MEP EP #133: Tales From an Electrical Engineer – Ideas on Mechanical Design

Podcast Transcript

Host 3     00:11

Hello and welcome to the macro fab engineering podcast. We are your host, Stephen Craig and Parker Dolman. And this is episode 133. So Parker, you got some exciting stuff this week, right?

Host 2     00:23

Yeah. Um, a couple weeks ago, we talked about that thermal detonator 3d printer thingie I've been working on. Yeah. So I've been slowly assembling the hardware. So I've got an Arduino micro or Juno nine nano camera, which port it is one little tiny, cheap ones. That little the little tiny one. Yeah. So I've got that guy running off a nine volt battery. Yeah, nine volt battery. And then I have a PWM pin that comes out of it. And that goes into an LM 386 op amp, like, boost converter circuit.

Host 3     01:00

Yeah, yeah, like a big beefy op amp,

Host 2     01:03

Not a boost converter, a amp, just an amplifier. And so basically, it's what its gonna do is that's going to produce on the other end of that lm 386 is a piezo. And so that will just make the buzzing noise that it makes and in the movies, for those that don't know, thermal detonator is basically a grenade in Star Wars. Yeah, it

Host 3     01:21

Has like a little slide switch on it and some LEDs and beeps. Yeah, little side switch. Yeah, yeah. So this is sort of like your unofficial submission to the design contest. Right? Ah, yeah, that's

Host 2     01:33

Good idea. Maybe I should like, I should change my name to Domon Parker and then enter.

Host 3     01:42

Darko Tillman. Yeah. I think you should

Host 2     01:47

Do that. Yeah. Yeah. And so the, that's such a better idea than what I did for the example project. Oh, well, next year, right. Yeah. Yeah. And then so it has a like a 3d printed slide piece that goes back and then on the inside I hot glued a a micro switch so that when you slide it back, it activates a switch. And basically, that's just gonna be an on off circuit. So when it turns on, it just runs through the code and blinks LEDs and, you know, does its sound effects? I don't know why I'm gonna finish it. Hopefully next week. I'd be really nice to be done with it. Because I've been like, teasing that thing for like, six months now.

Host 3     02:29

Actually come to think about it with the 3d printed stuff. It's

Host 2     02:32

So simple. I'm just soldering little tiny things together. just haven't gotten around to do it.

Host 3     02:37

It's that's just that's life. Whatever happened to that Arwing that you 3d printed and you're going to town on?

Host 1     02:45

It's in the drawer. I didn't work. I'm almost finished with this.

Host 3     02:52

Oh, yeah. The T Rex skull that you 3d printed? Yeah. Well, I

Host 2     02:55

3d printed this thing like a year ago. It's like the first thing I've 3d printed on my new printer.

Host 3     03:00

How long did that take? It's actually pretty big.

Host 2     03:03

This took about 36 hours total to print. It's in two pieces. Right? Yeah,

Host 3     03:09

It's it's pretty big.

Host 2     03:10

Yeah, I'll say I'll take some pictures of the podcast, but like it's all sanded, primed, all needs. All this thing needs is like a good coat of bone colored paint. And then like dry brushed a bit on the on the highlights, just to you know, tone them down a bit. So it looks like ancient bone. But it turned out great. Yeah, it looks awesome. And the thing is, it just sits up here on my 3d printer. And I always look at it. I'm like, I should finish that because it's so close.

Host 3     03:40

Yeah, yeah.

Host 2     03:41

I'll post the link to that. That way you can get the STL files for that scope on Thingiverse or something like that. Yeah, it's I think if you actually just search for T Rex skull on Thingiverse is like the first thing that pops up.

Host 3     03:55

Yeah, yeah. Cool. Did you just scale that up to be as large as your printer can print?

Host 2     04:01

Uh, actually, yes, I did. I scaled it as big as I can print it. Cool. My idea was to see how that turned out and then painted and everything. And then I'd have like a good piece for like my desk at work. And then I wanted to print like an almost full sized one. So I cut it up into pieces and printed on the printer. It's like the size of a table. Well, I said almost full size I wanted printed like the size of like a deer skull and so you can mount it on your wall. Ah, so and then I bet you know I'd cut a piece of walnut and get a brass plate that says T Rex, like and then make some like, When were they they weren't alive in the Jurassic period. They were live in the quotation.

Host 3     04:44

I have no idea.

Host 2     04:46

Crustacean is a manifestation it's it. Or John rose. Um, I don't know my biology.

Host 3     04:53

I think I think my my aspirations of being a paleontologist died when I was like five

Host 2     05:01

When you saw Jurassic Park, you're like, nope. But I want to print one that's like about two feet long. And which will take me like eight years. Oh, you're sure? Yeah. But so I can put it on the wall. And then they get looked like you hunted it and killed it and mounted it and stuff. You know, actually,

Host 3     05:22

Funny, funny side tangent about not getting stuff done. I think it may potentially be slightly genetic, about not getting projects done. And the reason why my father, before I was born, he bought an RC airplane, and he built the entire airplane. I mean, all the way. Get this the airplane has a gas engine in it, he got all the way come to completion. The only thing he needed to do was buy a radio for it at basically turn it on. And it has still has not happened. Although two years ago, he found an original, an original kit, the same airplane on eBay, unopened in the box. So he bought a second one. Oh, no. Because his his thought is like, well, if I ever need to repair it, then. So I'm 31 and this thing has still never been touched. So I mean, but don't

Host 2     06:23

You have a project just like you have an airplane, but you haven't finished?

Host 3     06:27

You know? Okay. No, I do not anymore. And yeah, I do not I do not. And here's here's why I do not. But what I promised myself, I would not move again with that airplane, unless it was finished. And like a week before we moved up here to Colorado. I called everyone I knew who had like children who were like, this is a really cool airplane. If you want it, you can have it like and everyone was like no, I don't want it. And it ended up going in the dumps. Oh, like I traveled like, I moved like five locations with that airplane and kept it like there's a p 38. If I recall. Yeah, that p 38. And it had a wingspan of like four feet. It was awesome. I was like 12 When I got this airplane kit, and I kept it for until I was 31. away. I wish I could go back in time and tell my like, you know, 1213 year old self be like, this is just gonna end up in a dumpster one day like incomplete.

