 and welcome to Lady Aida. Hey, everybody, and welcome to my desk. It's me, Lady Aida, hacking on electronics. I did get to do a little bit of hardware this weekend, so I thought maybe I'd show off some of the stuff that I worked on, some of it. I didn't, you know, I had some successes, some, like, not as many successes, but that's okay, that's kind of what engineering's all about. So let's start, and just leave this board out of the way, let's start with, hold on, let me wire up this, this board first, so it's in the middle of doings. Okay, go on, awkward if this doesn't, oh, you know, I know, this is on the wrong panel, one second. Let's go to the overhead, and just give me one second. Do this, okay, so this is my UPDI programmer. So we talked about this design a few weeks ago, I designed two UPDI programmers based on open source design. One is, like a plain UPDI that can switch between three and five-volt logic, and it uses a CH340E, and it's got a little regulator on it, and like a little connector here, and the thing about this is that you can use this with any, like AT Tiny or like AT Mega Chip that uses UPDI, but for some of these smaller chips, this AT Tiny 816, which I'm actually gonna look real fast, can you go to the computer real fast? So this is just because I realized, it's not on pin 13, it's pin 10. So this, let me have this upload while I talk about it. So these AT Tiny chips are like really, really tiny, they're actually 0.4 millimeter pitch. I like them because they're very inexpensive, they're like a dollar a piece, and so we use them in our C cell boards, or I squared C to whatever converters. And what's nice is that instead of having like a six pin, like two by three header, or requiring an open OCD SWD programming, you can actually make a UPDI programmer with just a USB serial cable and one resistor, although having a nice all-in-one programmer with adjustable voltages and everything is much nicer. And the UPDI pin, which is on the back here, is for these small pins, double usage, it's both a reset pin and a UPDI pin, a programming pin. So basically, they minimize, they maximize the number of GPIO, which I kind of like, but the trade-off is that for the smaller ones, not the two series, but the zero and the one series, the programming and reset pin is the same, which for my purposes is fine, I don't really need a hardware reset, but when I'm doing development, it would be really nice because instead I have to like cut and reset the power, I prefer to just have a little reset button. So let's see if you look, okay, yeah, go back to the overhead. So this is, I just programmed it with a correct pin 10, red LED blinking, and when I press the reset button, you'll notice it's in reset, the LED no longer blinks and when they let go, the LED starts blinking again. So this is the button acting as reset, and the reason I can do that is because I've set the UPDI pin to be reset and require a high voltage pulse. So this programmer is very similar to this design, you see it's a little bit longer and of course it's green, it's a prototype, but over here there's a little boost converter and there's an analog switch. Maybe I'll upload the design real fast, but what this means is that when it's time to program, when you open a serial port, it toggles the RTS pin ready to send pin high and low, and that connects to an analog switch which sends a quick 12 volt pulse in which kicks this into programming mode. Now ironically, the opposite is what happens on the Arduino reset circuit. So if you go back to the computer, let's see if I can find, yeah, okay. So I think this is like my design too. So this is like a reset circuit. The DTR pin connects to a 0.1 microfarad to the reset when the DTR pin goes from high to low, the pulse, the AC pulse goes through the capacitor, yanks down the reset signal low just for like 10 microseconds or whatever, 50 microseconds, just long enough to trigger the reset and that's how it auto resets the circuit. So this is kind of the same thing, but the opposite direction, it pulses high. So let me pull up the design and I'll show you all really fast. You PDI friend and then you have the high voltage friend. So I had to, I made a couple of mistakes I had to fix, but none of them that were that serious. Let's go to the screen, okay. So this is, you'll see the very similar design capacitor where the resistor, except this is the opposite when what we want is, no, sorry, it is the same way. When the RTS pin goes from high to low, that is when you send is activated because it's an inverted signal. This pulls down low, which means that this goes to low signal, which means that the 12 volt is, the 12 volt power rail is connected to the UPDI output. And then when this floats back up to VDDIO, the normally open connection RXD is connected to UPDI. So basically it just gives you a little pulse to 12 volts, which is kind of nice. And it's just an analog