Chasing Oscillations

Hello, and welcome to the Mac fab engineering podcast. We're your hosts Parker Dohmen

and Steven Craig,

this is episode 114. And so before we start today, we have some events that we want to announce. Every Friday at 1pm Central, we do a Twitter chat, which I talk to our followers on Twitter, talk about basically PCB design engineering. Current hashtags are my favorite because I get the meme it up. We also have the hardware meetup that's here at macro HQ. That's the last wind note, third Wednesday of each month now, we moved it from the last Wednesday to the third Wednesday. So that is going to be at April 18. And this This month, we're going to talk about parts of the Arduino which I'm going to be giving that talk and then trade German will talk about off shelf enclosures and customizing them for your product. To Tom trade German was on some podcasts long ago, yeah, long ago. He's actually been on two podcasts. He has

been on two podcasts. And I think we actually talked about this. Even on one of those podcasts. He's come into McAfee have a handful of times showing off his custom enclosures and how he got those made. So this will be a good one. Yep.

And then we are going to be starting a Houston hardware happy hour. And that's going to be the first Thursday of each month. And the first one is May 3, because technically the first Thursday would be in a couple days, but it's kind of short notice. So this is going to be at slowpokes, which is a beer coffee food place that's really close to the fab.

It's a super hipster coffee place.

Yeah, but it's awesome. It's a really good place to bring your hardware hacks and that kind of stuff. I wanted to find a place that was gonna be it's kind of quiet there so you can talk to people and show off your your widget that you built. So yeah.

Awesome. May 3 at slowpokes in Houston. Yep. And

every every podcast, I'm gonna reiterate these this stuff. So

what time? Is that for the 6pm 6pm?

All right. Right after work. Perfect. Yeah. So Steven, what are you up to? You're supposed to have a synthesizer here for me to play.

I you know, I am. This, this was supposed to be the episode where we would have Parker actually played this in. And, and we had actually planned on doing it. And then I texted him earlier today. And I was like, oh, you know, I forgot I left it in my wife's car. And she's out at work. So it's, it's gonna be a different episode that we do that. Regardless, I have some other stuff to talk about. Because I always have stuff to talk about. That's good. I don't I've actually been doing some, some some design work recently on some voltage controlled filters. Okay, so a lot of breadboard work. breadboarding on the FX dev board, actually, you know, the thing is, I haven't used that thing in months. And then I started doing some like actual breadboarding. It's like, Ah, I really wish it would have done well, because it's like, I love it, it's so easy to use,

I think we should push that project again,

along with all the hundreds of 1000s of projects that we're gonna we're gonna push Yeah. So. So regardless, I've been I've been designing some circuits. And for voltage controlled filter circuits, most of the time, they're controlled, using a current as opposed to using the voltage. And when when you want to control something using a current, you can, you can typically just, you know, put a voltage across the resistor and you'll get a current out. And that works pretty well. But if you're just using like Joe Schmoe op amp circuits, you're only ever going to get like a linear response such that, you know, you put in a voltage, if there's a gain on it, it's always just gonna be like a straight line with, you know, some slope to it. So to get more like bang for your buck, in effect, you can create an exponential current force. So that's, that's a way that you can put in a linear wave and get way more range out of it, because the low end and the high end are exponentially apart from each other. And so you can get wider sweeps on whatever you're doing, it's actually a really good trick to just increase the range of whatever voltage, you know, you want to control any circuit, which doesn't have to be a filter can be anything. And there's some really traditional circuits out there for creating an exponential current. And most of them rely on the kind of VBE tricks of BJT transistors, such that you know, if you have a VBE, which is the voltage from the base to emitter, do you have a VBE of like zero, up to about point seven? Yeah, that transistor is not in it's like saturation, right? It's not in its full range. That kind of transition between zero and point seven volts is exponential in full marks in how it works. And so if you actually take two transistors, and you kind of pair them up such that they're emitters are connected together, you make what's called a differential pair. So putting these two transistors together, you can kind of cancel out a lot of nasty terms in the math, and you can make something that works really easily to convert a voltage to an exponential current. So I've been trying to do this recently, and I've done these a bunch in the past. They're kind of like a circuit block for me at this point now, because I've done a bunch of them. But I started making a new one the other day and I you design? Well, yeah, a new design somewhat. It's just like a kind of like a rethought design, like, the design is still like the core is effectively the same. It's just like a few things that are different. And I spent like six hours trying to get this thing working. Like, it's not that there's not much going on in this thing. And it's just it was blowing my mind because this thing was not working at all. I put in my known voltages, everything was working exactly the way I thought it should, except it wasn't spitting out any current that was intelligible, I had previously simulated this entire thing. So I've got my computer to the left me that has a simulation running of showing me like exactly how it should work. And then I've got my breadboard on my table, and it just ain't doing nothing that I expect. Most of the circuit is working like I'm turning pots, and I'm seeing voltages swing in the way that I expect them to. And I made a cardinal mistake. And and I've kind of the whole reason why I'm talking about this is just so like, other people won't make this mistake. This whole circuit that I'm trying to do design and build right here is just DC. So and I don't have my scope on it, because I don't care. Like literally I just want to plant it on a DC value and it does something. Apparently, I didn't put enough compensation on one of the op amps that helps control the entire circuit or the entire differential pair. And that op amp is teetering right on the edge of zero volts. And zero volts is kind of like bad territory and puts an exit on its output. Okay. Well, it's sort of I have to show you this. And

