[sdiy] Noise of the 909 type.

[BRADSHAW]

Thanks for the help.

Ed.


> From:          "Steve Ridley" <spr at spridley.freeserve.co.uk>
> To:            "BRADSHAW" <E.K.Bradshaw at newcastle.ac.uk>
> Subject:       Re: [sdiy] Noise of the 909 type.
> Date:          Sat, 2 Jun 2001 16:03:35 +0100

> > - I tried looking at the data sheet for the 4006 but it's just 
> > scary.  I also found a good site that explained all the parts of the 
> > 909 except the noise bit - so neither was any help.
> 
> I don't have a 909 schematic here at the moment, but if there's
> a 4006 in the noise circuit, it's probably using a pseudo-random
> noise generator - a very fast and long sequence of logic 1s and
> 0s that sounds and measures like white noise.  There things are
> more consistent in level than using diodes or transistors, so they
> need no adjustment.  If the sequence is too short you can hear 
> the repetitions in the sequence as a chugging/throbbing, but
> most percussion sounds are too short for this to be noticeable.
> 
> There's a good explanation of these things in "The Art Of
> Electronics" by Horowitz & Hill.  It's a book work having, and
> any half-way decent library (especially at a University etc - I
> see you're .AC) will have a copy.  It'll explain it better than
> anyone can do in an email.  
> 
> 
> 
> Steve Ridley
> 
> 
>