Opamp-timal Power Supply

Parker Dillmann
Hello and welcome to the Macrofab Engineering podcast. I'm your host, Parker Dillman.n And I'm Stephen Kraig. And so this week we're gonna be talking about our stupid simple, was it simple stupid? Super stupid power supply.

Parker Dillmann
Super stupid power supply. Yeah. And so why don't you first introduce our what we'll want to do with this power supply.

Stephen Kraig
So okay, let's take a step back and look at kind of the way that Parker and I, kind of envision things. So we sit next to each other at work and we just pass ideas by each other all day long and, you know, I would say something like 90% of ideas are just absolutely stupid which is fantastic. I love that and, but we we we've been wanting a power supply for our bench and of course when you start talking about a power supply, you start, you know, putting together what you want, the the requirements. Yeah, spec wise. Yeah, the specs and of course it just keeps growing and getting bigger and having more features and doing more and more ridiculous stuff.

Stephen Kraig
So we ended up, creating kind of a beast of a power supply at least in our heads. And so now we're trying to set forth and actually make something.

Parker Dillmann
Yeah. Make something that at least meets most of the specs. We do have a a Regal 3 what? 380 whatever it is?

Stephen Kraig
Yeah. I can't remember.

Parker Dillmann
It's a was it 3 channel 30 volt max? Yeah. 15 amp?

Stephen Kraig
Yeah. The one that has the I can't remember. The dial indicator option on the front.

Parker Dillmann
Yeah. It makes it look like a like a speedometer in a in a car when you press the button. It's a little silly but it's a really good power supply.

Stephen Kraig
Yeah. Yeah. We've been real happy with it so far.

Parker Dillmann
But the problem is it only goes up to 30 volts. I think it's 5 amps per channel.

Stephen Kraig
You know, each it's 3 amps for for both the 30 volts and then it's 5 amps for the 5 volts. That's right. Yeah.

Parker Dillmann
That's right.

Stephen Kraig
Which is pretty typical actually.

Parker Dillmann
Yeah, it's a pretty beefy supply and it weighs, you know, it weighs enough to bend the shelf it's on. But anyway, so we wanna basically make a more powerful power supply and also be able to do kinda like high powered signals as well with it. Basically be able to output low voltage AC and that kind

Stephen Kraig
of stuff as well. Yeah. So one of the ideas that that came up is is more like what if what if you have a DC coupled power amplifier effectively? Basically. So so what if you can, basically output a DC with an AC wave riding on top at 10 amps or something like that.

Stephen Kraig
So just just an absolute beast and,

Parker Dillmann
And so, we, well actually you found this really cool op amp. So how did you

Stephen Kraig
find this op amp? Well, okay. So so occasionally what I'll do is I'll just get on Mouser or Digi Key or one of the big guys and I'll just go look for the most ridiculous thing I can find. Like, go to the resistors and go filter everything. Like, what's the biggest resistor

Parker Dillmann
out there? Oh, or most expensive.

Stephen Kraig
Yeah, or most expensive. Like, just for fun. Just kind of thought experiment kind of stuff. So I did that with with op amps one day. I was like, what's what's the biggest beefiest op amp I can find?

Stephen Kraig
And I stumbled across the OPA 541 made by, Burr Brown. And this thing is Well,

Parker Dillmann
I think it's also, I think t I well, it says t at the bottom.

Stephen Kraig
Oh, my bad. Yeah. Yeah. Yeah. On the datasheet here.

Parker Dillmann
Says Burr Brown from Texas.

Stephen Kraig
From Texas Instrument. I guess I guess Burr Brown did the design and Texas Instrument bought it out or something.

Parker Dillmann
Or Texas Instruments just bought Burr Brown. I mean, you could typically do that.

Stephen Kraig
Yeah. Yeah. Burr Brown actually has a bunch of, really good chips. They, they're pretty well known for for their quality. So so I was looking through this op amp and what basically it's almost an all in one package.

Stephen Kraig
It's the the the tail end of an amplifier, I guess you could say. The thing that's crazy about it is it works just like a regular op amp but its output capacity is just obscene. It's it has rails that you can you can take all the way up to 40 volts. In fact, the supply voltage negative to positive is 80 volts on this thing. Mhmm.

Stephen Kraig
And its output is, up to 10 amps I believe. With a power dissipation of a 125 watts in a 220 wide package. Or a t020 wide package.

Parker Dillmann
Yeah, a 125 watt internal.

Stephen Kraig
Yeah. Yeah. Yeah. So so it's it's started scratching my head. It it seems like we might just be able to use this chip and get almost everything we want out of it.

