[sdiy] Noise Transistor

[Oren Leavitt]

Hi Ray and all interested,

Try also varying the amount of current you are passing thru the reverse 
biased junction.
I've found that various devices have a "sweet" spot for best spectra and 
output.
Old technology zeners from 30+ years ago and greater than 5V are the 
best! Sometimes you'll get one that "crackles" with the current on the 
low side and "whistles" if the current is on the high side of the sweet 
spot. Modulating the current on one of these ought to be fun!
Mixing noise from two or more junctions can give you more spectrum, too.

ASChematic: (fixed font for best viewing)

V+ (or a modulation CV :)
|
|
--  Adjust pot for "sweet" spot and best spectrum
5
0<----| 47K |--------| cap |----- To amp
K                |
--              ___
|                A  Reverse biased junction
|                |
Gnd or V-      Gnd or V-

Junction noise is fun,
Oren

raywilson at comcast.net wrote:
> Hi All
>  
> What suggestions do people have for a reverse biased NPN e-b junction 
> noise generator. I am using 2N3904s with decent success but I would like 
> to know if there is a guaranteed noisiest reverse biased NPN e-b 
> junction transistor that is readily available. Does anyone ever use PNPs 
> for this?
>  
> Just curious.
>  
> Thanks
>  
> Ray
>  
>