MEP EP #136: Classy NASCAR Badgelife

Podcast Transcript

Host 2

Welcome to the Mac fab engineering podcast. We're your hosts Parker, Dolman.

Host 3

And Steven Gregg.

Host 2

This is episode 136. And before we get started, I would like to announce that Alicia White will be the judge for the macro fab. Design Contest, blink and I led sponsored by Mouser. Alicia white is the host of the or one of the hosts for the embedded FM podcast. And we chatted with Alicia on the back flap engineering podcast episode 110. Tell me how people hurt you. her Twitter account is at logical elegance.

Host 3

Thanks a lot, Alicia. That's gonna be a lot of fun because I think she's gonna bring like a completely different aspect to it. Yeah, I

Host 2

Think so to that.

Host 3

I'm super excited for like the judging base. Because it's not like one mindset, I think. I think it's actually going to be really hard to pick from the submissions because we already have something like 15 or something submissions. I can't remember how many it is. And they're all like, super different and really creative and a lot of fun. So it's gonna be it's gonna be

Host 2

Great. You all have one week left to submit. Yeah, remember, all

Host 3

You got to do is blink an LED. Yeah, blinking LED simplest thing in the world. Right. And, and spoiler alert, one of the one of the submissions, Parker and I were just looking at it. There's a guy who connected basically two LEDs with some resistors to the mains lines. It's just two resistors and two LEDs that he connected directly into the wall.

Host 2

Yeah. So blinks at 60 hertz, which is technically a blinking LED. Technically, he

Host 3

Did it. Yes. Yeah. Good. Audio was awesome. Alright, so Parker, let's, let's cover your stuff. What you've been up to

Host 2

That wagon chime module I talked about last week, it's got that conformal coating on it. So I tried to clean it or like remove it off, I guess. So I use brake clean, because that's kind of like the solvent, the choice for mechanics. It that did not remove it. It didn't make it didn't make it soft. It just didn't. It was not phased, it just made it greasy. Right? Or actually, it removed all the grossness off the board. So at least it's clean, but it did not remove the conformal coating at all. I think the next thing I want to try is just like some aircraft, you know, that aircraft paint remover that you can buy in a spray can and just coat that and yeah, hopefully doesn't eat anything else besides the conformal coating, where some

Host 3

Nitrile gloves or whatever, because that that airplane stuff will eat the first like, 15 layers of skin off your

Host 2

That's like all the layers of skin I think, yeah,

Host 3

Yeah, pretty much. You can always try the the old, tested and true screwdriver method that takes conformal coating.

Host 2

You know, actually, this stuff seems to be really attached to whatever it is, and I tried, like mechanically removing it. Yeah, it doesn't really want to flick either. It's really stuck on there.

Host 3

Oh, it doesn't chip. Wow. Okay, so they use some really aggressive stuff. Yeah. So I don't know what it is. So is it is it kind of yellow? In color? Yeah, it's yellowish in color. Okay, cuz that might be the UV cure stuff, the UV care stuff. That stuff dries unbelievably hard.

Host 2

And I'll put this way is when I was trying to get the iron to fix the couple was replaced in the capacitors last week. It did not want to melt either.

Host 3

Hmm. I wonder what the what kind of stuff that is? I don't know.

Host 2

Hopefully someone has an answer. In our Slack channel.

Host 3

I've had a couple of situations where I've wanted to take conformal coating off of the board. And in general, it's really difficult to do most of the time you just kind of like scrape at it with a screwdriver or something like that kind of pick away at it. I've even called manufacturers before to be like, hey, I want to take your stuff off. Do you have a solvent? And usually the answer is just like, No, go away. You know.

Host 2

There's a silicone base compound we're using for a customer right now. It's like really goopy. It's, it's like, I've actually never seen that substances stick before. That's still like a fluid, I guess. But it's got it's got a remover for it. Well,

Host 3

A lot of times they they're they're intended to be, you can open them up so you can repair things underneath them and then seal it back up. In fact, some of them you can you can just put a little another dab of the stuff in, it'll remelt into whatever it is, especially if it's urethane you can actually get away with that. So sometimes, you know, they, they do the whole environmental protection thing, but they're also repairable sometimes especially with like the real dark, hefty urethanes they just dry like a brick and then it's game over,

Host 2

You know, yeah, you can't even chisel it off without breaking parts off. It's awful. So hopefully I can get this stuff removed. If not, then I'll just start. You know, I'll just crank to it. Never been hotter to get through it just as melt. They're just trying to melt through that thing. Get

Host 3

Your big like stick iron thing that you have. Oh, you know that huge soldering iron that you have.

Host 2

Just melt it all off that that Weller gun. Yeah, that would work that things like, oh man that's like a 300 watt iron, I think. Yeah, I

Host 3

Bet you'd go right through there. Yeah,

Host 2

That would par work. I'll just use that.

Host 3

You could also just for a short period of time, take a torch to it and see what happens. Obviously, they'll

Host 2

Like, burn off. Yeah,

Host 3

I mean, just do like quick, sweeping motions around it. So you're not like just blasting it with a few 1000 degrees.

Host 2

Yeah, I can try that with appropriate torch after after the podcast. Well, I can try to acetylene torch after that.

Host 3

You pull it away. And there's a hole through the board and punch the holes.

Host 2

Yeah. Apart from work again after that. Yeah.

Host 3

Good luck. Thanks.

