[sdiy] EXT Re: 808 Q35

Tue Jan 31 14:55:50 CET 2017

Try the PIC from electricdruid

www.electricdruid.net/product-category/lfos-noise

Best Regards,

Patrick Logue

  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Jacob
Watters
Sent: 31 January 2017 13:30
To: Michael Zacherl
Cc: SDIY
Subject: Re: [sdiy] EXT Re: 808 Q35

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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