Host 1     07:34

20 years later.

Host 3     07:38

It was it was really cool, though. I really I liked that airplane. Yeah, so maybe, you know, maybe I should have just posted it up on like the Slack channel and been like anyone want a really cool airplane?

Host 2     07:49

Yeah. How about you someone were taken to here in Houston? Oh, well,

Host 3     07:52

I tried. I legitimately gave it ever. You know, I was contacting that. Basically everyone I know. And everyone's like, No, I don't want that.

Host 2     08:00

Okay. Oh, well, we'll pour one out for the P 38. Model. Yeah, for the

Host 3     08:06

Yeah. So give us an update. I know, there's got to be a car update this week. Oh, well,

Host 2     08:13

Before that more electronics. Pin hack Rev. Eight has been we actually started testing a lot of the software even writing for the kernel. And we can get the Raspberry Pi part to like switch video, like HD video really quickly and load it really fast. We're actually writing directly like C commands directly to the or C calls, I would say directly to the Raspberry Pi's GPU on that Broadcom chip. So we actually I actually bought a book with these commands in it to learn them. It's the first time I ever bought a software book to like learn about learn about a system, I guess, what's the name of the book? Oh, it's something like it's something like really generic like Raspberry Pi. Like how to program the GPU or something like that output link. Just like It's like your idol is what it is.

Host 3     09:15

Like, you can't judge that book by its cover. Yeah, exactly.

Host 2     09:21

And so I'm working on a hardware version rev eight B, which puts the audio DAC on the board just to like, limit how much crap you need when you're like prototyping for the system. Because right now you need like, you need a rev eight and you need a a special cable and you need the PCM five oh man I completely forgot what that part number is PCM 522 Something anyways it's it's that dat gap it's using a couple months ago and we've been we've talked a lot about so that will go on the board and and you need to pick it right you habit, that's normal, you're just assuming. Yeah, I'm just assuming that you need a programmer for it. So I'm basically trying to limit that custom cable and that daughter dashboard and put it on the board. So hopefully next hopefully in a month, I have like those built because the design is almost done. So that's doing pretty good software is progressing slowly but surely. Now, vehicle Jeep things. So the I basically been taking part, so I got all the engine stuff, we're done, the AC is running right now. Great, right. And so I go and like putting oil into it, starting it up, and I back out the driveway, it's running great, I hit the switch to lower the real rear tailgate window and it doesn't go down. I'm just like. Sounds like I'm at the point where I'm like, everything is working except that so like, pull it back into the garage. So I took the whole tailgate apart. And I always knew the rear wiper didn't work, which is in the rear turret gate as well. And I'm like, well, since I'm in here fixing this switch, because it's basically what happened is the key switches on the back, when it goes out, it will disable half your motor. And so I'm like, Okay, I need to replace switch and replace switching, you take everything out of the tailgate, it's like the what it's like the first thing that goes into the tailgate. So of course, it's the last thing you need to pull out to fix. So I'm like, Okay, I want to get the rear wiper working. And the rear wiper, the original one looked like it caught on fire at one point and the previous owner, just like snip the wiring harness to it. So I pulled it out and threw it away and started looking around online. And I was able to find someone who had modified a Dodge Durango, 1998 to 2000 rear wiper motor assembly, and got that the fits. And it works. And like it actually, it's the same kind of wiring scheme as the, the wagon. So you just splice the wires together and it all works. And so actually, that's what I did today. I took like, a half day from work. And I drove over to the local junkyard, so basically you just like, go there, and then you like, use wrenches and stuff and pull the parts and you go inside and say how much for this that the one I went to is down 40 But they actually really nice. This is like the the cleanest one I've been to like, every car was like in a perfect row. And they had them organized. And if you and I asked him like How much for a rear wiper motor and they just they could tell me the price. And that was the price when I showed up with the rear wiper motor. So I was like, that's the first time that's ever happened to me. That's awesome. Yeah, I can't remember the it's kind of like you pick you pay, I think is what's called, I'll put the link because they're, they're pretty cool. And the fact that like, when you went to go pay it was heavily air conditioned. Oh, that's nice, which was really nice. So it's like when you're like they didn't take care of you. They're sweating out in the yard and then you come back in like oh, it's like walking the Walmarts or targets, the industrial air conditioning blowing on you. Yeah, that that place is really cool. That's the one I that's probably my favorite place. So for $33 I got a rear wiper motor, all the brackets, the wiring harness and then the wiper arm for a Dodge Durango 1999 was the one I pulled it from. I actually had to go to two other ones like the first two I found they were in the same age range but they were missing part of the trim on the wipers. So I can someone needed like the cap. Yeah. And I'm like I need all the trim.

Host 3     13:53

So how much how much like modification do

Host 2     13:56

You have to do I had to just drill a bigger hole in the tailgate and that was it.

Host 3     14:00

Oh really. So the bracket fits nicely.

Host 2     14:04

So okay, I had drilled two holes in the tailgate and one hole in the bracket and then it fit. Okay, okay, the other the person who did this previously I can't remember his name. I had the link for the forum post. He like made a brackets to make it work. Yeah. And I was just like looking at the stock bracket. I'm like, if I just draw a hole right in the middle of it, it'll fit inside so I didn't said okay, there's a lot easier than trying to make a bracket I thought

Host 3     14:30

You were gonna do another freeform jazz Odyssey welding adventure to get another bracket made?

Host 1     14:38

No, I'll try and do the least amount of work possible on this one. That's good.

Host 3     14:42

Yeah, man for 33 bucks and a half day of work. That's not bad.

Host 2     14:46

Yeah, so it all works. I got the rear defroster the work and I got so the the rear window works the rear defroster works and the rear wiper works and I am waiting on a couple parts to get the like sprayer that sprays windshield washer fluid. Yeah, because the stock one, you can't get that part anymore. So I'm kind of like modifying some stuff from other vehicles to get the work. And when that part shows up, I'll probably have the only fully functional, grand wagoneer. tailgates on the road. Like, everything works on it.

Host 3     15:24

Yeah. Nice.

