Slow/soft Start devices and circuits, Shark Fin sound effects, and Belt Buckle Badge Designs.
AND!XOR comes to Texas to talk about #Badgelife, the craziness of DEFCON, and their new badge design.
John Adams joins Parker and Stephen to discuss IoT Security, Crappy IoT Devices, and WS2812B LEDs.
The MacroFab Engineering Podcast Design Contest sponsored by Mouser Electronics currently going on! The topic is Useless Machines! We have cash prizes up to $1000 for the winners. The deadline is August 10th and it is closing fast! More information can be found on here!
Visit our Public Slack Channel and join the conversation in between episodes!
Parker is an Electrical Engineer with backgrounds in Embedded System Design and Digital Signal Processing. He got his start in 2005 by hacking Nintendo consoles into portable gaming units. The following year he designed and produced an Atari 2600 video mod to allow the Atari to display a crisp, RF fuzz free picture on newer TVs. Over a thousand Atari video mods where produced by Parker from 2006 to 2011 and the mod is still made by other enthusiasts in the Atari community.
In 2006, Parker enrolled at The University of Texas at Austin as a Petroleum Engineer. After realizing electronics was his passion he switched majors in 2007 to Electrical and Computer Engineering. Following his previous background in making the Atari 2600 video mod, Parker decided to take more board layout classes and circuit design classes. Other areas of study include robotics, microcontroller theory and design, FPGA development with VHDL and Verilog, and image and signal processing with DSPs. In 2010, Parker won a Ti sponsored Launchpad programming and design contest that was held by the IEEE CS chapter at the University. Parker graduated with a BS in Electrical and Computer Engineering in the Spring of 2012.
In the Summer of 2012, Parker was hired on as an Electrical Engineer at Dynamic Perception to design and prototype new electronic products. Here, Parker learned about full product development cycles and honed his board layout skills. Seeing the difficulties in managing operations and FCC/CE compliance testing, Parker thought there had to be a better way for small electronic companies to get their product out in customer's hands.
Parker also runs the blog, longhornengineer.com, where he posts his personal projects, technical guides, and appnotes about board layout design and components.
Stephen Kraig began his electronics career by building musical oriented circuits in 2003. Stephen is an avid guitar player and, in his down time, manufactures audio electronics including guitar amplifiers, pedals, and pro audio gear. Stephen graduated with a BS in Electrical Engineering from Texas A&M University.
Special thanks to whixr over at Tymkrs for the intro and outro!
The macro fab engineering podcast design contest sponsored by Mazur electronics is currently going on the topic is useless machines. We have cash prizes up to $1,000 for the winners. The deadline is August 10. And is closing fast More information can be found on macro fab.com/blog.
Welcome to the macro fab engineering podcast we are your hosts, Parker, Dolman and Steven Craig. This is episode 184.
So Parker, what's up with your chair?
So I'm in Vegas right now for DEF CON. And this chair because I'm doing work, macro fab work. Like in the mornings, usually. And then like afterwards, I go hanging out with people. This chair is built incorrectly.
That here's here's the thing like Parker and I were chatting before the podcast, you know, getting all of our notes ready. He kept mentioning like, oh, this chair, this chair is like, dude, the chair is built wrong. You got to talk about it on the podcast.
Yeah. So what is built wrong about it is it's the top part, the seat part is put on backwards from the base.
So was it was it designed incorrectly or just assembled? Incorrect. This
one is assembled incorrectly, because I went to one of my friends rooms, and it's the chairs fine. Because I'm like, you sit in the chair. It's weird, because like it's tilting you forward, like the butt part is like tilted forward. So you wanted to slide out of the chair. Oh, that's and then if you click the little thing that allows you to like, you know, lean back, the chair actually leans forward. So it's like an ejector seat style lever, like the,
the bond seat, the passenger seat in the Bond car, right where you just press a button and it shoots a mass,
except that just puts you on the floorboard surging forward. Just tips you forward.
Well, I'm gonna be there in two days. Yeah, I'll be there Thursday evening. So I'll have to check out this chair. And that's kind of all of the engineering issues with it.
Yes, I actually was thinking about flipping it over and just like fixing it. Or I can just call room service and be like, this chair sucks. Give me a new one.
That's what most people would do the fact that you even considered like fixing it for that means something.
Yeah. Which means no one's actually complained about this chair before. It's kind of weird.
Or that it's new,
right? No, it's pretty grungy.
Why don't you just get a new one you've been dealing with for a couple days, right?
Yeah, I've been dealing since for two days now. Yeah.
That's That's awesome. Okay, so what do you what you've been jamming on?
my phone just was like, Oh, do you mean that you want to talk to me? It's like no Google. Been working on penetrator a bit. The Rev one. I think we said last week it's working. We have a pinball machine flipping with it. So I start working on like the auxilary stuff that we will need, like LED light boards. So we're using those apa 102 C new 260s. And we're making them in like strips. We just we just played with this concept last year, but I think we're finally gonna go forward with it. And so most inserts and pinball machines have a like, set offset. It's like an inch and a quarter or something like that. And so if you design your playfield with that in mind, then you can use just like prebuilt strips of LEDs is what we're thinking.
What do you mean offset? You mean from like, the bottom of the playfield? To whatever?
No, no, like from center to center between the inserts. Oh, lights. Got it. Got it. Got it. Yeah, the center center is about inch and a quarter on most machines. And so if you designed with that in mind, and what we're gonna do is basically build a whole panel of LEDs, but the pitch of the LEDs is 1.25 inches over this panel. And so then, and they're all connected, so you just cut what you need. So if you need like for your cut for out. Yeah, so Well, just like the pizza cutter to do that. You know, V score only on one side of the board. You know,
funny funny story about pizza cutter. We have one at at at WMD. But we actually don't deal with V scores very often. There's a couple of customers that request them so we do it for that.
