[sdiy] General White Noise Question

[René Schmitz]

Hi Ray and all,

Ray Wilson wrote:
> 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've been using 12V zeners with good sucess, btw. (on 15V supplies 
only..) Lower voltage zeners seem to be less noisy. The advantage is 
that the breakdown voltage is something specified.
Some transistors can produce a more non gaussian distributed noise, 
albeit at a higher level.

What made me shudder for a moment was that there is no bypassing on the 
resistor that feeds the current through the noise element. A 4k7 and a 
100u decoupler would be a very good addition with such a high gain 
circuit. (Like on the noise gen on my page.)

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159