Thomas

Hi audioguru, I think you have a point there. Using higher rated opamps would be a much better solution. Even if the tl081 won't go bang at the first time, they will fail at some time later because of getting too much voltage for a long time. Okay, so I need to have high-voltage opamps. I'm going to read the other thread about this project in order to get more informations about the neccessary opamps and other needed changes. It's the one about getting 5A Output current from this project, isn't it? Thanks for your great help :)

Hi audioguru, I haven't seen a schottky bridge module either, but I could build it easily with 4 single diodes. But since I have complete "normal" modules here, I think I will use them instead. They look as they could stand >10A. Very stable things which can be bolted. Adding a few more secondary coils to the transformer works nice. I need ~2 coils to get more 0,5VAC. If anyone else wants to do the same: check that the direction of the windings is the same as the secondary coil. If not, you'll get even less voltage. Could there be a problem with core saturation or the higher secondary resistance of the coil? Surely less secondary current? Something else I wouldn't dream about? So I could do some "pimp up my trafo" to 24V and gamble with the opamps. I'm going to buy a few more, so I can replace the burned ones. Doesn't look that bad anymore :)

Hi audioguru, First of all thanks for your quick help. There are a few things I'm not getting. If the absolute max. rating of the opamps is exceeded by using a 20.5V transformer, hoy can you use a 24V one? Surely a 24V transformer has a even higher voltage if unloaded? And where do you get 31,7V from? I understood that the 33,05V are the absolute max. by using this transfromer, zero load and a ideal filtering? Okay, there are also tolerances in the line... The little diodes could be replaced by bigger ones. Either bridges (which I also have good ones) or (my favourite) Schottkys. I don't see a big problem there. And I could use more 2N3055. Is there a way og getting more output voltage from the transformer by adding a few more secondary coils to the core?

At first, hello to erveryone. I was able get 2 toroidal core transformers with 120 Watts from some old devices. So I think the power itself should be enough to build 2 power supplys. Unfortunatley, the transfomers have a secondary voltage of only 20.5 VAC. I wonder if that would be enough to get a maximum of 24 VDC when the schematic of this project is used. I also could aquire 2 capacitors of 50v/10.000