So I sit on one side of a warehouse and actually I'm kind of all by myself, way away from a lot of other people. So there's not a lot of like noises that happened back there other than the noises that I create, and that machines create back there. So I'm pretty used to what to hearing what I normally hear back there, especially with the CNC running. Well, I'm walking back from grabbing a cup of coffee, and I hear this like awful like grinding noise that just like, oh shit, what's the CNC doing? Because it was running a program and I'm, I'm expecting to walk back there and see that thing like twitching on the ground like, trying to I don't know, but somebody went back there and brought brought our pizza cutter, V score cutter machine, and they were they were just back there doing that. I was like, holy shit. You scared the hell?
Because those pizza cutters don't make a really nice sound when they know it's Yeah, yeah, it's really awful. So
it's a diamond encrusted blade going through fiberglass.
Yeah, right. Yeah. It's not really designed to sound very good.
Yeah. And that's, that's actually, that machine is why you had to have components with a certain amount of space between it and like the edge of the board. That blade is not like the guard on it is not, you know, super skinny. So you need to have like, what is it like 20 mils or something like that away from the board edge?
Yeah. Which in general, if you're doing V scores you would do anyway. Yeah. But But ya know, you need to have enough room that you like, yeah, you can cut it. But you can also clear the pizza cutter. Extra crap,
right? Yeah, I think it's a guard or it's basically something that's on the edge that help you align line the boards.
Yeah, it looks like the kind of It looks like a miniature version of the guard that you'd see on a table saw?
Yes. Because if you don't, then your ceramic capacitor will just pop right off.
I saw pictures of the Penetang. It looks awesome. Yeah. Thanks, guys did like a version from an OSHPark? Board? Right? Because it was all purple.
Yeah, we went with an OSHPark board just for like, we were running up against time schedules. Then when needed, like boards in like three or four days. So we did that way. But the funny thing is, it ended up not being cheaper at all.
To do OSHPark.
Yeah. So we got three. So this so a pentatonic and singles at macro fab was like if you remove all the through hole, so it's just SMT stuff. And singles. It's like 550 bucks. Yeah, makes sense. It was 550 bucks to get three OSHPark boards, just the boards, just the boards, the board that you have three of them. And then you have to add all the component costs on top of that. So yeah, not I was actually kind of disappointed how expensive it was to do it that way.
Oh, support for large format boards is really expensive.
Yeah. But we did get them in like, four days. And then you know, Ben took like two days to build one. So you know, you'll Orly time was like six days. So that was pretty nice.
Right? Yeah. But you had six days. full attention. One thing. One thing? Yeah. But it's actually functioning I think I think he talked about that last week, but But you actually got it pretty much all working right.
Yeah, it's actually it was, yeah, we only had one hardware issue. And we just jumpered it with a big gauge of wire. works. So. Yeah, and our SMT FETs work great. I'm pretty happy with those. Yeah, cool. That was kind of a we didn't know if they were gonna work out too well. Mainly because most actually almost every single pinball platform out there uses like IRL 540s. I think stern uses something else now though. But they're all like to to 20 style through hole stuff. And yeah, we went with just a no SMT package and tried to make that work. And it worked great. Yeah, I think the trick was, we found one that was has a low enough on resistance. And so it just keeps the heat down. Have you have you started like measuring heat? No, no, but basically, we're just making sure like when it's on it's not like heating the board up a lot. Because you're switching them really fast. In some some cases. Yeah. Right. And then we did actually like calculate out how fast they would actually turn on for right you know, we did that calculation that simulation.
Stupid fast. Yeah. Way faster than pinball needs.
Yeah, way faster than pinball needs. And the it doesn't take a long time for them to turn on, which was good. Oh, no. Because you're you basically want to get into saturation as fast as possible. The MOSFET,
right you want yeah, you want to go through the linear zone because they you're burnin an extra heat in that in that air. And so you put larger gate resistors on all of them, right? Because I think originally it had like 10 ohms, or something like that.
Yeah, let me see, I'm gonna think you bumped it up to 1k
Or is sort of where we started. I think that's where, like in our simulation, we bumped it up that far, to kind of act a little bit as current limiting for the inrush charging.
Yeah, because we didn't want to burn because we're using seven, four, HC five, nine fives to drive these things. What we were worried about was you only had 20 milliamps of current to drive them. And are you going to burn up your 595?
Right, right. So we
was it? 100? Okay, yeah. 100 rooms? We started out with 10. Right. And then but and then kept creeping it up. Yeah. And then we did try 1k. But it would it that slowed it down like it was in the linear range for a long time.
Yeah, but But you didn't. You haven't actually put one case on the board.
Right now we only did. We built them with this. 100k 100 100 Ohm. Yeah. Yeah. 100k would probably not turn on. Just take longer. They're just always been in linear range and just cook those MOSFETs off. No,
it would eventually charge it up, right? Oh, well, I mean, if you're sending it like really fast pulse, and maybe not. Right. Yeah.
So I've got that going on. The I've been working on starting the next project that's going to be sponsored by Mouser. It's that IoT compressor.
We've been talking about that for a long time.
Yeah, this is a project that we started back in, like, Episode 68. And we're 184. Now. Yeah. So over 100 episodes ago, we started this project, we actually built a circuit board and some code and actually did work. It just we never finished it. So basically, we're going to start over on it and basically fix some of the issues that the original version had. So some of the things I want to do is the big thing is like finding an enclosure, that works better, because before it was just a project box, and goop like compressor, goop and oil and the crap would just get in there and just like followed up,
man go in. Look at our friends. What is it to Kouachi or Takashi? Yeah, they have man, I liked their enclosures, they got really cool stuff.
So I want something that's ruggedized. But panel mount, so you can like bolt it to the compressor and stuff. And it has to be sealed as well so that the circuit board doesn't get all messed up. Right? And then, like gasketed and stuff. Yeah, and it only needs two cable glands. So you need power in. And then actually you need three power in. So the circuit board gets powered up, and then you need the pressure transducer. And so I'm going to use the same one because it worked really good. Which was the p x three A n to be s 250 P ax.
Oh, yeah, that one?
Yeah, write that down people and your notebook. It's a Honeywell pressure transducer, heavy duty guy and works really well. It was really easy to get set up for on a microcontroller. So that that needs a have a gland on it. And then the other one is the controls for the solid state relay. And I actually never really tested that solid state relay. So that needs to be tested before we spend another board for this.
Is this one of those solid state relays that are like for brewing like the brick ones.
