regulated negative 25v 4amp PS

[soaphead]

I am looking for a way to use either a couple of LM337 in parallel to get 4 amps or lm723 with (2) PNP power transistors to get negative 25v and 4 amps. I think I could get it with the LM723 and (2) MJE2955. but my knowledge is limited on how to construct it. I studied the LM723 paper and am confused on the pinouts. any help appreciated.
thanks soap

[mjf]

hello.
a powertransistor parallel with a voltreg. can do that............but often the problem is heat dissipation.
what kind of application is it?
are the 4 ampere continuous or only short current peaks?
greetings..............

[soaphead]

application is a 30-40w audio amp with peak current around 4amps. I tried to use unregulated supply but could not get a 120 hz hum out from rectifier. no matter how i routed my grounds or how big my caps were. it uses dual rail 27vdc power. I found this schematic at national using an old LM333 power regulator. I thought I would use LM337 in it's place. But I think an LM723 with a couple of power transistors would work better less noise. I have to study up on power transistors and the LM723. the LM723 doesn't look too easy.

thanks for reply..
soap

[mjf]

.........so the problem is the 120hz humm.
usually with a few 1000uf per rail an amp works without humming.
perhaps there is a bad rectifier(-diode) or something else.......
the lm317/lm337 are often used.........have a look at the forums here - there are some psu examples that use them.
greetings..........

[ikoflexer]

Definitely your hum problem isn't the lack of a regulator. I'm sure if you post details about your build you'll get help to get rid of the hum.