[sdiy] +-12V supply

[Roy J. Tellason]

On Thursday 13 January 2005 06:55 pm, Chris CROSSKEY wrote:
>  Toss out the 7812/7912 and use a 723 on each side with a big bypass
> transistor.....

Why,  if the simpler setup will do what you need?  Did I miss something there 
that indicated a massive current draw requirement or something?

> that said, don't overdo the resevoir cap or it will start to make ripple an
> issue, a series of decade divided bypass caps isn't a bad idea... 100uF
> tant, 10uF tant, 1uF, 100nF,10nF, 1nF polyester...OTT but you get a nice
> warm glow from the knowledge that everythign is getting caught.... they
> ain't no such thing as an oversized heatsink, overspec the rectifier to
> make sure it runs cold, over spec the transformer adn make sure it's
> toroid.....

The first article I remember that showed how to use the 723 allowed for 
something like 50mA with the chip by itself,  500mA when a 2N4918 boost 
transistor was used (that's a 3A part),  and 2A when a 2N3055 was added to 
the mix.  Only a little bit overdesigned,  eh?

> ----- Original Message -----
> From: "Pat Kammerer" <spivkurl at wearerecords.com>
> To: "sdiy" <synth-diy at dropmix.xs4all.nl>
> Sent: Thursday, January 13, 2005 12:57 AM
> Subject: [sdiy] +-12V supply
>
> > Okay I'm making a PCB for an improved power supply (based on 7812 and
> > 7912 TO-220), and I had a quick question.
> >
> > Other than larger filter capacitors, are there any simple modifications
> > to the "basic" regulated power supply which would enable even lower noise
> > floor?  Maybe it's too vague, but I'm not sure how else to put it.  I
> > just want to make a good simple low noise linear PSU.
> >
> > Thanks for any help,
> > Pat