this is between what to 15 volt rail, so 15 Plus, that's right. Yes, zero. So yeah, no,

this is an op amp chugging between 30 volts here. So it's got a real wide range. And its entire goal is to actually force those transistors to, you know, spit a very specific amount of current out and nothing else. And the thing is, the way that you run it is you put it in such a mode that it that kind of forces everything to stick in place, basically be stable. And op amps are kind of the like drama queens of electronics, you know, like they don't really do well, if you if you get them into like bad territory, they start to freak out and go all over the place. Well, I spend all this time like working things out. I even drove to the electronic store and bought new transistors because I thought my transistors might be bad. Yeah, no, seriously, because the the numbers I was getting, were just like, unintelligible I was like, this doesn't work how, like, these numbers just don't work in my mind. And then and then I had a capacitor just lying on the table. And I pick up the capacitor, and I put it in the feedback of the op amp, and the whole circuit just sprung to life. It did exactly what did she put the

that you put it in, in series? Or did you put it across ground? Well, I guess,

okay, well, so so so. So here's the thing, the, the circuits weird because this op amp is in a negative feedback path. But it has both a resistor and a transistor in the feedback path. So it's hard to calculate what gain it has, because it has a transistor in there. But the op amp is trying everything it possibly can to make that transistor behave nicely. But it's right on the edge of zero and zero for the output of a transistor is kind of like, well, okay, does it go all the way up to positive 15? Or does it go all the way down to negative 15? Like, it's sort of doesn't know it's right there. So you have to have a capacitor kind of slow it down, such that if there's a change, the op amp doesn't just freak out and go nuts. So

what was happening is that that oscillation was starting to get above that response to that op amp.

That's right. Yeah, I don't know. And the op amp, so it was a teal 082 which has a gain bandwidth product of one megahertz I believe. So it was probably oscillating somewhere around there will a plus whatever parasitics are on my breadboard, which was probably nasty, but but it was oscillating in such a way that if you tried to read the DC on all the points, which was what I was trying to do. I was getting these completely wacko values, because your multimeter was not updating fastener. Exactly, exactly. And well, and it was screwing with everything they actual current was. So yeah, just just a small like few 100, Pico farad cap just put it in the feedback path to compensate for all like the craziness that it was trying to do just killed all the oscillations and it's like perfectly stable and it does exactly what the simulation says it should do. And like, all the calculations are exactly right. And it's just like, God, I wish I didn't wait six hours. And the thing that's really sad is I've been in this situation before, not with this exact circuit, but like, I've had that exact same thing happen where an analog circuit like freaks out and you know, you're trying to like, just go down to like the basics and say like, Hey, you know, DC, you know, what's what's going on here. The thing that was crazy about is I actually pulled the cap out, again to make it oscillate again. And I put my scope probe on there because I wanted to see the oscillation after I figured out the one mega ohm impedance input impedance in my scope probe was enough to squash the oscillations. So even if I tried to see it, we wouldn't be able to we're using one extra tenant, I was using 1x. I flip it to 10x. Yeah, switches

10x 10x will have even more impedance on it. 10 times the MP Yes. And it was parasitic and blah, blah, blah,

right? Yeah, you get a lower input capacitance and stuff. But regardless, like if, you know, if I just picked up a probe and didn't flip it to 10x, you know, and I'm trying to sniff out an oscillation, I wouldn't have been able to see,

I bet you this is this circuit was hooked up to a speaker, I've actually put your finger on it and would have fixed it.

Problem. Yeah, the capacitance of your finger is enough for sure. Yeah, for sure. So you know, it kind of sucks. But like all the textbook examples of analog circuits, they work purely in theory, they work really great in a simulation program. But in real life, you have to just deal with this kind of crap. And it's super annoying. But but it works now. So I'm happy with it.

Yeah, it's actually interesting, cuz you, you brought up this topic. And earlier this week, in our Slack channel, Chris G, was talking about a, he was basically making the emitter follower with a transistor. And he was having crazy oscillations. And I'm like, I'm a digital guy, I'm like, oscillations, you fix that with bypass Betsson. Some, like, throw a though, you know, bypass cap from, you know, Vcc to ground. And he's like, Well, he's using a linear power supply. So he's like, it's probably fine. And then couple hours later, come back to the Slack channel. And he said that he put a capacitor there and it fixed it.

Well, and really, what you're doing is you're actually, you know, slewing, the phase of things. And like I said earlier, kind of slowing it down, such that it doesn't get 180 degrees out of phase, and then just freak out, you know, and I'm actually a little bit surprised, because an emitter follower is a you can make an oscillator out of an emitter follower. In fact, you know, traditional oscillators, like Colpitts oscillators are emitter followers. But an emitter follower inherently has negative feedback. Well, it has negative feedback, but it also has less than unity gain, it is impossible to have an emitter follower have, you know, one positive? Well, 1x is there's a way to trick you can bootstrap an emitter follower, such that you get really, really close to the you know, one times gain. But even one times gain, you know, in a lot of cases isn't actually enough to oscillate, you have to have a little bit more. Usually what happens when you when you get an emitter follower that that does oscillate is you got parasitics going all over the place and you have no freaking clue where crap is flowing. Well, yeah, so So but but but in general, emitter followers are pretty not susceptible to oscillation. So I'd love to see what he did to actually like accidentally make that happen.

We can ask him Yeah, that'd be cool. Actually had some pictures of his like scope and stuff. And he had he had his Vcc line and just like all over the place so yeah, sure. It was off a lab power supply, but it was a switchmode lab power supply probably he said was linear but looking at the the frequency that's coming out, right. No way. It's it's got some switcher in there. That's like going crazy. Yeah, yeah. Yeah. It will mean your ones aren't perfectly quiet. No, not you know, you got three at least minimal three foot power leads that's picking up 60 hertz from the fluorescent or 50 Hertz. If you're in Europe, well, and

you're draping them on like a table that has a lot of other electronics on it or crossing them over cables. Yep. So yeah, you're gonna pick up last stuff. So yeah, that's what I've been doing trying to chase oscillations. It's uh, you know, It's actually funny, like, a lot of times when you're designing something, and you get the solution right away, like if I had put that cap in, like, within the first 15 minutes, I would have been like, oh, yeah, this is awesome. Well, but the thing is like, yeah, you're right. I wouldn't have learned something but but the thing that's funny about is like, after I did figure it out and put the cap there, I didn't feel like a sense of accomplishment. I was just like, damn it. Yeah, I was pretty much Yeah. And it's really dumb, too. Because like, the, my goal wasn't to make the exponential current converter for at least for that day. My, my goal was to make something entirely different. I just needed that as a like a base circuit block, and I couldn't even get that to work. So the funny part is the once I got that working, all the hard stuff, the actual voltage controlled filter, that part just, like worked perfectly, so that was good thing. Yes, it was. Alright.

So last last podcast talked about the the deck project. I've been working on the magic deck. Yeah, the match deck.