switch that can handle the 12 volt signal and then passes through the UART signal normally. And then what you have to do is, if you're using the teeny mega core, which I use, there's a little area called expert mode. And you have to uncomment this manually. It's not like selectable nearduino IDE. You disable, sorry, you remove the hash marks comments here and they add to the menu UPDI bricks chip without a high voltage UPDI programmer. And this is a fuse that you can do. So you can actually set that pin to either be a GPIO, so you can actually use it as like, meaning like one more GPIO, or you can set it to a reset. But again, once you do that, you have to pulse it with 12 volts every time. So I already set that pin up. So this programmer is good working. And so I've ordered it. So that's one design out the door. Another design I worked on, so let's close this, is this one's easy. So I'll go through this one first. So this is the DS4420, which actually like I started designing this in 2021, and I did a little bit more work on it in 2022, but it was just, it was just hit very hard by part shortages. And it's not a very important design. So I kind of like shelved it. And I was like, well, I'll get back to it later. But now I'm digging, I have this box. It's like all the things that are pending that you should revisit. And I'm kind of picking them out as I go through the year. So the DS4420 is an interesting chip. It has an I2C input and then has audio, differential audio in audio differential out, and it's a gain controller. So it'll do volume control without a potentiometer. It's fully digital, controlled over I2C, which is kind of like kind of cool and fun. A simple little chip. But one thing I didn't realize is as I was, when I did the first design is it requires five volts on the VCC pin. It's not a 3.3 volt friendly chip, which is very unusual. Like that's quite odd. Most, almost every chip I use these days has 3.3 volt compatibility. Sometimes they don't go above 3.3. Sometimes they don't go below, but it's like 3.3 is kind of like the lingua franca, but this one in particular requires five volts. And so to deal with that, I just did another revision this afternoon. I had a little bit of coffee and added an AP3602. It's my favorite switch cap converter. Just about a hundred milliamps of clean five volts output. It boosts the VIN signal and then does an LDO on it. So it's basically like, you get the clean signal of an LDO without a lot of space required. You only need basically, input cap and output cap, but you only need a single one microfarad capacitor. So I love this chip. It's like 20 cents or whatever. I think we've uncovered it on a previous great search. So hopefully with this respin, I kind of wedged it over here. With this respin, this board will now be able to work with three or five volt logic. That can be useful if you wanna do like audio signal gain without having to, maybe you want to use a loader encoder or do it programmatically. So that's one revision. And the other revision is, I worked a little bit more on this S35710 timer. So this chip is a chip that I I covered on the INPI. And I thought it was very cool. It's a very, very low power 0.2 microamperes, which is tiny, right? Even the best ESP32 deep sleep is 10 microamperes. This is much, much lower. Built in, you can have just wire up a crystal and it can keep track of time and you program the time over I squared C and then it will trigger the interrupt pin afterwards. And what I wanted to use this for was a deep sleep situation where if you have a chip that doesn't do deep sleep, like it has no low power mode, like let's say you're using an RP2040, which has okay low power, but I don't think it goes below like maybe one milliamp or something. I don't know, don't hold me on that. But let's say you had a chip that was like, oh, it doesn't go below like one milliamp and you really want microamp here. What I wanted was a way to like a chip that you could program and say, hey, shut me down for 10 seconds and then wake me up, like enable me after that 10 second or whatever delay happened. And I was trying to get this working, but there's a little bit of an issue where the reset, it actually did work except on power on because when you first powered up, the signal is high and what I would have preferred is that the signal is low at reset, like, you know, at startup because then the chip would be enabled, like I would invert it, the chip would be enabled and then it would, during the countdown, the signal would, the high signal would disable the chip and then after it's done, the signal would go low and it would re-enable the chip. But because when you first plug it in, the signal is high, it doesn't quite do what I wanted. And I was like, oh, I could like maybe do something where like the reset pin is below and then I have a diode until they pull it low and then I have an X or whatever. It got really