EEVblog #224 - Lab Power Supply Design - Part 3

Part 3 of the Open Hardware lab power supply design. This time the prototype build on a breadboard and some basic measurements, checks, and playing around.

[captiveimage]

Eight years old and still relevant. Absolutely awesome. Havn't seen anything like this anywhere else; not only talking through the circuit but walking through the whole design process with a master. Priceless.

[andre-michelgoulet]

Excellent series so far. Love how it evolved from "tap, tap, tap-tap!" to "bang! bang! BANG!" Awesome energy you have. 

[Bouteille]

Thanks for the awesome video !
Love the automatic subtitles generation (6:40) : "1 milliamp current source" -> "1, 000, 000 carrot sauce" :D

[StephenHendersonActual]

Wow, Dave. It's really special to see this latest series of vids. Comparing where you started to where your at now, I can discern no less determination, charisma and honesty than that first vid... but without the distraction of that day job, well, what your doing here is really meaningful and helpful. As a father, I'm certain that Sagan will be proud of what your helping people everywhere learn to do (both in terms of EE, but more also generally: how to help other people and make ends meet too)

[EEVblog]

@SuperEvilbug Yes, this will hopefully become a kit. The final design I have in mind will be more than what you see here, and rather novel I think.

[Mtaalas]

It's wonderful to see that you're doing so much work every day. This really is an example of "how it should be done". This will be the quality I'll start to want from everyone who even desires to make any tutorials about subject x :D
Without people like you Dave, YouTube wouldn't have any quality videos. Keep these coming :)

[horfittunge]

Wow, this must seriously be the best tutorial I've ever watched. Super great job Dave!

[gmanutube]

Dave, great stuff, as usual. You are the EE equivalent to khan academy. Very well set up, good explanations, give reasons why/why not, etc. You're a wonderful teacher, keep it up.

[mirkomueller]

Wow - a must have Video not only for all electronics and digital oscilloscope beginners. Wonderful What is so fantastic in this series ist that you not only say what is but also what one might think but in fact not is. Sometimes i think you just read my mind. Fantastic !

[ThSu]

This series of videos has been well planned out and very informative. Thank you for posting these. I really do appreciate the effort you put into your videos. When you get around to doing the video for the final project I would hope that you also include some information on "the traps for young players" when designing the layout of the PCB. I will be looking forward to more of these educational videos from you. Thanks

[rotlerin]

I only wish that there was someone with your knowledge and personality in the electronics repair indusry. I am familiar with Jestine from Malasia and Dave from Oregon, but apart from that no one seems to come near your standard. For a newbie like me 70% of this great video soared over my head.

[chalisload]

EEVblog I am learning so much from your channel please dont pay the haters any mind, keep on doing your thing . We need to design a circuit to slowly electrocute the haters ..

[princebatswater]

When the nerds finally take over the earth, truly thou shalt be crowned as their

[EEVblog]

@superdau You didn't miss anything, the fact that it was available led me to use it, and it was helpful to show show the issue with identical comparator inputs. You can certainly use another transistor, and that's a more accurate way to do it.

[riko]

It's good to use regular diode in series with zener diode, to minimize the voltage-temperature changes

[vstoykovbg]

17:20

To make the LED indicator for the "current limiting" mode work correctly, you can use comparator to monitor the voltage at pin 7 (input voltage to the transistor) (to compare it against about 0.6V - this voltage can be derived with voltage divider from the 2.5V reference).

[rafaelvisintin]

Hi Dave! Thanks you so much for the class. I am designing a voltage source with current limit, using a 2n3055 and 2n2219 as a darlington, because there are so many in the stock where I work and we need some voltage sources. In my simulations, when a put a capacitor of 22uF, the overshoot in the current flowing to the load is too big for me. In the simulation, I change the load from 24R (24V, so sucks 1A) to 1R, trying to mimic a short in the output. In this cenario, the current limt circuit start to act and the output voltage drops till the current finds the setpoint. When in continuous current mode, there is a small oscilation in output voltage of 33 mV and a current overshoot of 2A, when I use the 1uF capacitor in the darlington's base. Against a current overshoot of 15, 5A and a voltage oscilation of 3, 3mV when I use a 22uF capacitor. So I have decide to use a 1uF capacitor in there. The oscilation in the load voltage was not very big. For me was more important to limit the current overshoot than the oscilation present in the Continuous Current Mode. Because, I dont pretend to use the source as a Current Source. Just use this feature to limit the current and protect the transistors and the load. Do you think is a good way to do it? Thanks again!

[EEVblog]

@Microman171 The LT3080 is designed to be stable. If you roll your own, you have worry about stability over a wide range of loads. May or may not be a problem for you, but something to watch out and test for.

[petersage]

38:50 Can't remember if this series was before or after the videos about scope input microphonics, but that screen tap was a great unstaged example.

[fdk]

Really interesting to see the startup transient on the digital scope. You weren't able to see that on the old analog scopes!