Yeah. The the sounds like something sold on TV. Yeah. Well, it's

like the magic Jack, which was that I when I ot was the voice over IP thing. Oh, I didn't know your phone into it or something like that. I didn't know about that. Yeah. Anyways, I'm waiting for circuit boards to show up for that so I can finish that article. So that's gonna take two three weeks. So that's the show up. Um, and then I've been working on this is like, I haven't really been doing a lot of like electronics spin, like,

what are you feeling alright, is everything

I've been doing a lot of like, like writing and stuff, cuz I'm redoing the knowledge base here at Mac fam. I'm basically ripping it all down and putting up new wallpaper and stuff. If, if any of our listeners have suggestions, what they want to see in our knowledge base, it's Mac fab.com/help. Go check it out. It will change and probably by the time this article comes out, this podcast comes out. But if there's anything you want us to add to it, let me know in the Slack channel or email us. But yeah, that's what I've been doing for like the past week is just knowledge base stuff.

Ordering PCBs and writing papers. Yeah. Cool.

Fun. I'm hoping to get back to design work after the DAC articles done.

Well, you can come on oscillations with me that yeah, that I'm sure that would drive you insane.

I imagine this like in the African like Sahara desert, where it knows like, the British get up with the hat and stuff. And like, we have oscilloscope probes for javelins.

Yeah, hunting oscilloscope hunting oscillations in the desert. Yeah, yeah. And oscillations like snakes. Danger noodles, noodles. Yeah. There we go. Now, this is only half a barrier.

This is just like what goes through my brain all the time. Okay, RFO. Oh, all right. Yeah. So the first one is the Voyager One, which is the satellite that's the farthest away from Earth. And distance. I don't think it's the fastest. I think Voyager two is faster. That's right. But it hasn't caught up to it yet.

Voyager One is the one that's technically outside of our solar system, right? The sphere of influence or something like that? Yeah, it's got a it's got a different name than network or cloud or cloud. Well, it no it entered into the Oort cloud or whatever it is. Yeah. So

anyways, so apparently, it's going to die. You know, it's getting really far away. Because the solar panels aren't are in, it's not in the correct orientation anymore. And the thrusters that use it are called out altitude thrusters to fix it. Well, they're like, all out of fuel.

They probably frozen.

So they decided to try, NASA decided to try to use the TCM thrusters, which stands for trajectory control maneuver thrusters, okay. The ones used to like align it to like planets and stuff, so you can get better orbits around them and stuff. And they haven't been fired in like 37 years. The last thing they fired was like around Saturn. Oh, wow. Okay. And so they basically had to go through all the old code and figure out how to test it. So they had to go through assembly code to figure out how to test all this stuff. And apparently it worked. They were able to fire the thrusters and because these vessels were designed for continuous operation for like long burns, but the altitude or like little puffs just slightly tilt the the satellite, it's not a satellite because it doesn't orbits. What is it? Craft.

It's a probe probe. Now okay, probe,

so yes, it's slightly ornate the probe so that you can beam the signal back to Earth and get more juice from the sun.

You know, when I visited the what is it the the satellite facility out in Colorado, that manufacturing facility, they showed me some of their thruster programs. And like what, what they use for it in one of them. I was surprised I didn't not know that this was like, legit. But outside of one of the satellites, they have a small piece of what looked like coax cable. It was like a small like not even the diameter of your pinky. And when when they they actually turned it on for us, and it just like, made a huge like Spark like a massive like explosion spark. And it was like 30 something 1000 volts. And apparently, if you just like spark the end of a coax, you can just put a little bit of force on on a satellite. So they actually were using those, like turn satellites. I

read about that. Yeah,

I don't I don't Yeah, I don't remember the name of it. But like, the guy like he turns it on. He's like, watch out. This is gonna be loud. And I was like, what? And then go, bam. And it exploded. I was like, Oh my God. But yeah, I did not know. I mean, I mean, I guess like, in a way there's energy being dissipated. And so it makes Yeah, so it makes sense. But I mean, it was literally just like a cut piece of coax on the outside of a,

b sound because in, in, in space, you can't hear your satellite spark. So

yeah, so that's like an electrical engineers horror movie. Yeah.

We got to look that up, is what that technology is called. Yeah, gotta remember. Spark electro propulsion lecture of Spark propulsion here. Something like Spark Plugs hanging out of your car.

