 The Great Search brought to you by Digikey at Interpret every single week. Lady Audio User Power of Engineering, help you find things on digikey.com. Lady Audio, what is the great search of the week this week? I'm glad you asked. This week's great search is we're going to look for some 2.1 millimeter DC jacks. Let's go to the overhead and I'll show my design and the part I picked. I'm focusing, focusing. Stay on target. This Metro RP2040 prototype that I'm working on, one thing I really like about this shape, this is kind of the classic Arduino shape, which I call Metro because I don't want to use the word Arduino. It means something. But for those boards, which I really like, they're kind of nice and big and one of the side effects of having plenty of space is that you can have a lot of accessories. So not only do you use USB type C or micro B for power and data, there's a reset switch and some micro SD card slot, but you could also have a DC jack. And you know, even though a lot of things plug into USB these days, like almost every device I buy these days has a USB port for charging. There are times when having a DC jack is really handy. These DC jacks can provide up to your 12, 24 volts. They can do five amps. Yeah, USB-C can do that as well, but it's often easier to get a DC power supply that you have handy. And then that voltage ends up out here on the VN pin. And so if you want to use it for powering motors or steppers or LED strips or solenoids or actually a lot of industrial equipment uses 12 volts. So, you know, if you need 12 volt DC, yes, you could make this USB-C do power delivery and get 12 volts, but it's easier to just have a dedicated non-power delivery port here that you know, I'm going to give you, you know, 9 or 12 volts DC. So, let's go to the computer. I'll show some other stuff that at least at Adafruit restock that uses the same size. So, this is, you know, an example of, you know, the DC jack with a switch built in. But you see it uses this kind of standard barrel connector used in, you know, there's a lot of different sizes for barrel connectors. There's 5.5 millimeter outer, 2.5 inner, 4 outer, 1.3 inner. But the most common that you see these days is 5.5 outer diameter. That's the diameter of this jack is 5.5 millimeter. And the inner diameter, the little nubbin that sticks out, that's 2.1 millimeter diameter. So, we have a lot of, you know, adapters and plugs and cables. And if you look at, you know, we have a 12 volts, 12 volt 1 amp power supply. This also has the same 5.5 slash 2.1. So, you know, a very standard connector. And, you know, yes, I've been doing some magical future. We'll all be using USB power delivery. But, yeah, at least another decade of this stuff. So, if we want to use these sort of power adapters, we'll need to get a DC jack. And there's a couple of things I've learned about using these DC jacks. So, I'll show you what I've learned because this is, you know, before USB, this is kind of the standard. If you look on electronics from like, you know, the 70s and 80s, you know, basically once they started not using mains power directly with devices, they went straight to wall warts or power adapters. This is the standard connector. So, let's look for DC jacks. And there's a couple of things. So, there's cables. So, if you want cable assemblies, this is one category. But what we want, and this, you can actually see this is a inline adapter, but we want something that goes into a PCB. So, let's go, oh, and also if you want, of course, power adapters that this goes with, you know, Digi-key stocks, every voltage, current, whoa, that's weird. It goes the opposite direction. Usually, oh, because I typed in jack. If I typed in plug, it would have plug versions. So, I was like, why is it the opposite polarity? This is, here you go, like this one. So, you see, this is very standard. Wall adapter, you plug it in and they come, you know, there's versions also that are, that come with, you know, European, Australian, US, Japan, et cetera, different voltages. This one's 12 volts, 12 watts, but they go up to 24 volts easily. So, let's say, let's look at some of the voltage outputs. There's some adjustable voltages, but it's not too, you know, you can get up to, I think, 24 volts DC. Yeah. So, it's like, you need a high voltage. You're not going to get 24 volts out of USB power delivery. So, also it's maybe a little bit less expensive because you're not dealing with the overhead of USB type C, which needs its own, like, big power plug. So, let's, so I go back and look at, again, DC jacks. So, under power connectors, barrel type, you know, because it's round and thin and circular and has a hole in the middle. So, it's called a barrel type. So, let's just look at all the power connectors and