 The Great Searcher brought to you by didjakeenator for you. Thank you so much, didjakeenator for supporting The Great Searchers. The Great Search is Lady Aida's attempt to share her wisdom of searching for parts. And boy, is that a useful skill now, because there ain't no parts. There's not a lot of parts. It's true. So what's The Great Search this week? Okay, so The Great Search this week is, it's actually interesting. This week I had a little bit of a scramble. I had to go and find a bunch of 32 kilohertz crystals. And I know we did crystals on The Great Search a while ago. We did 16 megahertz crystals for a design. 32 kilohertz RTC crystals are tiny bit different. Not like super different, but you know, they're very common. There are a couple of things to look for. So I thought I would show on didjakeenator.com and also looking for the data sheet for this chip how to find the right crystal for this new design I put together. Okay, let's do that. So you're going to go to the computer? So this board uses the SAMD51 and one thing that's interesting about this chip is, you know, some crystals, sorry, some of the controllers need like a 12 or 24 or 48 megahertz crystal. Those numbers particular 12, 24, 48 are pretty common because, and 16, because they divide evenly down to a USB frequency of 12 megahertz, which is the kind of the frequency that a lot of USB native chips want to use. The SAMD51 does have native USB, but it doesn't use a 12 or 24 megahertz crystal. Instead, it uses a single one 32 kilohertz crystal. And you're probably like, hey, USB doesn't want on 32 kilohertz, true. But inside the SAMD51 is a phased lock loop. And that is a circuit that takes the 32 kilohertz frequency and multiplies it up to like 12, 24, you know, 64, whatever megahertz it needs. In this case, the SAMD51 actually runs at 120 megahertz on the inside. And it can do that dynamically scaling by phased lock looping onto the 32 kilohertz crystal. There is an oscillator inside, but it uses the 32 kilohertz crystal to tune it to make it nice and precise. So the crystal we use here is 32 kilohertz. So you know, why 32? Because if you want to go into a low power, like ultra low sleep mode, you can actually run directly. Not on USB, you can run off a 32 kilohertz. Or if you're having a real time counter inside the chip, also 32 kilohertz is really common because it's a two to 15 divider of one second. If you have a counter that's 15 bits, you count up every cycle tick, you'll get to one second when it rolls over. Great. So in the datasheet, there is a little section on this crystal. And they tell you here's what you need to do. This is the crystal itself, which they model as a sort of complicated, you know, LRC circuit. This is a true capacitor. This is a true capacitor. And this is a C-straight. This is not a true capacitor. That's the internal capacitance of the pins and the PCB and the pads, which is going to be very low. It's going to be, you know, picofarads, maybe femtofarads. So basically they say, look, you know, make this crystal 32 kilohertz and make the load capacitance no more than 12.5 picofarad, which is quite common. You'll often see 12.5 picofarad, 6 picofarad is also very common. And then the external crystal value is calculated down here. It's basically two times the load, minus a little bit. So for 12 picofarad, you multiply that by 2, you get 25. And then you subtract a little bit for that C-straight, which is, again, a picofarad or two. And you basically get 20, 22 picofarad, which is why you're going to see often 22 picofarad, right? Two times the load capacitance. Now, when you're buying 32 kilohertz crystals, especially now during this semiconductor shortage, and by the way, these are not considered semiconductors, but there's a shortage of crystals, probably because people are hoarding them, because if you have a semiconductor, you need to have the matching crystal, and, you know, they're not cheap, and there's not that many suppliers, so you want to get them, have them in stock and ready for when the rest of the components come in. And so these are kind of having a, there's like a secondary shortage of crystals and oscillators. So that said, you know, you saw in the data sheet it said maximum 12.5 picofarad, you can go less, sometimes you can get six or seven picofarad, and then just don't forget to change those load capacitors from 22 to 14, but that's easy to do, you just swap them out, you know what I mean? The most important thing is the physical package. The capacitance itself doesn't matter. 12.5 picofarad, again, is the most common, but if you're picking the load capacitors, you can go with six or nine, just FYI, I haven't had to do that yet, but I'm ready to do it if I absolutely have to. All right, so we're doing stuff in TikTok now, too. Oh, there's our cat. Cat passed away a couple years ago, that's a monster. Hi. We use Eaglecat, but we also use Geekat, and we publish all of our files, and before anyone gets hung up on it, it doesn't matter what tool you use, just publish your files. It doesn't matter if you use Windows or a Mac, you still can do open source. Don't get hung up on that stuff, everyone needs to chill out. Do you think that the TikTok teens are angry about open source life? TikTok teens are cool. They're actually chill. Okay. So next up, someone says how bad is the shortage, is the components are gone, or they're much more expensive, both? Both. Actually, this is the SAMD 51 I wanted to show. This part, if you look, you can actually get 8,000 in the next two months, which is not bad, but if you want more than that, you'll have to wait exactly a year until 2022. So it's one of those things where sometimes you can get the parts, and then sometimes you're getting, I'm getting lead times about a year right now. So it was a year back in January, and it's still a year. So it's going to be basically two years of not being