot easier. You kind of have to work backwards, ie if i need a diode i see what jlc has in basic and make my part choice accordingly.
I wasn't trying to choose a footprint/etc ahead of time. I would need, say, a 3.3KΩ resistor, and I would not filter for anything else other than the resistance yet, then I would choose a listing that I could use and that had a reasonable footprint and etc.