0-30V Stabilized Power Supply

[audioguru2]

There was a video posted on some page of this thread, where output voltage raise briefly. And that was with these new opamps. That's why I was thinking to put back Q1.

If the output capacitor C7 is electrolytic then it has "dielectric absorption" which causes the output voltage to rise with no load if the project is powered or not. A film capacitor will not do that. An output load resistor can discharge a film C7 when the power is turned off.

When the positive supply drops when the power is turned off then there is a low voltage where U2 does not control the output anymore. I think then Q1 also will not have enough voltage to work.
Try it to see.

 

[mizikono]

Is it necessary for the elements "REV3" make a new board? Can I use the old PCB, but it does not plug in Q1, R13, etc.

 

[audioguru2]

Is it necessary for the elements "REV3" make a new board? Can I use the old PCB, but it does not plug in Q1, R13, etc.

There have been many pcb designs for the various versions. The original pcb used parts that were too small so they overheated. Some of the newer larger parts do not fit on it.
The latest schematic (REV 3) has calibration trimpots added.

 

[mizikono]

Did someone already do for REV3 PCB?

 

[audioguru2]

There are at least two latest pcb's. One (Picmaster's?) changed all the parts designation numbers so it is difficult to talk about. One or both of them moved around some of the parts so their schematics are different from mine.

 

[mizikono]

Is there a PCB for your "REV3" version? I draw a good PCB unknown. I am curious if anyone has done

 

[audioguru2]

Is there a PCB for your "REV3" version? I draw a good PCB unknown. I am curious if anyone has done

I did not save any pcb designs because I don't know if they work properly and I don't use Eagle pcb software.
I never made this projec, instead I discuss corrections and improvements to it..

 

[Tompa1]

HELLO

Today I spent 4 hours (more/less) that I reviewed all 90 pages of this topic.

And I think it would be good to put all good things (in my opinion) in 1 place.

That's why I made ​​a zip file containing the following items.

zip file contains:

folder:
- audio (audioguru schmatic and part list)
- EL_PS6_redwire ( redwires pcb (which is made in EAGLE), part list, some pics)
- tesseract (his version of PSU)
- picmaster (his version of PSU)
- pictures ( PSUs images of those who made ​​it (fly3rman,gfrotti,surubel, and some others)


and some other stuff(pictures) like:
-diffrece betwen audioguru and redwire project (difference _red_audio)
-0-30V current regulator at 3A
-0-30V current regulator at zero
-0-30V reference circuit
-0V - 30V Redwire's schematic
-0V-30V latest current regulator
-0V-30V power supply

Download link (10.05 MB):
https://rapidshare.com/files/394978044/PSU.rar

or

https://rapidshare.com/files/3793630850/PSU.zip

PS. If someone thinks that there is unnecessary (false) things feel free to warn us/me. Or maybe something needs to be added

Sry for my bad english... :/

 

[audioguru2]

Thanks Tompa.
I downloaded your RAR file and tried to extract its files with Windows XP and I got 116 errors.
The RAR file is 10.5MB.

It extracted one folder named PSU. Inside the PSU folder is more folders:
Audio (empty)
PICmaster_str50 (empty)
tesseract_str27 (empty)
EL-PS6_redwire  Inside is more folders:
Borad (empty)
Plocica_PDF_holt_26str (empty)
red_multimeter (empty)

pictures Inside is more folders:
fly3rman-str83 (empty)
gfrotti_str64 (empty)
surubel_str66 (empty)

tesseract_str27 (empty)

I rarely use RAR so I don't know what to do.

 

 

[Tompa1]

hmmm. i don't know, i tried to download it again and evrything works fine for me..

Try to download .zip(10.05MB) file ( last one was .rar)

https://rapidshare.com/files/3793630850/PSU.zip

 

[audioguru2]

Thank-you, Tompa.
Your zipped file unzips perfectly.
I don't have time to look at it all.

 

[samsagaz]

Let me ask maybe an stupid question. If NPN transistores used are 2N3055, that support 15A. Why i need to use 3 in parallel to get 5A? (as i read on the thread).

Thanks in advance!

 

[zulcao]

Well, one will probably work, but gets VERY hot and needs a huge heatsink (with fans).

 

[audioguru2]

A 2N3055 transistor has a maximum allowed collector current of 15A but works poorly at 10A and more because at 10A its minimum current gain is only 5 and it has a maximum saturation voltage loss of 3V when its base current is a whopping 3.3A.

If you can keep its case at 25 degrees C somehow, its maximum dissipation is 115W.

In this 5A project, the power supply to the 2N3055 output transistors is 40V and there is a loss of 0.55V in their emitter resistors and a loss of 1.35V in the current-sensing resistor. Then when the output current is set to 5A and shorted, the output transistors must dissipate a total of 5A x 38.1V= 190.5W. One output transistor will be much too hot and two will try to dissipate 95.3W each which would be impossible to cool. So three output transistors are used and each dissipates up to 63.5W which is a lot of heat to remove but is possible. 

 

[samsagaz]

oh, thanks very much for the answer! are incredible easy to understand. Btw, so if i just want to allow 10A current, can use 6 x 2N3055 in parallel . Right?

 

[audioguru2]

If you want an output of 10A then of course you need a transformer with more current, a bridge rectifier with a higher current rating and a bigger main filter capacitor.

What will drive 6 output transistors? The single little BD139 driver transistor cannot. Replacing the driver transistor with a more powerful transistor will not work because it must be fast and powerful transistors are too slow. So use two paralleled driver transistors.
But then the opamp will not be able to drive them. So you need to boost the current from the opamp.

 

[samsagaz]

Well, thanks again, really dont know what to drive, i just want to make an bigger Power supply for my bench.

Of course that bigger transform, rectifier and bigger caps will be used. Its the easy part (just more expensive). The problem will be parallel BDs and to boost the opamp current.

will search about it.

Thanks again.

 

[xristost]

I almost finished my PS. The two boards are completed, tested and they work wonderfully! I have ordered and I am expecting power transformers and digital panel meters (voltmeter and ammeter).
Here some pictures of my work: http://diyfan.blogspot.com/

 

[du.facc]

a Hi everyone, I´m a electronic engineer student and I need to develop a project for March, it´s a PSU with one criteria, the “way out” has to have more than 1A. I chose it for understanding that this might be a great supply for my next projects. I tried to make the original first but I had some issues with the Proteus software (a friend told me that it does not work properly with the negative power supply) and I´ve been reading some old posts and I noticed that this is exactly what you have eliminated. Which one should I use, Redwire or Audio? I downloaded  the Tompa archives and I liked the PSU from Redwire, because it seems to be easier to deal with, but Audio is pretty good too, so now I don’t know which I should try to use. Do you know if there´s a link to Multimeter, that Redwire created. I liked very much, it has everything I need, even temperature, if not, i´d like to make a multimeter with PIC, so I could learn now what I will have to study in college in the future. Both archives from Tompa are in AtMega, is it really good?

Thank´s all !

 

[audioguru2]

Redwire's and my versions are almost the same. We both added the calibration trimpots at the same time without seeing the other one so the trimpots are in different locations.
I think there is a pcb designed by Redwire but I didn't design one. There are also a few other pcb designs.