It's kind of like a brick one. It's a yeah,
I'll go ahead and say the name.
Oh, it's 6225 a XSZ s dash DC three. So it's a DC powered like three volts turns it on, which is really cool. So basically, you can drive it directly from the microcontroller.
Right, right, right. Okay, this is this is basically a brick one. It's just got a fancy cover on it.
Yep. Cool. And it's got it's the same, like whatever that standard mounting bracket is. It's that and so this solid state relay is basically going to be on all the time and its entire job is to turn the compressor off. If the control brains decides, hey, something's not right here, turn it off. It's not the compressor IoT is not there to control the compressor though. compressors pressure management, like it's a new mat pneumatic system. It like pressures up in a little, little tiny baffle moves, it trips the pressure transducer that's in there, right. It's kind of old school style, but a lot of compression of store run on that way, that way. It's cheap and easy. Yeah, I think it's just super reliable. So we're just gonna let that do its thing. But this is here for basically, they prevent the compressor from killing itself, because it's only supposed to have like a 10% duty cycle. And if there's a leak in line or someone leaves a line to open downstream, or a copper tube on the intercooler breaks, because that's happened before many of times, I
was I was about to say you need to you need to tell the story of why this project even began.
Yeah. So the and this was like two years ago. So two years ago, we had just moved to New fab. And I'm going to guess what happened is like, the compressor got knocked in move when someone moved it, like the two because the tube that comes off the compressor is copper that goes into the intercooler, I guess to help with cooling. That's the only thing I can think of is why it's made out of copper.
I don't know. Yeah. It work hardens. That's what I know about copper.
Yeah. And that's like the worst thing is vibrating like crazy. Between like, one end of it is fixed on the intercooler. Yeah. And the other one is on the Compressor Head. That's vibrating. Yeah. And it's like it's broken again. So I don't maybe it's not even just like,
maybe, maybe it's meant to be broken, though. Maybe there's some kind of reason behind that.
Yeah, well, the thing is, when I went to go pick up the spare part, like the guys, like we never, like sell these spare parts.
Oh, okay. That was really what I remember. Okay, so we came in on a Monday, and the compressor room was like 300 degrees because the compressor was like running on in there. Yeah, it was running full duty cycle because this tube had broken and it wasn't shutting off. And it was like a super custom copper tube that has a 90 degree bend in it and a flare fitting on the end of the flare
fitting was a weird it's not a weird size, but it's like a size that you can't really get a tool for.
No, and this was not a Home Depot kind of thing. You know?
Yeah, most flair kits are for like automotive stuff. It's like the max size is like maybe three eighths of a flyer. Like for a fuel line. This is like a full on like three quarter hitch. copper tube.
Yeah, right. Right. Well, and so the whole thing is the manufacturing floor is without pressure. And when you have machines like a pace jetter that runs on pressure.
Then then, you know, people are starting to scramble and Parker and I are like how the hell are we going to fix this thing and like the floors down because of a copper tube. You know, luckily, there was a shop in town that had it.
Yeah, so yeah, drove over there picked up the two came back, popped it in and it worked great for two more years. Right, right. And then actually about five months ago, the intercooler failed. Ooh, nice. So yeah, I don't know, the intercooler just developed a hole in it. And there was on the other side where the copper tube goes in, I don't know why it failed. It basically just developed a hole and so we had to order the intercooler because that place that we originally bought those parts from, they didn't have the intercooler and stocks we had to order the intercooler but they had the parts basically so I could unconverted like the compressor from the intercooler style to non intercooler styles, basically, it just dumps from the compressor right into the tank. And so I bought those parts because I get them right there right away and do the conversion and then convert back. Yeah, then like, three days later, when the intercooler showed up, I converted back nice. So I have all those parts. Now, the thing is, you think these parts will be expensive too, but they're like, they're like 20 bucks apiece, and the intercooler is only like 100 bucks. It's like, compared to the overall package, I guess. They're just very inexpensive. But um,
well but so so all of this is the reason why you even wanted to make this device to the original thought was to just have like a vibration sensor to detect if the thing was on and vibrate us for longer than it should be. Because you know, it ran for 60 hours straight. Yeah,
we have no idea how long it was running for long enough to cook that room. It was hot. Yeah, it was hot night room. So yeah, so it's gonna have a it has a like an accelerometer on it basically just to say is it vibrating? I actually was thinking about changing that out and just putting in got, like a, like a little Mercury tilt switch? Just if it's bouncing around, that's bouncing around then yeah, it that's an easier to read, instead of having like, basically sample and figure out if you're vibrating or not basically the magnitude of the acceleration is changing. But the thing about the accelerometer is you also can get frequency from it. So you can say, is it running well or not? Like what is what should it be vibrating? Why
does your compressor have a knock?
Yeah. Well, then there's a pressure transducer. So you can just read the pressure. And that's just a data point. I want to know. So basically, it's like, is it running for a long time? If yes, shut down, is what it is.
Well, you got this pressure transducer, though, you're gonna put that in there somewhere, right?
Yeah, well, that's just reading the, the, the tank pressure. Got it? I guess technically, you can figure out if it's running with that, like if the pressure is actually changing. But, you know, I think doing it by vibration is probably the easiest way to like actually determine if it's running or not. I guess you can actually do, you can do a current sentence on the power line to
I was just about to say that that's probably the easiest. But that doesn't give me a frequency. No, but you could also put a microphone on it and just listen to it, and then determine the frequency that way.
Yeah, that would work. Just take an FFT
of it and find your peaks. Yeah.
I bet you'd be like, majority is 60 Hertz. Yeah. What is what is that big AC motor on it?
Yeah. What what is the actual piston running it? Or the diet? The diaphragm or whatever it is? I don't know.
Cuz it's off a bell not
gonna be 60. It's not gonna be 60 hertz is? I doubt it?
