Hej Michael Rigby-Jones. Tack fšr ditt meddelande 11:24 1999-09-01 +0100 enligt nedan:
> > At 09:13 AM 9/1/99 +0200, Imre wrote:
> > > White noise generator, design by dr. Imre Bartfai, 8/30/1999
> > >
> > > +---------------------------------------------------------------------
> > Vdd
> > > |                           220k                    220k
> > 5V
> > > |                       +---\/\/\---+           +---\/\/\---+------+
> > > |                       |           |           |           |      |
> > > | Ge                    |    |\     |           |    +------+      \
> > > | EFT317 PNP      +-----+----|- \   |           |    |             /
> > 220k
> > > |      C          |     |    |    >-+----| |----+    |     |\      \
> > > |   |/            \  +-------|+ /        47n    |    +-----|- \    |
> > > +--B|        220k /  |  |    |/                 |    |     |    >--+
> > >     |\            \  |  |  1/2 LM358            +----------|+ /    |
> > >       |E          |  |  |                       |    |     |/      \
> > >       +----| |----+--+  +                       +    +             /
> > 47k
> > >       |    47n    |     |                       |    | 1/2 LM358   \
> > >       \           \     \                       \    \             |
> > >  4k7  /        1M /     / 2k2                1M /    / 2k2         + out
> > >       \           \     \                       \    \
> > >       |           |     |                       |    |
> > >       +-----------+-----+-----------------------+----+----------------
> > Vss
> >
>         Robert A. LaBudde wrote:
>
> > Where does the transistor collector go? Presumably to Vdd? (Unconnected as
> > shown.)
> >
>The collector is not connected.  This circuit relies on the reverse
>breakdown of the Base-Emitter junction which produces a lot of noise.  More
>or less the same as a zener diode, which can also be very noisy, although a
>transistor is usually worse (or better depending on your point of view).
>
>Regards
>
>Mike Rigby-Jones

Suggestion, untested: 

I would think that connecting a cap between B and Vss would increase the noise output. (making a "stamp-off" pointfor the transistor noise voltage with much lower impedance than only the 220k resistor)

The idea is to in next step reduce the amplifier to just one opamp stage.

Regards
/Morgan
Morgans Reglerteknik, HŠllekŒs, 277 35 KIVIK, SWEDEN
   tel +46(0)414-446620, fax -70331,   mrt@iname.com