Regulator Noise

[jean-charles maillet]

>that having been said, I must admit I have managed to build PSUs with
>an astonishing amt. of noise......but the worst things I wrestle with
>are transition spikes from triangle generators in LFOs....NOTHING
>stops some of these....
>
>paul perry melbournw australia

I've seen a bunch of these situations remedied on synths cards and other
60's/70's audio gear ... it's a fix to ground loops when the circuit can't
be star connected easily or cheaply ... to fix the problem they cut the
traces feeding the +Vcc and -Vee/GND return and insert a 10 or 22 Ohm
resistor bridges (it's important to do both).  Large electrolytics (10uF
and up) are inserted on the noisy circuit side of the resistors.  These
provide local charge reserves to accomodate for large transient current
pulse sinks, their grounding location may need to be randomly tried in
cases where the current pulse is really high, in which case the caps may
need to be connected to the chassis ground where all grounds lead to (i.e.,
basic star grounding principle) ... often the caps will be connected across
the resistors but one should be careful with that one.  The resistors and
cap will be seen as an isolation filter coming from the power rails side
though we are trying to prevent a dip of voltage on the rail side comming
from a rapid currenr sink on the circuit side (which is heard as a click)
... by experimenting with resistor and cap values this should work for you
too ...

jc

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