Yeah, I don't know. I gotta look and see what the belt conversion is. Yeah. Is that what that would? What the diameters are different? Yeah, it's a reduction, because it's a small pulley driving a big pulley that then drives the pistons. So I don't know what that ratio is. I guess I can look it up. But, yeah, cool. So that's gonna be that project. Yep. So I'm gonna start on that probably next week. It's gonna run, we're gonna still use like, particle photon, because I already have that stuff. And then the trophy for the contest. That thing? So I've been learning more Python. And it's like, the contest ends, like this Saturday. Right, right. And I don't really have anything kind of working for that yet. I just been like taking classes and learning how to do it. Yeah. So I did find this Python GUI called, that works on the Raspberry Pi called GUI zero. So I've been learning that and made some little tiny, crappy applications and stuff. It's like you can put an image and then you can change some numbers. And I'm like, perfect. That's what I need to do
and put a button or something on there.
Yeah. And so I got that kind of stuff working. And then I was like, Okay, that's great. But this thing does need to talk to the internet. So it's actually can do its thing, which is, you know, it needs to hit that Mars weather API endpoint basically.
Right, right. Which means that whoever we give it to, they have to connect it to their Wi Fi, right?
Yes. And so it's like, how do you make that work? Like, does that something like I have the right or do we? Do we make people like plug a keyboard into it to set the Wi Fi cuz that's kind of lame. And so I found a, called a, like a software package called commit up. That's Wi Fi connectivity for like IOT devices that are on the Raspberry Pi. And so it works like a how most IoT devices, like commercial ones work, where when you first plug it in, the device broadcasts a Wi Fi SSID you use a computer or your phone to connect to it. And then you feed. It's the Wi Fi credentials for your house.
Oh, that's neat.
It's really fancy. So we're gonna do that.
Yeah, that'll that'll be nice, because then we can just provide the final thing and just, they just get in.
Yeah, yeah. And then as they set it up, they don't have to open it up and plug a keyboard into it to type in a password. So Steven, how is the enclosure coming along?
So Just before the podcast I showed up to my house and sitting outside was a package with new drill bits and new taps. Reason I got new drill bits and taps was because I was going with him three screws, but they're just a little too big. So I'm going to actually take a,
I guess a play from the playbook of clicks bring the YouTube guy, I'm gonna build the entire box with super glue, and like position everything and then drill it and tap it and just use a torch and I can just break it apart. Just so I can like, because I was going to chuck everything up in the mill at work, but I don't want to go back to work and do that. And I can just, I can just do it on my bench here if I just and also with with super glue, I can kind of glue it up and just make it look really pretty and then drill it that way. And what I might end up doing is not mine, what I'll probably end up doing is just glue it and then use the center punch and mark all the holes and then I can break it all apart, drill it and tap it. So before DEF CON, I have to get that done.
Yep. Well, it's a lot further along in the actual software part.
Yeah, I'll have the the enclosure will be ready for DEF CON. That's for sure.
I might actually need to get I think about it the USB hub or not have the I guess USB extender for the power input. It has two holes. I think they're two point fives. Well, they're just passed through holes. So I just need to I guess I'll just tap that within two point fives and one of them will just throw some screws in there. But all the other ones are like flush. Nice screws. So we'll I think they're Allen heads. So maybe I should bring some Alan's? Yeah, that'd probably be okay. I can't remember what I bought now.
Yeah, it would be nice if we could assemble it.
No, we probably will be able to assemble it. I'm either going to drill it out tonight or tomorrow night. Or maybe a combination of both. I got I saw all of the holes are going to be blind holes for obvious reasons. They kind of like drilled into the side of the chassis.
So I bought some starting taps and some blind hole taps. So bottoming taps. Yeah. So I think all the screws, all the screws I bought were 10 eight or 10 millimeter long, something like that. So I'm gonna I'm gonna drill them out. I bought some. Actually, I bought some cool screws. McMaster had screws, I'm sorry, drill bits. McMaster had shorty drill bits that are like, half the size of a regular job, job or drill. But they're stiffer. So I can drill it out that way. Because I was thinking about it, I might do it by hand, you know, instead of in the press instead of a drill press. So if I don't do it by hand tonight, then I'll take it to work and do it on a drill press at work tomorrow. We'll find out. Yeah, it's really good.
But that should all work out. I guess I need to bring some super glue also. So we can glue the screen bezel. Yeah, the bezel in front plate thing. If I get it all if I get all maybe I'll glue it up tonight. I don't know, whatever. I'll figure it out. But I'll send you some pictures when when we're there. And maybe we can post them up for like just the chassis design. Yeah, it's it's beefy. You could throw it off a building and it'd be fine. Not recommended and it's useless. uselessly beefy,
uselessly beefy. Yeah.
So I've got a story I have a quick story I want to tell about why I think the robots are not going to take over anytime soon. I think I think we have some time on this. And this comes from a personal experience that happened yesterday. So I get to work. In Mondays. I always start off with my weekly maintenance. I have like a maintenance sheet and it's the first thing I do on Mondays after I get coffee. Just sort of like it's done. And on my CNC what I need to do is we have a Renishaw probe I have to clean the contacts on that I clean all the schmutz off of it. We have a handful of other things I clean the collet blah blah blah there's all this stuff. Well I've I always wipe down the machine and clean off all the all this stuff inside but I looked over at the at this screen which are CNC has a touchscreen for all of its stuff. I looked over at the screen and I was like oh the screen is kind of dirty. You know like it's just got fingerprints and it's got other stuff on it Austen crap all over it. Well, yeah, and powder and things like that. And we've had this this meal for months now and I hadn't cleaned off the screen. So it was like, Oh, well, it's doing whatever test it was running at the time. I was like, I'll just wipe down the screen and I had a microfiber cloth that was not wet, but it was damp with alcohol. So it's just like, Okay, fine, I'll just wipe it down with that. And on top of that, I'm gonna, I'm gonna qualify this one more time. It has a like, transparency film on top of the screen on top of that. So I go start wiping down the screen, and the CMC flips out, just goes, goes apeshit. And this little light pops up at the bottom of the screen that it's a, it's a hand with an X on it. So all the touch controls are gone. The machines throwing errors, all this crap. And I'm like, Oh, my God, what that what the hell happened? Did I like what what did I do and the machines stopped operating. So I'm going, I've got no controls left over the keyboard still works. But I can't, you can't actually run the machine from the keyboard, you have to run it entirely from the touchscreen, while the touchscreen is no longer accepting touch anymore. So I ended up I ended up getting the point where I have to call their like tech support, and he has to like walk me through how I can shut down the machine without using the touchscreen and restart it because it thought that someone touched it too much. And that's like a that's like a safety precaution if like, say it was running in the screen, I don't know, fell off and it was on the ground. And it's like, oh, it was being touched too much. Well, it detected there was an error. But it happened because I was cleaning it you know, and this is exactly why I'm like it's a long time before Skynet actually will take over. You know, if if a machine of this like caliber craps its pants, because I cleaned it, then yeah, we've got some time.