Host 2

So the next next thing I've been working on is that powered mirror module. And so I got the board, the schematics all done and the boards laid out. And I decided to use while I was using the BTM 7742 G, motor drivers, because I already had them designed. And at the time, I was like, oh, yeah, I'll have plenty of space to use these ginormous motor controllers ended up I did not have that much space, I took the door panel off, and the hole that's in the door is pretty small. Like it's actually only a little bit bigger than the panel facade, I guess is a good way to explain it. Sure. Yeah. Whereas labels like what what it is and stuff like that the little chrome piece that's on the door. So it's only a little bit bigger than that. So I had to actually shrink the board down quite a bit. And so I found the some smaller motor drivers work, I think they only pull they they work with two amps instead of like, eight of the BTM 7742. But, again, these powered mirror motors only pull like, you know, 400 milliamps, so it's not a lot of power. And so these are DVR 8872. And they're in an SOC eight style package, except it's got a thermal pad underneath. So it's like a nine pin package, I guess.

Host 3

Okay, so there's just, I see, I'm looking at the datasheet that Texas Instrument datasheet for it in the in the block diagram, the output is just basically, you know, MOSFET pairs that just hammer it basically hammer the motor. Correct. Okay. Yeah, that's cool. So it's a

Host 2

H bridge in a SRC eight package that's got kind of a motor driver front end kind of thing on it. Yeah. So it's probably got some glue logic in there that, you know, handles how the H bridge functions.

Host 3

They call it core logic. core logic. Yeah.

Host 2

Ci thing, right? Yeah,

Host 3

Probably. I bet you they have Yeah, core logic TM, or whatever.

Host 2

I got that design. So I'll post up the picture of the layout and stuff on the on the podcast notes. It's got all the typical mounting holes and all that crazy stuff. I'm probably gonna order that this week. And hopefully in a couple weeks, I have the board done and tested and working. I hope

Host 3

And then then you can move on to the next thing that doesn't work with the jeep.

Host 2

Yeah, the next thing that doesn't work, like everything else. You're gonna show up

Host 3

Next week with something new. I'm making a prediction right now.

Host 2

Actually, here's the new thing.

Host 3

We don't even have to wait a week, it's right here.

Host 2

Because on the on the Jeep on the old Jeep, the red Jeep, the radio was pretty good. And so I modified the radio to have Bluetooth and the wagon, the radio that's in it is not stalking anymore. It's some crappy aftermarket thing that was installed probably a couple years ago. And it doesn't have Bluetooth doesn't have auxilary it just has funnily enough it has satellite connectivity, but I don't have a subscription to it so I can't use it so I was thinking like okay, let me find like a stock radio for this vehicle and I'll just put it in the problem is the stock radios for the wagons are a little bit rare and so they're kind of pricey and so I started looking for cuz it's like it's a standard one din slot which is a standard size for for car radios

Host 3

It just just educate me. Is that really how they're measured? Is it considered a DIN

Host 2

Yeah, so like the the it's about six and a half inches wide by like two and a half inches tall? Yeah, or two inches tall that's one den and then there's two den three den etc which is just stacked up right I didn't know it was called didn't know it's similar to like rack mount style where one Den is a certain unit of size.

Host 3

Well yeah in rack man, I guess they call them use right? Yeah, use a one u two u Yeah. And it's 1.75 inches per you think that's what it is something like

Host 2

That. Okay, cool. Yeah, go ahead. I started looking around on Okay, let's let's go a step further than the Jeep radio and let's design our own radio. Yeah, cuz that's the next step, right?

Host 3

Of course, yeah.

Host 2

Cuz I can't, I couldn't find anything that I liked. So I don't want to be all fancy and new, I kind of want to look retro, you know, have like a product of its era, which is like a VFD display and knobs and buttons and stuff, instead of having LEDs and crazy, blinking stuff. So I started shopping around for radio modules. And I found some like ICS that work for that do FM and AM D modulation. And they basically spit out audio. So you would just pumped that right into probably your amplifier multiplexer. Because that way you can like get Bluetooth in it. And you can also do auxilary in and you control those chips for like i square C or spy. I think like Silicon Labs make it at the part number is escaping me. And then I was chatting about this in the Slack channel and Hiren have an XOR suggested, hey, what if you used a signal Defined Radio, for your front end? Because then you can sample any frequency and listen to any frequency out there. Um, like, that's a really good idea. Let's look at that. And you

Host 3

Get to pick up all the number stations and things like that. Exactly. Yeah,

Host 2

You can pick up anything. So I started looking around and he suggested the RTL SDR because it's a very low cost one, and I think you can pick it up on Amazon for 20 bucks. Alright, so I picked it like the $25 model, which comes with like an intendant stuff just so I can test test it. Yeah. And I got that over the weekend. I hooked it up to my my Windows computer and download some software to so I can just listen to stations. And it works. You can listen to FM am with this model you can listen to I was listening to some weird like beeps and boops coming off of some like ham radio stuff, huh? Someone was like transmitting some data. And I could listen to it. I had no idea what it was what I was actually picking up but you can listen to it. But yeah, so you can it works really well. And I think what I'm going to do with it is I'm probably design a a old school looking radio with my either big like, four character by 40 character VFD display. Yeah, it's a big, big beefy VFD display and put some buttons on it run the the signal to find a radio through that interface through Raspberry Pi. Nice. I did find some, like I just searched like raspberry pi signal to find radio car entertainment systems, because there's actually quite a bit of projects out there that already do this. But they use a touchscreen as the interface. And I'm like, I don't want that. That's like the last thing I want is a touchscreen in the wagon. And so I'm going to build the front end or the the human interface device, the head will be a knobs buttons, really nice VFD display. And then now those will probably interface with a microcontroller so that the interface is responsive. And then that will talk to the Raspberry Pi. And do basically like Talk soon really to the pie and the pie will control the signal to find radio. And there's also some cool things I feature creeped onto this. Oh, nice. The easiest way to get internet would be just to buy a 4g modem USB dongle. Because basically, the Raspberry Pi has USB now that's, you know, has a system hub and everything. So you can just keep if you want a new feature, you just plug it in to the USB. And so I'm going to put a 4g modem in it so that way I can get like Pandora YouTube through the VFD display. That's gonna be interesting how I'm going to figure out how to make that interface work like do you have to scroll and type in what you want on youtube I don't know yet for searches for. But then I want to add GPS. But not for actually doing like yeah, navigation or anything. I want to do GPS so that you can actually control the signal to find radio with the GPS. And so if you're driving down the road, it can look say hey, the International Space Station is right above you right now do you want to switch over and listen to the the internet space station? And so you can click yes,

