My First PCB (2019)
lindzey.github.io
lindzey.github.io
> I passionately hate Digikey’s search interface. It is shockingly bad at having the right metadata for filtering to be effective.
I disagree wholeheartedly. Digikey has amongst the best interface for parts searching that I have ever used.
What exactly about the interface do you dislike?
It's certainly not great, but it's definitely the best of any electronics component vendor by a large margin. Mouser's filtering facilities are dramatically worse.
compared to a lot of other web interfaces, its not exactly intuitive but once i got the hang of it its nice.
You can specify value (6 mH) and tolerance (+-10%), but not joint values-and-tolerances. So if you really need at least 6 mH minimum, you technically want to search >6.7 mH +-10% and >6.3 mH +-5%, etc, but that's extra work.
Sometimes the parameter you care about simply isn't available in Digikey's filter, because it's a little obscure like... high-frequency CMRR, or something. So you have to dig into each part datasheet one at a time. That's not really Digikey's fault though; they've tried their best to guess the parameters that are most important, and nobody else has done better.
Where it does get very frustrating is when you need to search through ranges of ranges of values. Like, if your application has a supply voltage that could be between 3.3V and 5V, then you want to filter out parts that require an input voltage higher than 3.3V, or are damaged by an input voltage below 5V. But there's rarely an easy way to do this; often Digikey has one column containing value ranges like "1 - 4V", "1 - 4.1V", "1 - 4.2V"... "1.1 - 4V", "1.1 - 4.1V", and so on. Some of their filters have gotten smarter, but many are still like this, and it takes a long time to go through and select all possible acceptable parts and reject all inadmissible ones. So to save time you end up just guessing at a few likely ranges of values, but then later you discover that there's one really good part that's perfect and cheap but it can tolerate voltages all the way up to 25V for some reason, and you just filtered it out early on because it would have taken too long to scroll that far down.
Searching for connectors can be very frustrating, because there's usually no easy way to look through related parts in a connector family, like to find matching male and female crimp pins and their respective housings.
A lot of frustrations like that are very common, especially when approaching a design from a blank slate.
Aside from passives though, you’re never going to get exactly what you want from any reasonably bounded database. For a FET you’re trading footprint, thermal impedance (both up and down), SOA, parasitic capacitances, turn on times.
When I’m picking a key part, I’ll start with a DK search, get a sense for which MFGs are leading the field, make a list of 10 or so parts that look promising, and go through the material on each, filling out my own spreadsheet as I go.
That’s even more true for anything with digital logic, where it wouldn’t be possible to sort by the enumerated features in a meaningful way.
Gate capacitance is a great example because if I'm considering MOSFETs in parallel I'll want to bound the sum of their capacitances. Again, easy to do with expressions, hard with DK's interface.
What other sites do (eg. TI) is have a bunch of extra search fields but make them collapsible.
Also, specs aren't well standardized between manufacturers. TI has some good videos explaining what their power MOSFET specs mean and how those definitions vary across the industry.
Automatic optimization can only get you so far.
If there's a part that would have worked better, but you weren't able to find it, that's a problem with search.
Furthermore, cost is just as an example, the same applies if you're looking to minimize package size, temperature rise, power loss, etc. Any component selection is an optimization process and ideally, a good search and filtering will enable you to sort for exactly the specs you need to find the best component candidates more quickly. Maybe that doesn't mean filtering by price, but by (voltage*quiescent current + conduction loss + switching loss), and so on. Or (rise time + propagation delay), etc. Of course you still need to read the datasheet to make sure. We're just talking about better search to find the parts that meet your actual requirement. The point of good search is it should do the mechanical work for you of finding parts, rather than making you try different parameter combinations again and again by hand.
Digikey is still the best, but that doesn't even mean it's good.
Finding parts is still the slowest and most critical part of a PCB design, and it's especially difficult for a beginner because it's hard to even know what you might want to look for. Even with years of experience I can find myself spending days just trying to find the right keyword or set of different keywords for some functionality or another, and the search is pretty dang useless for this (maybe it is something which LLMs could help with: parsing and understanding a gigantic database of datasheets which I could query by saying "I want a part that does this that and the other, with specs like so. What part or combination of parts can do this?").
Sadly Autodesk is actively depricating Eagle and I can't recommend F360 for new users.
Digikey Dkred is a heckuva deal, about $1.50 a square inch. Start designing some simple 1x1 inch pcbs, get some for $20. The learning experience alone is worth it. A BOM? what's that?
you can see how it works on the KiCad Interactive HTML BOM Plugin Demos
Joe Bob says check it out (for anyone that remembers Joe Bob Briggs)
Relatedly, reflow for assembly makes this feel like a super^2 power. I had always struggled with SMD components with an iron, but once I finally took the plunge and tried reflow I realized I could never go back. Not only is it considerably easier and cleaner (you place the parts, bake it, and do minor touchup with a braid and a hot plate--it just works!) but you can just build so much denser, more technologically advanced devices!
I occasionally make PCBs, as a hobby, and I would love to find a manufacturer with a next-day delivery guarantee to the US (California) for simple 2-layer PCBs. I would pay $50 just for shipping for that service, even for just 2-3 small PCBs that fit in an envelope. But to my knowledge this isn't possible. I hate designing a project, and having to wait a whole week to get my PCB. This truly hampers my creative flow... sigh
JLCPCB started making the board in less than a day, was done in two days, and mailed it to me in 3 more days (DHL delivered it a day earlier than expected). They had it in the mail to me before oshpark even sent my design to the fab (which then took a week to make the part). And oshpark was much more expensive (5X for 3 simple 2-layer boards).
I could see getting into a week-cycle (design board over weekend, send to jlcpcb sunday night, get results friday for testing), and then just read Hacker News in the down time.
As for next day, you can pay to get anything like that. Years ago I worked for a large company that had an in house PCB fab because it was cheaper than subcontracting out prototypes and production builds to third parties. They were quoting 500-800 GBP a board and much much more for Rogers for the same week production. We are truly in magical times now for how cheap this stuff has got.
But it looks like even now at best you can etch two sided boards at home.
> Designing a PCB and sending it off to fab is surprisingly accessible and feels like a super power.
That may very well be the case if you live in the US, Germany, France or the UK. Go anywhere else and it's a different story. To give you a bit of context, there is a shop that makes them 15 minutes walk from my place. The prices are ridiculous. If you ever need to go through 3 prototypes to fix some mistakes, you are looking at 3-400 bucks for a total of 9 pcb's. And while you can order from abroad easily, shipping costs+the additional time you need to wait makes the price tags identical. Meaning it's cheaper to get a laser cutter/engraver or an sla 3d printer and make them at home. Sure, they turn our a bit sloppy, no matter how much effort you put into them but it's worth it at the end of the day. Kind of a shame that laser cutter, sla printers, CNC's have become dirt cheap. I would have imagined that some sort of democratization of pcb manufacturing would have happened by now but here we are...
Apparently those times are over now, but I still think that it would be faster (and subjectively more fun) for such a simple circuit.
If you were academic they'd let you order just 1. That's what I did.
I remember being at school eating lunch when my brand new flip phone rings, and it's a sales rep from Advanced Circuits asking me about my estimated annual volume, while my friends where throwing pizza slices at the lunch table.
It seems like a non coercive type of education, where people follow their curiosity and at the end finnish up with something tangible.
I honestly think if education is to change for the better, it should turn into something like many Recurse Centers, for Music, Technology, Medicine, Pharmacy, Art etc.
And the kinds of stories, like the one linked always make me think that I am right. I like listening to them.
My dream is to one day make enough money and build something like Recurse Center in my country.