Junction Noise

[Scott Gravenhorst]

Martin Czech <czech at Micronas.Com> wrote:

>Again: the individual transistor parameters have a great influence
>on noise. There is a lot of variation. Low noise types are often
>selected devices. E.g. a 2SC828 may differ in this respect from
>manufacturer to manufacturer. Most transistors amd diodes
>are not designed to run in avalanche breakdown, there's
>no spec for this mode, so I wouldn't expect that a specific
>type would always behave the same, if you pick -say- 100
>transistors with the same stamp but diffrent supplier.
>You have to select, and I think this is the main reason
>why shift register noise became fashionable.

Well, I'll say that I got tired of unsoldering and soldering
different trannies pretty fast.  It's funny you mention shift
register noise since it kept occurring to me as I tried 
transistor after transistor.  


>btw.: what about scarmbling junction noise with such a
>shift register? The spectral density should be fine
>as well as distribution, and it should be real random,
>not pseudo, since the junction noise sometimes
>toggles a bit in the first stage, for example.

Do you mean mixing analogue and digital noise?  or some
way to clock a shiftregister with "squared up" noise?

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