Host 2     15:27

So pretty accurate that and I'll say, again, the number one way to like fix vehicles is just get the factory service manual because those schematics are invaluable. Just trying to figure out what wire did what. So I when I hooked up the Durango motor it like worked exactly the right way. Hmm. So Stephen, you haven't been working on a wagon, but you have been working on another project that you've been working on for quite a while now.

Host 3     15:55

Yeah, and it is coming along quite nicely. I'm actually pretty happy about it. So my you tracer, PCBs finally arrived, which surprisingly, I only ordered them, you know, a few days ago. So it's amazing how fast China will get a board whip together and sent off to you. So but no, I'm super excited. I got my boards in. Parker can see this. But I've already posted some some of that. Is that a hassle or lead free hassle? This is straight hassle. You know me, if I'm going to do a project myself, I'm going to go straight L capital cheap.

Host 1     16:34

I'm like, look at me and

Host 3     16:36

Find out. Yeah, so I got the board's in. And this is actually for myself, personally, the first time I've ever done, like, actually pasted aboard a personal project. Because most most of the projects I've just never really felt the need for doing it. But I was like, You know what, it was seven bucks to get a steel stencil made for this. So I was

Host 2     16:54

Like, okay, oh, so you're going to stencil board now? Well, I actually already

Host 3     16:59

Did. So yesterday, I spent some time doing doing the actual assembly on this. And it went super well. I'm super happy with how it's come out. So far. I've made one mistake, which is just super annoying. It's not a mistake that like requires a design revision or anything like that. But when I originally started this project, I was planning on using five volt relays on for all the relays and there's 56 relays on this thing. But I found out or realize that the relay that I wanted to use in the 12 volt version was first of all cheaper, and it was easier to generate 12 volts at the higher current than it wasn't for five volts. So I switched all the relays over to the five volt trouble the thing or sorry, 12 volt. Yeah, the thing that really sucks is all of the driver chips that I chose to drive the relays and the LEDs are the UL and 2003 l is what I picked. Now the L at the end means that it is eight volt maximum is what that chip can tolerate. It's not really a big deal, because I can get the other version of this chip from Mouser. Just I mean, it's just there and it's a 50 volt version. But I had originally spec the eight volt version expecting five volts to be on all my LEDs and my relay close, but I have 12 there. So the only thing that sucks about that is you know, once I get the processor up and running on this, I literally can't do anything with the board. I can't test any of the displays, or flip any of the relays until I get these driver chips in. Which you know, it's Mouser it's only like two or three days. So I'll probably be able to do it this weekend. But I've got most of the board already assembled. So it's just like I just want to like turn on LEDs so I can see it you know, so have you refloat it yet. Yeah, I have one and I was kind of like doing it in section. So like the whole FTDI chip section. I've done most of the display and relay driving section minus those actual driver chips. That kind of stuff. So I already started reflowing it and it's it's beautiful because I bought leaded paste from Amazon was a 6337 Oh, that's

Host 1     19:16

A good stuff.

Host 3     19:16

Yeah, that stuff really good. And do hit flows. So it's it's really really easy. So yeah, no.

Host 2     19:24

Are you hitting it with? So you hitting it with like, sorry, did you cut up your stencil? How do you stenciling certain sections. Now

Host 3     19:32

I got full sized stencil for the board. So this board is six inches, I'm sorry 10 inches by five and a half inches. And I got a full size steel sheet for it. So I just built a little frame out of other PCBs and then just pasted the thing with a credit card. It turned out really well. So I haven't I haven't had any shorts or anything like that. So

Host 2     19:55

You paste the whole thing. So then you just hit it with a hot air gotten them to reflow certain sections.

Host 3     20:01

I've done this entire board with Yeah, with a hot air gun. So it's been super easy. I just put on my TV and did like four hours of hot air. But But since it's leaded solder, it melts at a lower temperature. So you can you can do larger sections with hot air.

Host 2     20:20

And it probably has. It's probably rosin flux, so it won't dry out.

Host 3     20:25

Yes, fast. Yeah, exactly. So so there was a couple of other you know, small things where I accidentally had a resistor marked as a wrong value. So I'm going to throw together a bill of materials later tonight, and get that all purchased up. So I should have this thing actually flipping relays and showing stuff on the displays this weekend, hopefully. So next week. Next week, it should actually be doing something, you know, something useful. I don't know if I'm going to have like all the tube testing functionality going because I've got some programming to do on it. But regardless, you know, another another really good thing is, everything fits perfectly. Like I milled that box, and everything. And all the holes line up everything is exactly where I want it to be like, it kind of turned out exactly how it should. And I always have my fingers crossed when doing one offs. Because you know, if you're if you're in like a production environment where you're like doing multiple prototypes, it's not the biggest deal when you make an issue, because you just picture on the next revision, but like, with this, I sort of get one chance. Right? You know, I mean, yeah, I could always do it again. But that's just more money. So hi, yeah, the price go up. So I'm excited. Because all the mistakes that have happened so far are cheap, and readily fixable. So, yeah, so yeah, we'll see. I mean, who knows, it still has yet to actually function. So we'll see what happens with that.

Host 2     21:55

It mean, you apply the the voltage to it and see if it lets the smoke out or not,

Host 3     21:59

I'm going to install the processor tonight. And actually put power to the board and just see if I can talk to the processor. That's kind of that's a good step. Yeah, that's tonight's goal. Like I don't, you know, like I said, I really can't do anything else with the board. But I can start programming. And, you know, I've dealt a bit with STM 32 chips in the past, especially at macro fab. But I designed a couple of jigs that communicated with STM 32. And I certainly did my fair share of programming, you know, customer projects and things, but I had never really actually implemented one on my own project. So this is the first one where I've actually used an STM 32. So the other day, I started getting into, you know, all the software that I need. And I'm actually fairly impressed. Not fairly, I am impressed with the whole ecosystem that STM has created. You know, for a lot of our listeners, I bet you, they're, they're probably like, well, this is all old news, you know, but regardless, like, I'm coming to the game late, and I'm like, wow, this is really cool. So, you know, STM 32, they kind of have an ecosystem that starts with their cube MX program, which is basically just a configurator. And it reminds me a lot of the EFM eight stuff, where it's a graphical version of the chip, and you can like select peripherals and things like that.

