 and welcome to Desk Lady Aida. Hey everybody, welcome to Desk Lady Aida. It's a Sunday night. Happy Mother of Dave, those who celebrate. And we're here at the desk where I'm doing electronics as always with me is Mr. Lady Aida. Word to your mother. I'm camera control. Okay, let's kick this off. We're gonna do a pretty fast show. We got a lot to do Lady Aida. What are you working on this week? Okay, well first up I had a bunch of samples so I thought I would show them off. So on the overhead, the first sample is this conductive rubber sheet. So this, we have in the store a rubber cord. But this is I think used for like EMI gasketing because it has resistance. Hold on, let me dial in my multimeter and then I can measure it. So this has 300 ohms resistance across it. So it's flexible, it's conductive and the resistance does change with stretching, not a ton, but it does. So maybe I'll just hook up these alligator clips so I can demo it. Maybe I'll put the alligator clip here. And there, and then I'll just have this on the screen. So naturally it's about 350, whoops. And then you stretch it, it goes up to like 400. I'm stretching it like this. You can see it's like 400 or so and then when it bounces back, it changes again and then eventually it slowly goes back down to the original resistance. So kind of interesting material was good for. You could make sensors where you could make like weird conductive shapes that or capacitive type sensors that are flexible and curvy. So this is I think half a millimeter thick material. So I got half a millimeter and one millimeter. So that's one sample I got. Another sample I got is this motorized pots. Let me move the multimeter out of the way and turn it off to save battery. One moment, put it back on my desk. Okay, so this is a motorized potentiometer and you can see the motor here and this is a five volt motor here. And there's a little gearing kit here. I don't know if there's like multiple, you guys had one gear. And then there's a little belt drive that goes up. So this still acts like a pot. And you can move it back and forth. And here's the potentiometer pads here. So you can, and then there's like the one, you know, there's always one on the other side. So this is like the one pin and then the other and then the center. And then the third pin, cause you wanna like, why is there three pans? There should be, sorry, there's four pans total cause there's one here and there's three here. The reason there's four pans and not three like you'd expect for like one, two. And then the slider is because it's also like a passive touch pin, which is the resistance. It's just actually connected to the metal, I think of this at the check cause I just looked at the data sheet. So it'll let you know when you're touching the slider. Of course you have to have a metal slider cap, but that way you can tell when somebody's touching it because if you're driving it and somebody's touching it, it should immediately release the drive and let the person move it. So for my demo, I've got, I just hooked up a Metro mini and I have my little DRV 8830 driver chip going on there. And then let's see, I thought I had this going. Maybe I don't, oops, I hope I didn't reprogram it. I might have reprogrammed it. One moment, let me check my Arduino port. It thinks it's powered, but it's not. So why not? Uh-oh, I hope I didn't break it. Well, I had the live video, I had the video that we shot. I guess I can get that in case. Yeah, I wasn't expecting this to not work, but I also, I don't know if like maybe something got loose. I also could have like broken it. All right. You wanna play the video? Well, it'll just take me a second or so because it's not available. Okay, why don't you, why don't I look at something else and then I'm weird, I have to figure out. I also never used this motor drive before, this was like the first time I used it. Another sample I got is this DWM-1000. So this is a ultra wide band module. I actually got these a while ago and I've been needing to use them and I kind of get around to it. So these are kind of interesting because they look like, you know, wireless modules, but what they do is, yet, you know, there are 2.4 gigahertz and I think it's based off of like ZigBee or something. But what they're used for is, I guess they use like ultra wide band signaling and use like the time of flight or like the frequency change bounce rate or something between these modules to do indoor positioning, which is a really hard problem. A lot of people are always asking me, how do you indoor positioning? Like I wanna know where in 3D space something is in a room and I'm like, that's actually really, really hard. It's quite easy to detect outside where you are using GPS. It's good within 10 meters, but if you want something precise, you know, yeah, you can do like Bluetooth, RSSI signaling, but you know, these ultra wide band modules are kind of the only solution I know of. I know that there's also like, you know, expressive try to implement something like this with their modules. And I think also there's also an attempt to do this with microchip, one of the microchip boards. They had like some capability to do like time of flight distance measurement, but what's nice about these modules is they actually have like API and code ready to go. So I designed a feather wing to go with these because they