 The great search brought to you by Adafra to digi key lady user powers of engineering every single week to show you Yes, you how to find things on digikey.com lady data. What is a great search of the week this week? Okay, this week. I was working on this little infrared emitter and Infrared LEDs are really useful for controlling remote control stuff, which there's still a lot of like TVs still use IR remotes Stereo's often use IR remotes air conditioning units. In fact, I just saw a post on on hacker news about somebody who Used an Arduino to turn on and off the air conditioning unit in their computer room To keep the computers nice and cool and they did an automatic way by just having the Arduino like every three hours or whatever when the temperature Changed to emit the IR codes to turn the Air conditioner on off. So let's go to the overhead real fast. I'll show the design and I'll show how I spec the LED So for IR LED, so this is you know power ground and signal wires come out here you want to have a power FET because our LEDs are Different than normal LEDs normal LEDs, you know indicators non Illuminating LEDs you really want to drive that maybe five ten or twenty milliamps That's kind of what the LEDs are designed for in friendly. These are different The dies are much bigger and they're often heat sunken heat sink and they're intended to Allow you to put continuously 100 milliamps through them and they can peak at one amp So like really like they're they're meant to blast not for a very long time You want little spikes for the signal the infrared signal that is modulated at 38 kilohertz or so But you do want to blast that very very powerfully So this breakout board just you know, you can see the signal comes in. There's this fat There's two choke resistors just 10 ohms. Just you know, you should have something there Even if you're drawing, you know amp through it. You want to have some resistance. I should be a thermal runaway And then I have two IR LEDs. Maybe I'll wire this up again really fast so people can see the the two directions there's Two SMT LEDs, so this is the LEDs off and then I'll Turn them on So now the IR LEDs are on so you see there's two IR LEDs one is Right angle and one is vertical And then you know this way you get nice coverage. This is continuous, you know, obviously I'm powering it continuously I've measured it's only a hundred milliamps. This is this is totally safe to do But in general you wouldn't want to have the IR LED on all the time you would again flash it still To make this design inexpensive. I wanted to go with SMT LEDs So there's no through-hole process. No hand soldering Even if it means that the LEDs maybe are not quite as bright. We'll see maybe we can get them as bright It just makes it a lot easier to manufacture. So let's go to the computer and Ooh, it's actually a little toasty So this is the IR LED that I normally have used we use this in the TV gone can't a lot of projects This is the IR 3333 5 millimeter infrared LED The wavelength is 940 Nanometers that's important to know there's some infrared LEDs that want 800 but 940 is like 99% of remote controls Um They are you know usually made with this chip material the forward voltage is quite low It's usually like 1.3 volts much lower than you'd think or 1.7 volts But again the continuous forward current 100 milliamps continuous and then peak For a current is one amp. So the important thing that I want to note is the Flux Output for the radio intensity. So this is how much, you know, how much light is being emitted Obviously the angle varies, you know, sometimes you get 15 sometimes you get 40 degrees the basically 20 milliamps you're gonna get 20 milliwatt 100 milliamps you're gonna get 85 Milo and then Current for current one amp max 750 and that's these are these are quite good We have turned off many an LED with what many a TV with these LEDs on the TV gone You know with a hundred to one amp current draw So I want to find the LED that's similar to this but again service mount. So We're gonna go. I'm gonna dig a key. Glad you asked so let's look for infrared LED and Note that there is You know this this section UV infrared and visible will go here And if you feel like it if you don't want to even have that, you know, some search You can go just to the cat category. So the first thing is that, you know, I only want active products and I want Only the infrared Infrared color visible not exactly sure what that means. So I'll just select it Next up the wavelength is important to me because I need you know, it needs to be the 940 ish nanometer I can't use any other color so I'm gonna school down and Find 940 And I'm okay with like maybe 950, you know, that's not the end of the world 935 Yeah, I can be plus or minus a couple nanometers Okay, let's look. Okay. We're starting to get some good LED some surface mount some these do look like the right angle quite nice, but let's Let's make sure that I'm looking only at surface mount I'll give you surface mount surface mount right angle and and dash just in case, you know, something filters through And then so now I'm looking okay These are looking really good and there's actually quite a few options. What's another nice thing is they're all in stock Which is pretty sweet So next up let's filter because a lot of these have the radiant intensities is Kind of low, you know, some of these are as little as 0.5 milliwatts. I want something pretty powerful I want something that I can drive at High currents again. Also, some of these don't have High forward current. I want to do at least a hundred milliamps. So Although I don't completely trust this number to be honest this DC forward max because that again might be continuous whereas if I'm gonna Be sending a spiky 38 kilohertz signal, maybe it's okay. That said, I do want to get a slightly better Radiant intensity out of here. So Remember the previous one was 80 milliwatts or so at a hundred milliamps You know, let's do maybe 60 and up Of course, some of these are at higher currents, but I feel like if I get this You know, I definitely don't want anything less than 60 milliwatts at a hundred milliamps. Okay, fly and Then finally, I think I'm only gonna look at stuff. That's normally stocking and let's see what we've got here. So Lot of options some of these are definitely not right angle like this is definitely not Right angle style still it's kind of good to see what's available Let's change this to right angle Only and We'll see what what comes up. This is not a lot of options here, which is really which actually kind of good So some of these are interesting. So this is like, you know, it's a through-hole LED with like a little bent legs Kind of cool, but not super excited to pick and place this it's a little bit of a weird package Some of these look really good. You know, you can see they're thicker so they'll sit flat on the PCB No, this one is a kind of a cute guy actually get the black little emitter look to it Let's um, let's look at what's up with the weighted intensity. Some of these don't have the radiant intensity Indicated so I have to look at through the data sheet That's how it is But let's look at let's just sort by price. Let's see what what comes up here So this one looks really good Uh These are good, but they're not available. So that's kind of a bummer. Oh, let's look at pricing with 1,000 pieces so I can actually get like a good sense of it. So these are out of stock. So that's that's not that's not great Let's see this is orientation. Oh, I can check the orientation as well. Let's do side view So that gets rid of some that slipped through Okay, ooh, these are good. So this is side view side view. Not that even though this image is showing it pointing up It's actually you can see it's thick. It's meant to be side mounted Not uh Not fun mounted looks like it looks like there's a couple good options. So I like I like these but let's look at This top one Because this says 100 milliamps forward current and 92 Uh milliwatt so that's kind of good looking at the data sheet Okay, so good news that this is really side view. There's a little mechanical pattern center. So that's good Let's look at this. Okay infrared looks like you can do a peak of 1,000 milliamps, which is nice Forward current at 100 milliamps 940 92 which is good. That's a good amount of Brightness they don't have the radiant intensity at one amp, but it does say you can Amit at one amp so You know, I think they're like, well, you know It doesn't look like you get. Oh, no, you do. No. Oh, it looks like you can get It shows you that it's almost linear. So at 200 milliamps You'll get 200 almost percent of the radiant intensity of a hundred milliamps. So I guess that's Better than nothing Again, most things don't get actually driven at one amp. They get usually driven or about a hundred milliamps But it looks like you can you can max it out as long as you have a Duty cycle of under 1% which you know, you would be for infrared. So this is it. This is what I'm gonna go with this is a nice LED and I like the nice thick pads mechanical brightness is equivalent to the five millimeter LED and The price is really good to the prices, you know, 20 cents or less in quantity and it's in stock Congratulations in a lot