[sdiy] Ferrite beads or 10ohms resistors in series with +/-15vdc ??

[David G. Dixon]

I don't use either.  I simply put a 10uF electrolytic and a 100nF ceramic on
each rail near the power connector, and occasionally another 100nF ceramic
near something which is generating sharp edges (comparator, schmitt
triggers, etc).  My system has virtually no noise.  YMMV.


> Browsing a lot of DIY module schematics all around the net
> I noticed some builders use ferrite beads in series with their bipolar
> supply lines
> coming to the PCboard. Some other use 1/4w 10ohms resistors the same way.
> That makes me wonder..
> I'm on the making of a MIDI2DAC 6 voices polyphonic module using +/-15vdc
> and a separate 5vdc
> supplies for digital stuff. I started using 10ohms resistors in series
> with my 15vdc lines
> but rapidly found that these dropped my actual 15vdc voltage too much..
> I'm using 12 X 12bits DAC's here, a douzen of opamps  and don't want to
> disturb my 1v/oct outputs
> because of not stable supply voltages..
> So I changed the 2 resistors for 2 ferrite beads instead
> and now my 15vdc supply lines are precises but do I get
> a good noise barrier still compared to 10ohms resistors ?
> 
> Your thoughts welcome.
> JP
> 
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