complicated and I was like, you know what, I'm actually, I'm trying to use this chip for something different. We have in, oh, this is the DS4420 I was just talking about, so it's a cute chip, but yeah, it's five volt single supply, somehow like, I read that as like, oh, it could run at five volts, but it's five volts. You know, in the shop, we've got the TPL low power timers and these actually do that. These are adjustable with a potentiometer. I did, you know, I was kind of looking to see like, was there ever an I-squared-C version made of this and some TI, like Dave said in some forum posts five years ago, like, oh yeah, we're totally gonna make an I-squared-C version of this chip and then like, I guess they never did or I don't know. So, you know, that didn't happen. But this chip could be used as a watchdog. So instead of using it as like a low power interrupt timer chip, which would have been cool. Instead, what we can do is have it be something that gives us an IRQ if we haven't or, you know, resets the chip if we haven't kicked, if we haven't written to the I-squared-C port in a while, which could be like a good way to detect hang. So basically, you know, when you start up, the interrupt pin is high, you know, maybe that's tied to your reset signal and then you write the 10 second value of the timer and it starts counting down. And then you have to keep writing 10 seconds to reset it because if it ever gets to that full 10 seconds elapsed, it'll reset you by pulling the int pin low. So, yeah, I don't know. I mean, I think this is still a useful chip, just not as useful as I would have liked. And then as I was looking, I found this other kind of cool chip. This is a resistor set oscillator and slot 23 with like a divider. I might make a breakout for this. It's kind of a cool little chip. We have a programmable version, like the SI 5351, but this is kind of cool because maybe like the little pot, you use a pot to change the frequency. I don't know, it's kind of neat. So the way I just redesigned this is I have a little, I added an inverter here. So the output can either be connected to the interrupt or can go through an n-channel FET to invert it because maybe you want like the opposite direction and this would just be like an easy inverter that's also open drain. So then a little slide switch lets you select which one you pick. So that one is also ordered. Okay, cool. That's kind of like what I've been working on, right? Is there anything else on that list that I sent you, Phil? I think that's it. That's it. Okay, great. Let's go to the great search. The great search brought you by digikey and April, you know, you use the power of engineering to help you find things on digikey.com, Lady Eda. I'm not gonna be able to find it. You know, there was a tweet. Okay, so today what I was gonna do is I saw somebody on social media and the link is in the text, but I don't have it. That's okay. So check the text for the YouTube. And they were fixing a Sega Master System and they needed a 7805 to replace it. And somebody was like, oh, you know, there's also 7805s that have higher current output. And I was like, oh, you know, I never covered just finding your standard 7805 circuits. So pretty much every engineer, when they start, you know, doing electronics, one of the first things they do is they build a power supply off the 7805. Off the 7805 because, you know, basically you give it seven to 35 volts. It gives you five volts output. It's like pretty indestructible. You know, you do have to give it fairly high dropout voltage, which is one of the downsides of the 7805. And if you want to give, if you want to actually sync 1.5 amps, you have to heat sink it. Like you can't, you can't just be like, magically, you know, one and a half amps comes out. You do have to have a heat sink. And so I think we have in this shop, and of course, Jijiki has tons of, you know, if we haven't covered heat sinks, maybe I'll do that next time. You'll definitely want at least heat sink. You can even see this is a 7805. This one will give you like a little bit more juice out. If you really want to get a lot of current, use a very big heat sink. To be fair though, if you're going to start spending money on a heat sink and stuff, I would actually say like, you know, these days you can get a very inexpensive buck converter for the same price. I think we have a DC, DC buck that is, yeah. Like these, for example, but there's tons of them. You know, Treco makes them, other people make them. They, you know, take the same regulated output with the same LMXX regulator spacing. But because they are buck converters, they're extremely efficient and you don't need a heat sink. So I'll definitely recommend, you know, and then the Jijiki stocks use as well. Maybe again, like I'll show them really fast. Using these is definitely an upgrade. They're chunkier, so they may not fit. So let's go and just, let's just quickly