- Physicists build circuit that generates clean, limitless power from graphene
- University of Arkansas physicists
- Energy harvesting the thermal motion of graphene
- Without getting all quantum about it, it seems to work by configuring the graphene as one electrode (or both) of a capacitor. As the graphene flaps in the breeze (actually Brownian motion, I assume), the changing geometry will change the capacitance.
- The team’s next objective is to determine if the DC current can be stored in a capacitor for later use
- Youtube video
- New test equipment design – picking the right opamp
- Current sensing with a bit of a twist
- Powered by +/-12V
- Need to read current on the +12 and the -12 along with a +9V rail
- Opamp needs to be capable of reading a voltage drop in an environment where the common mode voltage is at or near the opamp supply voltage
- Current sense amplifiers
- INA1x9 series amplifiers from TI
- Supply and common mode range are independent of each other
- 2.7v to 60v
- Convert a voltage to a current then change the gain by selecting an appropriate load
- Iphone 12 doesn’t come with a charger?
- Are chargers necessary?
- Don’t we have like 300 of them lying around?
- Apple states environmental reasons for dropping the charger
- Also no earbuds
- Examples of other products that lack the equipment necessary to function
- Video game consoles?
- Internet router?
Special thanks to whixr over at Tymkrs for the intro and outro!
About The Hosts
Parker Dillmann is MacroFab's Co-Founder, and Lead ECE with backgrounds in Embedded System Design, and Digital Signal Processing. He got his start in 2005 by hacking Nintendo consoles into portable gaming units. He also runs the blog, longhornengineer.com, where he posts his personal projects, technical guides, and appnotes about board layout design and components. Parker graduated with a BS in Electrical and Computer Engineering from the University of Texas.
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.
Host 2 00:00
Oh oh man, you were in your Van Halen shirt.
Host 1 00:13
Gotta represent dude.
Host 2 00:14
Rip, Eddie, you want to start this one?
Host 1 00:18
Welcome to the macro fab engineering podcast. We are your host, Steven Gregg and Parker, Dolman. This is episode 246. So,
Host 2 00:27
Apple has a new iPhone coming out, or is it out already?
Host 1 00:31
Well, they announced it today. Okay, they announced the specifications of it today. I mean, everyone knows it's been coming out for a while.
Host 2 00:39
So what why is that on our notes? Typically, we don't talk about consumer electronics,
Host 1 00:45
We typically don't and, and there's there. So it's, I've probably mentioned this before, but I'm not necessarily the biggest fan of Apple.
Host 3 00:55
And because they do some odd things, and they there's something I want to talk about specifically with this release. So this iPhone 12 does not come with a charger in the box. So you get a phone and you do not get a charger. And actually technically it also does not come with earbuds. But that's like, okay, whatever kind of thing doesn't have a speaker still? I don't know. I mean, I would think so. Like I think that's something that they would now is that
Host 2 01:24
Just transmitting waves directly into your Elon Musk's neural link implant
Host 1 01:30
By more apple all day, every day by Tesla's so yeah, so the new iPhone does not come with a charger. And Apple's official statement on this has to do with environmental reasons, effectively saying that, you know, I think the argument is effectively, there's enough chargers around and we don't need to provide them. So basically,
Host 2 01:56
Yeah, what they're saying is everyone's got like eight zillion of these in that junk drawer in your kitchen?
Host 3 02:02
Correct? Which, which I think is, which is probably true, because I started after I read that article that it doesn't come with a charger. I was like, really? And then I started thinking, like, how many? How many wall bricks do I have lying around? And how many have I purchased? Because I was like, I went on vacation. I forgot one or blah, blah, blah, all the reasons. I'm like, Man, I probably have a ton of them.
Host 2 02:23
I have an entire box down here that is full of just those things,
Host 3 02:29
Things of that sort. So I think that's totally in that sense. That's actually totally reasonable to say like, yeah, we do we really need to just create more e waste by providing or providing a charger guaranteed with it. I've bought phones and gotten a new charger and still had the charger from my previous phone. And it still works. You know, I've had that probably multiple times.
Host 2 02:51
Yeah, when you actually trade in a phone, you don't have to trade in the accessories you have for it.
Host 3 02:55
Right. And actually, I think that's that's where he kind of hit something on the head there. The charger is considered an accessory, right? It's not critical to the function of the device, or is it?