fit very nicely on like a feather wing shape. They're very, very slim. And they use SPI and again, there's, you know, the company publishes Arduino library code and Python library code to interface with them. So the only thing is, you know, I bought four because you need to have, you know, two base stations at least, probably three base stations in order to triangulate where in space this thing is. So probably three, you know, static devices and then one free floating device. And then you can, you know, as many more free floating devices you want within your 3D space. And so one thing that's really common, you know, folks who contact me is they're doing like theater or like escape rooms or interactive art. And this is, you know, a problem they're trying to solve. Like I want to know when a thing has moved a certain distance or to a certain part of the room. So another funky sample. So this is the DWM module kit. There's a new version that just came out for 3000. I don't know the difference. I think it seems, it seems like to have a couple updates. All right. Did you want to try to? Yeah, the video. Okay. Why don't you play the video because my thing stopped working. Past us did a good job. Yeah. Hey, what is this? This is a motorized pot. Not sure if you've ever seen one, but it's a potentiometer and you can see the potentiometer points here. And then there's a motor that connects to it. And it actually goes through this little gear and it can move the slider back and forth. So you can either, it has a touch sensor too, by the way, for capacitive touch. So you can either set the resistance or you could have it automatically set to like a presetting. And I'm controlling it with this breakout board that I kind of like designed right before COVID and then I've never finished because I got distracted from COVID with a DRV 8833 STEMI QT breakout. So good news is this works and this works and this is kind of fun. Seems alive. It's almost like a possessed electronic. Yeah, it is a little bit like an angry. Yeah, less, more. No, I'm angry. I was like, hi, here I am. Yeah. Maybe it's waving hello. Yeah, hi. All right. So it's the motorized pot being driven by a STEMI QT motor board. Okay, we're back. Okay, one second. It's gone. I have another sample I thought I could maybe, maybe, maybe, maybe, because I don't remember which one of the samples I was testing. Also have this sample. Maybe I'll quickly test it out. Okay. Yeah, some of the things were live demos. Well, we had a video, so it doesn't matter. I could have even pretended that wasn't real, but I feel like- I think the motor driver, I think I best remember. I feel like you should always be honest with the- No, no, no. I think I broke the motor driver and there's this other. Oh, you know what I can do is I can just, I can just connect it up directly to power. So hold on. Let me, let me grab my screwdriver and then I'll just, we'll do it live. I'll just remove. All right. How about, do you think you can handle a question while I'm doing this? Yeah. I'm just doing the chemical. I'm just gonna- Stuff? Yeah. Okay, my ESP32 S2 feather won't go out of its FTHR S2 boot state when I upload the CircuitPython UF2 file to it. It just resets and comes back with neither the UF2 file nor CircuitPython. Do you know why? Post in the Discord for CircuitPython because it's very hard to help when I can't type right back. Yeah. Post in the Discord, help with CircuitPython or just post in the forums. Yeah. You're probably just selecting the wrong file. Yeah. You might ask for some screenshots or some other info. Okay. So- It looks like you got something on. Yeah. I'm doing manual H bridge. Yep. So, yeah. This is what the motor driver would be doing. Just going back and forth. Yeah. But it does work when the motor driver's busted. And I thought these would be really fun to have. They're used in AV boards, like really nice ones where you can like make presets. This is kind of fun. I can like move it and I'll shift back. It's, you know, they're used, you know, you can create presets and then like you can load the preset for like whatever music type you're doing and all the filter adjustments. You know, if you have like a cutoff or band pass filters or, you know, a treble bass adjusts, they will all automatically go to where you want. And then once it's preset, you can adjust it. So you're not like sitting there and like tweaking, you know, 25 sliders all at once. So this is fun. This is from Alps. But I don't know the part number off the top of my head. I don't know, maybe seven, two CC. But there you go. Yes, this is a, this is one type. There's another type I got. I didn't like this one as much because it was, this motor was chunkier. Even though this was less expensive also, I didn't like this open top. I liked that this type has a kind of a more closed top and doesn't have the belts as exposed whereas this one has, you know, this exposed belt, which I thought was a little scary. So this sample did not make it. The other sample did. Okay. I think that's it. Oh yeah. And then I'll, I'm going to transition. How long? I'm going to just put everything away. Put everything away. Okay. Hold on one. Okay. And then finally the thing I'm working on tonight is my NAU 7802 testers. So this is the NAU 7802. And this is a Wheatstone bridge. So actually a 24 bit ADC, which I'm using as a