Or, you know, it starts tomorrow.
Actually, I know it's really mad that I cleaned it and started.
You go into work tomorrow, and it's just like, Steven,
I can't let you do that. I can't let you do that. Well, it already told me that I was no longer allowed to use the touchscreen. I guess in all reality, what probably happened is, you know, whatever small amount of alcohol actually did get on the screen. It didn't like that for whatever reason.
Yeah. Now I can see it in like in like 30 years, like that CNC machine is in court, and you're like being tried. And the judge CNC machine goes, where did the operator touch you?
It's like everywhere. Yeah, show me on this little like inflatable or this plush CNC to show me where he touched?
Yep. Oh my gosh. Okay, well, before this goes more downhill. Let me go into some other stuff. So a few weeks ago, we had Ross on the Josh Roser on the podcast, and he talked about the transformers that he had designed. And what he is designing? Well, he and I have been kind of working together on some, you know, end products for what those transformers could be used for. He's not just designing transformers for designing transformers, like he actually wants to use them in something. And it's really it's been really fun and interesting, because well, frankly, I don't know about you, Parker. But I don't I don't deal much with designing from scratch transformer circuits. A lot of times I just use reference designs or within an industry you kind of have a feel for what's going on. Or if you do need to buy something from Mouser or whatever, you can just kind of like piece it together and work it out for whatever your circuit needs to be. But I actually have the opportunity now to fine tune every little piece of a power supply, which is kind of cool. So instead of just going to Mauser and picking whatever, voltage tap I need, I can go the other direction until Josh Rocha. I need this tap with this characteristic to get an end result DC voltage. And did you take any power supply classes in college?
I did not. I didn't take any power classes.
Okay. Yeah, you were all embedded all the way right.
Embedded and like ces like video. Video. Yeah, image processing. Nice. Well, so
I took one power supply class in college that I really, really enjoyed. In fact, I've got the textbook right right here, which I probably you know, everyone complains about this, that $900 text. I bet you this was 300 bucks. And and it's literally like, printed like photocopied it Xerox. Yeah. Yeah. Xerox, and, like, yeah. Kinkos probably assembled this for my professor. But I still have this because this book is an excellent reference. And it covers half wave rectifier, full wave rectifiers and then the second half of the semester was all about buck, boost and buck. boost converters. And that was, it was super awesome. It was really great. But so I've been referencing that a lot in going forward, because now Josh and I are designing some stuff that is moderate voltage. So like 1213 volt kind of stuff with a generally healthy amount of current, like, between half an amp to an amp kind of thing. And when you, when you start playing with that, and you start getting into regulation, you have to start working from your load backwards to the transformer. Because you say, Okay, well, I know my load is going to be this, I know it's going to draw this much current, therefore I have a regulator, that regulator has a dropout voltage, so I can withstand this much ripple. And you know, you start working backwards. And eventually you get to the point where you say, okay, my transformer tap needs to be XYZ. But it's been kind of fun and interesting, because I've had to basically work that direction, and then tell Josh, I need this tap. And then he has to work forward and say, Well, I can give you this tap, but it's going to have XYZ coil resistance. So it's like a balancing game where I have to give him something back forward, we have to keep going back and forth. Yeah, it's really interesting, because like most, you don't get that option. If you go to, if you go to Mouser. And you just look for a transformer, you get a tap and you're that's it, you're done. And if you're trying to manage wasted heat, and extra power, there's, there's, there's not going to be a perfect tap for you if you're just searching transformers out there. But if you get one custom wound for you, now you can play a completely different game, where you really have to start thinking about all that. And what's cool about it is most, okay, so if you go look for a transformer or go spec one, a lot of times you'll get, I guess what, three things, you'll get the voltage, the output voltage, you'll get the, that voltage at a particular current. And then also, if you're lucky, you'll get a regulation figure. And that regulation figure tells you the difference between your loaded current and your non loaded current. And that's about what you get, you're not, they're not going to you will you rarely will you ever get some kind of internal impedance or coil resistance or anything like that. So it's kind of it can be difficult to simulate, unless you actually have those figures. But what's interesting is trying to calculate a transformer tap that has series resistance with a bridge rectifier into a capacitor resistor load is is actually not very trivial. It's it's pretty difficult. And there's there are some like rules of thumb that you can use, but a lot of times they don't give you super accurate results. So we've been kind of trying to figure out like, what's our best, like attack plan with it? And there's there's a couple of like, general rules you can use. Like, I think I have some written down here like okay, so Hammonds manufacturing, if you they have like a little PDF chart that's like, if you have a bridge rectifier, you can use this ratio, multiply it times your your V AC, and this is in general what your DC is going to be. But what if I want to be more accurate than that? You know,
I found in one of my books that I have here, the title of the book is power supplies for Valve amplifiers, written by Merlin Blencowe. On page 38, he's got this really great chart. In fact, I'm going to hold it up so Parker can see it. This really fantastic chart that basically you look at your source resistance and your load resistance. That gives you some kind of ratio ratio. Yeah. And then you look at one of the axes on the chart. And depending on what your reservoir capacitance is, and your mains frequency, you can look up on this chart, and it will give you a pretty accurate to within maybe 535 percent, your DC voltage without even simulating it. I wish I could post this picture, but I haven't asked the author for permission, I might, I might end up doing that I have his email address. So I might ask permission for that because it's a really cool chart. And I've never seen this before. But if you want if you want to look and just say like, Okay, what's I have XYZ transformer? What's my,
what's my DC voltage going to be? You can look up in this chart, and it'll give you a pretty accurate result. Unless you're doing something excuse me like super weird, like if your source impedance or resistance is similar to your load resistance. In other words, low voltage high current, you're gonna get some pretty terrible DC values on that. So you probably look You're not going to really run into that a whole lot anyway. So a lot of the a lot of the equations you find, if you go to Google and just type in, like bridge rectifier DC equation or something like that, then you'll get equations out there. But they're not, they're accurate within a range, they're not accurate across an entire, like, they're not always accurate, you kind of have to know your source impedance of what the coil is actually doing. And on top of that, it gets more complex, because you got to know your primary coil, like so you have your mains coming in, you have your secondary going out, you have to know all of that in order to be able to actually like, really predict what your DC output is going to be. And so all in all, in a nutshell, Josh Raj and I are trying to actually do that. So we can burn the least amount of heat in a design that we're doing, because we don't want to just like, throw a ton of extra voltage and then have to get rid of it and regulate it down linearly. Because it's just wasteful. And then you have to design heat sinks and all this other stuff. But if we can get our tap just right, such that we take into account the tolerances of the whole circuit plus the tolerance of mains fluctuation, then we can actually get the DC that we
want, then you will be your ldeo will be a lot more efficient.