Yeah, a whole lot of a lot

of work on Earth. So yeah, that's cool. I was more interested in like reading, like, all the stuff they had to go through. Like, it wasn't just like, oh, yeah, just turn this thing on. And it'll work. It's like, no, they had to, like, read all the schematics and back then, and all the assembly code, and probably none of the engineers that worked on this project are at NASA anymore, because they probably all retired or dead. I mean, that's the morbid way to look at it, but okay. But, yeah, I actually would want to know what kind of language assembly language maybe someone can let us know.

And, and and have you ever looked at schematics, old NASA schematics from back then, like, I looked

at the schematic for the Apollo Control Module,

that that schematic is it's super cool. It's old mandates. It's an It's a brutal amount of digital logic. Yeah. It would be no, there you go. If you if you have enough OCD, you can write a Karnaugh map for the entire Apollo lander. Boy, that would be horrible. Yeah, no, but but we're looking at those. I mean, even even the Voyager I think I've seen some stuff from that day, it still uses just a whole crapload of hardware gates. Yeah. So it's, it's, you know, nowadays, when you see gates, we all call it glue logic. But back then it was like, processing logic. Just yeah. Yeah. It's like, that's what you Yeah, it's not just an end for two signals. It's like,

huge equation that you're responding to processor by then. Oh, and I'm sure

it was, but it but it does.

Kind of like a 68k, Motorola or something?

Probably something like that. Cool.

Okay, so the next top two topics are going to be about capacitors. Okay. So I was looking up parts for replacement parts, or not replace substitution parts. Because this capacitor shortage is getting pretty crazy. We really don't know. Manufacturers of capacitors and passes pretty much chip parts really. There's a worldwide shortage of them. And it's mainly because the margins are so low on these parts, that manufacturers aren't building new facilities to make more. So they're just going and we're just going to run out and just drive the demand up Panasonic will do it or just yeah, that is dry. It's actually happening. Man for six years ago for semiconductors, it was the same thing where semiconductor prices for like, like, quote, glue logic unquote, to use your term parts were there was a there was a there was a supply issue because no one was making fabs to make more of these even though we needed more. And there's other other reasons too but

those well they the the solar panel game those guys steal a lot of pure silicon. Oh yeah. So once that once that I mean then industry start is large now but when it was up and coming, it was stealing a lot of so so just the introduction of solar panels was making icees go up.

Yeah. So, basically Yeah, so what are these manufacturers like Panasonic? Or was it Yao? yaoi? Or iego? J Yo, that's what I think you know? Yeah. merata all these guys basically x AV X. Yeah. So these guys aren't making new fabs and so there's, they're there a lot of more also consolidating how many parts are selling to push up margins, which makes sense. And also the big drive on on I like, you know, tablets and phones is driving up these prices are not part prices, but driving the supply down to demands way up.

Well, sure for like, oh, 201 parts and no

four two, but that's the thing is a lot of manufacturers are are discontinuing a lot of their 1206. And oh, 805 stuff. Because they're retooling stuff for this. Oh, oh, 201. And oh, four, two, we'll see it what will happen. Apparently, something factors are starting to bring stuff online. But I would suspect that passive parts, the price is going to start going up.

I got to a point I would expect after, you know, with with the way the electronic economy works, eventually somebody is going to be like, well, that's a pretty good game to get into. So they'll, they'll spin up a fab eventually, when it's, you know, it's worth it. And then prices will go down again, but we're just kind of in a crap period right now. Now.

Anyway, so I was looking up and found some new styles. aparts new packages I've never seen before. Whoa, yeah. Oh, 306.

Like, oh, 306 not the metric version. Oh, three shakes. Like right, the Imperial. Oh, this is a it's got a crown on the laser etched into it.

So it's the same size in? Oh, 603. But it's hamburger style. Instead of hotdog style? Ah, yeah. On the 60. The terminals are on the 30. Yes, are there? I didn't never seen these before. I was like, that's crazy. Why would you have that? Why would you spin up new tooling to build something like that? Apparently, this is really is bizarre like is like the new thing starting to come out because I'm seeing more and more manufacturers starting to build this stuff. So AV X, I don't think was the first one. But it was the first one I found like, why would you have this part? So they have like an article about it? Mm hmm. And it's for reducing the distance between the pads. Yep. So you can put pads closer together, which means you can make your current loop smaller for your switch mode power supplies. And that's exactly right. You can make every basic cop like you can make your path from your power trace down to ground for your bypasses are shorter. So you reduce your parasitic impedance.

