EEVblog - 2011-11-28
PART 1 is HERE: http://www.youtube.com/watch?v=CIGjActDeoM Part 2 of Dave's Open Hardware constant current linear regulated lab power supply design. An in-depth look at the LT3080 datasheet, the LM334 current source, and a few more circuit tweaks before it's ready to build in the next episode to see if it works!
This series of videos has taught me more than many university classes.
Seriously. Although, I start my first basic circuits / digital logic classes in two weeks.
I love the phrase "fairly jelly-bean low end precision opamp"...
Poor Dave, trying to make videos and you can hear Sagan crying in the background!
More like, poor Sagan. All that frustration because he's too young to understand the world around him, and lacked that ability to communicate just yet.
I love it how the baby cries at 10:46
Really, the sound quality is so good that it made me think something is happening here in the middle of the night.
@TheCrazyInventor Yep, there will eventually be a PCB for it.
I like it. I'm learning a lot. It's fun and useful to take time to design. More of these type of show, Dave!
I think I'm gonna build one myself as I watch the next one. Thanks Dave.
this is an advance tutorial for electronic engineer. the best electronic engineering tutorial I ever seen... increadible
@Kankki1 Good question, and one for the IC process engineers out there.
@TheMcMonster I have little interest in very high power supplies.
Love the videos, perfect level.
Tap, tap, tap-tap! Lol.
@spelunkerd Yes, Part 3 will be testing the circuit on the breadboard to see how it performs. The real build will come later, I have an idea in mind, and will do another Part 4 when that is complete (that will take some time).
the hell happened to your thumb in that video?
My thought exactly. I thought it was an errant hammer swing that missed the nail head.
Is it really the best way to up the amperes by adding more LT3080's?
And how to increase the voltage range?
@compaq1275 No surprises, I'll build it as shown. Although the final built product (as opposed to breadboard) will likely use a current sense amp instead of the opamp based diff amp.
@TheMcMonster I don't know, maybe. There is a specific reason why I'm building this "simple" design, and you'll see why in the future (not the next video though). And AFAIK there aren't that many PSU circuits out there that show you how to control traditional voltage and current regs simply from a micro with PWM, hence this design.
@Nadrealis TO-220-5
what can i say, as always wonderful video, good teaching , thank you very much Sir - I am thinking of building a 0-30v 0-30A power supply, should i build or buy?
@PetrFM The LM317 neg supply would actually make it more complicated. Not only the 7660, but the output divider will have a varying current based on output voltage, and that throws out your current sensing at low values. The LT3080 and LM334 is simpler IMO.
David, this video is amazing! Thank you so much!
@williefleete Sure, but likely not great at the low end on the diff amp due to the offset voltage. You could trim errors out though with pots, but that's rather medieval. I'll be using a slightly better TLC2272 in the build.
@CampKohler Never heard of it...
Hi and thanks alot for this video! You sir are awesome!!! Can I use lm2576 instead of lm8030 for this project(with some math work of course)? I need a little bit more power for my soldering iron which requires 1.5A...
I havent learned so much neither at my university nor any other youtuve video, thank you so much for share your knowledge with all of us
is there a part 3? I cant find it
Magnificent video Dave!
Great job Dave, Thanks
Very interesting, as usual. Thanks from France.
Very good explanation. Nice job. I hope you'll do a video on designing a PC for the supply as well. I'd love to hear about the PCB design considerations.
op amps are awesome.
@milos1993milos PWM is simpler though. You need a 10bit one to get 10mV resolution in 10V output.
man I love this long videos
Could you add some circuitry that drains the output capacitor when you hit the current limit? (And also when you decide to lower the voltage)
@EEVblog Once we have learnt simple stuff like linear circuit design (RLC), and stuff about transistors and other simle components and OpAmp configurations, how do we move onto being able to use such exotic ICs? ICs with datasheets that have so many words that look so unfamiliar? I really want to know that. There are soo many ICs how do we know which one is best. since our criteria only defines some of the things, and there can be soo many ICs that fit that criteria.
@sabamacx You can, but not arbitrarily high like 1M. The discharge resistor can't be that high otherwise it'd take forever for the constant current to kick in.
What type of package did you use for the LT 3080 in your final design?
This is a great video; I just had to laugh at the design requirement change! Even though, in this case, it makes perfect sense (for the application). Your design specs are 0V out. I wish I could tell the product spec guys that -- eh; 0.9V is good enough! Instead, we end up spending more design iterations and dollars to give them the 0V out -- in reality it won't be used down there!
20:50 Dave, you're reading it wrong. The whole solid line is the 2.2 μF cap, the 10 μF cap is represented by the dashed line.
Is there a negative voltage equivalent to the lt3080?
Hi dave, can you make a µ function-generator? I would really like it.
Cam for the video content. Stayed for the content AND the accent
Much as I like Dave's videos I have to turn the sound down really low. His squeaky antipodean accent is like drawing fingernails across a blackboard.
So this supply will not actually be 0-V-full-range?
I think you made a small mistake with the equation at 16:45. It has to be V_In / V_Out not the other way round or your V_Out will explode (75 dB ->2811 V; 20 dB -> 5 V) and you won't get anywhere near the results you gave.
For those who wan't to go deeper into ripple rejection in linear regulators this document from TI gives a nice summary about this topic: www (dot) ti (dot) com/lit/an/slyt202/slyt202.pdf
@DanFrederiksen I'm not sure Dave's YouTube subscribers are the target market for such a circuit walk-thru.
Great video , might have a go at building this as i'm trying to learn more about DC power supplies LDO's bucs charge pumps etc :) Think it would be a great idea if you did a video of a dual rail positive / negative dual rail tracking supply? Theres a lot of audio types that would love it !!! Or maybe dual rail is a bit over complicated for beginers like me? Anyone know if the LT3080 can be used for the negative part of a dual rail +-v supply ? have two and reverse the output of the second for the negative rail and link the amp & voltage control pins together for the tracking ?
..amazing knowledge and presentation, that's great, Dave. But what I don't understand is - when you have so much troubles with pulling your minimum output voltage down to zero (status quo is 0,8V?) ...why don't you bring the GND up to this level - which means: why not realizing a "virutal GND" which is rather easy to do with a smart op-amp configuration (especially for a skilled and smart engineer like you are)?
What rail to rail op-amp are you planning to use?
Very nice design. I really like these design to execution projects, and your explanations of the traps for young players really help out for those of us that don't know about the foolishness of the datasheets. But I have to know, do you have a Clint Eastwood shirt for Lab Power Supply part III? :-D
Link to the part 3: https://www.youtube.com/watch?v=8-qar5vgnbc
As a relative beginner in this field, I've listed these two videos as favourites, for when I have more time to learn the details. What would be nice would be a practical view of the box and circuit board, so I can have some idea of what I need to put it all together. This is definitely one of those projects were effort in will reward the student later. Thanks for going through this. Is there a part III?
Skynet Cybernetics - 2016-01-01
Lots of traps for young players
Rainbow Cookie - 2019-12-05
From whiteboards to paper
What's next he tap on a screen