[sdiy] Invers Goofing!

[karl dalen]

> LOL !!!
> 
> You were correct.

I was right and wrong at the same time! :-) , silly me!
 
> You CAN base it on a stable power supply... but NOT on the "assumption
> of a stable power supply".   You would be a fool to count on that !!!
> 
> This is a mistake that many people make in their designs. Just because YOUR
> supply was good, does not mean the next one will be. Might add that sometimes
> they don;t become BAD until you add the next module.

We have all passed that goat at some time in our lives!
 
> I had a hell of a time with an EFM VCO4d and an EFM VCF2e combo.  When I
> would
> crank the VCF to the highest frequency, it would oscillate. That made the VCO
> drop about a half step in frequency. The ultrasonics rode the power supply
> rails, and got into the ramp reset comparator which was derived from the
> power
> supply. The decoupling caps on that particular layout were not located where
> they could help.
> 
> Adding more decoupling helped. Using an on-card voltage reference for those
> critical
> points killed the bug dead.

CEM3340 has this bad habbit of listening to other
things at the PCB board, even when supplies are clean!

> Another funny story was my Aries VCO and VCF... which had very bad noise
> problems as delivered by the factory.   I cured them by adding decoupling to
> the trim pots. These were old metal shell types. I assumed that the metal
> shell
> was picking up noise and my
> decouping the pots stopped it.  SILLY NEWBIE.  What I was really looking at
> was
> my own sh!tty power supply.  The noise was self inflicted... and they used
> the
> rails as reference, so the noise walked right in.

Absolutely!
 
> When I rebuilt these a couple of years ago, I found those added caps and had
> a  good  laugh... because I realized right away that I had done the right
thing, for  the  wrong reason.

And havent we all passed "that" goat too! :-)

Inverse learning by missapplying!

KD

 
> Unless you are building a closed system from the ground up, remember to NOT
> use
> the
> power supplies for critical reference voltages.  If its a closed system, do
> what works for you !!!
> 
> H^) harry
> 
> karl dalen wrote:
> 
> > > > > After words:
> > > > > In any additive wave thing in wich phased saw waves actuaclly are
> > > > > wave amplitude are the crucical inferno. So dont base your phase
> > > > > waves on the asumption of stable power supplies! ugh!.
> > > > > Its very simmliare to the basic saw to triangle converters!
> >
> > I just relized, what an absolute ludicrous/preposterous thing i just said!
> > Shure you can base it on stable power supply, everything are based on that!
> > Im sorry for that horrendous goofing! heh! :-)
> >
> > KD
> 
>