Stephen Kraig
Because like I said it works like a regular op amp so you can just apply feedback and get gain right from the output. Yeah. So just putting a signal into the input, there you go. You got you have your capability of doing high current, high power output almost directly from a micro.

Parker Dillmann
Yeah. And actually reading the feature list, the best thing about it is it says industry standard pin out. Is there an industry standard pinout pinout for, op amps? Or is it just Bert Brown's industry standard pinout?

Stephen Kraig
You know when when you look at like a single and dual package op amps they are there there is an industry standard with that but but for this t o two twenty eleven pin package I'm sure there's not a standard.

Parker Dillmann
Yeah especially where 40 watt, a 100 25 watts. Yeah. And speaking of a 100 and 24 watts, we're gonna have to sink that somehow and either it's gonna be big copper heat sinks or we could just water cool it some the sucker.

Stephen Kraig
Water cool

Parker Dillmann
would be fun. Yeah.

Stephen Kraig
So yeah I'm actually I designed up a, kind of a breakout board that has 2 of these packages on it. So hopefully we can pump 250 watts out of of this little breakout board.

Parker Dillmann
Thing's gonna be the size of a playing card.

Stephen Kraig
Yeah. Yeah. It's gonna be it's gonna be monstrous.

Parker Dillmann
And let's see, Applications, motor driver, servo, amplifier, synchroexcitation. I have no idea what that is. Do you know what that is?

Stephen Kraig
My best guess is it's some kind of

Parker Dillmann
motor coil that it requires a ton of power. Yeah. Synchros. Well, synchros remind me of the gears and transmissions. Yeah.

Parker Dillmann
But I don't know what that means in terms of op amps. And then audio amplifier. So I guess you can probably use this as an all in one audio amplifier.

Stephen Kraig
Yeah, just capacitively coupled the output and then just honestly, I bet you could just make us a power supply to supply the 40 volts to this Mhmm. And plug plug it honestly your your audio input from whatever source, apply the right amount of feedback and you basically have a single chip 100 watt 125 watt you know monster here so.

Parker Dillmann
And then of course number 5 on the list is programmable power supply. So I bet you someone's used this before to make a

Stephen Kraig
silly stupid power supply. And actually in the datasheet they have examples of putting these op amps in parallel for increased current output just in case, you know, you need more tubes. You know

Parker Dillmann
we should put like 4 of these. We're gonna have to supply it with 240 volts from the utility closet. So here in the States you don't have 240 at most outlets. You have to

Stephen Kraig
have another line. Yeah jump across the lines.

Parker Dillmann
Yeah so you basically have to have an outer phase 120 volt. Right. And then you get 240 when you combine those 2 well opposite sides.

Stephen Kraig
So we haven't talked about the one downfall or the one downfall that I can think of right now. In singles, this chip cost almost $23. That does everything. Oh, yeah. Yeah.

Stephen Kraig
Yeah.

Parker Dillmann
And like the only thing it lacks, I mean I haven't checked the dash sheet completely, but it doesn't look like it comes with a kitchen sink. Okay. Voltage so if you do 5 amp continuous then. So it's 10 amp peak.

Stephen Kraig
10 amp peak but what, in one of the application notes I was looking up for this when you, they were saying on the on the the parallel operation, you put 2 of these in parallel Mhmm. They could do 15 amp continuous. So I'm not sure how that Yeah.

Parker Dillmann
How does that work?

Stephen Kraig
But I don't know. I'm kind of tempted to

Parker Dillmann
because usually what it is they rate the peak is is what it can do in a transient for a short period of time because it's way over its thermal junction rating. Yeah. Right.

Stephen Kraig
Right.

Parker Dillmann
Right.

Stephen Kraig
And it it doesn't But over a short period of time, the the temperature is not gonna rise to a point where it gets damaged.

Parker Dillmann
Yeah. I mean, it says a 125 degrees c operating. Wow. Yeah. That's really hot.

Stephen Kraig
Yeah. I think we're gonna have to have a monster heat sink on these things. Yeah.

Parker Dillmann
I'm thinking water cool with dual 120 millimeter fans and giant heater core. Coolest guy. You're gonna turn this thing on and then the power will dim in the

Stephen Kraig
whole building. Well the thing that's great about it is we can just program up a micro with a DAC on the output and slap that right in front of this guy and then you have a full on controllable power supply. In fact, you know what would be kinda cool is, a digital pot in the feedback loop so you can not only, control the input, you can also control the gain of the whole thing.

