EEVblog #221 - Lab Power Supply Design - Part 1

[adisharr]

My new favorite video blog - thanks for all your work on these Dave :)

[santoroma17]

any advise for a beginner high school student

[AgentDexter47]

I am going to technical high school and I really must say that you explain much better than most of my teachers XD

we are currently doing right that - internals of power regulators!

I really love your vid's

Now I see that I've missed whole "Lab power supply" series

this is going to be a long night =D

[javedkhan0258]

GOD BLESS EEVBLOG lol

[deebsboy]

I needed to see this. Thanks so much for the great videos!

[waswestkan]

I figured Dave bruised his thumb nail by jabbing on the white board or meter face too hard. Good thing Dave isn't chef with a knife in his hand when he starts accentuating a point he wants to make. Tweeting your ouwies Dave? Must have been a slow day ;)

[linagee]

With this video you seem to have separated the hobbyists from the true EEs... Hah. :-)

[waswestkan]

@linagee I'm a true hobbyists not even close to an EE. I hung through to the end of the vid caz I'm here to learn

[t4kdungdung]

Dave the coolest guy I ever know!!

Keep sharing your knowledge Dave, thanks a lot!

[matiasvdtube]

Great video. Thanks for sharing knowledge.

[Vassisme]

Stop TAPPING the board, it's bloody annoying !

[marcela4u]

i like your t-shirt!!!!

[EZCyclone]

Somebody count how many times he taps the white board!!!



[dealio82]

Hai dave can it be done with LM338 for your constant current and constant voltage? Please help

[tejonBiker]

you are a genius!!!!!, I never resolver how to control the current without the drop voltage, Good Job :D

[heroineworshipper]

Op-amp discussions are always intimidating. Would personally just PWM the voltage & current with ADC's & rely on clever feedback control to make it as smooth as possible.

[fridgebulb]

Awesome first part, look forward to the follow up finishing it off!

One question though, whats up with your right thumb dave?

[EEVblog]

@fridgebulb You need to follow me on Twitter :-> I slammed it in a door jam. Why does everyone assume I hit it with a hammer?

[PrimaSilica]

@EEVblog probably because it's a round bruise. Maybe they assume you've got bad hand-eye coordinatation! :P

[sorin0306]

Good job Dave!

Thanks for your wonderful videos.

but, don't you think that driving LT3080 through external OP, compromise the circuit stability of the LT3080???

[EEVblog]

@sorin0306 No, it won't affect the stability, the topology used ensures that.

[colt4547]

Good Stuff, just built a similar supply a little while back. Thanks for sharing. I've always enjoyed your videos.

[38911bytefree]

This idea can be easyli expanded to some sort of basic function generator ...

Also consider some sort of PC connection just to add remote control or arbitrary wave form generator. Usign PWM looks nice.

[CHIBA280CRV]

Great info. Dave , thanks for the great video..

[rampike74]

You got my head spinning there. :-D

[SajjadBro]

Good Circuit. Well dave question remains! how do i control current and voltage from a controller? I really don't wana use Knobs or potentiometers and i dont want dozen of voltage dividers to set current and voltage on the current controlling op-amp and voltage controlling op-amp????

[EEVblog]

@SajjadBro You mean actually getting a PWM signal out of a microcontroller? There are plenty of tutorials out there on how to do that.

[GoneBadKiwi]

@WakkoXtreme but if you did go to college, wouldn't mind dave as the teacher. He explains it better than teachers/lecturers do.

[321reh]

Always A Pleasure to watch your Videos!!! Dave,, I Learn Learn  Learn!!!! Thanks

[c436237]

Brilliant. I had to watch over & over 'till I understood. I don't mind the length at all. Its good for us who are learning.

Good Job Dave.

[DanFrederiksen]

any reason why all that analog control couldn't be replaced by ADC in the micro sensing current and voltage?

[DanFrederiksen]

switchmode. switchmode is the greatest.

[joshstube]

I love these style of design videos Dave!

I don't know what's coming up next with your next 2 installments, but can I ask why you chose 1Amp? (nice even number?)

This project would be more useful to me if it were 1.5A or 2A . . . but I'm guessing there would be too much heat, and you would need different parts??

Am I right?

How much higher could you drive your current with this configuration?

Love the EEVBlog Dave!

[EEVblog]

@joshstube Look at the LT3080 datasheet, you can parallel up devices to easily increase the current capability. It's 1A because that's all I wanted for my supply design. There are a zillion high current high voltage lab power supplies out there, this isn't going to be one of them. I may consider increasing to 2A by adding another device though.

All will become clear in time.

