[sdiy] +-12V supply

[Roy J. Tellason]

On Friday 14 January 2005 09:45 pm, groovyshaman wrote:
> I am curious Harry - what is the advantage of a soft start mechanism?  Does
> this in some way help alleviate the initial heavy current outrush that
> occurs when turning on the power due to all of the decoupling caps on all
> of the modules in my system?
>
> I've noticed that from time to time when I power up the 800ma power one,
> one rail "goes flat" due to current limit circuitry I think - and I
> immediately shutdown when this occurs.  Hopefully this does not harm
> things.  (although I think I remember someone mentioning that running
> certain ICs with one dead rail for any length of time will kill the part..)
>  I'm still running the supply below the rated output once things power up
> ok.  It's the initial current draw that's causing problems.
>
> George

I've wondered about that,  operating some parts with one rail getting there 
before the other or one possibly going away due to some system fault.  I 
don't remember anything in any datasheets about this,  though.

One of my projects from way back when was a "tracking regulator",  that would 
match both rails to each other.  Used an MC1468 (?) chip,  I think.


> ----- Original Message -----
> From: "harrybissell" <harrybissell at prodigy.net>
> To: "Ken Stone" <sasami at hotkey.net.au>
> Cc: <synth-diy at dropmix.xs4all.nl>
> Sent: Friday, January 14, 2005 11:41 PM
> Subject: Re: [sdiy] +-12V supply
>
> > I considered building a relay based "soft start" for my PowerOne
> > supply as "building my own power supply".  The only time I would
> > build my own is....
> >
> > 1) when I want cheap and dirty and don't care about performance
> >
> > 2) when it has to fit into a custom sized area
> >
> > 3) when I need an odd voltage not readily available
> >
> > H^) harry
>
> <snip>