EEVblog

PART 2 is HERE: • EEVblog #222 - Lab Pow...
Dave shows you how to design a simple constant current and constant voltage lab power supply that can be either software (PIC/AVR et.al microcontroller) or traditional pot controlled.
Starting with the venerable LM317, and ending up with an LT3080 solution, and the some thought processes that go into it all.
Part 1 is the conceptual design of this Open Hardware design.

[@dadbrad852]

What a fantastic day and age that we live in where generous individuals like you can teach through tutorials like this. Thank you so much for taking the time to do this, especially the theory explanation, I absolutely love it. Keep doing what you are doing!

[@EEVblog]

Thanks, glad you found it useful.

[@TechnocraticBushman]

EEVblog I am an almost complete newbie and looking through LDOs to build my own power supply (like real men do). I saw your new rigol PS and I figured I can code the software for one just like it, with color display, a nifty graycode encoder and all. I came across the same part and pretty much came up with the same schematic, except for the buffers which are an awesome fix I could not figure out (thank you for the opamp explanations as well. I finally understand the t-shirt). This tutorial is by far the best I've seen, for people like me, as it explains the train of thought that went into designing this which is far more important then etching techniques or explaining how to drill holes in aluminium. I also wanted to get more then 1 amp from it so what I did, since the part is based on a comparator, I put a PNP from vcc to output and it is opened by the _IN_ pin. Now I can get it up to 10 amps with proper cooling and a huge transistor. Spice shows some 20ma through the IC for a 3 amp output so I suppose I can get it up to 15-20 amps no problem, with an even bigger PNP and more cooling and it's still dirt cheap.

[@ArumesYT]

Well, generous... He was getting paid pretty well already by KZbin when he shared this information. Don't get me wrong, I have nothing against David or this channel, I'm learning a lot from his videos too. But you have to be aware there's not just generosity at play here.

[@ProteinFromTheSea]

@@ArumesYT youtube doesnt pay very well, especially at the sort of range of veiws that he got at the time of your comment. his time could be more lucratively spent elswhere, so although he does get compensated for this, his decision to share this knowledge is definitely partially out of generosity.

[@ArumesYT]

@@ProteinFromTheSea So I say there's not JUST generosity at play. You counter that by saying it's at least PARTIALLY out of generosity. Why counter my comment when you agree? And Dave already was a full-time vlogger a this point, so apparently the pay was enough.

[@fdk7014]

This is brilliant! You should do more of these longer "let's build something" series

[@yasithgamage]

you posted this in 2011 and still this is like the best video that explains how to make a power supply design ! thanks very much for this !

[@MrCrystan]

i really can't express how helpful and useful this tutorial series is! Thanks a million for describing in so much details, it's like a 2nd year uni stuff for someone who never did Electronics beyond college. Love it!

[@meirbns]

I have 40 years of electrical engineering experience . Just out of curiosity I looked at your video. I must admit it is an excellent presentation. I liked very much the ingenious way you build the presentation with all the "twists" in the design. Thank you very much for the brilliant presentation.

[@kunalsalvi8382]

meirbns exactly what you did as an EE? 😃

[@evanbarnes9984]

This is exactly what I've been looking for! All these years later and it's still relevant. Thanks!

[@martingannon132]

That's why I love this channel, Dave never misses a thing!

[@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.

[@Ray-ej3jb]

Hi Dave I'm getting back into electronics after at least 30 yrs. I can't begin to tell you how useful and informative this and the follow up videos have been. thank you so much please please do more of this type of design videos

[@adisharr]

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

[@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.

[@williammorken7484]

I appreciate all the help you have given me on my path to engineering. You are a great teacher.

[@Renegade30]

Dave, I tip my hat to you. I've been pulling my hair out trying to work out how this is done and why the adjustable voltage is so simple yet the current limiting looks so complicated, but you have really spelled it out in a very descriptive way. Thanks so much!

[@Dileptor1]

Thank you very much for the work your're doing for all of us. You guides are great!

[@scottieburr]

Only just watched this video and really enjoyed it Dave. I've always been fascinated by test equipment and power supplies especially. I've designed switched modes for a living but never got round to designing a decent bench power supply for myself. this might be the inspiration I need, off to watch part 2!!

[@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.

[@anjayv8347]

thanks to dave i finally understood how to set current with any micro controller. thank you so much dave!!!

[@t4kdungdung]

Dave the coolest guy I ever know!! Keep sharing your knowledge Dave, thanks a lot!

[@NathanaelNewton]

This is still the first result for power supply circuit design Excellent 😁

[@TediCreations]

Thank you Mr Dave. It is a very good tutorial. I learned a lot. Now I am off to part 2.

[@clickfix]

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

[@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

[@MarkMcDaniel]

I personally much prefer proper, long form videos like you tend to make. It allows you to explore as in depth about the subject matter as you are so inclined. I love that, tbh.

