Jump to content
Electronics-Lab.com Community

0-30 Vdc Stabilized Power Supply


Sallala
 Share

Recommended Posts

So you are saying he is a liar or just stupid?


I build the original 30V x 3A PSU and it works pefectly, but after some ...


I have to take his comments for face value. When he says it works perfectly for him, I have no doubt. I think your comments are rather arrogant in this regard. Especially since I doubt you have even built it.

MP
Link to comment
Share on other sites

MP,
I am not arrogant!
Mixos, the owner of this site built this project and got together with Staigen, our expert power supply member. They reported the problems that Mixos had with his project in the topic about modifying it for a 5A output. The problems that Mixos had are the same problems that other members had with the ones they made:
1) At an output current of only 2.1A the ripple voltage increased with an output voltage of only 25V and higher output voltages were not possible.
2) The transformer, rectifiers, Q2 and Q4 were overloaded and got very hot.
3) The opamps were operating at a supply voltage higher than their absolute max rating.
4) Mixos's project broke, stopping further testing.

So I recommended improvements to fix these problems.
Unfortunately, Mixos and others gave up with the project since it didn't work properly and wasn't reliable.

Link to comment
Share on other sites

Hey MP

Audioguru is right here, the PSU in its original form is a nono, it have problems when loaded down to 3 Amps, at both low and high voltages! I and Mixos where discussing it, when my computer brooke down and i didn't have money to reair it!
Mixos where testing it, when that happend. And later Audioguru took over. I belive the changes he did will work, but maybee i wouldn't do everything exactly the same way, but there is several ways to skin a cat! Hopefully no hard feelings.

//Staigen

Link to comment
Share on other sites

I do not see it as a nono. It has uses for many. This is more to do with application than fault. I will take a member's comments for face value. If he says he built a project and it does everything he wants or says it "works perfectly" for him, then who are we to differ? Especially difference from one who has not built this project. There are many different uses for a device and although it might not be quite up to par for some users, might work perfectly well for applications that are needed by others.
Purchase an audio amp and run it at maximum spec for long periods of time. You will see a failure. Anyone who tries to get the maximum specification out of a device is probably going to get disappointed at some point.
Sometimes, making many changes to a device produces many other problems. This cannot be done on a "theory" basis. To improve a product, bench testing must be performed. Something audioguru has never committed to doing.
I still see many posts from users who have tried to apply audioguru's changes and have problems. I do not think this cat is yet skinned in this regard, staigen.

MP

Link to comment
Share on other sites


Purchase an audio amp and run it at maximum spec for long periods of time. You will see a failure.


Why would anybody run an audio amp continuously at full power? It isn't a tool, it plays music that has a peak to average ratio of 10:1. A 100W amp averages only 10W when playing music loud, when the peaks clip a little.
Maybe you are thinking of abuse to amps by rock groups. They use heavy-duty amps that are designed for their function, not a home stereo amp.
I worked for a sound systems manufacturer. The speakers and amps we designed were extremely reliable and guaranteed with no questions asked. None failed.

This power supply project is a tool and must be designed to meet all its spec's reliably.
Link to comment
Share on other sites

I think I should add something here...

I made a few tests by myself while building my own (modified) project. I had to use a 29VAC trafo and a 10.000µF cap in order to get 30V/3Amp with (nearly) no ripple.
There is no way that the original 24V trafo and the 3300 uF cap could have been sufficient to achieve this.
I can't say much about the other changes audioguru and the others made, because I built the revised version. But, for instance, after making some tests with 1V/3A, my pair of 2N3055, which were mounted on a heatsink, burned down.  I don't think the single one in the original project can be sufficient.

So I'm quite glad that the project had been improved before I built it.

Anyway, I don't think that this fight between you has only technical reasons, but I just wanted to put in my two cents ;)

Link to comment
Share on other sites

Hi Thomas,
Thanks. I am glad that you agree with Staigen and me.
Your two 2N3055s burned down probably because your heatsink was too small or because you used insulators. Without insulators, the transistors have much better contact with the heatsink. Then the heatsink must be insulated from the chassis.
Did you use thermal grease on them?
115W to 120W is a lot of heat for a heatsink and if it isn't big enough then a fan is needed.

Link to comment
Share on other sites



Anyway, I don't think that this fight between you has only technical reasons, but I just wanted to put in my two cents ;)



Not sure if that was directed at me or the others, but I should point out that any project posted on the web can have improvements made to it. As I said earlier, when a guy builds the project and it does everything he needs it to do - it is a success. No matter that it does not meet it's best specifications, etc. There is nothing personal in my post. A guy posts that he built a project and it works perfectly for him, but instead of "Hurray!", he gets, "I bet it doesn't work right". This is not good. I congratulate you mix! Well done!

MP
Link to comment
Share on other sites


Hi Thomas,
Thanks. I am glad that you agree with Staigen and me.
Your two 2N3055s burned down probably because your heatsink was too small or because you used insulators. Without insulators, the transistors have much better contact with the heatsink. Then the heatsink must be insulated from the chassis.
Did you use thermal grease on them?
115W to 120W is a lot of heat for a heatsink and if it isn't big enough then a fan is needed.


Well, I used a heatsink and thermal grease. But I soon discovered that the heat can't get away only by thermal convection, so now there's a 92mm @8V fan on it. I'm positive that this should work quite reliable. Maybe I can post some fotos of the case I made for it as soon as it's done.


@MP:

Then let's just say that I interpreted your post wrong, okay? What I read from it was that the changes had been unnecessary, which clearly not the case. Sorry for causing any troubles ;)

@Mix:

Well done!
Link to comment
Share on other sites

Hi
    I have been following  this read and its interesting but the thing I don't understand is what is the best way to go about makeing the power supply?
  There has been a lot of post but still it seems like the whole project is still unsetedly. Mixo gave up on it for good reasons I think but its still going on.
Audioguru and Mp, please make it work and then talk about or go with mixo.
                                          Thank you
                                                  gogo

Link to comment
Share on other sites

Hi Gogo,
You can make this project any way you want. Make the kit and when you complain about its poor performance and unreliability then maybe the maker will replace it with one that works.

I've fixed and built many projects on this site and get thanks from many people and an argument from one. My improvement recommendations have been followed by others who were happy with them in this project and they even posted an updated schematic and pcb. Those people, not me, should update the project in the Projects Section.

The person who updates the project needs to make a detailed parts list which involves the selection of a suitable heatsink and maybe a fan. Therefore even mechanical spec's for parts must be selected. If I needed this project then I would do it.

The moderator should split this long topic into a few sections:
1) Improvements.
2) Troubleshooting for defective parts, backwards transistors or a short on the pcb.
3) Parts substitutions.
4) Arguements. 

Link to comment
Share on other sites

Hi Vaclav,
3 transistors are even better than 2 because they share the heat and have a higher current gain so their driver transistor will be cooler. The heatsink must still be big enough to dissipate up to 120W. Don't use insulators then they can conduct their heat to the heatsink better. Insulate the heatsink from the chassis instead.

We found that 2N3055 transistors have a very wide difference of current gain and that each one should have a 0.33 ohm/2W emitter resistor to equalize their gains.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...