take a look. So, there are tons of these. So, this one you can see here, it's 3.4 by 1.3 millimeter. This one is 5.5 by 1 millimeter. So, this is an SMT version. This is a 2.35 by 0.7, so much smaller. I don't, I'm not a huge fan of these, but I will say that this size is very popular on USB hubs if you want to have optional external 5 volt power, you know, because these are a little chunky. These are available. You can see this is a through-hole style. Another through-hole kind of narrow SMT, a little lower. This one is SMT, but it's pointing straight up, which is kind of cool. This one is like to the side. So, you know, different orientations and stuff. So, first up, let's just go and look only for the active and in stock. I picked in stock items just to, just to pair down to the ones that we want. We want a jack, not a plug. I will say that trying to use female or male gets very confusing because it's like, there's, you know, which way is the gender? It's very, it's unclear. So, I would not use the word male, female when trying to differentiate between what plugs in and what gets plugged into. Instead, use plug and jack. Jack is the thing that you plug into and plug is the thing that, you know, is plugged. So, especially when you're dealing with connectors that have like multiple like sinusoidal connections and inputs and outputs. So, we want a jack because we want something that it gets plugged into. A plug is what comes out of the wall. And now this is kind of like the thing that engineers have to deal with. There's what it's called and then there's what it is. So, we call it 5.5 millimeter at a diameter, 2.1 millimeter inner, but that's not actually the measurements. The measurements can actually be 2 to 2.05. So, let's just look if we just filter on 5.15 millimeter at a diameter. You'll see that first off, there's just like funky 1.6 millimeter. These are on. And then there's also the 2.5 and 2.55. So, there is a variant of this jack that looks like identical, except the inner pin is a little bit wider. And that means that it can carry a little bit more current. So, technically, you're not really supposed to take more than, I think, 60 watts, maybe five amps over a 5.5 millimeter, 2.1 millimeter jack and plug. So, if you want more wattage, you have like a monitor or a computer, like something that needs 100 watts, you're supposed to use 5.5 slash 2.5 millimeter. Whether people do or not, I mean, sometimes they do, sometimes they don't, sometimes they go to another connector. But you'll definitely want to make sure, you know, you can, if you plug a 2.5 inner diameter plug into a 2.1 millimeter jack, you won't get power coming through. It'll look like it's plugged, but like the thing won't turn on because the pin, it doesn't, isn't touching the cup. And if you're using a 2.1 millimeter jack and a 2.5 millimeter jack and a 2.1 millimeter plug, it won't plug in. Like, you'll try and it will like, it's like, you know, no matter how much you force it, it's not going to go in because it's 0.5 millimeter too big. There are once in a while jacks that can do either by using like a little bit of spring and it's 2.1 millimeter, but it pushes the pin up. So, like, even if you have 2.5 millimeter plug, it'll still fit. Just pick one or the other. I don't like to play these games where it's like, you can kind of make it work. So in which case, we're going to go for 2.0, 2.05, and 2.1. So there's a little bit of variation. It's basically all the same. And we're going to skip these. Wow, there's even a 3 millimeter. So like, again, totally non-standard, but it looks, to the human eye, it looks the same, but it won't plug in. Okay, next up. So there's a couple different versions. There's the SMT and through hole. I have used SMT. The SMT is actually fairly strong. I'm not using it on my design. They tend to be a little bit more expensive usually, but you would also definitely need to have really big pads. You know, I don't know. Let me see. I think our solar, I think one of our solar chargers uses SMT. Yes, this is the SMT. I've used it. It works. It's not as mechanically strong, of course. And especially because again, people might try to plug in the wrong side, they can actually put quite a bit of force on that connector. If you do go with SMT, make sure you get the kind with these nubs that help, like they point, they stick through the circuit board and they give you mechanical strength because this is not just this connector is not only electrical, but it's mechanical. And it's a very, very common thing that the DC jack is what cracks off and the thing stops working because it's easy to torque it or, you know, you've got the plug plugged in and the plug, you know, it gets kind of large and chunky and it's a great lever. You know, and