[sdiy] When building a White Noise module has anyone ......

[jays at aracnet.com]

Rykhaard,

This sounds like the noise source maybe putting noise on the power supply or ground busses. This could transfer the noise to all modules in the system and cause things like VCAs to put out noise without anything hooked up.

You may want to put more filtering between the noise source and the filter. If the problem occurs when you hook up the filter you may want to try putting more filtering between the filter and power supply. Typically you will have a larger cap 10uf-47uf and a smaller cap 0.1-0.01 between each rail and ground. These MUST BE BETWEEN the power and module. DO NOT run power to the module, use it and then filter it.

Right: PS->Caps->Load
Wrong: PS->Load->Caps

Good luck.
Jay

Rykhaard D.A.M.I.A.N. wrote:

> had it emitting noise, all over the place - through the air??
> 
> I just flipped on the power to my modular, to test out a new (to me) noise
> circuit from Ren=E9 Schmitz.
> Hooking up the roughly 2' banana patch cable to a VCF input, I get a lower
> level white noise emitting all over the place. :O
> Even with the Cutoff on the Filter down all of the way, and the input to my
> VCA, down all of the way.
> 
> Another odd thing with it - the output level of the VCA, when it's between
> about 10AM and 2PM is when I hear the noise.  Outside of those settings on
> the VCA's output control - I hear nothing.
> 
> ???
> 
> Outside of hooking up the WN module's output with a shielded cable, I am
> STUMPED.  I've never had this happen before, with any other noise module,
> that I've hard working. :O
> 
> Any ideas??
> 
> If it would help any - I have 0.1uF cap power supply filters all over the
> board, as well as 100uF and 22 ohm resistors, on the V+ and V- inputs to the
> entire board.
> 
> Thanks for any possible info, on this one. :O :)
> If it's not easy to fix - I could still keep it on the board, for a source
> to the Sample & Hold on the same PCB.  The noise is barely perceptible on
> the power lines, at 20mV.  Seeing that though - maybe I should apply cap
> filters to the PS inputs on the dual opamp, in the noise unit.
> Off to investigate. :)
> 
> --
> Take care,
> Warmth and Peace,
> Ryk
> 
> http://deathlehem.bravehost.com/damian.html - D.A.M.I.A.N.;s webpage - Jan.
> 0406 update