Host 2     23:24

Yeah, you go through a checklist and select things, what you want a pin to do. And that's right, yeah, add in peripherals is that like a crossbar will like a pin can be hooked up to like any other, or a comparator can be hooked up to any set of pins.

Host 3     23:39

It does have that but it's not, that part's not graphical that like, okay, the port that's graphical is it'll show your chip, and it shows all the pins, you select a pin, and then you tell it what function you want that to be. And then there's menus further deeper than that, that are just text menus that you say, oh, I want this, this to be an output pin with a pull up or pull down, or bla bla bla, and those are all like, just selectable lists and things. But, but it has it as a whole, like a whole section about determining your clock source and your your system speed. And you can basically what's kind of cool is you can tell it, hey, I've put up X megahertz crystal on the output, and I want the system speed to be this speed, and it will go through and it'll find the best pre scalars and all that stuff to kind of like get to that. Yeah, it'll calculate for you, which is I think that's pretty cool. I mean, like, all of these things are not like super magical, cuz you could do them yourself by just reading the datasheet. But it makes it it takes something that might take like 30 minutes of reading and five minutes of fumbling around. And it turns that into like, a few seconds of clicking buttons, you know, but the biggest cool, or the coolest thing I think with this Cuba Mex program is once you're done, you save that project, and it dumps everything into like, you know, all your SRC your includes your header files, and it gives you all the stuff already predefined and already set up. So everything is done for you such that once you actually suck that into your IDE, you can just immediately begin coding. And I think that's really cool. Oh, okay.

Host 2     25:18

That's all sorts of separate Oh, it's actually a configuration I'm actually looking at now. Yeah, it's, it's basically it's a configuration software thing.

Host 3     25:27

Right. It's a standalone. Yeah, it's a standalone thing. And what's nice about it is just doesn't feel super bloated. And say, if you if you pick a an STM 32, like a pic, whatever, family, it will automatically go and download all the all the latest headers and everything for that chip when you go and configure it. So it's not something that like it doesn't come with everything under the sun. It doesn't do the microchip thing where it gives you just absolutely everything you know,

Host 2     25:55

But the but microchip will give you absolutely everything except the compiler.

Host 3     26:00

Yeah. And like MP lab X has like 900 megabytes worth of just like stuff that you really need, like 50 megabytes worth of stuff.

Host 2     26:10

Yeah. But like you install all of it. And it's just like, now you need to go go get the compiler and just like why did this thing have the compiler in it already? Come on, guys.

Host 3     26:20

Exactly. And so yeah, I think that way, as teams kind of got it set up is they're really trying to like break it apart into like, here's how we help you. We know that you're really picky about your IDE, so you go get whatever you want, and just suck in our project, and everything will be great.

Host 2     26:35

You know, what makes sense is I think what they're doing there is they're separating, because and the FM eight, or even 32, or whatever Silicon Labs, they've combined that those two into the same IDE, whereas STM is separated out. And I think that's because that way, if you're at a big company, the hardware engineers only have to worry about the configuration software, right. And so the so you'd have a the hardware guys, when they're specking out the hardware and doing the pin outs, they can look at just the configuration software and not have to fumble through an IDE to actually set up the pin outs of their chips, right? They

Host 3     27:18

Don't, they don't even have to know how to read code to see how a pin is defined. Exactly. They can just look at the configuration. It's super,

Host 2     27:25

Like a hardware engineer, being hardware engineer and not even looking at like, pin functions or anything anymore. Exactly, exactly. More at the hardware registers and stuff, which is kind of kind of weird, cuz we both both have like Steven Knight, like we're both like on the middle, one foot in in hardware and one foot into the firmware. Right, right. Well, I know there's some hardware engineers out there that are PRs joke. All they do is hardware.

Host 1     27:52

Yeah. Right. And so this, this, this does kind of lend itself towards them. So but I so one of my buddies at work uses an open ID software development tool for the STM 32. It's called system workbench for STM 32. Which it's been around for a while, once again, listeners probably rolling their eyes being like, Oh my gosh. But regardless, Stephens been living under a rock. Yeah, exactly, exactly. I've just been designing things that don't require this. But no, so so that's what I'm, that's what I'm using. And the thing is, it integrates really nicely with STMS development boards. I bought a, a nucleo board, which is basically a development board produced by STM 32, or S T. That includes both an st link which is their programmer, and a development board and one. And it integrates really nicely with system workbench, because you basically just plug it in you, you've already configured your device through the cube MX program. So if it just detects it over USB, all you have to do start coding and when you press run it automatically programs, like there's not a lot of setup. There's not a lot of like going through menus or anything like that. And to be honest, what was funny is the first time I really started playing with this, I was like, that's all it takes, like, Where are all my configuration, where's my linking, Where's all my like stuff because I'm so used to like, you have to spend the first three or four hours making sure that your id Software is like happy, you know, but apparently they've got it down now to the point where like their ecosystem is tight enough where if as long as you have it plugged in USB, and you have the right chip selected, it will find it and it'll program it which I think that's pretty cool.

Host 2     29:41

So it's like it's basically Arduino had to happen before that to happen.

Host 3     29:46

I think I think everyone is sort of like realizing that if you make your your system easier, then people will pick it up and just develop long term on it. You know, they'll get into it. SDM family and then they won't want to leave kind of thing. But once you learn

Host 2     30:03

One thing, you kind of, you know, why should I learn another thing? Right?

Host 3     30:07

Well, although, to earlier today on the Slack channel, I was talking to a lot of the people about like, you know, what's your embedded choice? You know, what do you like to do? And one of our, one of the guys on the channel, zap, who's been on the chat on the podcast before, he actually was saying that he purposefully chooses different platforms just in a way to challenge himself and to kind of learn more and to go, you know, go further with it.

Host 2     30:34

It's apps a little weird. In a good way, in a good way, or

Host 3     30:40

Does in probably like, just like, that's not the normal thing. Yes. Although, like, I totally respect that. And I think that's super awesome. That's like, Okay, I'm going to like shift my paradigm here soon.

