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Power Supply 0-30V


bohko
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Where did the long topic of stabilized power supply dissapear??? I can not access it!!.

TNX
bohko

just the question i wanted to ask.

The long thread and other threads about fixing and improving the project disappeared when this site's data became corrupted.

Here are the latest schematic and parts list:

is the data recoverable? :(
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  • 1 month later...

Hello,

I have build this power supply long time ago, and it didn't work correct. U2 was overheating and output voltage of supply was just 25V. I have changed opamps with OPA455 and now works the same. I have checked every connection, every transistor and diode. Everything is correct. Can you please help me.
Now, I know you will say, there is a update of this project on forum and new partslist and all this. But my friend has build it with original schematics and parts list and it works well for him. Can you explain me that please ?

Sorry for my bad english

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The original project is a mess of errors. We fixed it but the thread is gone.
The fixed version uses a real BD139 power transistor to replace the tiny 2N2219 that was used as Q2 and a 28VAC or 30VAC transformer at 120VA to 129VA is used.
The main filter capacitor has a value that is much higher and the power ratings of many resistors were increased.

Opamp U2 should never get too hot unless Q2 or a power transistor is connected with its pins backwards.

I am busy now but I will post the new schematic and parts list again soon.

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Hi,
Collected the Power Supply. I turned on does not work. Strongly heats U2. In what could be the problem? The output of U1 (6) with respect to point 4 (-) voltage of 27V. Is this correct? ???

The output voltage from U1 has nothing to do with the heat from U2.
The output voltage from U1 should be 11.2V which is the 5.6V reference from zener diode D8 multiplied by two by U1 since R5 and R6 make U1 have a gain of 2.

U2 heats too much when its output current is too high due to a wiring problem with the pins of Q2, Q4 or Q5.
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The output voltage from U1 should be 11.2V which is the 5.6V reference from zener diode D8 multiplied by two by U1 since R5 and R6 make U1 have a gain of 2.

U2 heats too much when its output current is too high due to a wiring problem with the pins of Q2, Q4 or Q5.

Found an error at the output of U1 is now about 11V.
The scheme collected on TL081, transistors Q4, Q2 checked, replaced, still U2 heats, the power supply is not working at the output of 0,45 V. At shaper negative voltage must be much volts? I have a 0,7 V, is that right?
Sorry for my English
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Found an error at the output of U1 is now about 11V.

Good.
Zener diode D8 is a better voltage reference if you change R4 to 1k ohms.

still U2 heats, the power supply is not working at the output of 0,45 V. At shaper negative voltage must be much volts? I have a 0,7 V, is that right?

Your U2 is overheating because Q1 is turning on and is shorting the output of U2.
The negative supply is supposed to be -5.6V which will turn off Q1 if your transformer is only 24VAC.
Maybe you have zener diode D7 installed backwards.
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audioguru , thank you very much! All earned. Was a simple mistake, capacitors C2 and C3 were short-circuited, the holes in the board was unnecessary, did not find and solder properly. Oh, how glad I am !!!!!!!! ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D

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  • 2 months later...
  • 11 months later...

Hi to all!
This is my first post! I've been reading and reading about this PSU, this upgraded one and the upgraded to 5V and I've learned A LOT!.
Well I just wanted to ask you guys if anyone has the PCB for this new updated version?
Because I'm having troubles doing the schematic and then convert it to PCB, any suggesting on a relatively easy to use soft that can create the schematic, convert it to PCB and perhaps simulate it?
I've been using Circuit Maker 2000 but it's a headache... well probably the user is the problem!  ;D
And the other thing I wanted to tell you is that you can access the original thread of this PSU (I guess is the right one) form here: http://www.electronics-lab.com/forum/index.php?topic=7317.0;wap2.
It has 316 small pages and all the attachments are lost but the text is there! That's way I'm asking for the PCB.
Well I hope any one can help me out in this one so I can make this PSU.
Thanks to all and sorry for my bad english.
Best Regards

Kike

PS: Audioguru

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