Exactly. Yeah. And I've actually I found an LTO that has a dropout voltage of five, no, I'm sorry, 500 million, so half a volt. And it can provide up to two amps. So it's, so if we get our DC values, right, we can get really close to that dropout voltage, while still taking all the variability into account. And then, you know, we'll add five 10% or whatever, whatever level of fat tolerance we need in order to get it in there. So it's been really fun. And really kind of interesting, because, you know, I, I've done a handful of these calculations before, but I've never had to do it to this level of detail. extent. Yeah. So we're, and the thing is, we're trying to actually push these calculations backwards into Josh Rogers, transformer Excel spreadsheet. So we said we were going to release this spreadsheet, and Josh rose, and I found that there was actually a few small errors in it. So actually, we got a, we got a message in this week from, from Phillip, a guy named Philip asking, Hey, is that available? Can he see it? And I want to make it available? But let me get these calculations into it first, and then make sure it's correct. Make sure it's correct. And then we can and we've been actually verifying that what we're doing is correct on based off of simulations and things. So I've been doing PSPACE. And I have another simulation package to kind of, like, do this, at the same time, in conjunction with his spreadsheet, just to make sure that everything's correct. Because what I would love to do is say, I have a load, I want this much DC voltage at this current. You know, push it backwards through the calculator and say, What tap?
How do you design transformer, right?
And so the transformer is going to spit out, oh, you need this tap. But it results in this much resistance of the coil due to the nature of winding it. So it'll you know, it'll back calculate all those things. So eventually, we'll release that and fill it whenever we have that available. Rev two will will certainly put it up there. Cool. Yeah, sorry, that was a lot. But it's a that's been really fun.
So what's, what's the out, put of all this work?
Josh Rozier has wanted to make his own guitar for a long time. And he has built four or five for other people. But he's never designed one for himself. And so I'm stepping him through designing most of it. But he wants to, he wanted to do the transformers. So he wanted like all of it to be him. Gotcha. And it makes sense. And the thing is, like off the shelf transformers. If you just buy an off the shelf, then you're you have to play by their rules you like they give you the specifications. And there you go. But if we're wanting our own, well, then we can do anything we want. And so we're adding extra features that don't exist in most amps, because they just don't have a XYZ tap. Well, we do because we can calculate it. But in order to calculate it, we have to get it right, you know. So that's sort of the overall result of this. And in fact, he did build one. Well, so he we already talked about it, but he made an output transformer which totally worked great. And on Sunday, he just finished his first version of a power transformer. And that's actually where we found that everything in not everything. A lot of his taps were incorrectly calculated for his power transformer but because he puts his he puts his meter on it. And he was expecting 460 volts or something like that and ends up being like 520. He was like, oh, hit. Yeah, so yeah, good handful of the taps were incorrectly done. But a lot of that has to do with the fact that like these kind of like the chart I was showing where it's, it's not, it's not safe to just assume you know, the square root of two times u v, AC, that's what your DC is going to be like, if you go to Google and type it in. Like, that's a really easy way to describe what happens when you rectify an AC signal. But that's not what you're gonna get. It's way more complex than that. And so he had kind of built the simple equations into his transformer calculator. And the result is you get way hotter taps than they actually need to be so cool if you are fine with getting extra voltage but not cool if you're trying to actually hit a target.
Yeah, yeah. So we're gonna be looking forward to is a amplifier when he's finally done with it. Oh, yeah,
it'll be really cool. So I'm imagining Josh.
Roz. He's like, digging up like dirt to make iron ore.
I love that guy to death. Because he would do that. He would totally do that to make
blunder. Most engineer non engineer I've ever met. Like, absolutely, like he could have been an engineer, but the stars didn't align for him. Yeah. Cool. Onto the RFO
onto the RFO. So this is one that you found and it's a little ridiculous I think
just a little ridiculous and I just want to bring it up because I we were looking for our photos. And I just saw this as like I got it. I got to put it on here. The title of this article that comes from electronics weekly is Glasgow Tang has a taste for whiskey. And electronics weekly is I mean, usually their articles are like showcasing some PhD that has done some weird research or talking about some kind of trend in electronics, or an advertisement for an ice but when you have an article that says Glasgow tongue as it tastes for whiskey, I'm like okay, well, I gotta check that out. I got to kill that one. Apparently, Glasgow University researchers have made I bionic tongue that can tell the difference between Glenfiddich I can't even remember how to pronounce this Scottish whiskey, laugh frag. I'm butchering that. And Glen monarch. And the difference between vintages of each brand of those samples at ages 1215 and 18.
So is this like, I wouldn't guess like some professor had those things in his cabinet.
Or a professor wanted those things in his camp.
He said I know what our next project is. And of course it has to happen in Scotland because, of course, so in general, okay, so So here's the description from the article, it says sub microscopic slices of two metals arranged in a checkerboard pattern act as the tongues tastebuds, despite being 500 times smaller than the tastebuds on a human tongue. So the researchers poured samples of whiskey over the bionic tastebuds, and measured head, they absorb light while submerged. And then they claim that the tongue was able to taste the difference between the drinks with greater than 99% accuracy. So they still think this boils down to they just wanted whiskey.
Yeah, so they're using refraction.
I believe so. Yeah.
So it's actually like how a refractometer for measuring density of sugar and water. Right. Yeah, right. Interesting.
So I guess like, like, just, I don't know, they pour whiskey over this tongue. Then the computer says it's this sample, and they're like, Oh, great. And then take a shot and then pull the next sample over it. It's that sample. Great. Thanks.
It's correct. Take a shot. If it's wrong, take a shot. Take a shot.
How do you get how do you get money to do that kind of research? You know? Yeah, I don't know. And why whiskey? Also, like, if you're making this tongue, why didn't they do like, I don't know. It's funny. I like that.
So yeah, haha. I think the good question there is how do you get funding to do a research project like that?
I think it's exactly what we were talking about. Either the professor had the whiskey or he wanted
they just like yeah, we need to burn this budget.
Right. If we don't burn this, then we don't get it next year.
Right. Yeah, I'm reading the comments on this.
Oh, there's comments on it. I gotta check these out, are they good?
remarkable achievement, but why I would have happily volunteer to perform the same task.
And you know, for the first 20 minutes, you can have 99% accuracy. And then after that it just dropped. Yeah. Is it wiskus? Yes. 100% accurate.
So the next article is, so you want to build a CubeSat from the website, orbital index. And it's a really interesting article, that's kind of like just a collection of like, if you read all 800 of these links, you can probably make a CubeSat.
There are so many links on there. And actually, so al Williams, who's been on the podcast a couple of times, wrote a Hackaday article about this. And he has a little, a slight bit of snarkiness in the in his article where he's just like, oh, yeah, to make a CubeSat. You just make a frame. And then you make a processor, and then you make a battery. And then you make an antenna, and you make things go like it just keeps going
down. It's one of those drawn owl kind of things.
Oh, right. Yeah. So at the fab we, gosh, right. When we first started the podcast, there was two guys who were making a CubeSat for the use of Houston. Yeah, U of H project.
Now it keeps that was I don't think it actually went into space. I think there was just like building like the framework and control software for it.
If I remember, right, they it was something like a ton of students at the university were making them and they would pick like, in those would go
to, I always wondered. Yeah, like, how, like, just how CubeSats you like what you have to design for? Apparently, use a lot of like, what they call cots, which is commercial off the shelf stuff. That works. Yeah, parks. Yeah, it's it's interesting that the, like, there's different form factors for cube sets as well. And, like, how do you handle power? When like, half the time you can't get power? Because you're on the other side of the earth. And the sun
isn't the standard thing for a CubeSat 109 meeting? Yeah, that's
like a one you but there's like a two u and a three u which is like, more of the cubes stuck together. They're just
multiples of that. Right? Right, right. You know, how much okay, how much does it cost to get thing for
the last time I looked? It was about 10 grand.
10 grand? That's actually a bit more than I thought it would be.
Yeah, I think it's wrong. 10 grand, and you get like shot out of a rocket with like 1000 other ones? Well, maybe not. 1000 like 100 Other cube sets.
Oh, okay. I just I just Googled it. CubeSat launch cost average is between? Well, geez. 10,500 1000 Yeah. You know, be prepared.
It looks like other websites are saying
close a Mauser. If you want to sponsor that project, that'd be really cool.
Well, here's one launch you launch your satellite for 8000. What
kind of project where we launch with a CubeSat? Like, what would we do with it?
A satellite that constantly plays podcast episodes.
It just blasting meatloaf.
Just Hey, yes, I like that. Yeah. Like I sat at a hill which I totally bought that album the other day. So I don't have to play it. Oh, my. Oh,
you bought a vinyl sword. Record.
Oh, yeah. Yeah, I actually I got really lucky because like, it's in really great shape. That's nice. No crackles and pops. So
somebody bought it at one point you played at once? And we're like, that's, that's enough for me.
That's enough meat for me. What would you Okay, so what would you do with Yeah, cuz
it's one of those like cube set. It has to mean something that no one else has done before. And it's like, Oh, yeah. So you can put sensors on it and like measure like, are you in a vacuum? Yes. I don't I don't really know what I would have because like, I don't really have experiment, I guess I'd like to run it. That's an outer space. You know? I do like, I want to do like how a high altitude balloon just to take pictures because that's cool. Those are cool. But and that doesn't cost, you know, 10 grand to do.
The most expensive part of that is the gas.
And I don't know what I would want to do for an experiment to run, because I guess I just never thought about it. Like, what would I put up in the space? Doom guy?
That's so great. Yeah, I kind of I kind of like, I would have the tendency to just have my satellite look like a thumbs up or something like that. So it's just like this giant thumbs up, but not giant, this really small thumbs up.
So we had a crazy idea. We came up with this at Midwest gaming classic, I think, like two years ago. But to do like, because, you know, at DEF CON, there's like all these badges that people hack. And I thought it'd be really cool. Like, what if you actually had a CubeSat that people had to connect to when it was in range. And we started looking at like the orbital like characteristics, because first of all, most of the cheap CubeSat stuff, you don't really get to pick the orbits that you go into. Yeah, and
they just go into space and open the door, and it just spills out.
And so it's like, so you don't really get to pick your orbits. Well, I guess you can say you don't want to be on that launch. Yeah, well, yeah,
I think you could get the pictures here or well,
all the cubes, that's pretty much go on the same orbits. Because they're, they're like secondary payload did not put, they basically have to hitch a ride on the rocket. So the, basically it's like, okay, if you could get an Orbitz that would pass over Las Vegas. Right. But it's like, you'd only have like a 10 to 15 minute window, and then it's gone again. And then.
Right, right. And then they're a low enough orbit, you'd have to have Yeah, so it's like either you constant connection,
you have a lot of them, basically. And they're just like a train basically, of celebs, cube sats, blasting, meatloaf out down to down the Vegas, or like, it's just a window, and you have to grab the information from the CubeSat when it's over you. It's an interesting idea. But it's also really expensive to try. And it probably wouldn't work. Because you'd only get that window like a couple times, and then it would have moved too far off of its orbit.