Host 3

That's a great idea. Yeah. Oh man, I'm pretty jealous. I mean, this sounds like a pretty hefty project actually. There's a lot of stuff going on. And of course while you're going on on this I've got two feature creeps that are going through my head that could make this really freakin awesome. Alright, and what are they? Well, it all depends on how much space you have

Host 2

Either the entire back of the dash is empty on this wagon.

Host 1

Well okay then you got plenty of space for this. I'm going to upgrade and make three feature creeps is so here's the thing. First of all, I think you should make The front panel that covers everything I think you should do that at it would like actual wood, like make it super nice, like you did on your on your, your other. Yeah, where you use curly maple to make a hand hold all the hand grab Yeah, make make a wooden thing. Now, this is this is more me than you probably what I have a vacuum tube preamp that runs on one tube and it runs on 12 volts. It has a switcher in it that boosts up to 300 volts, but it'll handle all your signals. And if you had a little vacuum tube with a little window cut in the wood where you could see the tube that would look so cool. Oh, that would look awesome. Okay, so

Host 3

I can share that design. It's a really simple design, but it runs on 12 volts for the whole thing. So you could easily do that. Now, one other one of the thing that would be really cool is if across the front of your VFD, you put a clear, you know, either capacitive touch or resistive touch element. So you could have a touch VFD Oh, yeah, make a touch VFD Yeah, that would be cool. Now you know, you got some real stuff to go play around.

Host 2

I do. I do like the tube preamp for

Host 3

Yeah. And and I've actually built that tube preamp and tested it works. Nothing like you could install it right now no problems.

Host 2

And it would work and then just feed that into some solid state

Host 3

Well, and you know what I did with this tube preamp that's that's kind of goofy has sort of defeated the purpose. But at the same time, it's still like to be, what I did was I have an input op amp, that's a buffer, then it hits to tube stages. And it has an output op amp as a buffer. So both the input and the output are solid state, it just has tubes in the middle. And the reason I did that is such that you could plug anything into it and have high impedance. And you can output any it to basically anything and have like a known low impedance, you could dump those op amps if you didn't want them and just run the tube. But I would still suggest using the the op amps just so that you have, you know, unknown thing it's tubes are known to they're just a little bit more finicky. You know, and the whole thing with this preamp is that you don't really need much gain. So it's way overkill, but it's kind of cute to have a little tube sitting in there, do it and it's actually doing work. It's just not a whole lot. Actually,

Host 2

You should make it exposed. So someone's like, Oh, what's that? And I touch it and burn their finger?

Host 3

Well, unfortunately, this is the two preamps don't get super hot. Ah, dang, the power tubes are the ones that get to I checked the datasheet the other day and it was it runs at 220 degrees Celsius.

Host 2

Oh boy, that's pretty hot. Oh, yeah.

Host 3

It'll burn the shit out of you.

Host 2

Now, is that the internal grids? Or is that the actual outside of the two?

Host 3

From the datasheet? It said glass temperature. So that would be the outside? Holy cow. Yeah, that's a really,

Host 2

That's pretty hot. Yeah.

Host 3

But no, I think a touch VFD nobody's got that. That's super cool.

Host 2

But has to have old. All the functions have to work by just pressing big buttons, though. Yeah, that's what I really want. So you gotta switch channels or volume adjusting and stuff like that is done via knobs and buttons and switches and stuff.

Host 3

Sure. Yeah. You know, actually would be kind of funny. You know how a lot of newer systems I say newer, they've been around for a while. But you turn on your car and the whole screen like pops out and rotates up. Yeah, it'd be funny if it was a VFD that popped out.

Host 2

Like get a bigger VF it's because the four by 20 is pretty good. Because it's like about one in size. Yeah.

Host 3

But get a taller one get a dual. Yeah, I'm sure that's expensive as hell. And

Host 2

Then it just comes out and flips up inside actually an old school VFD display, that would be funny. I like that. So instead of feature keeping my project Steven, what have you been working on?

Host 3

So the huge rates are now being done? I've started to kind of like send it out to people and start talking about it. And one of the people I send it off to was actually the original designer of the you tracer itself. I sent him an email at like 10 o'clock at night here which he's in Holland I believe. So that's I don't know, whatever time Holland was at that time. And he got back to me in like Holland o'clock. Holland o'clock. Yeah. Holland Standard Time.

Host 2

What how many listeners we have from Holland.

