hello

this project took a lot of money and a lot of time
but when I done of every thing
the output of the power supply doesn't work as planed
the project should be adjustable of the voltage and the amp
but the ICs keep burning and the output cant be adjusted
I tried to simulate it on circuit wizard and its fine in some of the part of it
but the output wont be satiable at all
its show its adjusted to 13 volt and that's ok then its jump to 50volt down slowly to 13 over and over and over

please I need help on this
what went wrong

 

Bad design. That 28VAC transformer is probably going to be putting out close to 50VDC at light load currents which will blow up the op amps.

 

Take a look here:
http://diyfan.blogspot.ro/2012/02/adjustable-lab-power-supply.html
Compare power supply from there with you designed. Certainly there are notable differences.

 

It would be a lot easier if Q2 was a PNP and then the driver ICs could connect to a small NPN to pull down to drive the power transistors. You could use a lower voltage rail to run the control circuitry.

No offense to the original designer, but that design is an exercise in doing everything the hard way.

 

donpetru
I will try your design soon

bountyhunter
now its BD136 PNP and its stable
but I cant adjust it
the other thing its overflow (error) after few seconds with 999volts

 

donpetru

I did your PS (simulation )
and its almost perfect
yes its sets perfect and its stable and adjustable
but its jump to 35v and goes down to the correct voltage every few minutes !
why is that ? can I improve it ?
thx