Host 2 03:08
Hmm, exactly. Well, given that smartphones only last a day, charge maybe two days depending on the model and usage. I mean, if you're only planning to use the phone for two days, then yeah, sure.
Host 1 03:23
Right, then it's an accessory, right? Yeah, just spend
Host 2 03:27
$800 every two days that bam, you're done. Never have been charged or phone ever.
Host 1 03:35
Well, okay, so I thought I thought we might play a fun little game. And this game is what other products can you purchase that do not come with a critical piece of equipment to function?
Host 2 03:51
Printers and that stupid USB B cable?
Host 1 03:55
That's true. That's true. Yeah. Also well, and I think you could probably find some printers out there that don't come with ink.
Host 3 04:05
I would not be surprised. Most of them. Most of them do. But I would not be surprised if you could find some made. So I put down video game consoles because you can buy a video game console without a video game.
Host 1 04:18
And I would I would make an argument that that's critical for it to function. Especially
Host 2 04:23
Older older ones, and these new ones at least boot up and like you could go to the digital store, whatever and get a game. And some of them have free games now on digital stores. So sure, but But no, I would agree. Yeah, I would agree. That's a good that'd be a good one.
Host 1 04:41
So I bought a dishwasher not that long ago and it it guaranteed did not come with the correct connections or any connections I should say for for actually install installing it. So I think I would also make an argument that it came without things If that were critical to its function, I've never
Host 2 05:02
Bought a washing machine clothes washers that had everything usually you had to buy the hoses, the hookups, and then whatever electrical plug, because some you know, you have three wire or you have four wire. Right, right. And United States. So every now no most of the clothes want you to put a four wire on it and you're like, Nah, I can put a three wire on, it's fine. But yeah, yeah, cuz that's weird. Because yeah, you to use a washing machine, you'd be able to get water into it. So technically, I guess you could toss buckets into it. But having a water hookup? They do come with the drain? No, that's weird. Because they always had the drain hose but never had the fill hoses.
Host 1 05:49
I think I think what we are describing here is is a little bit more of these are installation based things that are they don't provide them because they're unique to your case. Could whereas a charger is not necessarily unique to your case. Unless that's
Host 2 06:06
That's your install on for your dresser by your bed. Oh, yeah, you're right, you're right. That's the cable that's plugged into the wall into your phone.
Host 1 06:15
And your installation may be different than mine. It's,
Host 2 06:19
I'm hoping it's the same thing that plugs into a wall and a six foot cable.
Host 1 06:24
How about how about an internet router may not come with an ethernet cable. So it is or the or the coax cable? So that would be I think you could make an argument that that's critical for it to run.
Host 2 06:38
Yeah, that's also installation base through though, right? But my last XFINITY box came with actually that's one thing I can give props with Comcast is when you get one of their install kits and actually has everything. Yeah, like legit everything. Yeah, has everything you need. I think actually added that list video game console might be the only thing that's legitly not part of like an install of a thing, right? Could be unique, though. It's like, get six foot hoses for your washing machine. And then you can pretty much put that anywhere. Yeah, so that's like, you don't buy unique hoses, like the fittings are all standardized.
Host 1 07:23
So that you think they could provide it with the hoses?
Host 2 07:26
Yeah, they could provide it with the hose because like, you're not going to buy like you don't, okay, most people don't need like a 50 foot hose, a washer and dryer.
Host 1 07:38
So I think I think what that's coming down to is it's somewhat strange to purchase something and not get a critical item with that thing for its function.
Host 2 07:48
Especially a phone. I would say that yeah, yeah. But I do kind of agree with there. Now I bet you that wasn't the original reasoning. Some executives did not say we need to reduce e waste in the world. So we're not going to include chargers? No, it was an executive saying, hey, we need bigger bonuses. So let's not put chargers in there. I cut out, you know, $5 out of our Bill of Materials.
Host 3 08:13
Well, and I think one of the one of the things about that is that maybe points towards that direction is that they they did X the bill of materials, they did X out the charger and earbuds, but the price doesn't seem to change. So you know, it maybe it would be different if they were like, Hey, we've reduced it by $15. Because we don't we're not supplying the charger. Well, that doesn't hasn't now. And
Host 2 08:42
If they really wanted to go down that route, then the iPhone should show up at your door or you pick it up at the iPhone store, whatever. And it comes in a plain cardboard box. Or they
Host 1 08:54
Just hand it to you.