Host 3

Yeah. Tell us what time it is when it's 10 o'clock in Colorado. But regardless, the he got back to me in like five minutes after I sent it. And he was super excited about the project. And he immediately went and threw it up on his website, because he has like a whole page like, I think he calls it testimonials, where anyone who's built one and sends in pictures, he'll post it up and he threw it up there. We we have a link to it. It's kind of a long link. So we'll just post it up on the show notes and you can go check it out. The website is actually das for every.com I guess that's the website that he had. But if you go to Google and type in you tracer, you can also direct you there In the email that I wrote to him, and a handful of pictures are up on his blog, so if you want to go check that out, that's up there. One of the things, though, that he was mentioning to me, he was asking, Hey, would you be willing to share your design files with people because he has a mailing list that he said is about 1600 people or so? I told him, of course, yeah, I'd be happy to share it. But one of the things I wanted to do was, it's always kind of been my goal to start a blog myself such that all of these projects that I do, I actually have a repository that I can put them and I can just like, you know, puke out all of my ideas into one location. So I ended up doing that last week. So I have started a new blog. If you go there, there is absolutely nothing. At least it loads. Yeah, it'll Yeah, I was, I was kind of hoping to have it ready for today, such that people could see my first post, which is, the huge rates are designing the whole thing. But I went really wanted to get nice pictures, because the pictures I was getting from my phone, and my camera, were just not really great. So I did purchase a lightbox, such that I can take, you know, some semi nice pictures with it, you know, however much me not being a photographer, you know, I'm going to get every fighting chance I can take good pictures. So, um, most of my blog is actually or this first post is actually written, it's just, I have tons of little areas where it's like, add picture here, you know, have an arrow pointing to this kind of stuff. So regardless, the the new blog is my new website, which is analog nj.com. That's analog emg.com, which I have also changed my Twitter handle too. So my new twitter handle is at analog, and I figured I kind of wanted to pull everything together and having macro and my Twitter name and stuff is kind of antiquated at this point. So kind of making a whole new ecosystem with that so and analog EMG comm was available. So yeah, I got

Host 2

It. You're gonna make me go through all the old podcasts on podcast notes and update your social information.

Host 3

Well, hopefully I'll never change it ever again. Because I actually kind of like analog edge. That's really good one. I think I think it's a good one. And I'm happy that I got that. I did also get the domain circuit jet comm which I might, you know, in the future turn into something else. Maybe that's a forum? I don't know. It's more projects, more, more stuff to do

Host 2

More stuff to do. Yeah. So I've looked it up. We have 28 listeners from the Netherlands.

Host 3

Oh, really? Very cool. Did they know what time it is? So yeah, so I've got analog nj.com. That very soon, probably within the next few days, I'll actually have my post up. Because actually, right after this podcast, I'm going to pull out my camera and start taking a bunch of pictures and loading things up. Ronald Decker over at the you tracer. Know, he's the guy who designed it. He said, As soon as I have my blog ready, he's gonna blast it out to all his people. So look for me on Twitter, I'll be posting my blog, and I guess maybe macro fab might pimp it also, thumbs up, probably. Yeah. All right. Cool. Yeah, that'd be fun. So look out for that. And, as I as I, you know, put more stuff up all the projects I do on the podcast, I hope to basically port over to the the new blog such that there's, you know, more ability to check them out. That actually goes into one other small project that I'm kind of doing on the side right now. I had to do a project with a power supply the other day, and I just ran over to my storage facility and grabbed whatever power supply I could find. And the one that was closest to me was my Hickok 5055, which is a old vacuum tube power supply. But you know, it's just a power supply. It's not necessarily specific to vacuum tubes, it just has a nice a lot of nice features that lend themselves to that. So it has a zero to 400 volt regulated supply. It has zero to 40 volt supply, it has a zero to negative 100 volt supply. It has a 6.3 volt AC supply, a 12.6 volt AC supply, and a variac all in one box. So it's it's kind of like every possible thing you could need, they just give you right there. So it's it's really nice. And I was using it the other day. And I realized that this thing is pretty old. I've never looked inside of it and I've never serviced it it just it's always worked well. So I brought it home and I just cracked it open the the other day because I was just like hey, you know, kind of want to check on the caps. Like every capacitor every electrolytic capacitor has almost had its head blown off. All of us though all of them are don't eat you know, what's crazy is, is it still works, and it's not noisy. That's one of the weird things and I have no idea what what how old this thing is. But those cats are ancient. And the thing is like they're, they're all domed. So I'm kind of like I should not turn this on again. So I started, I started just a quick little side project of of recapping this thing, there's a handful of like soldered in place electrolytics, that, you know, those are things I can get from Mouser. But the main capacitors in this old supply are the old ones, you know, the old clamp mount electrolytics, you know, where they have like, the clamp is actually riveted to the case. And then the capacitors are screwed in place on these things. And I would like to replace these capacitors with something similar, at least similar in size, because I don't want to go and you know, design something, I just I want to drop in solution for this. And surprisingly enough, this is not necessarily the easiest thing to find the because most caps are not like this anymore. So there's, there's one cap, that's a 2500 micro farad 75 volt, there's three caps that are 500 micro farad 75 volt, and then there's two caps that are what is it 500 micro farad 200 volt. Most of the caps are 35 millimeter diameter, the two 200 volt caps are 40 millimeter diameter caps. And those are not super common. If you go to if you go to Mouser Digi key and search for it. It's not like you have hundreds of choices you have like to and in a lot of cases those caps are like $30 apiece. You know, I don't I don't want that. So I've been I've been kind of like trying to get me on where can I get this cap? And where can I get that cap? And I think some of them are available on Mouser where I can get them for maybe like $15 apiece. But funnily enough, most of these caps, I've been able to find at least something that will work from my guitar amp vacuum tube suppliers, because the same style of caps we're using guitar amps for so long as main power supply ripple guys make sense. So I might just end up putting guitar amp caps in this thing, because eight whatever if it works, it works. And the whole thing is just it's the right size. That's kind of all that matters,

Host 2

I think gonna be fine gold caps, you know? No,

Host 3

Unfortunately, fine. Gold doesn't make it in that in that size. But there will probably be JJ caps, or at least some of them will. And JJ makes good stuff. Never heard of them before. If you've ever heard of them. I can't remember where they're I think they're in checklist lucky. They make vacuum tubes and big caps. Just big

Host 2

Caps. Is that what they're called? Yeah.

Host 3

If I had, if I had a capacitor company, I might just call it Big caps.

Host 2

You gotta you gotta share a picture of those crazy looking caps.

