[sdiy] Diodes won't make noise

[Ray Wilson]

Hi Scott

I'm glad you found the other 1N4744 that makes noise. Now we both have one
:). Its great to have such a cool resource as this list.

Cheers

Ray

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Scott Stites
Sent: Thursday, October 16, 2003 7:32 PM
To: Synth-Diy
Subject: Re: [sdiy] Diodes won't make noise


My one and only 1N4744 that I bought at the dusty, musty local electronics
store sure spits out the noise  (I'm using it in Ray's noise application
from his "Sample & Hold and White Noise Generator" circuit).  Of course, as
Harry points out, it's a higher voltage zener.  Or should I go back and buy
all of their vintage zeners? =-D

Cheers,
Scott


----- Original Message -----
From: "Oren Leavitt" <oleavitt at ix.netcom.com>
To: "Harry Bissell Jr" <harrybissell at prodigy.net>; "Ray Wilson"
<rayw at csd.net>; "Synth-Diy" <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, October 16, 2003 11:02 AM
Subject: Re: [sdiy] Diodes won't make noise


> Good point Harry!
>
> The 1N4742 I mentioned in my previous post is over 30 years old.
>
> -----Original Message-----
> From: Harry Bissell Jr <harrybissell at prodigy.net>
> Sent: Oct 16, 2003 9:00 AM
> To: Ray Wilson <rayw at csd.net>, Synth-Diy <synth-diy at dropmix.xs4all.nl>
> Subject: Re: [sdiy] Diodes won't make noise
>
> Of course the correct statement would be
>
> zener diodes are not the good noise sources they once
> were...
>
> zener diodes (iirc) operate in two regions... a
> low voltage area where they are essentially forward
> biased junctions (this is for less than 5V units)and
> an avalanche mode for higher voltages. So you should
> be using a higher voltage zener, less than 5V units
> are
> about sure not to work.
>
> That said, the higher voltage processes have been
> tailored for a LONG time to get rid of the
> noise...which
> is a bug in a zener diode... not a 'feature'
>
> There ARE special noise diodes, but in general you
> will be more sucessful with the reverse biased
> transistors...
> no one expects you to run them that way so they did
> not
> take special care to make them quiet
>
> H^) harry
>
>
>
> --- Ray Wilson <rayw at csd.net> wrote:
> > Hi All
> >
> > In some recent experimenting with my multi-noise
> > source I came to the
> > conclusion that zener diodes are NOT a consistent
> > source of noise sources
> > (that sentence sounds a little wierd). At some time
> > in the past I have used
> > the specified diode and it made more noise than I
> > ever saw before but that
> > seems to be the rare exception. Anyway I have
> > updated my multi-noise source
> > module to use a selected 2N2712 or a selected 2N3904
> > in case anyone is
> > thinking of building it.
> >
> > I also finally made boards from the artwork and they
> > do work fine. I tweaked
> > a couple of resistor values too.
> >
> > It is here:
> >
> http://atlas.csd.net/~rjwsoft/multinoisemodule_exp.html
> >
> > Cheers
> >
> > Ray
> >
>
>
>
>
>