Host 2 08:55
Yeah to like, yeah, because because I know I iPhones have really fancy packaging. It's that premiere experience of unboxing. Right? Oh yeah. And that all goes into the garbage like immediately. It's like two pounds of packaging right in the garbage. So that is definitely some PR spin. I think. I bet you more manufacturers are going to do it.
Host 1 09:26
Maybe maybe but but I'm also kind of like who else in the world what other company could sell you up a luxury. I'm doing very heavy quotes here. luxury item like that. That doesn't that is literally incapable of functioning. The way you purchase it like it will function for a few hours. And then you are boned.
Host 2 09:51
What you also have to get a SIM card to do you. I don't. I guess exactly you could use it over Wi Fi you're right you could use it over Wi Fi Oh, well,
Host 1 10:00
I mean, whenever you go and actually, well, okay, so it depends on where you purchase it if you purchase it at a, at a phone store that they install that so you're well Yeah, cuz
Host 2 10:08
I bought my because I have a google pixel two, I bought it straight from Google so like, it technically can only connect to Wi Fi. When I first got it, I had to go and put a SIM card in it. Oh, right, right, right. Yeah, but mine came with a charger,
Host 1 10:22
As do almost all other phones.
Host 3 10:25
Now actually, the last phone I got, I purchased it never once even used the charger it came with, because I do wireless, cheap Qi charging or however you say that I can't remember. And I prefer that a lot. As opposed to, you know, it's really funny too. Because this this phone, I purchased it. And I have pretty much never used the USB C port on it. Because I just from day one I was doing wireless charging. My USB C port does not work. I've probably in the life of this phone, which is a year and a half. I think I've probably plugged in USB maybe 15 times maybe 20 times and it doesn't work.
Host 1 11:05
And it's just I don't know, it's confusing to me. It takes a lot of wiggling to get it to work like this. Things should be brand new.
Host 2 11:13
Oh, okay. So I've noticed, because I plugged mine in, like three times a day. Yeah, it still works. And I've had it for do you have to get all the belly button lint out of that is what's in there is some tweezers and pull that stuff out. Because for some reason, when they we had micro USB, you know, it's a slightly smaller profile link didn't really get in there. Yeah, but the USB type C, it's got slightly bigger opening. That's like optimal for collecting lens.
Host 1 11:42
I'm trying to see if I have any, if I have some tweezers on my desk here, so I can go and excavate
Host 2 11:47
As I talked about. So we're talking about charging in batteries. That's a very good segue into my topic. Oh, go for it. Physicists build circuit that generates clean, limitless power from graphene. And so I saw that title on, like, how much bullshit is going to be in this article?
Host 1 12:07
I mean, from the name of it, it's just it's going to be a stinky one. Oh, yeah.
Host 2 12:11
So the article itself is from psi.org. I don't know anything about site.org or anything about them? How reputable they are, did I use that and went straight to the paper that was published by the University of Arkansas physicist. And so what is going on here? Is this sounds this sounds legit in terms of what the physicists are doing? Not that title. Okay. Because it's not it's not a perpetual motion device at
Host 1 12:49
All. What I mean, from that title, it kind of sounds perpetual like it. Yes.
Host 2 12:53
Yeah. My my also favorite is like the, what it says clean in there as well. It's like, me, so gotta build this thing. So this is what the thing is, okay. Is the researchers are this is like a research group that like just looks at graphing, okay. And they've been experimenting with the material. And then notice that so what graphing is, is a matrix of carbon carbon atoms that are in one plane, so that it's like one atom thick matrix. Yeah. Of just a sheet of atoms. Yeah, it's a sheet. It's actually, like, the most 2d thing you can make is like, a sheet of graphene. Right? I can only has one, like two dimensions.
Host 1 13:40
Well, the thickness of anatomy is the third dimension. Yeah.
Host 2 13:43
Yeah. Yeah. So what they were they were messing around with this material. And they started to to suspend it in the air. Right. And they noticed that it kind of it like, because it's just a sheet of atoms and atoms like to move around because of thermal their thermal energy, right? They just kind of randomly move around. They jiggle. Yeah, they Yeah, they jiggle around. It's, I think it's called Brownian motion. Is what this is, by way. I want to mess something up in this x plane. Because I am not a physicist and I, the last physics class I took was over a decade ago, a decade ago at this point. So Brownian motion, which is thermal motion, which is just basically the thermal energy of atoms just wanting to move around. So anyways, you have a sheet of this stuff, and that motion, makes it kind of wave. Okay,
Host 1 14:43
Almost like a trampoline or a flag or something like that. Yeah,
Host 2 14:46
I don't really explain exactly what it is. But to me, it sounds like it basically gets into this resonance frequency. That's at least what in my when I was reading That's what I came to is like, basically, you got this thing that's just like randomly moving around. And it eventually starts resonating at whatever the thermal frequency is. That's just my guess that could be completely wrong. Anyways, they they were like, Okay, we got this thing that's oscillating. Oh, what's also oscillating, alternating current? And so they put to charge plates. sandwiching that, that, that graphene sheets, and then that oscillating sheet in there, graphene sheet induces a charge on those plates.
Host 1 15:40
Oh, okay. Because it's in between the E field that's between the two plates effect. Yeah. So it's a graphene sheet inside of a capacitor effect. Yes,
Host 2 15:50
Exactly. And so as that thing's oscillating in their dueces, a, a alternating potential and current into your circuits, and you can get power. So think of this. So people like, saw that. And we're like, oh, limit this power from like, thermal energy. It's like that thinking about it more like a piezo elements, where a piezo is vibrating, you can get electricity from it, because you're taking motion out of something else, and turn it into electrical engineering. So what this is doing is taking the thermal energy of graphene and turning it into electrical engine energy. So it's taking the energy around it, basically the thermal heat and turning it into electrical engineering energy. And it's basically like, it's like energy harvesting, like super optimal, I guess. Because like, you're bypassing like trying to convert motions of like that you're like, going straight to like, just the atoms, I guess. We're going around.
Host 1 16:56
It's interesting. It's a different form of Pyro electricity. Isn't that you're, you're creating energy from heat. Yeah, Pyro electricity is a property of certain crystals, which are naturally electrically polarized, and as a result contain large electric fields. I'm reading Wikipedia. Yeah. Here. The basically, you can induce a charge based off of heat differentials across.
Host 2 17:24
Yes, that's, that's a different, completely different kind of mechanic that this is
Host 1 17:29
Using, right? Because this is actually this is moving in an E field. Based off of heat. Yeah. Interesting. And
Host 2 17:37
Well, heat in quotes. It's the thermal motion of the electrons, which is not really, I guess, maybe you might be I don't know what the classical physics example of what heat is. I think just heat is like, more thermal energy, right? Yeah. Okay. Okay. Right. Yeah, I just thought was very interesting that like, I guess what would you say? Limit? Okay, so one qualifier is, you could say it's limitless power, just from the fact that as long as that graphene sheet exists, like it's intact inside of whatever this thing is built into, and you haven't hit like, absolute zero, then it will continually draw energy out of its environment and make electricity.
Host 1 18:25
Also, graphene is incredibly efficient at thermal conductivity. And I believe also electrical conductivity to which would probably make sense as to why it would be good at this. Yeah, it is.
Host 2 18:40
It's probably you can probably make any really thin sheets of material that's that can produce in an E field. Right? It's just probably graphing is probably easier to make.
Host 1 18:54
I mean, I don't know the answer to that, because I think it would be it would depend on its ability to conduct. Right.
Host 2 19:01
Well, that's not saying if, if something if a material is moving around in the influence and II field, technically, that would work in this application doesn't have to be graphing it could be, you know, iron,
Host 1 19:14
Right. But graphene is probably one of the best
Host 2 19:16
Things to Yeah, it's probably in part, one of the easier ones because I think you can make graphene by like with scotch tape, right?
Host 1 19:23
Yeah, yeah. Yeah. You just keep sticking it together and pulling it apart. And eventually you get it.
Host 2 19:28
I think it's like you put it on carbon and then peel it off. And like that's one. Yeah,
Host 1 19:32
Yeah. Yeah, you just keep doing that. I can't remember. I watched a video not that long ago, but you have to do it a certain number of times. And then there's a some percent chance that you have a one atom layer thick. And it's just it's funny because Like, legitimately, that's how a lot of labs make it is just Scott. Yeah, I worked. I worked actually at a church with a guy who was a research He did. I can't remember exactly what research at Rice University in Houston. And he worked a lot with graphene. And he told me he's like, yeah, a lot of times that's how we make it because it's just, it cost nothing. And it's takes just a few minutes. Yeah. Now getting it off the scotch tape is kind of hard.