Host 3

I've got I'm looking at the supply right now on my coffee table. I left it open. So I could take a picture right after this podcast. So you guys get to see some puffy caps. And I can't believe these these caps, gosh, what do they say? I don't remember what the name is like, search with a T. Regardless, they were made in Mexico like decades ago. So it's one of those things where like they have their long draw dried out. I'm really surprised that this thing actually still regulates what it does. It's really I mean, I've had no problems with it. And I've used it for years. At and this is the first time I decided to open it up.

Host 2

I'm wondering if you need those gaps? I bet you you start pulling some current it'll start oscillate a bit.

Host 3

Yeah, well, the thing is, I think most of these caps are the input filtering caps that come basically right off the rectifier. They're the stuff that comes pre regulator, and the regulator, if it doesn't have that smooth stuff, it has to do more work. So it's, it's, I'm probably beating the hell out of my the regulator in there. And it's probably heating up more than it needs to because it's having to do extra work. And I'm just surprised maybe maybe this thing is way over designed. I'm just just surprised that I'm not getting more noise on the output because it just from the looks of these caps in their age, they can't be doing barely anything, you know, but maybe they are I don't know, maybe they were designed to, you know, last with very little electrolyte in them. Who knows. So you did a little bit of feature creeping, I was thinking about a little bit of feature creeping with this device, I thought it would be really, really cool to add some digital control and like a keypad to the front of this thing. Because everything is just potentially honors, this, this power supply would be really, really useful if I could just type in a voltage and it would just give it to me. I don't know if I really want to do that because tracing this thing out looks like a nightmare. So I don't even know how the circuit works. I was thinking about tracing it out because I've looked all over the place and there's forums where people are asking, Hey, you know, I have a Hickok 5055 And it doesn't work. Does anyone have a manual or schematic and nobody has it? So I could be that guy and you know write out a schematic but Gosh, it's it's a rat's nest inside, it would take forever just to draw it out, is it?

Host 2

It's not a circuit board in there, then is it point to point wiring?

Host 3

It's half and half. There is there's two circuit boards in there. And they all have flying wires that go absolutely everywhere. Cuz most of the most of the high powered devices are off board mounted to, you know, some wall in the chassis. I mean, this thing has, I think, five transformers inside of it. And they all have their own, you know, jazz going on and stuff. And I like it that

Host 2

Part ways the, you know, massive dying son. Oh, it is.

Host 1

It's very heavy. But it's built like a tank. You know, hopefully, it keeps working. I

Host 3

Mean, especially because it still works. And who knows, when this was built,

Host 2

You shouldn't measure the noise at different load levels for all the channels before you replace gaps, and then do it after you replace gaps. And see if it actually changed anything.

Host 3

You know that that'd be, that'd be fun. This thing has a maximum output. I think 40 Watts is what it can deliver. It can it can deliver 100 milliamps at 400 volts or one amp at 40.

Host 2

So it's the it's the heaviest power supply in the world, but delivers the least amount of power.

Host 3

It's Yeah, well, it's way more specified. Like it's, it's clear what this was intended for. What's what's nice is you can use it for anything though. Well, almost anything. Because I mean, if you'd need if you need more than 40 volts, lots of times you don't need that much current. So use the high voltage rail, you know,

Host 2

So gone to the RFO. So this is a cool one. I found this last week for the Kentucky Derby. So the Kentucky Derby is a social drinking event here in the United States where horses race

Host 3

It's kind of like NASCAR, but with legs instead of wheels.

Host 2

Well, NASCAR is seen as a trashy thing to do here in the States, where Kentucky Derby for some reason is like classy, but exactly it same thing sometimes with horses.

Host 3

It's just classy NASCAR. That's classy NASCAR class car.

Host 2

So the they actually built a I can't remember what TV show it was for but there was a custom PCB badge built for like the announcers or the people who are on TV. And the cool thing about it was it actually has an animatronic course on it that moves. No, that's cool. Yeah. So when like badges, like the badges get close to each other. The horse starts running. Very cool. So I thought that was really cool.

Host 3

How did additive? What how did it since proximity?

Host 2

I think it has like an RF chip or something on it. Okay, yeah.

Host 3

That's really cool. I guess the Yeah, so the the whole badge life thing is extending to everything really?

Host 2

The Kentucky Derby. We just call it class car class car. Yeah. Classy NASCAR.

Host 3

Yeah, rich folk, NASCAR. I like that. Cool. So I had a pretty interesting thing happened last week at work that I thought would be pretty fun to discuss. So last week, we had a few of our units enter into our test room, and they seem to be having a bit of trouble with their testing, and they were doing some kind of funky stuff. We spent, you know, some time here and they're kind of investigating them. They were a little bit on the backburner. But as time you know, progressed, the the issue was was kind of odd with them. They didn't seem to be responding the way we wanted to. Bill, the the owner of the company came up and he took a look at them. And it didn't even take him that long. He just looked at me goes, Why are all these capacitors, different colors? They're, they're all the same. They're supposed to be the same cap. And we were like, oh, no, we might have an issue here. So we popped the caps off and found out that all of those caps that were they were actually 10 micro farad Oh, 805 caps. They were all shorted or close to shorted in some cases. So they

Host 2

Had a really low ESR like, non existent ESR

Host 3

Yeah, yeah, basically. So so that's what you

Host 2

Wanted to cap right?

