0-30 Vdc Stabilized Power Supply

[audioguru]

Another member also had C7 explode in his power supply. He used the power supply to power a high power high frequency switching circuit.

Your flyback circuit also has high power and high frequency which exercises C7 too much.

Your flyback circuit should have its own pretty big main filter capacitor then the ripple current in C7 of this power supply project will be much lower.

[_TwisT_]

Thanks audioguru, I've added a capacitor (10000uF, 63V) in parallel with flyback, C7 no longer explodes (and even does not warms up).  8)

[fabio]

I was wondering whether someone had a PCB layout file (Eagle or analogous) and would be willing to share it.  ::)

Thank you so much,
Fabio

[josko]

Hi, great design... but I need even more powerful one  ;D
How to modify this circuit to by usable for 2x 0-35 V DC at  0-12A ?
Because I have unused 1000VA transformer with output 2x 30V AC so it is about 42V DC on caps so I think that it would be sin not to use it.
I think that using more powerful transistors should be enough (do you know some more powerful sort usable in this circuit?), but what about that OPAMPs, do I have to use some sort for higher voltage?

[audioguru]

The 30VAC transformer is needed because of the voltage loss of the main filter capacitor, output opamp, output transistors and current-sensing resistor. Then the output is regulated at 30VDC.

Two 2N3055 transistors can dissipate a total of about 140W when the heatsink is pretty big.
When the unregulated positive supply is +40V, the output is set to a low voltage or is shorted and the output current is set to 3A then they dissipate 120W.
For the 5A version we decided that three output transistors can dissipate a total of 210W.

You want 35V at 12A. Then the output transistors must dissipate 420W!!
You want two of them to heat your home.

In the long thread about this power supply, we discussed 80V opamps then finally 44V opamps that do not need the negative supply.

[Ich Will]

Hallo everybody!
That an output transistor did not warm up, offer here such regulator. He supports the difference of tension between an entrance and output of stabilizator equal 6v. Works, it is tested!
It is taken with http://radiokot.ru/circuit/power/supply/02/
You will forgive me my bad English  :(

[josko]

To audioguru:
Thanks for answer!

So is it possible to do something like this? To use it as symmetric power supply...

I don't want to have 2x 12A now, 2x 5A is enough for me, but transformer is capable of deliver such power so I want only know that there is such possibility with this circuit.
And also is there PCB design for this last version?

[audioguru]

Hi Josko,
You are shorting the transformer.
The two power supply circuits must be fed from completely separate windings or separate transformers for the negative output of one to be connected to the positive output of the other.

Your kind of transformer could be used if one power supply regulates its positive voltage like our project, then the other power supply must regulate its negative output.

[josko]

Thats OK... actually, my transformer have separate windings. I draw it wrong on schematic.
This is photo of my monster transformer (it has 12 kg), that 9V battery is just for comparison sake.

And what about that PCB design?

[audioguru]

I think somebody made a pcb design of the latest schematic.

[Ich Will]

Hi!
See this

[josko]

Ich Will:
Is it for this one: http://www.electronics-lab.com/forum/index.php?action=dlattach;topic=7317.0;attach=16065;image
And do you have better resolution?

Audioguru:
What about original PCB... are there many changes from original design?

[audioguru]

The original design used many parts that were too small and got too hot.
The new design is almost the same but uses some bigger parts to keep them cooler.
Driver transistor Q2 is in a different case and pins layout. Its heatsink probably will not fit on the original pcb.

[Ich Will]

Is it for this one: http://www.electronics-lab.com/forum/index.php?action=dlattach;topic=7317.0;attach=16065;image
And do you have better resolution?

No, it for http://www.electronics-lab.com/projects/power/003/index.html
On SMD details. If take interest, can throw down *.lay file

[redwire]

Hi, Josko,  you may want to be cautious about using a pcb designed for 3-5 amps and try to pump 12A through it.  Although most of the components will only experience ma's, a few tracing will need to supply the full 12 A.  Make sure they are wide enough.  Also your main cap will need to be huge and will not be able to fit on the pcb.

[josko]

redwire: I know that I'll have to redesign that PCB to have wider traces. I wanted some starting point, just didn't want to design PCB if there is one already designed...

[Hero999]

Use the heaviest copper board you can and cover all high current carrying traces with a thick layer of solder.

[indulis]

Or soldering a copper braid (i.e. Solder Wick) on top of the trace.

[Kevin Weddle]

Is it somewhere in between a 0 volt power supply and a 30V power supply? You need to be more specific on the voltage requirements of the circuit. Your talking about designing a very expensive power supply.  I would use a variable voltage regulator for most applications. If you have a general power supply, you can add  variable  voltage regulators to get the voltage you need.

[audioguru]

Kevin,
This power supply project is supposed to have a regulated output voltage of 0V to +30V and a regulated output current of 2mA to 3.0A.

It gets much too hot to use an IC regulator. Its ouput transistors dissipate a max of 113W.
A regulator IC in a TO-220 case can dissipate only 18W .

[Kevin Weddle]

My mistake audioguru, I misread the posting.

[Bart1988]

I posted my pcb a few threads back, these are the pictures of the case i promised.

The front, one digital voltmeter broke because i didn't have a galvanic isolated supply for it. I'm building my own now, pictures of it are below. There are 2 leds, one for the current limitter and one wich glows green when the fuse is ok and red when it's blown. The little switch next to the red switch is to turn the fan on, i'm searching for a broken pc supply to get it's fan regulator.


The side, you can see the fan.
[img width=680 height=510]

At the back i used this socket to power the power supply.
[img width=680 height=510]

I only have one 2N3055 because i only got one heatsink. The top pcb is the power supply, the pcb beneath it is a 5V supply for my displays. I need to modify it so it can also supply -5V. On the top pcb is also a little transformer mounted because i needed galvanic isolation for my meters. When closed the fan blows directly on the 3 heatsinks.
[img width=680 height=510]

You can see the two big electrolytic capacitors beneath the power supply pcb.
[img width=680 height=510]

My self made digital voltmeter. It's vacation and i don't have the equipment to make a pcb like in school so it doesn't look that good but it gets the job done.
[img width=680 height=510]
[img width=680 height=510]

Mounted in the case of the broken meter.
[img width=680 height=510]
[img width=680 height=418]

I made this supply for my latest school project. I haven't used it yet but it regulates between 0 and 29V with all trimmers unregulated. So i think i can push more out of it.

[okan3535]

thank you

[okan3535]

thank you

[okan3535]

teskurler