Host 2 20:16
I would imagine so because it kind of sticky. Yeah,
Host 1 20:21
I think you have to just basically, you have to use chemical processes to get oh, dissolve the Yeah, just dissolve the tape.
Host 3 20:29
That's interesting. I, you know, it always bothers me when you get clickbait titles like that. Because the second I see that, I want to immediately just say like everything
Host 2 20:40
Next is garbage is garbage, or disregarded, because it's just going to be perpetual energy, you know, thermal law dynamic, violating crap. But no, you actually go to the paper, read it. And it's like, okay, this is what it's actually doing. is basically just, you know, they're, they're basically making a very efficient thermal pump, basically. Yeah, yeah. It's just taking energy. It's just taking heat from one spot and moving the work somewhere else.
Host 1 21:11
Right, well, doing a small scale efficient conversion of energy. Yes. I, you know, I would be, I would be curious to see. Like, how, how efficient is this? And how large Can you make it? I mean, is this something that's just going to be? That is possible, but it's, like, limited by size? Or is this something that like, eventually, you could have, I don't know, some kind of large power generation based off of this?
Host 2 21:39
Because technically, you could do this with like a piezo. But you have to, like, you know, continually vibrate it in pisos. Will there ceramic devices? Yeah, the kind of almost, it's a Pico is a, quote, scaled up version, because thermal energy on a mic on a micro scale is just vibrations. Right? Right. And then a piezo is taking mechanical vibrations into electricity. It just the, the graphene is just way more efficient at doing this than the piezo ever will be because it's lighter and a hell of a lot smaller. Yeah, hell a lot smaller. But, um, until I started seeing, so I didn't really see any power ratings of like, well, how much like, what the power density is something like this could be, there might be something in the actual paper, but it's pretty long. I haven't read the whole thing yet.
Host 1 22:37
TLDR, man? Yeah. TLDR is free energy for everyone. Yeah. So there's actually a whole YouTube video about this. Um, I had not even heard about this before. Parker were talking about it. So I'm gonna have to watch this.
Host 2 22:51
Yeah, it's that it's the video is the
Host 1 22:56
Oh, it's basically just like the principal. Yeah, it's
Host 2 22:59
The professor that's theorized it in and putting forth the research and stuff like that. Paul, the bato is, well, I'm going to guess that how you pronounce that last name?
Host 1 23:14
Oh, okay. So this is Wait, let me see. Did you write this down? Okay, so so the title that that you wrote down for this article is physicist build circuit that generates clean limitless power from graphene. But then you go to the YouTube thing, and it says, in the title is a potential source of clean limit. limitless energy? Yes. Is a little bit of a difference in those levels of difference there.
Host 2 23:38
Yeah, it's so interesting to think about it as a as a if you take a step back and figure out okay, what's, what's it actually doing? It's taking thermal energy vibrations, and turn it into electricity, much like a piezo is doing the same thing.
Host 1 23:54
Okay, so So if that's the case, follow me here, like nothing is free right there. Like there. There is no such thing as limitless energy in terms of perpetual motion or any kind of device like that. So you always have to input something and you always lose something, right? So this this device, the input is thermal energy, and the output is electrical energy, in whatever form you take. But if it's consuming thermal energy, then this would cool down whatever is inputting thermal energy, right. So if you take enough of these, and bring in and really utilize it properly, like you would actually make a cooling device out of this, right. I mean, probably like a massively inefficient cooling device.
Host 2 24:43
Yeah, well, technically, yeah. But you have to move that, that work somewhere, that energy somewhere, right. And so you'd be heating up somewhere else as well. It's like your air conditioner is your air conditioners is a heat pump.
Host 1 24:55
Well, I mean, not not necessarily because you You wouldn't necessarily be heating something else. Because you would you're converting the energy, right? You're converting heat energy into electrical engineering energy. And then that goes somewhere. Right? So
Host 2 25:09
Is that how we solve global warming is by building a lot of these just charging up a bunch of capacitors and just
Host 1 25:14
Letting them sit? Right? I guess well, okay. Now now we're really getting into it, because a capacitor has internal resistance, and it will eventually discharge right. And it discharges as heat. Right across that internal resistance. So the net is zero.
Host 2 25:33
Yeah. Well, I mean, that's the idea, right? Is your net is as close to zero as possible, because you're temporarily
Host 1 25:38
Cooling, but you're just storing and heating something else a lot slower.
Host 2 25:44
Yes, yeah. Entropy always wins.
Host 1 25:47
Yeah. Something has to be concerned. That's, I think that's I think that's what they taught me in school, right?
Host 2 25:53
Yeah. Yep. Yeah, that's the thing is you can temporarily cool some, but you can you. I mean, that's what how an air conditioner work. So it's like, you're, you're compressing the gas and expanding that gas somewhere else. But then you're compressed when you compress that gas, it gets hot. And so you, that's the that's the energy that you're extracting from inside your house, as you dump it outside?
Host 1 26:17
Well, and the efficiency is how much hotter the outside gets based off of how cool it gets on the inside, which is like you put an air conditioner inside a room and you run it in a closed room. It's gonna get hot.
Host 2 26:29
Yes, well, it's like your refrigerator or same way. That's actually one thing I was ever able to design my own house is figure out a way to vent the the heat waste of the refrigerator. Because I don't know if you're like, sit around your refrigerator. But like a hot. Yeah, your feet gets hot, because that's where it's exhausting all that that air at.
Host 1 26:59
So I wonder what percent efficient refrigerator is? Like? How much heat does it produce to produce so much cold?
Host 2 27:09
Like, if you're producing while I was about to say wattage, but it's, it's probably joules what you want to talk about?
Host 1 27:17
Yeah. So there's a, like I said, with an efficiency? Like, is 50% of your, of your input energy converted to heat? In a fridge as opposed to cold? Or is it 90%? Is it 10%? I don't know. I have no idea either. Be interesting to find out. Maybe someone on our Slack channel knows tell us if you are a frigerator master because it would not surprise me in the slightest that there's somebody on his Slack channels like I've designed refrigerators since 1856. And I know all these AC
Host 2 27:49
Host 1 27:53
We gotta you know, this week, I saw some some really cool stuff come across this lecture. And I know we always talk about it and, and gush on it a little bit. But like, I was really happy earlier this week, because I saw that somebody just asked some questions. And there were just tons of helpful people there. And it was like, there's some, there's some weird, like purity about our Slack channel. It hasn't been tainted by the internet yet. And I'm me saying this means that it probably is going to be like, we haven't had any bad apples. And it's just a bunch of good engineers on there who are like, Hey, man, I need some help. And there's like, 15 people are like, I can help you it. I don't know. I was looking, I was like, Yeah, this is a good place. I like these people. Cool,
Host 2 28:35
Host 1 28:35
That's much we'll join our Slack channel, and be helpful person.
Host 3 28:41
So okay, so check this out. I got I got a new kind of project that I sort of assigned myself at work. In other words, I pitch something and the the owner was like, yeah, go do it. And I was like, Okay, great. I just realized, like, I pitched something. And now, that means I have to do it. So so in the past month or two, I've been doing some circuits outside of work that have to do with current sensing, because I was doing that current sensing in low currents and high voltage situations, which that's still on its way. I just kind of have to save up some fun cash to be able to actually purchase everything.
Host 2 29:21
Those parts were not cheap. Those parts
Host 1 29:23
Are not cheap. And I've been having to do a lot of work on my house. So like my fun fund is, is a little bit dry right right now.
Host 2 29:31
Yep. But your furnace is burning it up.
Host 1 29:34
Yeah, actually, my furnace is leaking right now. And we got a quote yesterday for a new furnace and they wanted $10,000 for a new furnace. I'm like, Oh, God,
Host 2 29:45
Can you just put some flex tape on it?
Host 1 29:46
I'm thinking about it. I was like, I got a TIG welder. I can just, you know, zip some things up and call it good right?
Host 2 29:54
Is it what what is broken on it? Ah,
Host 1 29:57
If you run the AC right now you It freezes over and then it just leaks everywhere. Like the the evaporation coils apparently are broken somewhere.
Host 2 30:10
So you do have a gas leak. Possibly coot your what do they call that? Your refrigerant is what they call it. Yeah. is leaking. Right. Right. Dang. Yeah.