[@kurchak]

@@MarkMcDaniel Me too. Natural talking without a script. Scripts make things feel forced and unnatural. I hate scripted videos.

[@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.

[@00Skyfox]

"If you don't have specs to work from, well, it's gonna be a dog's breakfast." Where do you come up with these great expressions? I love it!

[@jimle22]

He's from down under. I have and aussie friend he says things like that all the time.

[@jeffmcclain]

Very nice progression from simplistic to more complex implementation of the design. It would be great to see an additional session dedicated to putting a "remote sense" in place...

[@dylankirdahy9591]

Fantastic video! Thank you, Dave

[@deebsboy]

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

[@jazzzzzCat]

Tank you Dave! Highly educational video for a second year electrical engineering student such as I

[@321reh]

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

[@petermpeters]

I learn a lot from you, i appreciate your videos. you have a massive amount of talent. keep up the good work. thank you.

[@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.

[@colt4547]

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

[@jagank.b.614]

This is just brilliant.. I love the your way of starting simple.. best tutorial...

[@jonayamaha3215]

even i understood it omg, greetings from argentina thank you so much for the free classes.

[@ausprobierendannweisstdues8686]

Thanks very much for this circuit, this is one of most important circuits for me

[@myousefi4060]

Thanks Dave Your explanation is fabulous

[@ArbieJamesarbiegroninger]

Always motivating!

[@user-kx8qb2ee2m]

man you're great. I really enjoyed this! Escpeccialy the time you took to explain the theory to us. I cant believe you re going to build it even if you know its not perfect yet xD

[@mozportal]

Your accent/voice is actually the main reason I'm here, and maybe enthusiasm about electronics design. Really great blog, honestly. May I request that you do a review about low-cost (0-80$) dc adjustable (0~30V) laboratory power supplies? Greetings from Turkey.

[@EEVblog]

Available in my Mech store. I drew it myself.

[@melplishka5978]

Love your vids bud. Your so excited about things lol. Great job ty.

[@FirstWizardZorander]

You make it seem easy. Well, it's not that hard, but I feel rather motivated now. I'll just get a larger apartment so I can fit an electronics lab somewhere. Thanks, as always!

[@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.

[@anacierdem]

Always a great blog ...

[@Genuigr]

I first watched this video maybe 2 or 3 months ago and I had no idea what was going on because I had never done electronics before. Now I can see this video and follow it (at least). I think I have to return some more times till everything gets clear and I can say that I (will) have built my PSU and not only used some things from "the guy on youtube". Thanks Dave, I love you videos and hope you'll do them for a very long time!

[@emekauche7505]

THIS IS WONDERFUL WATCHING AND LISTENING TO THE LECTURE SESSION. MY LANGUAGE IS SPOKEN HERE. THANKS.

[@thomaslanik7215]

Very nice, Dave. BTW, I easily found the TI Data Sheet for this device and it has great info and application info that supports and supplements (dare I say compliments!) your friendly tutorial presentation with other benefits. Excellent! Cheers, mate.

[@danielcarroll8889]

This video was better than most of my electrical engineering lectures I paid thousands of dollars for

[@StuffBuilder]

Thank you for the great explanation!

[@marhar2]

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

[@lean04]

you could just said: hey guys copy this schematic!, but your "ladder" explanation through all of the options from simpler to harder is brilliant. It's like university for us non engineers.. congrats!!

[@harryhirsch3637]

Really nice video, especially at 17:31!

[@flash001USA]

Very nice demonstration.

[@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.

[@EEVblog]

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

[@emrahinan1]

Great Engineer Dave jones, Thanks.

[@ELECTROMAN_MX]

that 1989 LM317 come back to work after 33 years...

[@adamlumpkins2000]

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

[@dizzolve]

what is the best video series for learning basic electronics -building circuits- etc. Do any of you have advice. Thanks for the great vids EEV

[@MsMegaEdu]

very informative useful and easy to understand, thank you.

[@chimera5588]

This video is great, but the trapping is driving me nuts! Lol thank you for the amazing content, and thank you for teaching a person who is learning to solder, and build electronics on their own!

[@projectsdone3248]

Click on the link below to a Digital power supply without a microcontroller: A Digital Power Supply Without a Microcontroller! Great video Dave!

[@heitorsousa1830]

You're the best. Thank you.

[@rkrrkumar511]

Great work.

[@NoviceRobot]

Every time the guy tap the white board with its pen, drink.

[@mnovo]

Can you put the feedback loop on the LM317's adjust pin as in this design with the LT3080 to cancel out the 1.25v?

[@FooBar89]

wow, I finally understood what that voltage inserted at the bottom via the voltage buffer does :) 22:51

[@BogdanSerban]

How can you use this for a dual rail supply? And what if you want higher voltages and currents?