Parker Dillmann
Oh yeah. So you can

Stephen Kraig
you can reduce the gain and get higher accuracy at lower. And then when you need to go up to, you say 40 volts at a couple amps you can pump it up that way.

Parker Dillmann
Yeah. That'd be pretty cool.

Stephen Kraig
Yeah. Yeah. Yeah. So Parker, you've got some ideas for the front plate on this thing right?

Parker Dillmann
Yeah. So the whole power supply is gonna fit into a 4 u rack case. And so to make it look cool because that's the most important thing about engineering is well first of all look cool and blinking LEDs.

Stephen Kraig
Oh yeah, yeah, yeah. Who cares about functionality?

Parker Dillmann
Yeah. Who cares about functionality? I mean, so the whole idea is to make it all LED'd up on the front and basically old school power meters, LED readouts, Basically make it look like the interior of the DeLorean from Back to the Future. Awesome. Yeah.

Parker Dillmann
It would be pretty sweet. If I could make neon tubes work, it

Stephen Kraig
would totally have neon tubes. Talk about adding noise to your, your output though. Yeah.

Parker Dillmann
I would just isolate that part. It's all for show. Like then you turn it on and it's just like the border. Yeah. It just the border glows neon.

Parker Dillmann
You know when you use cold cathode rope? Well

Stephen Kraig
okay. Yeah. We could do that. Have you okay. So yes.

Stephen Kraig
You can isolate you can isolate those those things but try plugging both of those into the same power strip. Even if you're isolated, you're gonna get garbage on on your sensitive stuff. Neon tube spits so much garbage back on the line. It's it's not not cool.

Parker Dillmann
Yeah. I actually have an old Budweiser neon sign and when you plug the thing into the shop you can hear it's actually only the far fluorescent tube. It starts to go It doesn't flicker but it does not like it. Definitely does not like it.

Stephen Kraig
Yeah. LEDs are quite a bit quieter.

Parker Dillmann
Yeah, and so we're gonna be probably the microcontroller we'll choose to control it is probably the Parallax propeller because 1, price is an object, and 2, I actually really like programming spin which is I find, well a lot of engineers seem that to be really weird but you know whatever. If you like it you like it. Yeah. You like it you like it. I like the tools for

Stephen Kraig
it. Cool. Well that's the - What

Parker Dillmann
I have oh that stuff is basically designed I copy and paste that. Well yeah,

Stephen Kraig
yeah, if you have a backlog of code then it makes life a lot

Parker Dillmann
easier. Exactly. Cool? Yeah. So I think that's gonna do it for what we've been working on.

Parker Dillmann
Yeah. Let's go and move on to the rapid fire question. Rapid fire. So, recently, Microchip is buying out OutMail. And so this comes after, let's see, this comes after Intel buying out, Alterra.

Parker Dillmann
Mhmm. And this is a huge deal. It's like 3 $600,000,000 something like that which is that's an insane amount of money. And in fact, I think it's almost all cash which first of all I didn't even know Microchip had that much cash on hand.

Stephen Kraig
I guess they're bigger than we think.

Parker Dillmann
Yeah, I guess so. So what do you think about this merger?

Stephen Kraig
Me personally, thumbs up on this. I started my whole micro learning experience with pics. So I say thumbs up. It's great in my opinion. What do

Parker Dillmann
you think about the what do you think is gonna happen with the tool sets? Are you thinking of merging or keeping them separate or

Stephen Kraig
Personally I would like to see a merge because both sides of the of the realms are are so big and there's so many fanboys on both sides. I'd love to see them combine together to make something better than each one of them individually. Yeah.

Parker Dillmann
That makes sense. I'm just interested whether or not we'll be able to buy a pick 8 MEGA 328 8p kinda like a AVR with, like, the peripherals of microchip.

Stephen Kraig
Yeah. Yeah.

Parker Dillmann
Okay. So got that. FTDI gate 2 point o. So apparently they're messing around with drivers again.

Stephen Kraig
Breaking devices. Well, it actually in this one, they're not necessarily bricking devices. They're spitting back garbage, on on the counterfeit chips.

Parker Dillmann
Yeah. Counterfeit chip found or something like that's what's spitting out the cereal puss.

Stephen Kraig
This one's really tough. I was actually reading some stuff about it today. The whole bricking of devices, that doesn't seem like a good move by by FTDI. That just completely shoving people out of the market.

Parker Dillmann
Mhmm.

Stephen Kraig
Just doesn't seem like a smooth move. And and and they they got with Windows and updated their driver so that doesn't happen anymore. But now they're spitting out garbage information breaking it again. Yeah. Is that is that really the way to go?