Host 2     30:51

But the funny thing is, like, I started programming on the parallax propeller, moved to pics move to MSP 430 on then I went to pick 30 twos, and now I'm on EFM, eights. So yeah, I've done a lot of switching to but mainly because of out of like necessity, almost. Right, right. Yeah. It's not like, I'm going to switch just because I need to switch. Like, I want to switch. It's like, oh, I need a cheaper microcontroller. Oh, the EFM. eights are like dirt cheap. Let's use those.

Host 3     31:24

And that one on top of that, that one was sort of driven by macro fab. As part of the drive like you were you were looking at them as like, okay, yes, I can make things with this. But also, like, I can write articles about these, and we can talk about them. And, you know, you can update the macro watch from some ancient pick technology. Got that pick 16 something else? You got screwed by that one.

Host 2     31:49

And that was? That was funny. That was the most frustrating day in my life that Yeah, yeah, you were fuming that that must have been like episode like three or four podcasts like that.

Host 3     31:59

That was around the the genesis of the podcast, because that's when that's when we were talking about like, how do we like engage engineers at macro fab, you know, outside of macro fab, you know? And so we were like, spitballing a ton of ideas. And making the macro watch was one of those ideas along with the podcast.

Host 2     32:19

So go, go check out the original macro watch version one, so on GitHub, but the issue we're running into with that was, there is a default for like one of the pins is like to use the comparator. And so you had to like, right, you basically have to disable the comparator. And so it uses the GPIO. But that's in a footnote in this like 300 Page data sheets, unlike page like, 200, some odd,

Host 3     32:48

Right. And it basically made the entire project unusable. Yes. Until you found that out. Yes.

Host 2     32:54

Right. And I think the best thing is, I was even talking to a microchip fa e. And we could not get this thing working that day. And there was that one register, we had to turn to zero.

Host 3     33:10

But But that's actually not necessarily a super uncommon thing. Like how many times has that happened to you where like it all it comes down to like one bit needs to be flipped. You know, like, I've had that multiple times.

Host 2     33:24

That is true. The best thing though, was his. At the end of the day, he's like, Parker, you should just use a more modern pick.

Host 3     33:34

We had originally chosen that. Almost purely off a price. It was 100% on the price. Well, and pin count. It had it had the right pins and like yeah,

Host 2     33:45

It has the minimal pin count for the price. Yeah, right.

Host 3     33:48

So Good times. Good.

Host 2     33:51

So that STM 32 Dev board yet the nucleo. You know that reminds me of what's that it reminds me of the MSP 430 board. It's very similar, especially with where the top half is a programmer and the bottom half is the dead Ford. Now what's really cool about that one is I think it's it's just like mouse bide. So you can just snap it right.

Host 3     34:13

Yeah, yeah. This this one. This one has slots cut out and it has some tabs. So I don't think I mean, if you really wanted to, you could snap this, I think it probably would be a little bit better to either snippet or a hacksaw would do it real fast. But I think that's I think it's cool because they actually have like legit st link capabilities with this. And if you've ever priced out an actual st link, you know, they're not like super expensive, but this is this is $22 and it's a dev board and an st link, as opposed to like the legit st link that looks like the little you know white beetle. That's I don't know 40 $50 Somewhere on there. And sure that thing is like a tad bit You know, it's not just a raw board with jumpers and things like that. But for most of us out there, I'd rather pay $22 And get this little dev board that I can play around with

Host 2     35:10

The MSP for 30. I remember cutting one of my first ones on the bandsaw. Yeah, cuz the only way to separate cuz I had dot dash is where you can cut it. But it's a solid board. We didn't have the little scissors, the little scissors, simple, something like that. Yeah, that's awesome. So I just use and but you can't cut through fr forward scissors. Yeah, so I use the bandsaw. To cut right through it.

Host 3     35:35

One of the first PCBs I ever ordered, I, I knew I wanted four different designs. But the place I was ordering from, they wouldn't let you put multiple designs, or like they would charge you per design. And I thought I'd get super cute. And so I like aligned all the boards, since they had lines going through them where I was like, I'll just cut them on a bandsaw. And I ended up getting an email from the place being like, we know that you're trying to do multiple designs, and then they charged me a whole bunch more. And I was super pissed

Host 1     36:06

Off. I was like, the one thing that I wish I would have done is I wish I would have just put dummy traces that connected all the designs to did didn't look like multiple designs, you know, it looked like I intended it and then just cut the traces. But

Host 3     36:24

Oh say lovey, yeah. RFO onto the RFO.

Host 2     36:30

So the first RFO is going to be the max Web Design Contest. So we talked about this last week. It's a, it's blink an LED, it's sponsored by Mouser. Electronics, we already have entries, which is really cool.

Host 3     36:44

Let's just do real quick, let's just do a real fast recap of that. So Mac fabs having a design contest, you can make a design that blinks an LED, there's four separate categories. If you go to the mag fab website and go to the blog, then you can get more information on that. So just put up one of your designs into one of these four categories. And in a few weeks, we will judge them and you can win $500 in one of those four categories. Correct.

Host 2     37:12

The first one is the bouncy thief LED blinking machine by Paul, this one's pretty cool. It's a jewel thief. That's like writing on a set of coin cells and a double A battery in a coil of copper. That's what a jewel thief does is it kind of like, as the name says it kind of like steals low current and boosts the current up to a higher voltage. I guess that's the best way to say it. But but he's got it set up to where as it spins on the battery and bounces at the same time. So when it bounces, it loses connectivity to the battery and sort of blinks. Yep, it's, it's amazing. It's

Host 3     37:57

It's brilliant. It's absolutely brilliant. And like you, you put this like hand wound coil over this magnet battery stack. And it like dances as it as it blinks. And it's it's beautifully simple, because it's just, it's two diodes, a capacitor, a battery and a coil. That That sounds more than just like super simple. But if you go to the hackaday.io project that he's got set up, I love it too, because it's not like super fancy drawings or anything like that. He's got freakin grid paper with like this hand drawn thing, which I've noticed, as the submissions come in, there's a lot of people giving, like grid paper with just like, here's my idea, and I love it. It's like men napkin drawings and stuff. Yeah, it's amazing. And there's actually like, he's actually even provided like a little bit of a sort of pseudo 3d drawing of what he would have expected it to be. And then like the actual thing next to it. So it's great.