show the 7805 options. Okay, so they're an LDO. And let's only look for in stock and shipped by Jijiki and Active. So ones that will ship. Let's do the stacked. And then 7805, the 05 means it's, you know, 5 volts output and then current output. So you're like, oh, 1.150 milliamps. Well, you can get 7805s in other packages. They come in a SOT23s or whatever or SOT223s or just D-Packs or whatever. So you'll get them with different current ratings. However, let's go for 1.5 amps because it's like a good, good chunky amount. And then we do want it to be a TO220, which there's a bunch of different families. So when you see like the ABFFP, that's usually the thickness. Sometimes they're like a little bit bigger or they have like slightly larger tabs, something to watch for. Any other options? So a lot of options. I mean, I would definitely say you can start with, you know, the 7805 classic linear voltage regulator in TO220, you know, available for like 50 cents, 20 cents in quantity. So like you just need a replacement. This will do the job. And then I think somebody was mentioning that there's also the 78SO5. So one thing is that they like to, people like to stick other letters in. So this one is a version that does two amps, although this is no longer manufactured. I don't know, maybe we'll quickly, just as we already found that regulator so fast, maybe we'll find another one that is TO220 and maybe you can do two amps. So let's do fixed and oh my God, there's so many options. We'll do through hole and okay, oh my God. Okay, down to a thousand. We want positive. It looks like there's a lot of series chips. One thing to verify is, you know, like some things won't be called 78, but they're still pin compatible and I'll show you the pinout compatibility. And then, yeah, let's look for something that has at least two amps of output. Let's say we want two amps again, you'll need to heat sink the heck out of it or pick one with a very low LDO. Okay, and then we want TO220, three pin, okay, that's my options. 70 options, let's see. Let's pick one that's in stock and only available at Digi-Key. Okay. All right, so the mic, somebody's actually a little bit familiar. So LT1085, whoa, that's expensive, $11. Let's look at pricey at a hundred pieces and okay, pricing. So let's look at this one, for example, this is the LD1085 and I'll tell you what to look for. So this one can do up to three amps. Let's see the pin configuration. Yeah, so it's input, output, ground. Ooh, I think this is actually different than the standard 70805. Let's look at the 70805 pin out. So thing to watch for is not every regulator is standard and I believe it's input, ground, outputs. Okay, down, down, down. Input, ground, output, yeah. So this one, despite being extremely cool, will not work because the pin out is slightly different. So 1085 series, you can't do. Oh, let's look for one that has five volts output, output fixed, five. I mean, maybe the 78SO5 is the only one. I actually didn't look at this ahead of time. Okay, 1085 we already know. How about this one, BA50 from Rome? Let's see what. Oops. Okay, let's see. Let's see how they got some big packages. LDO up to two amps. Let's look at the pin out. Cross your fingers. Input, ground, output. Okay, this one will work because it's got the right order. We don't use pin, this is the three pin version. 220FP, VIN input, ground, output and that matches input, ground, output. So this is another option. So if you want a two amp output five volt regulator, you could also check out the BA50DD0T. It's gonna be more expensive, but it's got this nice heat sinkable package. You can see how chunky the package is. It's designed for clamping into a pretty big heat sink. Okay, cool. Well, at least I found two options. Your standard 7805 and then your high current output non canceled, non discontinued 7805. So two good options if you're repairing electronics. Again, if you're using, if you're designing a new thing, stay away from the 7805 because it's got that huge dropout. And I would just go with a buck converter these days. They're so inexpensive. I think we've covered it a couple of times like a five volt two amp buck converter, especially if you're okay with doing SMT. You know, you can get those regulators and inductor for about the same price, it's 7805. That's great search. All right, thanks so much everybody. And special thanks to everyone who's been patient. We have about half the 80box 21s shipped out. We're gonna get to the rest of them soon. We have an 80box unboxing, March 20th, Wednesday, 8 p.m. Thank you so much, very much appreciated. You are what makes this go. We are an independent open source hardware company in New York City manufacturing. This is it. Yeah, that's it. Thank you so much everybody and we'll see you. There's another one behind me, by the way. Like that's it. Yeah. So we'll see everybody next week. All right, have a good three day weekend.