0-30 Vdc Stabilized Power Supply

[flippityflop1]

i know this is a stupid question, but i'll go right ahead...

i understand that's U2, U3 and Q4 mainly are regulating the voltage and current, can i swap them in the future with switching mode components/assemblies to increase efficiency??

 

[audioguru2]

i know this is a stupid question, but i'll go right ahead...

i understand that's U2, U3 and Q4 mainly are regulating the voltage and current, can i swap them in the future with switching mode components/assemblies to increase efficiency??

This is a linear power supply. The circuit for a switching power supply is completely different.

 

[remonx6]

Good Ideas.....Thanks Author

 

[remonx6]

need some theory/Calculation on it....give me idea about it.


Thanks

 

[audioguru2]

need some theory/Calculation on it....give me idea about it.

Opamp U1 has a voltage gain of 2.0 and uses a 5.6V zener diode so its output is always +11.2V.
Voltage pot P1 feeds from zero to +11.2V to opamp U2.

Opamp U2 and the driver and output transistors are a power amplifier with a voltage gain of 30.0/11.20V= 2.68 times.

Opamp U3 compares the output current in R7 with the setting of the current pot P2 and if the output current is higher then diode D9 reduces the output voltage until the output current is the same as the setting of the current pot.

Transistor Q3 turns on the LED to warn you that the current regulation is reducing the output voltage.

 

[Kevin Weddle]

Xristost, I like the stabilized 30v power supply you work on. So many people want a constant voltage...

 

[Kevin Weddle]

Xristocrat. Tell us what you mean by your earlier posts. What is the design?

 

[xristost]

Xristost, I like the stabilized 30v power supply you work on. So many people want a constant voltage...

The design in this posting in my blog is the same as the discussed one in this  topic.
There are number of small improvements that are mentioned in the posting.

The design in this posting is little different and is based on an old schematic published in a Czech electronic magazine.
The latest version I made is simpler, has only one dual opamp and is better suited for ordinary opamps like TL082.
As I said in my blog, I tested it with number of different opamps and it worked flawlessly. Couple of other people also reported that they made the schematic and it's OK.

 

[audioguru2]

The design in this posting in my blog is the same as the discussed one in this  topic.
There are number of small improvements that are mentioned in the posting.

The design in this posting is little different and is based on an old schematic published in a Czech electronic magazine.
The latest version I made is simpler, has only one dual opamp and is better suited for ordinary opamps like TL082.
As I said in my blog, I tested it with number of different opamps and it worked flawlessly. Couple of other people also reported that they made the schematic and it's OK.

Your circuit has problems:
1) Its supply to IC1B is only 33V so the maximum output voltage at 3A is about 25V with lots of ripple, not regulated properly at 30V.
The opamp has loss, R14 has loss, the driver transistor has loss and the output transistor has loss. The losses add to almost 10V.

2) If the output is set to a low voltage and is set to 3A then the output transistor will burn up.
It will try to dissipate 40V x 3A= 120W!! That is why the modified circuit here uses TWO output transistors to share the heat.

3) The current regulation will not work and many parts will burn up or catch on fire when the output is shorted because IC1A is missing a negative supply voltage and D7 cannot reduce the output voltage to 0V.

 

[xristost]

Your circuit has problems:
1) Its supply to IC1B is only 33V so the maximum output voltage at 3A is about 25V with lots of ripple, not regulated properly at 30V.
The opamp has loss, R14 has loss, the driver transistor has loss and the output transistor has loss. The losses add to almost 10V.

2) If the output is set to a low voltage and is set to 3A then the output transistor will burn up.
It will try to dissipate 40V x 3A= 120W!! That is why the modified circuit here uses TWO output transistors to share the heat.

3) The current regulation will not work and many parts will burn up or catch on fire when the output is shorted because IC1A is missing a negative supply voltage and D7 cannot reduce the output voltage to 0V.

It's obvious that you just repeat yourself endlessly. . .

3) I already said that two opamps are one dual opamp, so they have common supply, so IC1A have negative supply voltage.
Also read again that part marked in red ind the quote.

2) About the power dissipation you are right, but the number of output transistors is a matter of choice - if someone decide to use the PS at 1V/3A, he is free to put TWO or THREE output transistors.

1) And for the first "problem" - you heavily exaggerate here
But this "problem" have a very simple solution - we will call my schematic "Variable PS 0-25V" and everything will be OK, right?  ;D

 

[audioguru2]

It's obvious that you just repeat yourself endlessly. . .

I simply stated the problems with your re-design.

3) I already said that two opamps are one dual opamp, so they have common supply, so IC1A have negative supply voltage.