Host 1

Low. Yeah, it's, it's a short ohm resistor. So we Yeah, so we were like, Okay, well, maybe we had some bad units. So we checked some other units that had also had these caps installed, and they were also failing in our test department and found out that we've got a bigger problem on our hands because a lot of these caps are starting to fail. So we immediately go and quarantine these caps on the reels and start looking through some of the reels in each Inside the tape on the reels, we were finding that the caps were different colors in some of the trays on the reels. And some of the caps even had some physical damage to them. So it was like, oh, no, okay, so we got it, we got to take these caps and do some testing on them. And I ran in and did a bit of a bit of testing on them. Some of the things that I did were just testing cap values and things like that. But one of the big things I did was just charge them up, apply voltage across them, and applied varying different voltages to groups of capacitors, discharge the caps, and then test their value, and then you know, rinse and repeat and things like that. And one of the things that I found was before charging the caps, I tested them, and they all, they all were pretty much in line with what you'd expect. However, they were way on the low end of their tolerance. But as soon as I charged them up, discharge them, even if it was just a short period of time and a low voltage, I tested them again, and the capacitance value just dropped, just completely went, you know, haywire. And in a sense, and it looks like what we what we got was capacitors that were marked as 25 volt, when they were probably something more like 6.3 volts. And we were, you know, just generally over voltage over voltage them and causing damage to the dielectric or whatever happens when you over volt, a little cap like that. So, yeah, I thought it'd be a fun little thing to talk about. Because, you know, it's possible to receive counterfeit capacitors, it looks like we may have had that happen. So we've quarantined all the caps, and we're just gonna, you know, we're gonna pitch them and we've already dumped them out of inventory and things like that. But it's also like, crap, because we got a, we got to replace some luckily, they're all in our test department right now. So we can we can replace them all in there. But you got to watch out because it's like it can come and bite you in the bud every once in a while.

Host 2

Yeah, the interesting thing about that story is you're saying that the different colors, I wonder if the recycled parts,

Host 3

You know, it may have been that somebody went with tweezers and just put them in tape one by one by one who knows,

Host 2

I will send you a there's a PDF I found of a company that did some investigation into counterfeit parts. And basically, like, what I just said with recycling parts totally happens. People will just rip the caps off. I bet you you have real there. I bet you some of the caps are what you want, which is whatever for whatever capacitance at 25 volts. Yeah, but I bet you that when they took them off the boards, they just sort them by size. And that's it.

Host 3

Right? Yeah, absolutely. Could be Yeah. Or maybe they Yeah, they just test for the capacitance and if it's close enough, I mean, the thing was, these were supposed to be 10% caps and just directly off the reel they were testing like 12% low so they were already out of tolerance straight off the reel. So that means that had been reflowed before then maybe you never know exactly when you reflow I know this is true with resistors Tom Anderson from the Slack channel actually told me about this is when you have like a 5% cap, not 5% Cap 5% resistor in your reflow it it actually the tolerance widens.

Host 2

And the more times you heat cycled the resistor basically the wider its tolerance gets so that's why like sometimes you have to go with 1% in though at the end of the day you still get like 2%

Host 3

I guess is that because you heat it up and things kind of move around and then it solidifies in a different crystal and structures something

Host 2

Yeah, I never asked him why that is case but it makes a lot of sense and the couple papers I've read on the subject kind of reinforce that Yeah, yeah. So I bet you I bet those capacitors had been reflowed before

Host 1

It very well could be although you know I was able to change the capacitance values significantly just by applying a voltage to them that's the within this is without you know my cell free flowing them and I know that ceramic capacitors have voltage dependence so you know I made sure to properly discharge the caps before I tested them second time so I think I you know, if there was any voltage dependence just having voltage on the terminals there shouldn't have been any I took my time discharging them. So I'm really confident that that's you know, that I that myself charging them up I changed them somehow. And that's not good.

Host 2

They're probably damaged Yeah, and we usually buy you know, we

Host 1

Usually buy 25 volt, excuse me or higher, because our Eurorack systems run on you know, plus minus 12 volt. And most of the time these capacitors in fact, basically never these capacitors will ever see the Full 24 volts, it's just we always buy above the 24 volt rating just so that we're always safe on that. But I really do think that we got misbranded capacitors and these capacitors were Samsung capacitors. You know, they weren't like some rando capacitor thing. So I think yeah, I think we got boned on some stuff there.

Host 2

Yeah, that happens sometimes this cool little cool little thing. Luckily,

Host 3

We found it and we're able to identify it very quickly. And there's not a huge impact. I could see this being a really, really big bad thing. You know, if you send out like 1000s and 1000s of stuff with these on it's just like, Oh my God, what do you do?

Host 2

God take all the things back.

Host 1

Take Yeah. And we I would say that we got lucky because they actually failed, in general, catastrophically in our test department. So, you know, they they filled out a place where we could stop and be like, Huh, what's wrong with these?

Host 2

Yeah. And in general, when you're when you're doing manufacturing, and you change suppliers, or you're changing a part, you always do more testing on those units. And it sounds like that's what y'all did, and then caught that caught the problem early, which is always a good thing.

Host 3

Yeah, I mean, basically, yeah. So luckily, it worked out.

Host 2

So the next subject is, same thing with capacitors, I guess, capacitance multiplier video. So you posted a Dave Jones video in our Slack channel,

Host 1

You know, and I used to watch Dave Jones pretty religiously. And for some reason, it just kind of like, I guess it just waned off. But the other day, I was just like, Hey, what is he got, and I pulled it up. And it was a capacitance multiplier video. And I love these kinds of videos where he gives building blocks, these little like chunks of circuits that you can use, because they're super useful. And I think a lot of people don't, you know, have a good grasp on these kinds of things. So he has a whole video on capacitance multipliers, which, if you haven't seen it, go check it out, because I think it's very valuable. And it's really useful. And it has some really specific purposes, above and beyond what you would normally think. And not a lot of people use them. So capacitance multipliers are a little bit misleading. But they basically you can use them to reduce ripple in a power supply. But it's not necessarily only a power supply, it's just where most people typically use them. So if you have a signal that has ripple on it from, say, a rectifier or something that you can, you can put a capacitance multiplier, and you can squelch the ripple on it. Now, the thing is a capacitance multipliers is not a regulator. So it won't hold your voltage at a specific whatever, it will go up and down if the DC goes up and down. But it does take away ripple. And it's pretty good at it too.

