0-30 Vdc Stabilized Power Supply

[Staigen1]

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

 

[Staigen1]

Oops! Maybee Mix did not test the supply thoroughly at high and low outputs.
And it shall not fail when shorted, if it is intended to be short-safe and current-regulated!

//Staigen

 

[MP1]

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

 

[audioguru2]

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.

 

[Thomas1]

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

 

[audioguru2]

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.

 

[MP1]

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

 

[audioguru2]

Horray! Mix's project is a success. ;D  Congratulations Mix.

But he said it went up in smoke a few times. So I mentioned the other problems everyone else is having with the original project.

View attachment 38463

View attachment 38464

 

[Thomas1]

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!

 

[Oneeye_IO]

Hi all.
I have one simple question. Is this http://www.electronics-lab.com/projects/power/032/index.html

 

[audioguru2]

Hi One Eye,
This is a fairly complicated variable voltage and variable current well-regulated supply.
You don't need regulation for your driller. Do you need its voltage to be adjustable to control its speed?

 

[mix]

Hello guys,

Thanks all for help

 

[Oneeye_IO]

Hi One Eye,
This is a fairly complicated variable voltage and variable current well-regulated supply.
You don't need regulation for your driller. Do you need its voltage to be adjustable to control its speed?

I only need 18V and no adjusting. I'll set it and leave it on 18V

 

[audioguru2]

Hi One Eye,
You don't need this complicated project. You need only a 14VAC to 15VAC 3A transformer, a 5A rectifier bridge module and a 10,000uF 25V filter capacitor. Its output will be 18VDC at 2A.

 

[gogo2520]

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

 

[audioguru2]

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. 

 

[MP1]

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.

 

[audioguru2]

I also get many e-mails and PMs about this project. "I built this project and it blew-up . Please help me". I refer them to this thread.

 

[vjedlicka]

Hi all,
I have a heatsink available with 3 transistors 2N 3055 bolted on it. Can I use it for this project? I guess it can be only good to have 3 instead of 2 transistors. How about the resistors in the emitors, should the values be different?
Thanks for advice
Vaclav

 

[audioguru2]

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.