Host 2     38:52

I love it. That's great. So next one is a simple countdown timer, by CDM. And so this is a little board that has a when it has a visual countdown timer configurable for like five to 60 seconds. So it's a has little microcontroller on it. I think it's a 328 or 80 Mega 328 P. That's right. And it's a little board. He's using a lot of a Mac crab like house parts,

Host 3     39:20

And a and even the neck fed footprint for the tag, connect tag Connect.

Host 2     39:24

Yeah. So it's a little circuit board. So it's really cool. I can't wait to see if he builds it or not. But he's already got the design ready.

Host 3     39:34

And the LEDs are kind of in there in a circular pattern. So it has like a rotary countdown. It's sort of like an old like egg timer.

Host 2     39:41

Yeah, I think that's what's supposed to be Yeah, in the end. It's gonna be kind of like a rotary led egg timer kind of thing. Yeah, that's really cool. And then the last one I picked was this integrated lm 3909 By Dylan, and maybe some of our younger listeners. Don't know. But the LM 3909 was a National Semiconductor part that I've actually used this part before. And all this part does is blinking LED. So he basically took an LM 39 or nine, because you can't buy it anymore. And he basically re engineered it as discrete. Like diodes and discrete transistors and resistors and stuff and capacitors and recreated this lm 39 or nine on a board to blink an LED. And I'd love this.

Host 3     40:35

You know, I was I was really curious about this one, because I don't I don't remember what the order was. But this was I saw this one come in early, because we only announced the project last week. And this one was one of the first submissions. And it's like, holy crap, this guy's already got a board made for this guy. So I'm wondering if he had already had this made and kind of just threw it up there. Old projects

Host 2     40:56

Are completely fine. You just have to basically say why your project is good for our contest. Yeah, like, yeah, why is my old project I can't just rebrand it at the say also why it applies. It's just

Host 3     41:12

Got a blink an LED. That's all it's got to do it scuffling led

Host 1     41:17

These blinking lights, these blinking Christmas lights don't

Host 2     41:22

Work. That's a really cool project. I like that's like the 555 timer that's been disintegrated into its discrete parts. Yeah. There's also like a 6502, which is oh, you might get

Host 3     41:35

A monster 6502.

Host 1     41:37

It's like the MA MA. Yeah,

Host 3     41:38

That thing. That thing was done credible. Yeah. So I have to admit, one of one of my favorites. So far has is not actually a submission. Somebody asked in the Slack channel. And I apologize, I should remember. Who was who asked this. But somebody asked, they're like, if I had a circuit that could blink an LED. And then I put it inside of a sealed box, such that you don't know if the LED is blinking. According to Schrodinger. The LED is both on and off at the same time. So does that count as a blinking LED? And I was like, Oh, that's amazing. That's so great. I love how we can take something as mundane as blinking an LED and just get some really great creativity out of it.

Host 2     42:22

Oh, yeah. I can't wait to see what we get with get next week. Oh, yeah. Well, actually, next week, we have a guest. So we won't be talking about so hopefully two weeks we have

Host 3     42:31

We'll have love a fat stack of designs. Yeah, I hope so. Actually, yeah, it's because we only have I mean, this is only a month long project or contest. So there's three weeks left effectively, correct. Yeah, yeah. Cool.

Host 2     42:45

So the next RFO topic is engineering or electrical engineering phone applications. And I'm just going to expand this to be basically engineering phone applications. Or I would actually say, how about this applications on your phone that you'd like to use? As an engineer?

Host 3     43:03

That's that that there was like a path that went their

Host 2     43:07

Path to like the least common denominator there? Yeah, for sure. Because because the original question

Host 3     43:11

Was, specifically do you use or what do you use for electrical engineering phone applications?

Host 2     43:20

And I was like, I actually don't use any besides a, um, no, no, there's one I use called calc P C, A L c dash p, which is like a programming calculator. So it does like binary, hex and that kind of stuff, which I guess is kind of electrical engineering. It's more programming. But

Host 3     43:40

But but if you're using it in an electrical engineering setting, then it becomes that I suppose. Sure. Yeah. Yeah. So I, I have used some application I shouldn't use as the wrong word. I've explored some applications that were like schematic generation and things like that. And, and on a phone, it was just like, it was too clunky. And it felt way too. Like beginner free you know, it was just like here you can put down a battery and a resistor and calculate the current and that's great and all but it's just like that's not what I want to use it for, you know, like, yeah, I currently don't use any like, specific electrical engineering phone applications. Unless you want to consider calculator which I use that a lot.

Host 2     44:26

Yeah, I think calculator is the most used app on my phone. What's Drupal sue for Oh, thank god okay, so the universe hasn't broken yet.

Host 3     44:37

Yeah. So here's here's the thing and I'll go oh, this is this is what I think is important to mention with with applications is that you use whatever you need to in the moment to get whatever you need done correct. So what I mean by that is, most of the time, it will at least It's been my experience that electrical engineers do a whole bunch of random stuff. Like, a lot of times you get the idea of going to college where it's like, I'm gonna shut down and design a circuit. And like, yeah, sometimes that happens. But like, sometimes you're not doing that, or most of the time you're doing like all kinds of random stuff. For example, today, at work, we were printing some stuff on on a panel, and we were trying to get a really specific color match from an older device. Well, I downloaded an app that I could take a picture of the device with nice lighting, and then I could get the hex number of whatever that color was. And then, you know, like back calculate what we need to do on our printer in order to get that color. So I use the color detection app, in an engineering sense to, you know, calibrate our printer to get a certain color. So it's not like I use that every day. I downloaded it for that specific application, you know?