But then the opamps will probably over-heat. Single opamps should be used.
Also, the negative supply of only 3.0V is too low for a TL082 that has an input common-mode range of 4V from the negative supply voltage. When the output is shorted or is at a low voltage then some TL082 opamps for IC1A WILL NOT WORK!!
That is why I used opamps that have an input common-mode range that includes the negative supply voltage.  

2) About the power dissipation you are right, but the number of output transistors is a matter of choice - if someone decide to use the PS at 1V/3A, he is free to put TWO or THREE output transistors.

How many of your project will burn up?
You mentioned a fan.  A HUGE fast fan?

1) And for the first "problem" - you heavily exaggerate here
But this "problem" have a very simple solution - we will call my schematic "Variable PS 0-25V" and everything will be OK, right?  ;D

I do not exaggerate since some ICs and some transistors are not as good as others. You cannot buy "good" ones, you get whatever they have that still meet their specs.

EDIT: I forgot to say that R7 also causes an output voltage loss of 0.99V. So your circuit might not produce 25V at 3A, maybe only 24V.

 

[xristost]

Yes, yes, whatever . . .

You have only words, and I have working power supplies  8)

 

[audioguru2]

Yes, yes, whatever . . .

You have only words, and I have working power supplies  8)

You did not look at the specs for your opamps and transistors like I did so only SOME of your circuits will work properly.

I designed my circuit so that ALL circuits will work properly. I always use WORST CASE SPECS in my designs so that all my circuits work properly.

I have designed and had made and sold tens of thousands of fairly complicated circuits and tested every one of them before they were sold. Not one failed except for one that had its IC installed backwards and another had a shorted electrolytic capacitor. Not a single circuit that was sold had a problem. Most of the ICs were the TL074 designed by Texas Instruments but made by Motorola-ON Semi which is the TL084 selected for low noise. Maybe the TL07x is more reliable than the same or higher price TL08x. Millions or billions of TL07x opamps were used in audio equipment.

 

[gregtherider]

Hi everyone!

Im sorry but I didnt read through all 120+ pages of this topic so Im probably going to repeat a question that has already been answered..
Im going to build this power supply but I would like to have two same supplys in one case so I could use them like two seperate or like one in series so I could get + and - voltage.
Now the question is if that is possible and how should I wire the two together. I guess that ground should be isolated?

thx,
Greg

 

[audioguru2]

Each of the two power supply circuits must be COMPLETELY separate from each other. Separate transformer, separate bridge rectifier and separate everything.

Do not connect any terminal to earth unless you want it like that.
Then you can connect the supplies in series and get up to 60V out, or up to plus 30V and up to minus 30V.
You cannot connect the supplies in parallel because if you do then they will fight each other.

 

[WinDTrek]

You cannot connect the supplies in parallel because if you do then they will fight each other.

i have my supply connected in parallel and works fine.

 

[audioguru2]

i have my supply connected in parallel and works fine.

It is difficult to set each supply to exactly the same output voltage.
One supply might be 20.1V and the other is 20.0V.
The one with 20.1V will power the load and the one with 20.0V will cause the driver and output transistors to exceed their maximum allowed reverse-bias emitter base voltage (5V and 7V) and break down slowly, because the opamp U2 will see that the output voltage is too high and will try to reduce it by driving the base of the driver transistor to ground. Then all 3 transistors break down.

 

[WinDTrek]

It is difficult to set each supply to exactly the same output voltage.
One supply might be 20.1V and the other is 20.0V.
The one with 20.1V will power the load and the one with 20.0V will cause the driver and output transistors to exceed their maximum allowed reverse-bias emitter base voltage (5V and 7V) and break down slowly, because the opamp U2 will see that the output voltage is too high and will try to reduce it by driving the base of the driver transistor to ground. Then all 3 transistors break down.

i see... so far i don't see any problem with my 2 x 5A supply using in parallel. previously i did connect a 2 light bulb rated at 12V 50W each to test the supply in parallel configuration and i was able to draw 8+A of current from the 2 supply (4+A each) and run that for a while good thing it did not harm or damage the 2 power supply..  one thing i noticed though was that the ammeter reading was fluctuating..i guess due to load sharing..   anyway i will not use my supply in parallel unless otherwise it's really needed... thanks for the advise guru..

 

[Kevin Weddle]

oh yeah. how about that.

 

[cortiz]

Hi, I'm really a beginner, I'll like to build this power supply I see a lot if fixes and recommendation. my question
is Where i can get the latest diagram, BOM, etc …, the one on http://electronics-lab.com/projects/power/001/index.html is up to date?

I just want to be my first project so I can work on other stuff :d.

thanks for any pointers and help

Note A do have a really really basic Electronic background (really basic stuff V=IR …) ,
also could someone knows a good book or books to self learn a bit more (t build/desing basic stuff like counters, sensors …) stuff like that, I'll not build/design a Mark IV