Stephen Kraig
I mean it's hard because they're trying to protect their investment. They spend a lot of time on it. Somebody is stealing it and in fact, you know, they write cease and desist letters. That company disappears and a new one pops up the next day doing the exact same things, exactly the same people. Yep.

Stephen Kraig
It's a tough situation. I, you know, honestly I can't blame them for protecting their investment.

Parker Dillmann
Yeah. I I think they should, I mean, I think it's well within their right to do this. Yeah. Now is it the right way to actually respond? That's probably not my decision.

Parker Dillmann
But I would like to see them do something else like if you plug in a counterfeit device basically instead of spitting out garbage code which could do whoever knows what to that device it actually just says it just doesn't work or it pops up with a window or something, some notification on the window side to say, hey, this is a counterfeit device. Please contact blah blah blah blah.

Stephen Kraig
Yeah, yeah but when it comes down to it that's wonderful and lovely but what if somebody buys some consumer gear and they plug it into their computer and it says that I mean are they really gonna go that far? It's it's kinda difficult to look at it that way. You know some Joe Schmo just buying.

Parker Dillmann
Well, yeah. So Joe Schmo buys a piece of equipment, plugs it in, and it doesn't work. They return it. And I guess assuming, you know, most people will be returning these devices and then that gets shoved up to supply chain because it won't be Best Buy on the hook, it will be the supplier to Best Buy and then that manufacturer will go up the supply chain and figure out what actually happened. That's technically what's supposed to happen.

Stephen Kraig
Well okay I think I have a solution for this. You ready for this?

Parker Dillmann
Oh yeah. I'm ready for this one.

Stephen Kraig
Don't buy crap on Ebay or Alibaba. Buy from reputable sources. That fixes the problem.

Parker Dillmann
Yeah, it does. Unless the reputable source gets tainted which has happened before. Yeah I see. I think Digi Key got tainted, tainted.

Stephen Kraig
Wait, that's the IP chip.

Parker Dillmann
I think it was like one chip. I have to look it up. That was a long time ago.

Stephen Kraig
Digi Key buying stuff off of Ebay. 1.

Parker Dillmann
It wouldn't surprise me if it was a return. Yeah.

Stephen Kraig
And then it got lost in

Parker Dillmann
the mix.

Stephen Kraig
Yeah. It got lost in

Parker Dillmann
the mix and then got into someone's order.

Stephen Kraig
What I see is just a giant box like a huge like no more like a dump truck filled with chips and the guy who has the one bag chip kind of drops it in is like oh crap.

Parker Dillmann
And just whistles and walks away. Yeah. Walks away. Yeah, yeah, exactly.

Stephen Kraig
No one will know.

Parker Dillmann
No one will know. Okay, and then this this will not go away either. Solar roadways are making a comeback in France. They're gonna build one and it's gonna be really really long. I can't remember the exact distance but it was several kilometers which is less than a mile.

Parker Dillmann
I think like 2 kilometers a mile, right?

Stephen Kraig
Don't make me do math. I'm an engineer man,

Parker Dillmann
I don't remember. Where's your TI calculator?

Stephen Kraig
Oh geez I haven't touched

Parker Dillmann
that thing in a while. Anyways, so they're gonna build a solar roadway. Last I heard they built one in somewhere up in Scandinavia area. Yeah.

Stephen Kraig
Well, that that was a bike way.

Parker Dillmann
A bike way and it broke. Yeah.

Stephen Kraig
So let's put lot heavier items on that go faster and are more destructive. Exactly. That'll work.

Parker Dillmann
You know, I think in a perfect ideal world, this works. Problem is, I mean if you're one that even drives on a freeway, you always see a car that's broken down on the side of the road or

Stephen Kraig
a wreck.

Parker Dillmann
Yeah, Yeah. The moment a car wrecks on this thing, it's gonna just, you know, metal on that surface. Yeah. Gone. Yeah.

Stephen Kraig
It's it's done. Completely done. Yeah. So so you know okay so here's the thing that I think is funny about these kind of solar projects. So everyone gets caught up on efficiency.

Stephen Kraig
You know solar panels are x amount efficient. And and and you can do the academics and you can write down all the formulas and stuff and actually figure out efficiency. But if you think about it, the efficiency is, you know, what percentage of light actually hitting a solar panel becomes power. Exactly. Right, so 35% efficiency is pretty good for a solar panel.

Stephen Kraig
Mhmm. Right? But that's assuming that you started by producing the light or or you started with a certain amount of light. Really they're more than a 100% efficient if you think about the fact that you didn't have the light before. No.