[Vlakpage]

@EEVblog @joshstube As I found out today in the Linear's magazine, there is now LT3083 which is good up to 3A, only downside is lower input/output voltage range. Price per one looks to be about double but I think that one would make decent PSU.

[EEVblog]

@Vlakpage Didn't know about that, thanks. Yeah, a bit pricey!

[xasdrubalex]

i have a lot of LT3080 around! HELL YEAH!

[marcelojr]

Dave, you should do design videos like this more often man!! Tear down videos are also pretty slick but your design videos kick asses!! Congrats

[mechadrake]

gr8. Make videos, pay no attention to people asking for short videos ;) i'll be short in commments 4 u :D

[samgab]

Nice one thanks. A bit over my head but I'm learning. Keep 'em coming. Also, @15:00 it looks like a picture of a cool stylized stick figure frankenstein girl with stuff bolted to her head. :)

[googacct]

Looking forward to the rest of the tutorial. I like how you evolved the design from using more components to a little more elegant with fewer components.

[Ltb0b]

^.^

[LoreKrill]

Dave; in short fantastic. Long form? The iterative design process - setting design parameters first - then engineering to meet those goals makes the 'math' problems far more understandable. Someone else has already suggested a 'tutorial' channel which is probably more work - but I try to watch every single tutorial I can. Thanks for you efforts.

[clickfix]

Thanks you, this was one of your most interesting videos yet, taught me a lot!

[lartti83]

I can't belive that someone had something negative to say about this tutorial.

[lartti83]

Thanks so much Dave! This was truly a great tutorial.

[dynetrax]

A dogs breakfast! hah!

[MrDubje]

Hmmm... after watching this i wonder in what kind of electronics i have a degree in...

[Turkeylegs39]

you need to make a new channel for tutorials eetvlog

electronics engineering tutorial video blog

[EEVblog]

@Turkeylegs39 Have considered splitting into channels, but it just dilutes the content and the audience. I can't think of any benefits that outweigh the downsides.

[Turkeylegs39]

@EEVblog ahh never thought of it that way good point

[Microman171]

Thanks for putting the time and effort into making this! I've learned a whole lot about analog circuit design for this, and am becoming more familiar with the workings of various building blocks.

[xng14]

Hi Dave, very interesting as always !

What about going completely op amp based by using something like an LM675 power op-amp on the output? I've always wanted to try that.

[Guysm1l3y]

GREAT video, thanks Dave!

[dillond666]

The best thing for me is the way Dave is showing the thought process. Anyone can make a complex thing but only a genius can make it simple (badly paraphrased famous quote).

I have noticed Daves' channel attracts comments from a few smart arses so I'd like to say I've learnt a lot from Dave and am grateful, in fact I love Dave (but not in a gay way).

[lyrez62]

Great as ever ! thanks a lot !

[marhar2]

This is great... I'm learning a lot! Thanks!

[wildz0r111]

As many people have said before. I really like these kind of videos. You are a great instructor!

[noob64ilive]

I prefer using DAC's for digital control , more stable than filtered pwm , bigger resolution.

Check my channel , I have some demonstrations with my digital power supply .

[EEVblog]

@noob64ilive Yeah, DAC's are nicer for sure, but PWM is cheap and simple. A typical 10bit PWM in a micro is good enough for 10mV steps in a 10V supply.

[TheXGamer969]

Part 2! Part 2! Part 2!

[zox012]

ah i hate it when good stuff is being presented and then "to be continued" :) really looking forward to part x

[EEVblog]

@zox012 Yeah, I know. It was supposed to be one episode and I shot most of it thinking that, but when I got to editing, as is often the case, I was surprised at the amount of footage I shot. It was far too long, and kinda made sense to split up into a couple of episodes. So it should be at least 3 parts now.

[laharl2k]

why not use a buck-boost instead of linear? just a 555, 393, 385 and a couple of transistors and inductances from a scrap atx supply and a low resistance mosfet, and if you want it noise free add a lc filter

it's not that hard and it's also easy to understand.

[scientist375]

@TheCrazyInventor dude..........check out makezine's videos.....they are short n sweet......n why the hell r u arguing with me when im asking Dave Jones??

[EEVblog]

@scientist375 And the Makezine videos are quite lacking in detailed explained content. If you like that, fine, but it's not the way I like to explain stuff. I chose to show you some of my thought processes in the design, and that takes time. You can't magically shorten it, there is only so much you can fit in 5-10 minutes.

