[sdiy] EXT Re: 808 Q35

Jacob Watters jacobwatters at gmail.com
Tue Jan 31 14:29:36 CET 2017


If this is the case, then what is a better method for creating white noise?
I have seen some CMOS options that create pseudo random squarewaves, but
they seem to use a lot of components compared to the transistor option. I
was considering just using a tinyAVR instead.

On Tue, Jan 31, 2017 at 2:45 AM, Michael Zacherl <sdiy-mz01 at blauwurf.info>
wrote:

>
> On 30.Jan 2017, at 20:25 , Richie Burnett <rburnett at richieburnett.co.uk>
> wrote:
>
> > The tr-808 noise circuit reverse biases the base-emitter junction in
> order to produce noise. I guess this is from avalanche breakdown or zener
> action of the b-e junction which wouldn't normally see such a large reverse
> voltage.
> >
> > There must be some spread in noise level between transistors as there's
> a gain trim pot in the noise amplifier circuit.
>
> Hm, I thought that’s the classical approach to operate a transistor in
> reverse at higher voltage for analogue white noise circuits? But apparently
> such a transistor can wear out, as I had to change the noise transistor in
> an Oakley Noise Module recently. And I had to go through like 20 candidates
> to find the one repalcement with the sound and level I liked.
>
> Michael.
>
>
>
>
> --
> http://mz.klingt.org
>
>
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