Host 2

So it's kind of like a low pass filter.

Host 3

That's it's actually that's exactly what it is. Capacitance multiplier

Host 2

Is an it's an active low pass filters. What it is,

Host 1

It's a buffered Yeah, a buffered a low pass filter. So one of the best or easiest ways to get rid of ripple on any signal is to low pass it right. But you never know, I shouldn't say never, it's really rare to pass a power signal through a low pass filter, mainly because you have to pass it through a resistor before a capacitor, and you're just going to dump voltage. So

Host 2

Now you have the pass through basically, ginormous inductor, or coil and then through a big cap to low pass it correctly.

Host 1

Yeah, well, right. And and I mean, the easiest ways an RC filter, right. But there's no point in passing power through an RC filter, because you dump the power into the resistor most of the time. So it's sort of you don't get the benefit of a low pass filter, or the benefit of just a two component, low pass filter. But if you add a transistor into the mix, what ends up happening is your signal doesn't pass through the resistor, your your signal will pass through the transistor. But it gets the added benefit because the RC filtering is what actually controls the signal at the base of the transistor. So the RC filter actually does what it's supposed to do. But the transistor only allows the DC component to flow through, and squelches ripple. So with only three components, you can get a really nice ripple filter. And what's actually interesting in Dave Jones video, this was totally worth watching because I love this, he shows where he just takes a regular voltage regulator like a 7805 thing. And he puts ripple directly into it and looks at the output. And a huge amount of ripple shows up on the output. Because the voltage regulators not fantastic at rejecting ripple. It's really good at holding a specific voltage, but its rejection ratio is pretty bad. So if you take one of these capacitance multipliers and put it in front of a regulator, you get both You get rid of the noise, and you get the rock solid voltage. And one of the beauties is, the RC part of the filter isn't actually passing power. Because if you use a BJT, the only amount of current that flows through the RC filter will be the base current. Or if you use a MOSFET, the only power that flows through the RC circuit is the very small amount that goes into charge up the gate of the MOSFET. So you can use Joe Schmo resistor capacitors, and get the added benefit of the filtering with both of those things. So it's a really great little circuit, go watch the video and check it out. Because it's worth potentially adding to your, you know, your designs, and they're cheap. That's what's kind of nice about

Host 2

It. So I will definitely have to go watch that video now. Yeah, yeah, for

Host 3

Sure. And I have used these in a real design before, you know, in a in a grownup design.

Host 1

I had a I had a circuit once that I was designing that had a whole bunch of temperature probes on it, and it was galvanically isolated. And the only way that we could get power across the galvanic isolation is to use an isolated DC DC power supply. So on on the other side, on the the side that I was most interested from the galvanic isolation, I had a switcher that was you know, powering up. And I in reading the datasheet. And looking at the power up sequence, it could power up it was a five volt, but it could spike to seven volts. Now I was using a bunch of 24 bit ADCs on the input that were super sensitive. And their data sheet said, you know, never ever, ever go above like 5.6 volts or something like that. So I had a problem where the my little isolated, you know, power supply could potentially for a very short period of time spike well above what my ADD czar. And those add is really expensive. So I didn't want to damage them. So what I did was I actually put a capacitance multiplier in between them, because I utilize an extra little feature of the capacitance multiplier, you can set with the RC you can set a time constant on that effectively, where the transistor won't open up until the capacitor is charged up. So basically, if my DC switches spike to seven volts, the transistor wouldn't allow any that voltage through because it was still charging up and it would slowly like time up and open up. So it was a way to squelch that power on cycle and still protect. Yeah, you made a slow start a slow start. Yeah, but it also any ripple that came from the switcher was also squelched by the capacitors multiplier. So I didn't necessarily care too much about the exact voltage that was coming off of it, because I was still regulating it afterwards. But it ended up working out

Host 2

Really, really well. So Brandon asks, Is he asked this in that email? What do we think? So I think he's talking to Stephen and I think of engineering paper that is green and looks exactly like graphing paper. But isn't all my professors require it this semester, and I'm exceptionally fond of you and Stephen making fun of your respective academic institutions. Ignore my request at your peril slash benefits. Oh,

Host 3

I guess we better answer. So did you did you have to use a engineering paper?

Host 2

I used to use it all the time. I don't have any right now. I love drawing on it. I do too.

Host 3

I really like it. It's got like the nice front. And then if you flip it over it has graph paper on the back. Yes. Yeah. And you can sort of see the graph paper through it.

Host 2

Yeah, I really liked it for when I was in school. I really like basically I was getting I got my own. I've done all my notes in them. Because it's really nice because you could write normal words I guess is best way to put your notes would go in on one side. And then and then you can do diagrams on on the backside.

Host 3

Yeah, yeah, that was that was super great. I remember having multiple professors and the more than one that if you turned in your homework on anything, but that you'd get an automatic zero. Didn't matter if it was perfect. That was required.

Host 2

See, I didn't have I didn't have a single professor require this stuff.

Host 3

Oh, you chose to use it. I just chose to use it. Oh, interesting. Yeah.

Host 2

I liked it. I like writing on

Host 3

It. For the first couple years out of college. I actually purchased some and I used a met at work and I yeah, I really liked it. I don't I do not get why it's a requirement. I do it because I mean in the real world. Nobody uses it unless you just like it. Yeah. Like nobody requires

Host 2

It. So that's interesting. That's you had professors that required it as well. Like Brandon does. Oh, yeah,

Host 3

Yeah, yeah. And I remember griping about it then because it wasn't cheap. It was like three times the cost of, you know, graph paper or whatever paper you wanted to use it the DA. So

Host 2

That's why he's complaining about it. Yeah. Well, wants us to complain about it. Yeah.

