[sdiy] Weird Ripple Voltage

[Roy J. Tellason]

On Friday 04 April 2008 21:39, mike ruberto wrote:
> More strange power supply problems. This time I have a high pitched
> whining in the audio. I traced it back to the devices power supply
> where it seems to be originating before the regulator. On the scope I
> see a ripple voltage with the usual saw shape but it is shot through
> with  lines. Increasing the volts division I can make out a tiny
> sawtooth wave riding on the ripple at several times the ripple
> frequency.
>
> I disconnected the regulator to verify the origin and sure enough it
> coming form the rectifier/filter stage. That stage is a bridge
> rectifier with a ring of snubber caps and then the main filter cap and
> another 0.1uF cap. Am I looking at a problem with the bridge rectifier
> or is one of the snubbers bad?

One time that I saw something like this,  I had taken a c= 1541 chassis and 
attempted to rig it up to power _two_ c64s.  It didn't work.  No matter what 
I did to isolate them,  as soon as I had two connected I saw some really 
intense high amplitude ripple all over the place,  and neither machine 
worked.

Is it possible that something's interacting with something else there?  Or 
that your regulators are oscillating?  I see where you mention disconnecting 
the regulator,   but it seems possible that something else may be exerting 
some influence there...

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin