 The great search brought to you by digikey and adafruit every single week lady to user power of engineering to Help you find all the things you need lady. And what is a great search of the week this week? Okay? So this week this is actually I almost got made a mistake in this design And so I was like whenever I almost make a mistake Well if I make a mistake, I usually don't catch it till later And then I'll do a great search about it But this time I caught it before the error occurred which is I have a design that I'm doing that uses a slide switch a Vertical slide switch that is used for power selection. So Open up the original one Yes, well the computer so The way that this design works is you know, I'm using this I squirt see multiplexer and I'm moving in the signal from your five volts Controller to possibly three volts five volt or three volt peripherals. So I'm adding like a level shifting thing Not only my level shifting the signal, but I'm level, you know I'm power shifting that the connectors themselves what will provide power to The individual peripherals on the I squared C bus will also be either three or five volts It's not just signal level. It's power level and There's eight ports. So like, you know, that's the power adds up. I'm using the AP 2112 3.3 volt regulator this regulator. I really love it has about, you know, 500 milliamps output From you know, three to five volt very low dropout as well, which I really like so even if you have three volt in Won't drop out too much even at fairly high current. So it's a very good regulator. It's nice and stable But one of the things to watch for is when you are Using a switch for power and not signal because again a lot of people use buttons and Slides which is to signal something, you know, send a digital signal into a microcontroller or enable pin or You know, I showed the micro lipo. It's it's switching a resistor on the IRF pin of a Lipo charger of the amount of current going through and the amount of voltage going through the switch is very very small It's like, you know, maybe even a milliamp. Maybe three to five volts. It's it's fairly pretty much negligible The issue is when you're doing something like this and you actually want to switch power through now, you know If I'm switching more than 500 milliamps, I wouldn't go for a mechanical switch Especially a surface met one. I would use You know, some PFATs and I would you know make a proper You know solid state switch not a mechanical switch But in this case, I you know, it turns out I can kind of get away with this By doubling up the switch but also by making sure I'm speccing the right kind of slide switch. So let's to the slide switch just to Show what it looks like You know, it's You know, I don't have to use the exact same footprint, you know in this case I am but I want it to be vertical So I want it to be pointing up. You can slide it back and forth easily with your finger And I'll show that this is the same switch here. So I you know, I particularly like this switch I found these are very mechanically strong They they're easy to switch with a finger no matter how big or sausagey or smaller fingers are And they have fairly good availability for voltage and current But you know, we talk about jelly bean parts a lot and you look at like tactile switches and connectors Jelly beans are jelly beans, but you still have to look at the ratings. It's not just because it looks the same doesn't mean it's the same so Let's go to digikey. So what we want is a slide switch and we've we've looked for slide switches. We've looked for Side slide right angle slide switches. We're gonna look for again at a top slide switch notice the nice images like I like new new search style come in and digikey with pictures. So we want a slide switch We want active One thing that we you know, I'm not gonna look at because it turns out to not matter so much for this But shorting versus non-shorting also, you know, that's it just because it looks the same doesn't mean they're all Sliding versus non-sliding. Okay. We want surface mount and we don't want right angle. We want vertical pointing up So that actually gets rid of a lot of designs Now we can look at some images and be like, yeah, you know, this is kind of what we're looking at here Like this particular looks this is what I often use for some designs So here's where you want again look at the rating If you're using it for signal rating doesn't matter because there's almost no power going through it But we're putting power through so the first time I do want to have the voltage be above Four volts because I want to switch five volts signal on and you'll know that, you know, some of these are 12 some these are six But there's also, you know, this one Which is looks very nice, but it's only four volts so Sorry, gotta go can't have four volts because we are switching a five-volt power through Okay, next up I only want, you know, normally stocking parts because I want to be able to get it and Then let's look at what's available All right, cool So you'll see some of these, you know, 100 milliamps some of them 300 milliamp 300 milliamp the only thing is I do want it to be You know one of the things I'm doing here is It's a DP DT Yeah, which means there's two independent switches and each one has the contact rating. I Double them up. You see I parallelize them which on the board looks like so and That means I can get double the current and the voltage is the same but the amount of current going through the switch is essentially doubled So we do the same thing for relays by the way Just be aware like with relays that you know in these switches there might be a slight, you know microsecond delay between Connectivity just make sure that there is no There's no risk of the cross connection Okay, so I was going to Look for current so, you know, I do work to have You know at least 200 or 300 milliamps per Switch because I'm gonna double them up to 100 milliamp is a little bit too low Because even doubled up that's 200. I really want to be closer to 400 or 500 and then Let's look at what's available by price So there's a couple options here So this one's right angle. So, you know, even that's a kind of a nice switch not going to use that This is a DP 3t, which I don't want This one is kind of nice, but it's SP DT which means I don't get to double up the switch So actually I'm gonna go back and select only DP DT style Okay, cool. So now we're talking so these you know, they're they're I don't actually know 100% that they're exactly Pad compatible. I have to you know, I'm gonna have to look at more detail in the data sheet to make sure that the switches fit on the pads if not adjust the pads and the Footprint, but there's a couple good options here You know this one particular ironically, you know the cheapest one the one that they have the most in stock is actually pretty Nice, it's going Which means that it has good mechanical stability, which I really like like it's there's a So the 360 of this it's got you know the the pins that go out to the side So mechanically stable It's got a nice long actuator. It's pretty simple but you know effective and then it's six volt 300 milliamps rated Which is all so nice and if you look at the day I will I'll say one thing really read the data sheet by the way to make sure because sometimes the contact ratings Differ based on the voltage like for example here It turns out you can actually go up to 30 volts DC, but you'll only get a hundred milliamps So just just be aware like the rating you know that contact rating will if it is actually dependent a little bit not on voltage and current but you know the The product of the two So be sure to watch out for that and I'll also tell you The electrical life 5,000 cycles, which I think is fair. This is gonna be switched all the time and You know seeing K makes pretty good switches I've used them before and you can see you know they have a through-hole version and Then this is basically the same switch as the through-hole because they just bend the like the leads out And then check the footprint and then they also have a version of this switch Which is Hold on Let me find it at this one same switch, but no not this one Not this one. They're all the same this one. It's still DPGT. There's two independent switches But the leads are bent under so You know mechanically not quite as strong although it's still you know the pads underneath there are still long enough I feel like but if I need a little bit more space if this switch ends up being bigger than I expect I can go with this version so it you know conserve space on the PCB But for now, I rather like this one and it's it's really expensive to you. It's you know like 40 cents in quantity Six volt and 300 milliamps. So You know one of the things that I do is whatever switches I use that You know, I try not to have multiple versions of similar looking things with different ratings because I find that that's Just accidents are waiting to happen, especially with rework or repair or whatever So, you know, even if I have boards that are Using a slide switch for signal. I would still use this hefty power rated switch Just so I only have to stock one item So let my great search pick