[sdiy] Noise Transistor

[Tim Parkhurst]

Hi Ian,

So what method / equipment did you use to select and grade the transistors?



Tim (squeaky wheel / noisy transistor) Servo

"Imagination is more important than knowledge." - Albert Einstein

*************************************************

> -----Original Message-----
> From: Ian Fritz [mailto:ijfritz at earthlink.net]
> Sent: Friday, March 18, 2005 12:42 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] Noise Transistor
> 
> At 12:47 PM 3/18/2005, 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
> >
> >
> 
> Well, I obviously have an extreme minority view here, but I disagree
> *completely* that you want to use the noisiest device possible.  The
> reason, as I have posted many times, is that the noisy devices always have
> a large amount of 1/f noise, which gives a gritty sound.  The only way to
> get a good, smooth-sounding noise source is to find devices with flat
> spectra at low frequency.  I once went through about 50 3904's and only
> found three with suitably flat spectra.  The best device was actually the
> one with the *lowest* output level.
> 
>    Ian
> 
> 
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