Host 1 30:22
Yeah, exactly. And of course, the one model that I have, which was from 1997 is like, they only did it that one year and you can't buy this evaporation coil and you can't redo this one. You just have to buy a whole brand new unit. All right, that's that's the solution. And I don't know. I need some more opinions from other people. Before I go, dropping $10,000
Host 2 30:45
The problem with with welding near refrigerant is usually refrigerant is is flammable. Oh, I was
Host 1 30:53
Joking about that. I'm not gonna lie.
Host 2 30:58
I mean, for $10,000, if you knew there was no refrigerant in there, I probably would give it a shot.
Host 1 31:04
Oh, like if I knew if I knew exactly what the problem was. And, you know, Flex tape would fix it, then then I'd be I'd be all over that. But I have no idea what the problem is. The best part is, you know, I'm in I'm in Colorado, in October right now, I do not need AC, I'm doing a okay. It like, we just leave the windows open during the day and the house is cool. So I've got a little bit of time to sit on this. And the heater still works. It's just the the cooler, that's not, you know, up to snuff right now. So I have six months before I have to really worry about this.
Host 2 31:40
So the I know we're going down a rabbit hole on this one. But this is just me being me. When you have the guy come out, I say guy. Well, you had the technician come out there. Did they tell you where the leak was that? Like did they actually look for a leak?
Host 1 31:55
I'm really skeptical about this person. This is why I'm gonna get more than one opinion because we we got somebody to come out. And they're all like, Well, we think this is it. Here's a quote for a whole brand new thing. And yeah, that's true.
Host 2 32:09
Yeah, it's really furnace setup.
Host 1 32:12
I'm not doing that I want because
Host 2 32:13
Usually what you will do is you can either like it still has gas in it. You can get a sniffer, and you can detect where that gas is at. And then you can figure out what's leaking. Because you're it's usually the coils outside that leak, or your compressor leaks, because like the seals inside of the compressors are failing. When you said second 97 It's not that old.
Host 1 32:43
When we were purchasing the house, they were saying that they were saying the furnace is pretty old, you know, start thinking about you'll eventually need to replace
Host 2 32:51
It. Meaning that they knew it was leaking and they just put new gas in it.
Host 1 32:55
Well, no, I mean, that was my realtor saying that. I mean,
Host 2 32:59
Yeah, no, that's that's what
Host 1 33:02
Oh, is your real? Is my real? Derek says yes. Gotcha, gotcha. It's not in their interest to tell me that. No, no. Okay. Okay. Yeah, back back to the current sense back to current sensing fun stuff. Okay. So I've got I've got current sensing, but a different challenge to kind of tackle with this.
Host 2 33:22
So wait, let me guess low voltage high amperage, no,
Host 1 33:27
Get this. It's what it is, is I want to send current, but but all of my circuitry has to be powered by the rail that I want to sense current en. So in other words, I've got 12 volts coming in. And I want all of my op amps and all of my current sense amplifiers to be powered off of 12, but also read that current. So once again, I've got a situation where things are not like at first you kind of think about and you just you know, if you just write out Ohms law on a piece of paper, you're like, Oh, well, this works, right? Well, it's never that easy. Because if you tried to take say, a, just a Joe Schmo op amp, pick any Jelly Bean op amp, and you power it off of the 12 and a negative 12 volt rail, and then you tried to measure a voltage drop at 12 volts, that op amps gonna start crying and get mad at you because its input range is not optimal for doing that. So, uh, you know, I think it would be really fun one day to kind of do a deeper dive into like selecting op amps and and how different kinds of op amps because like, if you go to Mauser and you just type in op amps, like if this is your first circuit that you're going out and you know, and someone's like, you need an op amp for this application. You go to Mauser and there's like 35,000 choices. It's like oh my god, like there's not an option for ideal, right? Yeah, all of them are ideal, right? Yeah, it's just you just pick whichever brand you like
Host 2 34:51
Host 1 34:54
Yeah, price infinite.
Host 2 34:58
Limitless power. are.