Host 3

I, I had a professor who was, you know, for lack of better words, he was a pompous ass.

Host 1

He was one of the first professors I had, no, not one of the first classes I had with this guy. He taught an entire lecture on why engineers were better than doctors, and why they were, like, more necessary to society than doctors. And they do more good than doctors. And it was just like, wow, you know, screw you, dude. Like, I want to be an engineer, but I'm not I don't want to be an ass about it. You know? It, he kept he kept going on this whole like tangent, like, anytime anything would be difficult. He went on this tangent about the fact that B 17 Bomber wings had to flap I think his his number was they had to be able to flap 35 feet in, you know, the the winds over Normandy or whatever he was saying. And it was this whole thing about like, you think the engineers had to work that out? Yes. They had to work that out. No better than doctors. But he was the guy who was like, engineering paper or nothing. It's brutal. Yeah. You know, and at the same time, like a man now this looking back, this is really weird that he had like a really like this favorite student in the class. And he really made it clear that that student was his favorite. And this student never paid attention in class. And he kept drawing pictures of guns on his computer, but in like AutoCAD, like he was making like these really flawless pictures of guns in AutoCAD. And, and this professor really loved that kid. And he'd be like, look at what this guy could do. And he'd show it to the entire class and there'd be like a picture of a handgun up on the on the screen. That is really weird. It's super weird looking back, but that was back when I wasn't an electrical engineer. I think that guy kind of made me want to switch majors. Because I was like, wow, these aerospace guys are super weird.

Host 3

So there's my engineering paper ran.

Host 2

Did you have any electrical engineering students are not students professors require the scrap paper? No, but it was just aerospace. It was the mechanical guys.

Host 3

Okay, so

Host 2

That's might be why I didn't have any because I bought Petroleum Engineering. No one cared. But it's because it's petroleum engineering, because

Host 3

No one cares at all.

Host 2

Exactly. Yeah. Just dig a big hole in the ground and oil comes out. Yeah.

Host 1

And make, you know, $200,000 a year. Yeah, yeah. It Texas a&m is sorry, is number one for petroleum engineering in the nation. And I had some friends who left they were 21 years old. And they were making $110,000 a year when I

Host 2

Went to school. Actually, UT was number one in petroleum engineering. Basically, it's like a&m and UT like flip. Yeah, they

Host 3

Fight for it. I remember, your school was like 15th for electrical and mine was 17th or something like that. I can't remember exactly how it work.

Host 2

UT was number 1010. D. Yeah. It's like the highest ranked public school for electrical engineering. At least that was back when I was there. And then they tore down the electrical engineering building and then like, plummeted, did it really well, because they didn't have a building anymore. Then they rebuilt the building and they went back up. I don't know what it's at now, though. Yeah, the the crazy thing with the petroleum engineering building there is they actually have a well, they're at the UT building,

Host 3

Like legit drill, like drilled well. Oh, okay. That's cool.

Host 2

Yeah, they actually have a legit one there with a Christmas tree set up and everything.

Host 3

Oh, that's cool. So you can actually like practice on it.

Host 2

I don't know what it was for, oh, it just sat. We just got to look at it. I wonder if you could do stuff with it. If you're like, went further in the program. I was only there for like two semesters as a petroleum engineer before I switched over. So yeah. So our next subject is a site really a subject anymore. It's just a statement, I guess. So Tom Anderson had some experience. So let me back up a little more. Last podcast, we were talking about. 3d mice. Yeah. Yeah, that's right. Um, and then we were talking about 2d mouse's, which are just like normal mouse use. And then we came up like, what, what would a one D mouse be right? And you said, potentially ometer. So Tom Anderson says these actually existed, and they were rotary devices on your keyboard. And so you just be

Host 3

Yeah, I think he actually even posted a picture of an old keyboard with a one day mouse.

Host 2

Yeah. So it was just a knob that or rotary knob that you would adjust. And so it was for scrolling through text on terminals, which makes a lot of sense.

Host 3

It makes a lot of sense. And that's actually kind of cool. Yeah, I could I could see like on basic code and things like that. I bet you that's really useful.

Host 2

Any So the best thing about it was you didn't get carpal tunnel using them.

Host 3

People didn't know about ergonomics back then. That was back with like the old like brick mouse, you know like one sort of basically just like a square like it was like a Nintendo controller like the original Nintendo controller just like flat on a table. I wonder

Host 2

Who thought the original Nintendo controller was a good controller to use to play games.

Host 3

Honestly, I love that thing. I think I think it works so well. It works

Host 2

Well, but it has. It has two corners that just jab into your decide your hand. Yeah. And well, I

Host 3

Mean, I think that's why, personally, I think the Super Nintendo controller is superior, and it's one of the best ones Nintendo's ever made.

Host 2

The s&s is a pretty good controller.

Host 3

It's really good. It's really really good.

Host 2

So I think that's gonna wrap up this episode of The Mac fab engineering podcast. Yep, we were your host Parker Coleman and Steven Craig See you next time guys take it easy if you have a cool idea, project topic or capacitor multiplier that you want Steven and I to discuss, tweet us at Mac fab or email us at podcast at Mac fab comm also if you know how to remove this conformal coating on this board, let me know tweet me at Longhorn engineer. I really would like to get this board fixed. Also check out our Slack channels where Steven and I hang out and where we get suggestions to talk about you know things on the podcast. If you're not subscribed to that podcast yet, click that subscribe button. That way you get the latest episode right when it releases and please review us wherever you listen, as it helps the show stay visible and helps new listeners find us