20 Jul
2006
20 Jul
'06
5:34 p.m.
the -5v channel has 500 mV of noise, even with an
additional 1000 ?F
capacitor across the output (to hopefully filter this junk out)
All of this is high-frequency, excluding the -5v hum.
In short, it doesn't look [as though] adding an external filter cap
will help much, unless I go all the way and throw in a LC filter.
If the noise is really high frequency, that 1000?F cap may be too
large. Large-value caps tend to have a comparatively high effective
series inductance. If you want HF noise filtering, you should not only
use a large cap like that but also small caps, like .01-.1 ?F, in a
technology like cermaic disc that doesn't have high effective series
inductance. Preferably, scatter the filtering around through the
circuit, to soak up noise near its source.
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML mouse at rodents.montreal.qc.ca
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B