Yep. I saw a video on those a little while ago, and someone was comparing. It was a 1206 versus a no 612. And the same game, see, yeah, exact same game. And it was like, the whole time I was watching this video, I was like, Why the hell does it matter? And then it's, it's it comes down to the actual plate. Size, the physical size actually adds inductance Yep. Because it's longer. Right. Right. So if you go with the opposite that the, you know, oh, 306 versus the 630. Yeah, right. Right. Right, then then you can modify the inductance. But now it does have a you know, it does have negatives. Also, you do have to basically waste more space on pads. Yeah. So So there's, there's, you know, aspects to that. Now, I actually saw a design once that was super goofy, which this is something you can request of a manufacturer, it's not a very common request. But you can do what's called billboard components, where you could take even a Oh 612 and turn it up on its side. So it's basically facing up into the air. And it actually even takes up less room when you do that, but you still get the benefits of the in low inductance but the only problem is when you billboard components, then it pretty much means that you're not going to place it with a machine it has hand placed. So they're like really specific, but but their billboarding is actually common enough that it's it there's a whole like page dedicated to it in the IPC 610 documents. So it's it's a perfectly valid way of mounting components for you know, lower space. But you know, it costs more Yeah, so

there you go. Well, you take up vertical space,

you take up but but but the so the billboarding actually makes sense when doing hamburger capacity. Oh, because because Yeah. Because like you put it on a small side and then you lifted up in the

air when someone's going to load their tapes by default like that.

Yeah, I mean, the thing is, in a lot of situations other than say that cell phones, you have vertical space, you don't have xy space.

I wonder how hard it's gonna be there make it stay vertical, though.

You just have to make the little tubs in. In the tape. I'm thinking

when it gets, let's say it gets placed on the on the board. Oh, yes, surface tension of the solder paste gonna be enough to hold that part up until the reflow I

think it would be way more critical in that situation that you have your pads designed properly. Yeah. Because you know, you've seen Tomb stoning happen on components. And it's funny, because this is a kind of Tombstone thing that you would want to happen. But you can't really like force it to happen now. Yeah. So once again, I think that always comes down to that would come down to like hand placing in hand soldering and stuff. So you would only do a billboard with a hamburger in like a really specific situation.

Yeah. So I'm thinking these are going to probably start becoming more and more thing. I don't know if this is going to be something that like AV x will be like, we're not gonna do Oh, six threes anymore. We're only oh three or sixes. I don't know if they'll do that. But this is something to start looking at in the future. And especially with this part shortage, and seeing what manufacturers are starting to, like, push forward what they want to build, because eventually it's what, you know, if you can't buy a 1206 part, like 10 Mike fair part anymore. Like, you have to change your design.

Well, that's true. The thing is, like, I don't think that anyone would make that rash of a decision. Like a take, for instance, I'm just saying that's an example. Well, yeah, just an example. But But, but so the the the IPC 7530, blah, blah, blah, whatever. That's the standard for designing like pads for chip components, and things like that. And that document doesn't even call out designing pads for billboard, or hamburger components. It's still like the defaults, like the oh, 80506 or threes and stuff. So I mean, the world has harmonized and standardized under these these chip components, I bet you there'll just be a shortage. But who knows, maybe we will go to hamburgers, then it'll be fun. You know, what everyone will have to change their standards, like your your, like the MF passives library will have to change

is basically you're going to have to legacy designs I'm probably gonna have to change just to keep up with these, the the magazine that magazines, but um, catalog changes that these manufacturers are making now. So

yeah, well, bomb bombs are fluid, you know, they bill of materials, okay? All right, they're fluid, they change. Freakin every day. So

that might be something more legacy designs or math changes when? Yeah, if that 1206 50 volt part has, you know, no manufacturer makes that part anymore. Okay, we have to switch to a way to five now or whatever.

You know what I? I would love to see, maybe somebody has this. I doubt it. But I would love to see the iPhone X bill of materials like the official Bill materials. Yeah. Well, of course it exists. But like, for my eyes to see.

I think actually a lot of people do tear downs and stuff and have that

because like I would love it like it got to be like 50 pages of Excel sheets.

