i have some cisco 6000 power supplies i am trying to convert into a dual-rail power supplies (chaining them in parallel, already made sure the neg is not connected to chassis ground).. it outputs various levels of potentials, 3.3v 5v, 12v and 42v.. and i got them for practically free and they're 1300w so should be plenty for all sorts of projects
problem is they output a raw 42v and i wanted to create a 1.25 (or 0) to 30v variable output power supply using something like a lm317 or lt3080 or something along these lines.. Well, none of these regulators would really like 42v being fed into them so i need to lower them to around 36v somehow. I was going to initially resort to a few series diodes (i have a few 12a diodes with a Vf max of 1.5v which i thought would be good enough if i used like 4-5 of them on each side), but after looking at the datasheet of the diode closer, i think the Vf varies a bit that at low loads the Vf would not lower the voltage enough to still not exceed the Voltage Regs' max volt input levels..
So question is basically, how do i get 36V from 42V? The 42V outputs about 27amp and i dont need that much @ 36v but say 6amps would be plenty (i can then chain a few lm7815 and lm7905 to get a few fixed levels as well.
problem is they output a raw 42v and i wanted to create a 1.25 (or 0) to 30v variable output power supply using something like a lm317 or lt3080 or something along these lines.. Well, none of these regulators would really like 42v being fed into them so i need to lower them to around 36v somehow. I was going to initially resort to a few series diodes (i have a few 12a diodes with a Vf max of 1.5v which i thought would be good enough if i used like 4-5 of them on each side), but after looking at the datasheet of the diode closer, i think the Vf varies a bit that at low loads the Vf would not lower the voltage enough to still not exceed the Voltage Regs' max volt input levels..
So question is basically, how do i get 36V from 42V? The 42V outputs about 27amp and i dont need that much @ 36v but say 6amps would be plenty (i can then chain a few lm7815 and lm7905 to get a few fixed levels as well.