 The great search brought to you by Digikey and Ada for it. Thank you so much Digikey for Spartan. Just like Ada, great search is when Lady Ada uses all her powers of engineering and smarts to show you how to find stuff on digikey.com. Lady Ada, what is the great search for this week? OK, well, this is going to be an easy, easy, but goodie. So looking at this keyboard matrix, you'll notice that there's a lot of include and diode, sorry, an LED for each board, each key, which is the key. And then there's an LED above it. There's also a diode. So this is a diode matrix keyboard, which means that you don't have a key ghosting when you press multiple keys at once. For macropads, it might not be that important. But diodes are really inexpensive, and you just add one per key. And it means that you can detect each individual key press no matter what combination are pressed. And especially for people who do gaming, it's not unusual to have multiple keys pressed at the same time. You don't want there to be ghost keys that appear. So let's go to the computer, and I'll actually show. I saw a nice site. This is gammon.code.uau. So this is how normal low cost matrices are made. You've got the columns, and you've got the rows, and you've got these little switches. You test each row, you set each row high, and when this is pressed, this signal by default is pulled low. And then when it's pressed, it goes high. And that's how you know that this button is pressed. So you can scan through the whole matrix to find out very quickly which keys are pressed. But what's not good about this is that if you have a nice little diagram, if you have three keys pressed and they overlap on the column or row, the fourth key that's like the cross intersection of where those three keys meet, that extra key will appear as if it was being pressed, which is, again, not a good idea. If you're just doing something like a telephone keypad where people only press one button at a time, not a big deal. You can save $0.08 non-cludiods. But if you're doing any other kind of key matrix, this person was actually hacking an existing key matrix to add diodes because they were frustrated by the key ghosting effect. So to avoid it, all you have to do is add one diode per switch. And that just means that the current only goes one direction. You can't have the current flow back through and accidentally trigger another key. So what diode to use? Well, the 1N4148 is a classic. It's not just, you know, it's a little cliche, but it's also just a really good diode to pick why. It's incredibly plentiful. It's very fast. It has a reasonable forward voltage. It's super cheap. You can get it anywhere. It comes in all sorts of packages. Did I mention it's cheap? It's heckin' cheap. And again, you don't have to worry about not, like if all the chip shortages and component shortages, you're never gonna run out of the 1N4148. Sometimes also, people use 1N914s. It's a very similar family. Now I'll say that there's a lot of diodes out there and diodes that you can get Zener diodes and you can get shocky diodes and et cetera, et cetera. You just want small signal diode. You know, you don't need a 1N4001 power diode. It's not gonna be as fast. It's not gonna be as inexpensive. It's not gonna be as easy to solder. It's not gonna be as small. You know what the classic, the 1N4148, you're not gonna type any faster with a different diode. This diode is nanosecond speed. So let's go to Digi-Key and check it out. So we can just search for 1N4148. And what's interesting is actually, they'll show you some top searches. You can actually click on these just to get started. But let's actually go and just see all the options available real fast. So we're gonna go with active and in stock because we're gonna buy these right now to make our keyboard kit. We want about 100 of them because we want like one for each switch. And next, the only important thing is the package. You want surface mount with through hole and which size. So if you're going to make like a macropad like this one, which we found on plawboards.xyz, you'll see it's really common. You'll see that all the diodes are over here in a row. And they're through hole and they've got these little glass bodies with a black stripe and red glass. So you can even sort of see the 48 very lightly on here. So if you're using the glass side, the glass beaded ones with leads that you solder, those are called DO35. So you pick through hole and then I think there's really only like one or two sizes. Yeah, so there's basically die, which is, I don't know, look at small chip and then DO35. There's two options for DO35, Axial. So let's pick those and like boom, all the diodes you can want. Now, every single company that does semiconductors, like the first thing they do is they make a dial because it's like the easiest, cheapest thing to make. You might as well get good at manufacturing