Did you send me a text earlier today? How much it costs? Yeah,

I was watching. It's funny. I was I was watching a YouTube video where a guy he weighed a kilogram of silver and will not wait I'm sorry, a kilogram of silver isn't kilogram so but he he weighed in an iPhone and it was point 143 kilograms. So 143 grams. And it costs the same amount as one kilogram of silver. So totally dollar per weight is the same dollar. Well, no dollar per weight. The iPhone is seven times as expensive as just raw silver really? Seven times. Yeah. So so a an iPhone if you had like if it was like an element? iPhone Ium it would be $3,500 per kilogram.

Geez. Not more expensive and printer ink.

You know you buy a kilogram of gold for more than for less than printer ink. Yeah. Actually, you know, you know what's funny, the the most expensive thing per gram is potassium 41 which is like a really really specific isotope of potassium. There's one place in the world that makes it used for a in some kind of nuclear application, I can't remember exactly what it is. But it is $70 million a gram, or kilogram, I can't remember one of those. Regardless, it's like, ridiculously expensive. And it has a very specific and very useful use, but like, but at the same time, there's, you know, one guy making it and only 10 people needing it kind of thing. So

you don't take that secret to the grave.

So la dee da, was not a secret how to make it, it's just a pain in the ass. Basically, that $70 million, you're not paying for like intellectual property, you're just paying for some dude to like, sit and pick atom by atom out, you know, Potassium 41, that specific isotope. So, there you go. YouTube teaches you a lot of things

on that video. So the next capacitor article that was reading about is the old volt circuits came out with an article about a concise guide to ceramic capacitor types. Ooh, and this is actually how I got onto the Oh, 306. Is they had a picture of Oh, three or six part. I'm like, That is weird looking. What

is that big fat pads? Yeah. So

I started researching that guy. So this is an article that covers a different classes of capacitors, Class One, two, and three, which are the dielectric types. And this is like, was it x five R or x seven R

cog? NPO? Yeah.

And so C O, G, and NP? Oh, np zero, np zero. Our class ones. Yes. And basically, the classes just basically are the class ones are like super good. ceramic capacitors, class two are pretty good. And class three or whatever you. These are the cheapest ones,

the kind that you put in a salt shaker. And then you just shake over your PCB, and let them stick where they stick. And there you go. You got some good fasteners.

So usually the first character like X, Y, C, the notes that the lowest temperature the capacitors you can handle Yep. And I think like C is like the lowest and why is like the highest is something like that. There's a chart on their website that shows all this stuff. Put in the podcast description. The second character is how high of temperature?

I think I think that's right. Yeah. And the third is tolerance, right?

Tolerance. Yes. So why five V is like one of the worst dielectrics it's like plus 80 minus 20. This way, the the graph looks like a Gaussian curve. And it's top of its capacitance, yeah, of like, room temperatures right in the middle, and it just fall completely off.

You know what,

I bet you if I put one of those capacitors in that circuit I was doing earlier, it would still work, because it just needed some capacity. And so that's a situation that you would use a crappy cap for just when you need some

capacitance. And it doesn't really matter what value it is, or if it changes or changes. Yet I was actually thinking is why does a capacitor like Wi Fi ve exists? Where it's so bad, when you look at the specs is because a lot of times appliances and like stuff is always at room temperature. Now like cell phones, not because it's exposed outside cold, being in your pocket, that kind of stuff. But like a thermostat on the wall. Technically, it's supposed to regulate room temperature,

its goal is to get rid

of it can probably get away with Wi Fi ve capacitors?

Well, it also depends on what the purpose of the capacitor is. Yeah, yeah. You know, if you're using it to just like dump some high frequency crap. And the actual value of that capacitor doesn't matter at any one point in time, then you might be able to get away with a really cheap

and Wi

Fi reads are really inexpensive. Yes. And that's actually brings next things like why don't you just use class one all the time, like c zero G. Very expensive dielectric. And it's also class ones aren't very space efficient, like 8.1 microfarad. The smallest you get is 1206.

Yeah, right, right. Yeah, you usually when it comes to NPO, or cog, that those are kind of the cream of the crop, when it comes to ceramic capacitors. They have the absolute best tolerance and the absolute best temperature coefficient. Yep. And so you put those in critical applications. And I'll give you an example of that. In a previous life, I designed vibration sensors that were meant for safety devices. And so in the feedback of all of our filter paths, so if a customer said like, hey, I want my thing to detect lower than 1k, but not above one case, if we had a filter like that, where we wanted that cutoff frequency to be fixed, we'd put a cog right

there. You know, also why the Grilli good application is class one dielectrics or not microphonic right as well. So if vibration sensors, sensors you would be introducing, like vibration microphonics into that capacitor.