if your device falls off, the cable gets strung up, it pulls and it yanks and it yanks it out. So I, you know, for this design, it's a little, it's a little breakout board. It's an older design. It's okay. You can do it. But if you're going into production, you're manufacturing something that's going to be used by people in their, in their homes often or by folks who might be a little bit rough, I would not go with the surface mount. I'll go with the through hole. So let's select not panel mount, let's do through hole and then there's through hole and there's through hole right angle because there's the ones that stick up. I've personally never used the ones that stick up, but like they're very cool and I'm sure they work just fine. And if your design happens to need the power going up, you know, more power to you. Do note you can, sorry, for through hole, there's also, so these are the jelly bean, they're almost all the same. They look, they have these three pins. So inside is a switch and the switch, so there's three pins where you're like, oh, there's only two pins on the contact. There's a switch here that is normally closed. And when you plug it in, the third pin disconnects from the second pin and you can do that to have like an internal, like first we can detect whether, you know, something got plugged in or you can use it to switch out to a battery power. However, there's one thing you got to watch out for, which is that the thing that switched is the ground, not the power, which means that there might be another path to ground somewhere or somehow. And so you'll notice that pedals, guitar pedals used by musicians have center negative so that this is switching the positive pin. However, nobody else in the world does that. Everybody else in the known universe uses center positive, which is what you're almost always going to encounter. So stick to center positive. And then if you want, you can use the switch, but just remember it switches the ground out, not the positive pin, which is, we might have to think about your grounds and your earth grounds, make sure that there isn't another path through where you might, you might be surprised when your battery shorts to your power adapter. Okay, one more thing, there's these thin pin style. Again, I'm not a huge fan of it. I feel like if you're going to go for it, go for the large, chunky pins because you want a mechanical connection, not just electrical connection. However, side note, these do plug into breadboards. They plug in quite nicely. So if you're having to solder this into a perf board or breadboard or something else, it's a point one inch spacing. This actually ends up working out quite nicely and the pins go right through the holes. We don't want that though. We want something with chunky pins. Another thing to watch out for is they're not all rated for the same amount of current and voltage. Some are rated for 2.5 amps, some for five, some for 24 volts, some for 48 volts, some just for 12. So they're all kind of the same build, but you know, the rating is the rating. So you should probably obey the rating. Well, this one goes up to 10 amps. This is, oh, this is kind of a nice, oh, look at that one. It's got like all those contacts. This is very nice, but it's a little bit more expensive. It's four bucks. So let's, let's swap my price and then we'll just see what's up. You know, I don't want the vertical. So let me change the mounting type and I'm going to get rid of, I want right angle. Yes, I'm going to get rid of through hole so that I only do the right angle. This one's pretty good. Let's see, but maybe I want the five amp version. So I think this one's kind of nice and I like it's got the big, uh, chunky pins. Oh wait, this one doesn't have the switch. Never mind. Hold on. That changed my mind. I'm going to go for the version with the switch, single switch, normally closed, because I actually like, even though, again, even though I don't use the switch, I like the mechanical connection. Okay. Back here, let's see, this one, five amps. This one's good. Okay. This one. I like this one. It's got the pins, nice thick pins, uh, standard layout. It's got the kinked pins. So, you know, when you, when you soldered it, it stays in place. Don't forget you'll need plated slots on your PCB to, um, make sure that these fit in nicely. Oh, you can also use big round holes. It just makes it a little tougher to fill it with solder. Um, so I use plated slots just to check out your CAD program on how to create plated slots. All right. So if you need, can I have your generic 2.1 millimeter, 5.5 millimeter DC jack that can do up to five amps up to 20 volts? This one's pretty good. I'm going with this one, the GCT DCJ200. It's my pick. The great search. That's great search.