and taping components by making a dial. Can't go wrong. So you have a lot, a lot of options for diodes. Which ones to pick? Well, you can look at prices at, you know, 100. So you go up here and you enter in how many you want and then you click, you know, apply and it'll show you the lowest price ones for that quantity. On semiconductor, you know, classic Motorola, they're gonna have about a million in stock and they'll be about three and a half cents a piece. So that's a good deal. And you can get like, you know, any quantity you want. They'll come on tape. So, you know, it's one wheel and you just pull them off the tape and you're ready to go. So this is a perfectly fine diode. Love it. Let's say you want to do, you know, and again, they have, these are all different photos but they're all the same thing. You know, microchip makes diodes. V-shape makes diodes. NTE makes diodes. They're all, everyone makes diodes. You want diodes, you got them. All for about three to four cents. So let's go to the overhead. For this keyboard controller, to make the manufacturing easier, they don't use the through hole. The through holes are easier for humans. Much tougher for machinery. So this is a diode that's SOD123 size. You're probably like, how do I know what size it is? Well, first of all, I just deal with the size of diode all the time. But you also Google for diode sizes and my computer can you, uh... Go back over there. Yeah, go watch the computer. If you look for diode sizes, there's all sorts of comparison photos and like, this is a good one. There's lots of picks available that will compare the different. This is not a good image because these are not the scale. You want this to scale image. This is down. The internet barely works anymore. Hold on. Let me find out. You can just view this image. Well, it's small, but you can kind of see it. So there's SMC, SMB, SMA, SOD123 and SOD123FL. SOD123 is kind of like the easiest to hand solder. But you can still get a wide range of signal diodes. SMA and SMB and SMC, they're power diodes. You don't really want those. So let's look for SOD123... And this was also a really good image here because this shows you the comparison. I use 323 and 123, but 323, they're a little tiny. They're good for, again, pick-and-place machine. Does a great job of them. But for human, I'd say 123. So let's look for this in 123. So we're going to delete this filter and this filter and these two. Okay, and then now when we look for the packages, we're going to do surface mount, instead of through hole, because we want to pick-and-place a hole. And then, yeah, over here we have 123, 323 and 523. Again, it's a little confusing, but the bigger the number, the smaller the package. You know, what are you gonna do? The F and FL just mean how thin they are. So you can, they're basically equivalent. So let's pick the SOD123 and 123F together. And Ditto, let's look at pricing at 100 pieces or more. And then we've got this one. I mean, you're not gonna, you know, it's a very tiny picture, but it looks like you can, you know, there's not, oh, wait, hold on, they do have, oh, this is a, sorry, this is a marketplace. Let's exclude that. So you can basically get these for about six cents a piece. They're more expensive, which is interesting. Like they really want you to buy a full tape and like a full reel of these service mount diodes. But again, if you're doing a pick and place design, you really need to have, you know, some of these. So I would probably just pick up, you know, one of these or one of these. I think if you're getting a reel, which is a thousand quantity, yeah, they're like three cents or so, three, six cents, wait, hold on, I did apply. Weird, I don't know why I didn't come through. You can also search by stock number and it looks like Vichay. These ones, they have about 188,000 in stock and they're about, again, four cents a piece. So diodes, they're great, they're wonderful. Do note, like, you know, they're not super cheap, right? Four cents does add up, but when you're, if you end up getting like really large quantities, I think they go down to like a penny or two and you kind of do need them. Like, especially if you're making a macro pad, you might be able to get away with not having them, but for a keyboard where the humans are typing on, you really don't want any errant keys to come out and there are, I have seen people like post up matrix maps where they try to tell you here, if you pick these keys on your rows and columns, you're least likely to have key ghosting, but if you're gonna make a keyboard and you're gonna sell it, people are gonna probably pretty much demand that you have individually died protected keys. So, one and four and four eight, I don't know. It's a great diode, used it for decades, never done me wrong. Good everyday, single diode. It's a great church. Where in the world is that part I'm the DJ King?