That's right. You don't want any extra crap going on there. And and when you have a device that's rated from negative 40, C up to 100 degrees C, you want that capacitor to be a fixed value throughout the entire range. Yeah, yeah. And your feedback loop, because, you know, it might have a cutoff frequency at boiling. Or, you know, that's something different than freezing. You don't want that to be the case ever, especially in a safety application. Automotive actually, too, you have a lot of safety applications in there where you would want a cap to just always be a cap cap, you know, or that that specific cap. Yeah, that specific capacities, right. But if you're just getting rid of, you know, whatever, high frequency power supply ripple, that doesn't necessarily need to be

super specific X seven Rs, probably way overkill for 99% of the times it's been used. Yeah,

I mean, if you if you're talking about like, I don't know, bypass caps on every single, you know, I see in a circuit, a lot of times, sometimes those are critical a lot of times they're not.

And actually, I was going to put it on here, but didn't make this podcast like super long. Is it? I think the next time is we'll go over. Why 0.1 microfarads? Oh, yeah, that's a fun. So I have a whole bunch of stuff to sift through. And I'm actually going to write it up. And I think that's gonna be our next our, like, that's just what we'll talk about.

I know that that it goes beyond the electrical characteristics of that capacitor. Yes. It starts going into cost.

Cost. Yeah. That would be next time. Yeah, that'll be fun. But we got one more topic is once you know, we the heavy hitters. Now it's gonna be a little goofy. Oh, great. Oh, yeah. Four levels of transcendence. About projects.

I sent you this earlier. Yeah.

The transcendence meme is you explained to me,

okay, you've probably seen it, where it's a, I think the the images are actually taken from something that's like, sort of like describing like, your chakras and like, like the the levels of like, Nirvana that your your brain has reached in an effect. It's like a four pane comic, where it shows like, a small person's brain, and then they've reached some new level of nirvana. And it keeps going until they're basically a god in the end of this. So what are the four levels of transcendence Parker?

So level one is finishing projects. Okay. Level two is abandoning those projects. So once you started

projects, and then abandoned and just give up on level two,

level three is starting a new project before finishing the current project. So usually, does all this mean works, it starts at something kind of normal, and it

gets really ridiculous. Like, worse? Oh, he

thinks you reach new levels. Oh, yeah. When Yeah. So level four

is the end of this mean, would be continually coming up with new ideas without doing anything about it?

Which, for people who have listened to us for a long time, we are at minimum, level four, level five, what's what level,

starting a lifetime of projects in one month, buying old supplies and then not finishing them, and just having a stockpile of new parts sitting over there. And you're like, huh, I got a new idea for Project log on the Amazon buy everything in that in that Amazon box. And just,

you know, actually gonna get this, I was at my shop the other day, this is some level five shit right here. Okay, I was at my shop the other day. And I found a box from Mouser, unopened, on open, and I rip the thing open. And there's a whole bag full of parts in there. And they were clearly very carefully chosen parts. And it was an entire project in there. I can't even remember what any of it was for. Like, I don't remember the project at all

I learned early on is I put the P O number as what the project is now.

Because like, apparently, I had like an amazing idea. And it's just a bag of parts now. So it even happens outside of the podcast. So

level six. Oh, is running a podcast? Yeah. Not even doing anything about them well, and leaving it up to the listener to do them. Right, right

or leaving it up to the listeners to be like, when are you guys gonna finish this? We're just gonna keep telling you that we're gonna finish these projects. Yep, yep.

So that was it. We were your host, Parker

and Steven Craig. Let everyone go finish. projects

or use the ones that we've mentioned on the show.

Yeah finishing for us

Thank you. Yes, you our listener for downloading our show. If you have a cool idea, project or topic or project that you finished for us, email us at podcast@macro.com or tweet us at macro fab. If you're not subscribed to the podcast yet, click that subscribe button that way you get the latest episode right when it releases and please review us wherever you listen because it helps other people find the shows