able to get semiconductors at a regular rate. I'm going to call it. TikTok questions are great. Do you manufacture the trinkets and the feathers in New York City? Yes. Yeah, we do. Yeah. Not here in my room at the factory. Yeah. This is our tiny apartment as you can imagine. It's a very tiny apartment. Yeah. And it looks like, you know, as you can imagine, this is what our apartment looks like. It looks like an apartment. Yeah. But good questions, TikTok. All right. Okay. So you want to find this 32 kilohertz crystal. So at the top, you can type in 32 kilohertz. Now technically it's a 32.768, especially if you type that in, 768 kilohertz. I always shorthand it to 32 even though like you'd think it would be rounded up to 33. It's not. Um, and then under crystals, okay, so lots of crystals and they come in lots of shapes. That said, you know, one of the things that makes it easier for me is all of my boards use the same size components as much as possible, like we reuse the components. And that actually helps a lot in a shortage because you only have to source that one part. Even if it's harder to get that one, like it's easier I've found to get a lot of one part than to try to get lots of multiple parts, especially something like a crystal where there's multiple sources. Yeah. So this is the low part, the low part counts the cause of things going out of stock, almost as soon as they are, they hit the store for our stuff. Yeah. It is. It's hard to get stuff. And another thing is when things are out of stock, we have people signed up to not backwards, backwards, but they get notified when we're in stock. And so the longer it's out of stock, the more people are signed up. And then when we do go in stock, it just goes that much faster. Yeah. And then some people are freaking out and they're like, well, I better buy everything right now. It's kind of a self-fulfilling prophecy. Like I heard everything's out, so I'm going to buy everything all the time. I heard everything's out. Yeah. That said, we're doing pretty good. We're able to keep most things in stock. Some things are totally ridiculously unavailable, but most things are. Okay. So for this part, this footprint is 3215, 3.2 by 1.5 millimeters. So here's the thing, with crystals, you can actually go a little bit smaller and they'll probably even fit on the footprint. So if you're absolutely desperate, you can do that. That said, I think I'm going to try to get a part that's exactly going to fit. So this is 3.2 by 1.5 millimeters. So undersized in dimension, I think it's visible, I'm going to do. And this is weird because it inches and millimeters. So three points, well, first off, let me do only surface mounts. I'm going to answer a question while you're doing this. Yeah. I noticed that Digikin Micro Center has stock when you folks are not. Should I wait and order from Adafruit? So here's what you should do. Sign up on Adafruit. And the second it comes back in stock, order it. You could potentially order from Digikin Micro Center, but usually our retail customers on Adafruit.com, they get it first. But either do both. Yeah. I mean like, yeah. Do both. We try to supply everybody. That's the world we live in now. So the next thing is I'm actually going to get rid of these parts with four pads because my package is definitely, it's a two pad package. Let's see, front Vabprint. Sorry. Second this is, so this is the crystal, it's a two, this is the crystal and it's a two pad package. So going back here, let's do two SMD only. Okay. So now we're, we have only these. So now we have to actually do the size. So okay, size dimension three by two by one point two and three point two by one point five. I think I'm going to grab the three point three by one point six and two point five by one point two. Because again, I think those will probably fit on the same pads. And then finally, I'm going to select only stuff in stock because I want to get this now. Okay. So there's actually quite a few options. And this is where we can start looking at the load capacitance. Like I said, you have a couple load capacitance decisions to make. And if your chip, some chips actually have internal tuning capacitors, or if it's like a real-time clock, sometimes whatever it's internal and they really do say it has to be six, seven, nine, whatever, pico farads. For me, I kind of want to stick to the same, like I don't want to have two crystals with different load capacitances if I can get away with it. So 12 pico farads and yeah, there's some in stock. So I can sort by price. And you know, this one is kind of nice when there is a 51,000, I'll say that this is a marketplace product, which means it can take a lot longer. So this one is like, you know, 50 days to ship. If you do not want to wait that long, you can always exclude marketplace. Just click on exclude marketplace and then apply it. And then you'll only get ones that are like really in stock at DigiKey. And so this one by Citizen, Fine Devices, just a great name. So they have 90,000 in stock, which is great and about, you know, 40 cents a piece. Look at the specs, but it's got what I need, 32 kilohertz, 20 ppm, 12.5 pico farads, fundamental, SMD, 3.2 by 1.5. So this is good. You know, I think that they recently restocked these because I don't remember seeing 90,000 crystals in stock before I would have purchased them. But yeah, this is, you know, if you have a design and you are waiting for components, you know, definitely the semiconductors and the chips of course are out. But I'm also seeing a lot of annoying lead time issues with crystals. So I do recommend if you need a crystal to order it early. You can always wait on the capacitors and resistors a little bit. But crystals are definitely, they're being hit by this semiconductor shortage. Probably it's a secondary effect. But lots of these. So this one is good. Good for all sorts of uses. That's a great search. Yay.