Stephen Kraig
You don't have the power before and now you have more power. The way we have to think about efficiency is how difficult is it to purchase, to make, to install, to to maintain. Maintain. Right. That's where you have to start looking at your efficiency as opposed to just like lights hitting it and power comes out.

Stephen Kraig
Yeah. Exactly. So so when you start looking at that, your efficiency is just in the toilet. Now I'm also wondering is,

Parker Dillmann
you know most time like how often you see someone cleaning a road with a street

Stephen Kraig
sweeper? Not super often.

Parker Dillmann
Yeah. And here here in here in Houston, we never see it. I think I've seen like a couple downtown Yeah. Like after like a big like Mardi Gras.

Stephen Kraig
Yeah. Right.

Parker Dillmann
Right. Right. I mean, I've done done solar panel work up in Oklahoma for remote radio stuff. You pretty much have to clean them every month to keep the dust off them. Yeah.

Parker Dillmann
Because if the dust even just like a week's worth of dust knocks the efficiency down by half. Now you're talking about a road that you have to clean every week. Right. Right. So you have to add that cost

Stephen Kraig
in too. Yeah. Yeah. Absolutely. Well, and and above and beyond that, you have to think about the economic impact of actually creating these solar cells to put in there.

Stephen Kraig
I mean it's it's not it's not a trivial thing to go and harvest silicon and create the the panels and and build it. I mean so yeah Great. You make $13 a year on a mile of solar panels. I guarantee you that's a pretty negative return on what it took to actually put it in there. Yep.

Stephen Kraig
Know. So do you have a solution for this?

Parker Dillmann
Don't put them on the road and put them off to the side of the road. They're okay. Or, you know, why can't you just put them over the road? Because then it keeps rain off of them. Yeah.

Parker Dillmann
I think roads would get dirtier faster, which might because it's because no rain on them.

Stephen Kraig
Well and and these are in these are in, areas of the world that are fairly north. I'm sure they will get Snow. A feet of snow or a

Parker Dillmann
foot of snow. But then they'll be they'll get snowed on them anyways, and you didn't have to plow them. And then you have to be even more careful about plowing them. Right. Right.

Parker Dillmann
Because if you dig that because I mean, I I I mean, if you we don't have it down here, of course. But if you go up north, you'll see in the concrete where, like, a snow plow has dug into the asphalt and ripped up a chunk.

Stephen Kraig
Yeah. Well, and if you think about it, you gotta coat these things with something that is hard yet cheap and easy to apply And clear. And has to be incredibly optically clear Yeah. To get any kind of efficiency.

Parker Dillmann
And scratch resistant. Right. Right. Right. And impact resistant.

Stephen Kraig
That goes into it makes it worse. There's no variable that makes it better. Right? You know, I mean, you just put these things down, hope that power comes out, but everything is against you.

Parker Dillmann
Yep. Everything is against you. Again, put them above the roads, then sure. Keeps the snow off, keeps the

Stephen Kraig
rain off. Maybe we've they design little robots that go and clean them every day, something like that. Like little Roombas? Yeah. Something like that.

Stephen Kraig
I got it. What's that?

Parker Dillmann
Puts instead of rubber tires, sponge tires and they actively clean the road as they as everyone drives.

Stephen Kraig
That sounds like an absolutely horrible

Parker Dillmann
The ride would be terrible.

Stephen Kraig
Yeah. No. Absolutely terrible. And your efficiency in your car goes down to nothing.

Parker Dillmann
Because imagine that you have to have like soap applicators on your tires. Yeah.

Stephen Kraig
They slowly just drip on you.

Parker Dillmann
Drip on and then clean the the road. Yeah. Perfect. The tires are suddenly going

Stephen Kraig
But then then you leave a film of soap on on the solar panels and

Parker Dillmann
the efficiency goes to crap. Then half the cars are just water, half of them

Stephen Kraig
are soap. We make fenders that are a squeegee. Yes. Fender squeegees. Fender squeegee.

Stephen Kraig
Perfect. Next product. Done. We're making this.

Parker Dillmann
Fender squeegees.

Stephen Kraig
It just doesn't seem like a feasible think of ways to make this better, but why don't we why don't we focus our our time and our effort and our money into research to making solar panels even that much more efficient, that much more shatterproof, that much more have have a longer life span. It just seems like a better use of of funding.

Parker Dillmann
Yeah. Exactly. Well, I think that'll do it for this podcast. So I'm your host, Parker Doan. And I'm Steven Craig.

Parker Dillmann
And catch us next time on the Macrofab Engineering podcast. K. Get easy.