That would be kind of cool, though. If it was over Vegas for DEF CON, and everyone's trying to hack it. It would be really cool. That that'd be kind of cool. Yeah, sure. The trap and the data traffic jam would be
the craziest thing would be like you. You can't mess it up. Like there cannot be bugs on your satellite. Because you can't fix it.
I mean, I gotta go get it. You want it? You want to talk about multiple times the cost of
what they have to do with the Hubble
telescope going and getting it? Yeah, they launched it and had what aberrations in the they had to like apply fixed to the mirror. What is it the lens or something like that? Or the mirror the mirror in the back was just ever so slightly off?
I think that was one of the space shuttles. First things I know that's also that's
something that that like yeah, that's right. I remember exactly for now, what year was it? The while ago, but you know, okay, so this whole, like, this mirror in the back of this telescope has to be ever so perfectly aligned and everything. Like, how did you get into space without it getting unaligned? You know, like, like, that's, that's not like a smooth ride. If you ask,
actually, the thing is that, um, orbital index talks about, like, having to design your CubeSat to survive like a rocket launch.
Yeah, yeah. So they repaired
Hubble in December 93.
Oh, no. Okay, then that was not the first thing that this space shuttle Yeah, it was. was around when we were young. We don't know this. Yeah, the space shuttles blew up.
Very cool. Cool.
There's, so we also found this other website, that's www dot Nano sats.edu. And that is basically a database and a tracker of cubes acts. So if you are like an absolute data analytics nerd, and you want to just go see a whole bunch of data or do whatever, go to that website, there's like 2400 satellites that it's tracking data on. It's also kind of cool, because there's just like a complete database. So if you just want to see what's up there, and it's pretty cool stuff, what people have sent stuff,
and I like this. Pretty common here. I believe the big future of nano satellites is still to come. That's like who said that? It's a quote. Yeah, I'm gonna ask the person.
Is that on your front page? You
betcha. That's his quote. We should get him on the podcast.
Yeah, they're, they're missing a meatloaf satellite. I know that. They're, you know, actually, if we ate would be great if we went in there.
I'm not sure they're ones that played audio. And yes, you just repurpose one of those like meatloaf.
Ah, okay, so cube sets. Cube sets are measured in size, nano satellites. Satellites are measured in wait. So the database includes nano satellites and Pico satellites. Also, they have been smaller. Oh, there's Femto satellites. 10 grams to 100 grams. That's like just like an Arduino Nano just floating around in space.
There are a handful of us and Chinese nano satellites about which nothing is publicly known. Interesting
how many how many satellites manmade satellites that are attended to be there are in space
probably a lot probably more than we think there are. I probably say like 20,000 Maybe I wouldn't be surprised if there's how many satellites are in space only 1886
That doesn't make any sense. There's a database on this website then that probably but but they're probably not considering these to be a satellite you know proper
interesting least that's what a pity is saying. That doesn't make any sense because like the first line now this because the articles are all saying like expensive ones. 2018 estimates some 5000 satellites are in orbit. Oh, okay. 1900 are operational. Yeah, just log garbage floating around. Oh, so
there's just garbage floating around. Interesting.
Yeah. So the next last core pro for this week is how to master PCB pairs and why you should so II web article. And I picked this one. And it doesn't sound like me because I do a lot of PCB repair, especially for like old automotive stuff. And so it's a lot of stuff that's like, kind of like I didn't really learn anything new from this article, but hopefully someone will if they read it but he covers stuff like he's got some good pictures
pretty gnarly pan.
Let me pull up the pull up the video
you know, one of the things that is worth learning at some point in time is repairing traces on boards, and not just like green wiring. I'm talking about scraping away so yeah, he
talks about how you do that with like copper tape a
Basically like you put down a piece of copper that that has adhesive backing and that's how it sticks for for. I've done that a couple of times. Most some I just green wire it because that tends to be faster and easier, especially if you don't need like the board to look back to normal. I say the heart the biggest problem that I run into though is finding out what the part originally was about. For it went nuclear
Oh, like in the image he has here
what it's all the magic smoke outlet out puked its guts.
Yeah, every ounce of it. I'd actually I'd be curious to know what, what that actually even is because to make a component do what's
a MOSFET that failed, you know, open, not failed open, failed closed, shorted and fail short yeah that's the thing about SMT FETs is when they fail like that they tend to Ensenada themselves, which is nice. But this one kind of went right, right. Ballistic?
Yeah. This one bar this bar. There's like a hole in it. So yeah,
go if you haven't done any, you know, PCB repairs or anything like that, go go check out that article. Steven, I do that stuff all the time. And it's a skill that I self taught myself that skill, I think you did the same way. So
it's I actually my boss came up to me or late last week, and we were talking about doing some, some changes on a circuit board. And we he basically said, Hey, can we make these changes on this board, and then he stopped he goes, You know, I've seen what you can do with with green wires and wires. He's like, You can do this. Like, just because like, if you seen some of my prototypes, I mean, spin aboard. I just make the board do what I need it to. It's easier and cheaper. Most of them
exist. So you can actually test the rest of the circuit out.
Oh, yeah. Yeah, absolutely. And especially with analog stuff, like, sometimes you wired that up in an inverting configuration you wanted to not unlike I'll make it wired in
op amps with the negative the positive, positive negative. Remember that? Yeah. Yeah, that was because like my schematic I kind of hunt symbol does it didn't have a plus or minus on like the power pins. And I mirrored it. Yeah. Yep. Yep.
Fun times without marrying the power supply.
Cool, man. This has been a long podcast. Yeah, so I guess we'll wrap up this podcast. So that was the Mac fab engineering podcast. We're your hosts Parker Dolman.
and Steven Craig
AND!XOR comes to Texas to talk about #Badgelife, the craziness of DEFCON, and their new badge design.
Slow/soft Start devices and circuits, Shark Fin sound effects, and Belt Buckle Badge Designs.
John Adams joins Parker and Stephen to discuss IoT Security, Crappy IoT Devices, and WS2812B LEDs.