[sdiy] General White Noise Question

[Ray Wilson]

I've been using a 1 meg since I bought my first PAIA Gnome (which used 1 meg 
and a 2N2712). You can change the value to see what happens it's definitely 
not in stone but this works. I have a drawer full of 2N3904's and I tested 6 
to 10 random picks and got decent noise from all of them. The gain of the 
second stage may need tweaked to go a bit higher or lower depending on the 
trannie. If you have any 2N2712's they do produce a very nice noise signal 
in this configuration. Just about any NPN trannie with BVebo of 5 or 6 volts 
should do.

I'll try the 100K on mine to see how its sounds. Thanks

I tried to keep the runs around the high gain section short to reduce 
induced AC in the noise too. Thanks for the tip on the SMT ceramic.

Ray


----- Original Message ----- 
From: "Grant Richter" <grichter at asapnet.net>
To: "rdrake" <rdrake at data2action.com>
Cc: <tavys.ashcroft at gmail.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, August 06, 2006 1:25 PM
Subject: [sdiy] General White Noise Question


> The White Noise Source looks similar to the Electronotes designs.
> The Noise Ring noise source is also based on that, BUT
> I have had real problems using a 1 megohm in the R2 position for 
> production (as in some original Electronotes designs).
> I used a 1 megohm in the R4 position with the same C1 value and non- 
> inverting JFET amp.
> I had to switch to 100K in the R2 position to get all units to pass  test.
> Also do not use a SMT ceramic part for C1 or it will be microphonic.
>
> It seems (from experience of building the 100 modules) that somewhat  more 
> current into the zener biased transistor produces a more uniform 
> frequency distribution and output level.
>
> Any quantum scientists have a theory why that should be?
>
>>>> Hi All
>>>>
>>>> I have another offering called the "Noise
>>> Cornucopia" which you may find
>>>> interesting.
>>>>
>>>> Its here...
>>>>
>>> http://www.musicfromouterspace.com/analogsynth/NOISECORNUCOPIA/ 
>>> NOISECORNUCOPIA.php
>>>>
>>>> Cheers all
>>>>
>>>> Ray
>>>>
>>>>
>