0-30V Stabilized Power Supply

[audioguru2]

ok sir,, thank you!

I am glad to help you but I am not a SIR, instead I am just an ordinary cool dude.
I think a SIR was knighted by the Queen of England.

 

[vendaf]

Is this circuit working?? 1.2 - 15V/3A adjustable regulated power supply?? http://www.electronics-lab.com/projects/power/010/index.html

 

[Hero999]

It looks fine, although I'd say C1 is probably a bit undersized to expect a ripple free output at 3A. I'd recommend increasing C1 to 68,000uF or more.

The regulator will probably overheat and shut down, if you attempt to draw the full 3A, at lower voltage settings. A possible solution is to use a centre tapped transformer and tap changer to reduce the voltage to the regulator, at lower voltage settings.

 

[audioguru2]

Audioguru, have you got a copy of the last components list while using alternate chips. I apparently remember most of revisions were being in reddish.

The latest schematic and parts list are here:View attachment 41759

View attachment 41760

 

[lu2dlt]

Hello friends, and armed the source successfully, the only drawback, wherein R 5 and D5 heat slightly appreciate your help, greetings from Argentina 

 

[audioguru2]

R5 and D5 heat slightly appreciate your help, greetings from Argentina 

R5 is 10k ohms and has only 5.6VDC across it. Then its dissipation is only (5.6V squared/10k=) 0.003W which is nothing and it will not be warm.
D5 is a rectifier and it is normal for it to heat slightly.

 

[rosana]

hi from brazil!
i didnt understand witch connection i have to do with the legs of the trimpot witch the u2 (i am using the mc4071) and it doesn t have the connection like the tl081 ...number 1 and 5 ...sorry for my english and simple problem with electronic... thanks

 

[audioguru2]

hi from brazil!
i didnt understand witch connection i have to do with the legs of the trimpot witch the u2 (i am using the mc4071) and it doesn t have the connection like the tl081 ...number 1 and 5 ...sorry for my english and simple problem with electronic... thanks

The datasheet for the MC34071 opamp shows its 10k ohms input offset voltage trimpot connected to pin 1, pin 5 and the negative supply almost the same as a TL081 opamp. View attachment 41761

 

[dcy]

Good Day!
I assembled the original schematic.My problem is that the rectifier out turns to be more than 24V, around50V (unusual because the secondary output of transformer I had is 24V. The second problem is at U1 pin 6 output voltage is around 19V instead of 11.2V. The third problem is  P1 and P2 has no effect when I turn the knobs.so the  measured VDCout is the same as around 50V. Any suggestion will be appreciated.

 

[Hero999]

Good Day!
I assembled the original schematic.My problem is that the rectifier out turns to be more than 24V, around50V (unusual because the secondary output of transformer I had is 24V

Why is that unusual?

It's what you should expect.

24V is the RMS voltage, when fully loaded, the peak will be 34V, fully loaded, but when open circuit the voltage will be up to 20% higher so 50V sounds reasonable.

 

[audioguru2]

Cheap transformers have poor voltage regulation.

A Hammond 30V/4A transformer is 30V RMS at 4A. With no load its output voltage is 31.5V RMS so it has pretty good voltage regulation probably because it is huge and its windings have a low resistance.

I have a little Chinese 9V/100mA wall-wart power supply.
Its voltage is 9V when loaded with 100mA but its voltage is 18.5V (more than double!) when it has no load. It gets hot with and without a load. It is very cheap.

The TL081 opamps in the original project have an absolute maximum total supply of 36V.
The opamps in my fixed version of this project are rated at 44V. Their negative supply is only -1.3V.

24VAC has a peak of 33.9V which is reduced to 32.5V by the unloaded bridge rectifier. Then some of the opamps have +32.5V and -5.6V for a total supply of 38.1V if the transformer voltage does not rise without a load.
Of course the transformer voltage will rise without a load and blow up the opamps.

 

[Venz]

We seem to have lost the extensive discussion on this power supply topic.    I attached what I believe is the latest version.   I could not find the updated parts lists to attach.    


UPDATE 12/30/09     Added parts list and Eagle file for double sided board  (Shown in photo below)

is this the updated shematic and partlist sir? thank you..

 

[LEECH666]

No, this is the most recent parts list / circuit diagram: http://www.electronics-lab.com/forum/index.php?topic=19066.msg1010703#msg1010703

I really think someone should update the frontpage to the most recent version. That way everyone would find the most recent version of the circuit and it would also stop the people from asking the same question over and over again.

 

[plouf1]

furthermore does exist any info of what all these (5 variable resistors) do in the final version ?

 

[audioguru2]

furthermore does exist any info of what all these (5 variable resistors) do in the final version ?

There are only two variable resistors, the same as in the original version:
P1 sets the output voltage.
P2 sets the maximum output current.

There are three trimpots that are adjusted only one time:
RV1 is the same as in the original version and adjusts the output offset voltage to zero when the voltage pot is set to zero.
The 20k voltage calibration trimpot in series with R11 is adjusted for an output of 30.0V when the voltage pot is at maximum.
The 100k current calibration trimpot in series with R18 is adjusted for a maximum output current of 3.0A when the current pot is set to maximum.
 

 

[Javierhm1]

Hi everyone!
I did the schematic in Cadsoft Eagle.
may somebody check it?
I will send the board later if no mistakes.
Thanks in advance.

Placa_principal.zip

 

[redwire]

Was anyone able to open Javierhm's Eagle file?    I tried to open with version 6.3.0 with no luck.

 

[Javierhm1]

Sorry for the delay!
I was working in an Eagle 6.3 version.
I post it here including a bitmap.

PSU_Audioguru.rar

 

[audioguru2]

I can't open your RAR compressed file because it has errors.
Why not post the schematic as an ordinary PNG file?

 

[PicMaster]

I was able to open it try this one I've zipped it up

see how you get on

Placa_principal.zip