[mitpatterson]

Only complaint i have so far is at the breadboard around 9 minutes in is that you are using the red rail as ground, i know it doesn't really matter, but to me its confusing, and same with the supply, having it on the blue rail... confuses me, i know they are the 2 closest to what you are using, just a note

[EEVblog]

@mitpatterson It's orange :-> That's just the colour of various length pre-cut jumper links I have. I am using red and green for the power rails if you look on the left side.

[mitpatterson]

@EEVblog I was refering to the colors preprinted on the breadboard

[EEVblog]

@mitpatterson Oh ok, fair enough. That's not the way I typically use breadboards for simple stuff like this. Both top strips are power, and both bottom strips are ground. I think that's less confusing than having both ground and power on the top and bottom. It better follows how you would draw the schematic. Depends on the complexity of the circuit though, more complex builds can benefit from the other approach.

[TheUrdyggradsil]

Excellent episode, possibly one of the top 10 you've ever done! - next episode please... hold on, I may need to order some LT3080's first! :)

[ljay0778]

For an easy to learn controller programmed in "Basic" that does have a ready to use DAC and code snippets try the "PICAXE" read the 3 manuals here.

Grate video!

[laharl2k]

u dont need a dac inside the micro for simple proyects. just use a pwm channel and use a low pass filter, if the sink and feed currents are simetric then the curve will be linear

[daddyoca69]

nice it got me ff  my butt to look up parts to build a solid powersupply for 5v in a car... tired of all the cheap crap

[shiftplusone80]

Thank you, I've been looking forward to something like this.

[Soulflayar]

8:04 yo dawg i heard you like lab supplys so we powered your lab supply from a lab supply

23:42 lol had to pause till i stop'd laughing =D

Anyways awesome stuf as always, you could also do another tutorial about manufacturing or such as I find such in-the-industry information hard to come by.

[TheElectricnoob]

lab power supplies are overrated :P I hook my projects up directly to the psu i originally intended to use, and it it doesent work, well then i make it work :P

[JumperOneTV]

Nice one! I was thinking to build a linear power supply with MCU control for a long time :) But to make the design with MOSFETS, jelly-bean op amps and use additional transformer tap for driving the mosfets and for simplified current sensing. And then I can implement some presets, OVP(limit), PC control and other stuff in software. But that's gonna be a major project.

[PetrFM]

The minimum voltage in your final configuration will be 20 mV (10uA times 2 kOhm) this is no problem for practical use but your initial specs were 0 volt output ;-)

[EEVblog]

@PetrFM Part 2 spoiler alert!

[P55CxE9]

To Be Continued... :D Can't wait, this is really awesome stuff!

[xspoonedx]

As always Dave an excellent and informative video!

It was especially useful to see the design be "refactored" (can I saw that outside of a software context?) and made simpler.

Looking forward to part 2!

[killerman4ever]

I love the long videos, keep em coming!

[scientist375]

dude ur vids are nice but try making them in a lot less time-i mean that they need to be short

[TheCrazyInventor]

@scientist375 No, they really shouldn't. You can't explain stuff like this in 10 minutes or something. Otherwise you'd just get a "here's the schematic, hook it up like this and done" video. You learn nothing from that. If you don't have the patience to learn things, go look up some schematics on google and build your supply like that.

[EEVblog]

@scientist375 Sure I could drop a few minutes here and there if I used a script or went and re-shoot some parts to make them tighter, but it might get 40min down to say 30min at best. You can't magically compress 40 minutes worth of material into 5 or 10 minutes and keep the same content and explanation. I could make this video 1 minute long and say here's the schematic I prepared earlier, but what's the fun in that.

The next video will be 20-30 minutes of looking at datasheets and tweaking

[dgs117]

What does it mean "floating outputs of power supply"? Do you mean that they are isolated from the mains?

[JumperOneTV]

@dgs117 It means, that they are isolated from the earth ground.

[kingoslo1]

ELEGANT! Give us part 2. We cannot wait! :)

These tutorial-blogs are very stimulating. Almost addictive.M

[b4ra2]

please do more design videos, they are great (i didn't even watch this one yet, but i'm pretty sure this will be great too)

[zzzzbest]

Cool video, I had a go at designing my own CC+CV psu as well. Interesting how you say that that constant voltage design isn't stable. I was trying to get it all simulated in LTSpice and was having a hard time getting it stable across all types of loads.

Interesting CC in your design, in mine I had a differential amp across a shunt resistor and had the CC+CV selected by a diode AND gate.

That constant current design i

[adamlumpkins2000]

dave as allways spot on!!!!!!!!!!!!!

[GTXAbunada]

Wow, I am getting goosebumps just reading the title, still haven't watched, I am so excited.

[TheCrazyInventor]

Oh, fantastic. I always wanted you to do a video on lab power supply design. Insta-like. :)