Host 1 35:02
So it's actually kind of fun to get into these situations. Because when you start getting into these weird configurations, you start to see why op amps are different and why you have all these unique characteristics. So for an OP to pick an op amp that works in this kind of situation, you need. There's a category called current sense amplifiers that are designed with this kind of circuitry in mind where you're going to measure something that's at or above Actually, your power rail. And in fact, I found some some examples of some current sense amplifiers that I think would work. Well, in these kinds of applications. I haven't really done a huge amount of digging on this, I don't know if I'll use these ones, but I think they could work out. These are from Texas Instruments, they they are the ima 1x, nine series of current sense amplifiers, which are actually, I don't have it pulled up anymore, but I think they're called current shunt amplifiers. And so they're actually really convenient. So these amplifiers allow you too have completely independent common mode range and power supply range. So you can power them from a few volts and have common mode voltages all the way up to like 60 volts, as long as your differential input range doesn't exceed things, this this op amp is still happy. So you can have common road inputs way above your power supply rail, which is pretty much exactly what I'm looking for, even though my input common mode is the same as my power rail. These are kind of designed for this exact situation. And the big thing is that statement there about the supply and the common mode range are independent of each other. That's where it gets really nice for these op amps. The cool thing is with these op amps is they actually have a current output as opposed to a voltage output. So they actually have a transistor right on the output. And what that allows you to do is you can put a load on it and control the gain that you want based off of what load you choose. So it's like a gain selection based purely off of resistance. And then you know, put that into A, A to D or or do whatever else you want to do with it. Whatever signal conditioning you need. Makes it makes it really easy. So yeah, I just want to kind of highlight that I was I was playing around with in my head earlier today because I was like, I want this to be cheap. And I want this to be really simple because this is not like I'm not reinventing the wheel of doing anything magical here. So what do I really need? And the biggest problem I was going through in my head is like, Okay, I've got power rails and I'm wanting to measure the power rails, but I'm also want to power all my circuitry from it. That instantaneously means no Joe Schmo. jelibean op amps, so yep, op amps are cool.
Host 2 38:00
Here, we should have that big talk because I, my biggest thing on op amps is yeah, I go to like Mouser or DigiKey. And like, select, like a style, like a type and then like, okay, my supply voltages is five volts, select that. Okay, what's the cheapest one? For my application? Is that usually is fine. Yeah, yeah. 99% of the time, most time as instrument, I use instrumentation amplifiers, because I'm trying to, you know, measure a sensor or something.
Host 1 38:27
Right. So really, really, really high input impedance, right? Yes. Yeah, usually, and low offset, low input, current things like that. It's it I don't know, like, so much of what we learn in our electronic classes, just do not prepare you for that at all. Well, they
Host 2 38:47
They teach you like, here's all the configurations of an op amp, like, like, you know, the feedback loops and stuff like that, where in the grand scheme of things doesn't really matter, I guess I want to say, and that's a loaded statement there. But I'd rather have learned about the different style types of op amps and what they do for you. And like how you hook those up and use them? Well, yeah, yeah. And here is calculate the low pass with these three, you know, resistors, and the capacitor, it's like, oh, and the feedback loop goes through like this infinite one ohm grid, calculate the resistance of that.
Host 1 39:28
Oh, my gosh, I remember that we have where it was, like resistors in series and parallel and series parallel. Like,
Host 2 39:33
It's like, you pick any two points on this infinite grid. What is the resistance? It's just like, When am I ever going to build that?
Host 1 39:41
Right, right. And yeah, why? Why does it yet?
Host 2 39:45
I mean, I guess we could build it with graphene
Host 1 39:49
And get infinite energy. Yes, yeah. If anyone knows any op amp masters who want to come in and talk about op amps stuff, let us know. it'll be cool.
Host 2 40:01
Oh, yeah. It sounds like a good place to end this podcast too. Yeah, for sure. Anything else about op amps?
Host 1 40:08
I mean, I could probably go on for a while but I think that's good for this topic. I'll give an update when I have something actually working with this.
Host 2 40:16
Cool. Oh, speaking of updates my my breakout board for the energy harvesting solar panel energy harvester.
Host 1 40:26
Oh, for the cat feeder and reminder. Yes.
Host 2 40:29
So that arrived. So hopefully I'm I want to be able to test that by like next week. So that'd be fun. Nice. I haven't opened up the package yet. I think it came from like Norway. Somewhere in Europe. And European country that snows a lot. I think. All of them. Oh, no, it's not all of
Host 1 40:50
Them. Most of them.
Host 2 40:52
Are there. Yeah, mine. I'm gonna say something that shows I do not know geography. So that was the macro engineering podcast. We're
Host 1 41:00
Your host, Parker, Dolan, Steven. Greg.
Host 2 41:02
Let everyone take it easy.
Transcribed by https://otter.ai