[@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

[@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.

[@pjfadriquela]

Could you make a follow up video but with a switching power supply, buck/boost converter. Also it would be interesting to see a dual rail power supply.

[@matiasvdtube]

Great video. Thanks for sharing knowledge.

[@videobenny3]

"It's going to be a dog's breakfast..." LOL we never hear that in Minnesota.

[@fridgebulb]

Awesome first part, look forward to the follow up finishing it off! One question though, whats up with your right thumb dave?

[@DanielsGameVault]

Any way of bumping up the current limit higher than 1A ? I'm looking for something like 5A.

[@thebeginnerelectricalengin3717]

Technically, you probably could but with higher currents comes higher voltages, more power & heat dissipation and higher part costs. You'll have to be very careful with component choices due to said restrictions.

[@MrCrystan]

have you tried to use ATX power supply and use some voltage dividers/Current limiting circuits for it?

[@tejonBiker]

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

[@bashardabst]

Dave for president!

[@EEVblog]

No, it's my natural voice.

[@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.

[@definty]

Hi Dave, thanks for taking the time and effort to make this video :) I'm confused at the 8:00 part though, what are the bypass caps for? Is this to emulate a dummy load? Thanks

[@beppe3001]

Thank you for the video. Really usefull !!!

[@anurasenarathna1703]

Very informative. Thank you

[@alecjahn]

Now I'll have to go back to my LM 317 DIY supply (ATX PSU based) and rebuild accordingly with the LT3080. Which means I'm going to have to learn more things. Damnit, Dave! :) Thanks for this.

[@jesscast5122]

+alecjahn If it works.....Don't "Fix" it...... (goes the saying) BTW you can accomplish this with an "Emitter-follower circuit" No Darlingtons, linear regs. etc. All you need is NPN power tabs. w a power tab the V at the emitter output will always be about .5 v Less than the base bc of the Semiconductor junction. Also remember that Transistors are CURRENT amplifiers, So.... All you need to know is the BETA of the Transistor and work w it for Current regulation........ and Last, this vblog dude has his brain scattered all over the place........

[@hifatpeople]

+Jess Cast Engineers version is: If it ain't broke, fix it!

[@jesscast5122]

hifatpeople Ummmm. I am an Engineer and I don't believe that is correct.

[@hifatpeople]

Jess Cast Just because something works, doesn't mean it can't be improved.

[@jesscast5122]

hifatpeople That's true! It can also be fucked up and wasted.

[@TheCrazyInventor]

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

[@omsingharjit]

4:22 i think you can use single 317 for both current and Voltage controll

[@s_amoku]

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???

[@amramjose]

Outstanding.

[@Strawberrymaker]

Stm32f1 With integrated DAC only 2 bucks. Love those!

[@keithlegg]

best channel on youtube.

[@ashishkhanal957]

Hi Dave, Would you please consider doing a tutorial on MPPT Solar charge controller design? Thank You

[@StevenMcconnon]

Dave is a genius.

[@DantalionNl]

took my 20th minutes to find part one but i finaly found it!

[@EllaBananas]

19:00 So I've gone and made that constant voltage circuit, and immediately had the exact issues you were talking about. I'm using a single NPN power transistor instead of a Darlington pair, but other than that it is effectively the same. My problem is that, while I can handle the logic and math of these things no problem, when it comes to dealing with the more complicated parts of dealing with characteristics of different voltages and resistances and crap that is where my knowledge falls apart.

[@SmithKerona]

You need to make one node of the NPN device lossy so it doesn't oscillate. For example you could insert a small value resistor (100-200 ohms) between the base of the NPN transistor and the output of the op-amp and also add some capacitance between the emitter of the NPN transistor and ground. By doing that you are actually modifying what is call the 'poles' of the feedback system. If you are interested look up stability of feedback systems.

[@ManWithBeard1990]

I once built a switched mode power supply. Didn't work too well. I'm still proud of it, though. Especially since it was made almost exclusively from parts recycled from the ballasts of burnt out CFLs (being careful of course not to break the glass envelopes) The only parts I had to actually buy were a pnp transistor and a zener diode of the desired voltage. It doesn't have a pcb. Just soldered wires between all the parts and insulated it with duct tape. Good fun though.

[@humamramadan1328]

please can someone answer me '^' on minute 36:40 what is going to happen when the i set is bigger than the measured value of current on the shunt resistor

[@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.

[@user-xs1ej5mo1y]

Dog's Breakfast comment had me laughing so hard!

[@4mb127]

Oh man, I need more studying before I'm going to understand any of this.

[@nobytes2]

4mb127 need more doing...

[@Yosory]

You're breathtaking. After all these years

[@Rainbow__cookie]

I heard Keanu reeves say that lol

[@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!