Host 2     45:59

Yeah. Like, it's really funny is the there's I have a bubble level app. I think it's called bubble level. Go figure. Yeah. And I actually use that to calibrate pinball machines all the time. Yeah. So I put my eye because you're the playfields got to be at, you know, from left to right, it's got to be zero degrees. And from back to front, it needs to be depending on the game, of course, it's about six degrees. And yeah, and so you can put bubble level and you put your phone on it, and I, the one I have, it actually will talk to you. So it will, it will go like five degrees, and stuff like that. And so you can be underneath the pinball machine and you know, lifting with your, you know, basically you get on all fours and you push up on the pinball machine. So you can lift the legs up, and you can just like sit down, and I'll tell you what the angle is. And you keep adjusting until you're good. Yeah, it's really convenient. It's like sped up setting up pinball machines for me, like, exponentially. That's awesome. And then there's, and then there's the count P, which I use a lot. It's kind of really old school now. But I really like it. Because it's just a really good programming calculator that you can have on your phone. It basically is like a super calculator, compared to like the base Android one. Yeah, right. Yeah. And then I also use an app called cutter, which is not really a electrical engineer. I have used it to cut wire before. Is it a cut list generator? Yeah, it's a cutlass generator. Nice. So if you so I usually usually, I usually use it for cutting. Like, if I have a whole bunch of eight foot stock of like two by fours, or like two by two, two bean or whatever. I can say, this is what I need to cut. And this is what I have. And it will generate a cut list. And so I can minimize my waste, right?

Host 1     47:55

And here's the curve of my blade. It'll calculate Yep, you take that into account? Yeah. Yep. Cool. That's, uh, I, I wonder if it uses calculus to do that. Because I remember multiple times back in Cal one and two, that, you know, we had to do things like, find, you know, the most efficient way to pack a box of certain size with you know, these things were so you had to do like, you had you had to figure out like, what was the best, you know, method of packing a box and things. I wonder if these, if that calculator does something similar to that, I would think it would have to

Host 1     48:36

Probably be something similar. So

Host 3     48:38

There's, there's actually two other apps that I've used multiple times. And I don't know the names of them, because I once again, I probably just download them right when I need them. But your phone can actually make a halfway decent function generator for Joe simple circuits.

Host 2     48:55

Yeah. And that's actually the funny thing is when I was doing the Jeep, Jeep radio, Bluetooth, and I was sniffing signals. I was sending it a, I was sending my bluetooth chip a one kilo hertz sine wave from a function generator on my phone over Bluetooth into the device. So I can like if I can read a one kilohertz signal in the radio. Yep. I know the what the pathway is?

Host 3     49:21

Yeah, well, I mean, the deck on an output of a phone is, first of all, it's meant to drive a headphone load. So it can push a little bit of current, you know, some. And so you know, you can put it into most inputs of circuits and you're not going to load it heavily. And you can usually get what is it one volt peak, so you can usually get to two volts peak to peak out of a phone so it has a pretty usable range there. So zero to two volts peak to peak. And that's, you know, that's that's not half bad. It'll also do sweep generation and things And, you know, as long as you're not looking for like lab accuracy, it's usually pretty good. It's, it's very good for like the dummy checks, like, you were saying, does it work? Does it not that kind of stuff? Exactly. Really good. You know, and at the same time

Host 1     50:16

I, you can use your phone as an FFT. So use the microphone, I've done this. Yeah, yeah, I've, I've actually used that to detect oscillations before and, like, I'll have my phone, listen to what's coming out of an amp. And I'll be like, what frequency is that? And I can do an FFT, find out what the frequency is, and then figure out what part of the circuit would produce that frequency?

Host 2     50:39

You actually was the one who, who told me about that method. And I've actually used that to diagnose engine issues. Yeah, yeah. And so basically, what you do is you you take your E to A sound recording of your engine. And because there's an engine, there's usually two frequencies, there's the crankshaft frequency, and there's a camshaft frequency in the camshaft is usually double, and usually double your RPM. And so if you have an idling at 700 RPM, you take frequency, and it's 1400 hertz, and that's 700 Hertz. You know, it's in the top end where the valves are at and not in the bottom end. Right. It's amazing how that works. So I, you know, I

Host 1     51:20

Would, I would also think that if, you know, you could probably do this without an app. But if you're, if your engine was knocking for any reason, then you know, the FFT would probably look absolutely awful. Like it probably like, all full of harmonics and stuff. Yeah. But it's consistent.

Host 2     51:37

Usually. Yeah. The ones that you worry about an engine are the consistent ones. When it's not consistent. You're like, okay, that's fine. Well, yeah,

Host 3     51:44

It's some frequency other than the ones you expect. You got an issue.

Host 2     51:49

Exactly. Yeah. Cool. Yeah. And the last topic is going to be that was Hackaday. Yeah. Well, do you have another app? No, no, no,

Host 3     52:01

I don't. Okay, yeah. So ask Hackaday. So there was a, there was an article that came out a few days ago. And the question was, is there a common mechanical parts library? So a lot of us electrical guys are really used to there being part libraries, where we just say, oh, you know, this IC or this process, or this passive component, just uses this library. So I just suck it in and I use it. I guess, if you listen to our podcast, where we talked with embedded.fm, Parker, and I go on to a big rant about not doing that. But But But regardless, like, it's, it's pretty common for us to think of parts in that way. You know, like, there's, I have a library, I just open the library and I grab what I want. Yep. And someone was asking, is there the same thing, but for mechanical parts? And I think that's a really great question.

Host 2     53:00

And my favorite thing about this article is, there is sure there is it's called the McMaster car catalog. Thing is I found out mcmaster carr does not have everything.

Host 3     53:12

Oh, really? What did they not well, okay, they didn't have some obscure Jeep part for you

Host 2     53:17

Know, they have an obscure adapter I needed a five sixteenths 18 thread to seven sixteenths 20 thread. Well, stud. Oh, that's messed up. Yeah, weird stud conversion thing. And I was able to buy it from a friend from another vendor, but like McMaster car didn't have it. I'm like, that was one of the first times I'm like, Huh, well, then car let me down. You know, those

Host 3     53:45

Those kinds of situations right there, which I've, I've run into myself before. Those are the ones that make me feel like it's justified to spend $10,000 on a lathe, you know? Yeah, you'd be like this $10,000 was worth it.

Host 2     54:01

Yeah, the, the best thing was like, after I'm seriously the first time when I checked my MasterCard, and it didn't exist on they didn't have it. I'm like, I actually thought I'm like, maybe this part doesn't exist. That's

Host 3     54:15

A reason why it's impossible to make this part.