Wheatstone bridge amplifier such as for use with strain gauges. So strain gauges, you know, you connect, they're basically Wheatstone bridges. You connect two corners of the bridge to power and ground and then you can measure the differential. It's like the resistance changes through the differential ADC measurements of the white and green wire, which is awesome. The only thing is I couldn't get these chips for a really long time. And then a shipment that I ordered, you know, it was affected by the chip shortage. Pretty much everything for new Votan got really affected. But I finally got my shipment in. Yay. So these chips came in, you can see the prototype. So I'm just working on the tester now using this Metro board, so Arduino compatible. And what I'm going to do is this cable here, I've got to plug in, you know, to have just do a measurement to test the ADC, you know, I have this cable and then this will be cut off and soldered to strain gauge wires here, like one, two, three, four. And that way we can, you know, easily plug it in and then during test, you know, if you just squeeze this, it'll see that the resistance changes, the ADC changes. Oh, okay, okay. Do you want to go on to grade search? Yep. Let's kick it right off. The grade search right to by a friendage key, lady, user powers of engineering every single week do help you find the things you need, lady, to what is on the grade search this week. Okay. So this week, because I am working on my NAU-7802 tester, maybe go to the overhead. I'll show that again. So the NAU-7802, it's a 24 bit AVC. It's got differential inputs, which you need because it's good for measuring wheat stone bridge type devices like strain gauges. There's a lot of other sensors that are wheat stone bridges that are very sensitive, although strain gauges are kind of the most popular. And so the NAU-7802 I ordered a few months ago and it finally came in, so I'll be able to make hours. But the thing is, if somebody else was like, hey, I want to make my own wheat stone bridge amplifier, I'd be like, hey, you can't get any because if you search on digit key, this isn't going to come into stock till like early 2023. So I thought for the grade search, what we could do is I could find you an alternative because I got mine, but maybe you want yours and you don't want to wait eight, 10 months until these chips come back in the stock. So let's identify another good wheat stone bridge amplifier. So I'm going to look for something that's 24 bit. I use I squared C, but maybe SPI is also good. So we'll look for both. And we want something that has differential inputs and something, which is pretty common with AUC, so I'm not too worried about it, is in stock and it has a programmable game. So let's go to the computer. So one of the things that's kind of nice about the N80702 is it has, you know, the rate isn't very high. The reason it's inexpensive is it's like, you know, you pretty much run it at 80 samples per second and that's great for just measuring weight. It's not good for measuring, you know, a lot of like EMG type sensors or whatever, anything that's precision that you need fast responses on, but for weight, weight doesn't change that much. You know, you put something on the scale and then, you know, you're okay waiting two seconds until you get a stable measurement. But one thing that is really nice is it has this built in gain. So programmable gain amplifiers is quite nice. It has this analog section inside that'll let you adjust the gain. Higher gain usually means more noise and so you want to have like a balance, but you know, the higher the gain also, the smallest signals you can read. So, you know, you want a balance of like being able to read small signals, but also not, you know, blowing out your range because if there's a lot of movement in the signal, your PGA is going to overflow your 24-bit reading. So you can dynamically change it, which is quite nice. So, let's go to Digikey. And so the chip I'm using is the NAU 7802, which is this chip. The dip is in stock. So if you happen to be okay with that, I do have lots, which is wonderful. But the chip that I've been using is the SMT, the SOIC version. And then if you look, you know, it's not going to be in stock for a bit and it could be even longer. So let's find a good alternative. So I'm just going to look for 24-bits. I'm not going to select the other inputs. I will only go with one ADC because you're always going to pay for more ADCs and you definitely need one. And they definitely want to be surface-mount. But everything else is kind of like up for grabs. Again, I don't really care if the voltage range is 3.3 volts and also features, you know, there's always a range of features possible. And the configuration also might be different. Also, I'll show you the differential in single-ended. Like pretty much any ADC, once you get to 16-bit, they're all going to have differential inputs. It's actually quite rare to not see a differential input on an ADC once you're paying more than like a couple of dollars on it. Okay, so let's go for active. And again, we're going to later filter for in stock. But I'm going to exclude marketplace so we only see, we don't see like the reseller once. Okay, just samples per second against, we don't really care about the samples per second. Input type, I don't actually totally trust this. So I'm going