Hi,
note, that the transistor is an obsolete Ge-PNP dug out of the junk box.
The Zener provided far worse results. This, however, worked at 5 volts
definitely.

Regards,
Imre


On Wed, 1 Sep 1999, Maris wrote:

> For most transistors it takes around 7 volts to break down the reverse
> emitter/base junction so this circuit may not work at 5 volts. Maybe you
> can substitute a low voltage zener for the transistor.
> Maris
>
>
> At 09:13 AM 9/1/99 +0200, you wrote:
> >Hi,
> >as more people wished, here is the true h/w random number generator:
> >
> > 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
> >
> > Standard TTL can not be driven, but CMOS (and maybe LS) are o.k.
> > The power supply must be filtered thoroughly due to the high gain!
> >
> >Regards,
> >Imre
> >
> >
>
>