Host 2     54:18

Maybe it is. And then I did some Google searching, I found found the right part. But yeah, it was like, man, maybe this part doesn't actually exist.

Host 1     54:27

Well, okay. And so the McMaster thing. I think, personally, that the whole idea that McMaster is like, what, you know what we all go towards, is because McMaster is so nice for electrical guys because you don't necessarily have to be like super smart on the mechanical side of things like McMaster, kind of hold your hand a little bit through it. So like that was the first thing that came to my mind to was McMaster

Host 2     54:53

The best thing about Master okay, this thing about masters catalog is you go there and you're like, I need this part. And that's it. has a really good selection. It's just like finding the resistor, you know, you need a Nia 632 And this long and this kind of head and they're like, yeah, these are what we have. And these materials, it makes it really easy. And then when you finally narrow down your selection, you can click it and you get a drawing of the part. And it's exactly what you get. And I'm like, and you can

Host 1     55:23

Download a 3d drawing half the time. At the same time. If you're in Fusion 360 doing 3d CAD, they have a plugin that allows you to search mcmaster carr and suck in parts immediately.

Host 3     55:36

It's amazing.

Host 2     55:38

Yeah, it's just like, that's why I like cuz like, that's the thing is when you buy a part, like a LM 358, from from TI, you know exactly what you're gonna get, because there's a datasheet and you can read it and everything. That's what mcmaster carr is for mechanical stuff. Yeah. Is there is a drawing there. Sorry, my dog is chewing on a squeaky toy. That's how it is. It's just like, so I haven't read this article all the way. It seems that mcmaster carr is the only thing in here though.

Host 1     56:17

Well, okay, so the answer to like the underlying question, that's there is no, there is not a common mechanical part library. However, everyone that I've met kind of makes their own. And and what I mean by that is like, you you, for some reason, you needed a screw through your PCB. So you designed a part that is a screw or something like that. Or, you know, a standoff, a hex standoff or pick whatever you have, like, I've heard a lot of Electrical Engineers I've talked to they make their own like, EDA tool, mechanical parts.

Host 1     56:56

Like I have I have that. Yeah.

Host 1     56:59

You have that I've got my own. Yeah, like, I even have, I even have like a specific. I've created like a part that I can put onto my schematics that I call it bomb part. And what it is, it's a placeholder for a mechanical part that goes along with the PCB. It's a smart idea. So if I have a washer, or anything like that, yeah, so So what happens is, whenever I export a bomb from that, from my from Detroit, it automatically pulls in part number A mechanical part. Oh, man, that's a good idea.

Host 3     57:31

I want to start doing that. Yeah, it works super well. And so the answer is, yes, we all do that. But that's because that works for us. You know, it would be it would be really cool. If if there was some way to like, link it all together, or a bigger part library. And in fact, actually the the

Host 2     57:50

I got it was that I got it. It's going to be quarter 20. Bolts. Yeah. With a quarter 20 like nylon nuts, and skateboard bearings. That's all you get.

Host 1     58:04

But let's be honest, for the PCB world, you need to you have a separate one that's just like, em three screws and 440 screws and in different varying lengths and stuff. Yep. Yeah. And we don't need to worry ourselves on the electrical side. We don't need to worry about like, what kind of screw head or anything like that. Everything is Phillips and everything is just like a regular pan head screw. You know?

Host 2     58:31

What have you through iSM Jack is just the mess with people.

Host 3     58:34

No screw j because that's exactly what it does. It messes with people.

Host 2     58:41

I'm actually a big fan of hex head so

Host 3     58:45

Yeah, yeah. But like, I don't think you're gonna get a hex head and a 440 screw.

Host 1     58:50

You can I've got some really

Host 3     58:52

Tiny No, no, wait, when you say hex head you're not talking about socket head. socket?

Host 2     59:00

No like a button top. Okay. Yeah button top with a sunken in hex. For a like an Allen wrench.

Host 3     59:08

Yeah, those are socket head, nut, socket caps or whatever they call them. Like they call them hex head because the hex head would be like a bolt

Host 2     59:16

Oh you're right you're right right hex heads external hex and then a socket cap is a is socket cap is interesting. That's

Host 3     59:22

What that's what I'm thinking because I'm like manna hex head bolt on a 440 would be tiny

Host 2     59:30

Sure that pretty easily

Host 3     59:31

This is what happens when electrical guys start arguing mechanical stuff we get way off in the weeds and we're like we have no idea what we're talking

Host 2     59:37

About. button button head hex hex is why I like a lot mainly because they they just look nice. Yeah, they do. They give a more finished look to the product then hex head, you know not hex head,

Host 3     59:53

Phillips head and one way to add to, in my opinion instantly add class to your product. This adds cost to the bump. If you have a sunken or a countersunk hole with a socket, head cap or socket head screw such that it fits flush down into the hole. That looks really hot. That means your case is also really thick. If you can handle that, yeah, like I've seen a couple of anodized aluminum cases where the screw fits all the way down in and sits flush and that looks hot. That's really nice. But it's excessive in practically every way but it's looks really

Host 2     1:00:31

Nice. You got a quarter inch baseplate Why seek that head down?

Host 3     1:00:38

Yeah, this is yeah, Tales from an electrical engineers ideas on mechanical design

Host 1     1:00:49

So I think that we'll wrap

Host 3     1:00:50

Up this upset. Yeah, this one we apologize for the 30 minute episode last week. Hopefully this will this will make up for it. Oh, yeah,

Host 2     1:00:59

We I think just clocked over an hour. Yeah, there we go. So that was the Mac fab engineering podcast. We're your hosts Parker Dolman. And Stephen critic. See you next time guests

Host 1     1:01:12

Take it easy

Host 2     1:01:21

Thank you yes, you our listener for downloading our show if you have a cool idea project topic, Blinky LEDs, or mechanical libraries that you want Steven Knight to discuss, tweet us at backer fat or email us at podcast@gmail.com. Also, check out our Slack channel. 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, as it helps this show stay visible and helps new listeners find us. Also, if you want Steven and I to talk about video games some time let us know as well because there's some video games that we've been playing and be fun talk about them. Later, everyone

Transcribed by https://otter.ai