to ignore it as well. And then what I will do is, I'm going to go for the data interface. So SPI is okay, and I want I squared C. I2S I don't want because it's audio input and parallel I don't want and LVDS I don't want. So I'm just going to go for SPI, I don't know what serial is. A serial could be your, or it could be SPI or it could be I2C. And then let's search for those. And then, okay, so there's a lot of options, which is good, but a lot of them are kind of expensive. So I'm going to just sort by price because that's what we care about. And as expected, the NAU-7802 are like the cheapest. So the ones that we can't get are about like a dollar or two, which is unfortunate because we can't get them. But there is this one over here, this 3565 from microchip. One thing to notice, it has much higher sample rate. It has 153K, which is great. It still has two inputs. It's also differential and seeing on it. However, it's only I squared C. One thing that's a little, I was a little at first I was worried because I was like, oh, this doesn't have programmable gain. It also has a lower voltage range. Like it only goes up to 3.3 volts. But when I looked at the datasheet, because I was like, well, I got to look to make sure does it really not have gain. It actually does have programmable gain. It goes up to 64 times gain. Whereas the NAU-7802 does 128. 64 is still pretty good. I think it's probably fine. It has external clock selector, just like the NAU. It has differential inputs, like you'd expect. There's gain error calibration, so you can do, and it's very tiny. It's kind of cute. It's like, hi, I'm just a little, I'm just like a little bored here. And if you search for a typical application for a ratio metric, a Wheatstone bridge, pressure sensors and load cells, it's very common. So this is what it would look like. Pretty straightforward. Like the NAU, it's kind of nice. It can do the reference in and out. So you have any, if you're doing the ratio metric input, you want to make sure that your positive input to the Wheatstone bridge is exactly the same as your positive reference to the ADC. And so any noise gets canceled out, because again, you're only measuring the difference between the voltage divider between the positive and the negative rail on the bridge here. So what's nice is that you've got the reference in plus and the reference in minus and you just make sure they match up and they just need an RC filter. So this is for like, RTDs for pressure sensors for load cells like the before. You also use it for other stuff like thermocouple amplifiers and stuff which need precision differential inputs as well because you're measuring little microvolt changes on your K-type thermocouple. So this chip will do the job quite nicely. Looks like there's a few in that family, the 356X, they're all fairly inexpensive, comes with a couple options. And this one at least is in stock. So that's great. But let's also filter for only in stock. The other option I found, so that one was SPI and you might be like, well, I really don't want SPI, I really want I squared C. Well, I squared C is a couple but most of them are not in stock. The first one that's in stock, that's I squared C. Let's quickly go over here and select I2C. Not a lot of things in stock or normally stocking, but this one did come up. This is the ADS1219 which I downloaded the datasheet. So this is fairly also pretty fast. It's a one kilosample per second. ADC, this doesn't have as many programmable gains that it only goes up to a four times gain. So I don't know if it could be good enough for we stone bridge, but I think it would be tough without another amplifier. That said it has four inputs. So this is like, I think you could use it with a we stone bridge but I think you'd probably want, you wouldn't get as much signal, you'd probably want amplifier. Yeah, they don't have a recommendation. So it's the one that's I squared C but it's not great for that use purpose. However, it is I squared C in 24 bits. So depending on what you're using it for, you know, if it's not a load cell, it might be okay. If you are using a load cell, I would probably, and you don't mind going with SPI, I would say that the MCP356 series is your best bet. So you got two options to pick your poison, differential options. That's a great church. All right, and that is our show for tonight. Wonderful. Maybe you can try to take a look at this one. This is a question from earlier. What was about this? I don't know if this was related to our show. I don't know what they mean by NAU Civito2 talk. We're just, it's an old design and I'm going to, you know, I couldn't get chips for a lucky year, but I can get chips. So we're going to, we're gonna finish the tester and we're gonna go into manufacturing. Okay. I'm not sure. Yeah, I mean there's been two years. So unless you were here pre-COVID, you would have missed when I first designed the board. Okay, cool. All right, I just wanted to make sure I didn't miss that. Okay, well thanks everybody. We'll be doing the shows during the week. We have lots of fun surprises, content we're posting. Thanks for spending your time with us. We very much appreciate it. We're doing this thing together. See you during the week. All right, thanks everybody. We'll have some live shows and I think Scott might be back doing his stream this Friday. Yay. Great.