[sdiy] Noise as one unsteady tone!

[Fredrik Carlqvist]

If you go to the frequency domain (fourier transform and such), the
noise looks the same and is therefore said to contain all frequencies.
There is power in all frequency bands. This does not mean there are any
tones in it. 

If you have a narrow band pass filter, it will find energy no matter
where you set the center frequency when the input is white noise. This
way you can have something that sounds like a tone, but with an unstable
level.
 
Fredrik C


> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl 
> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of karl dalen
> Sent: den 5 september 2005 03:19
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] Noise as one unsteady tone!
> 
> Tip!
> 
> Some time ago i was looking for a low voltage noise source,
> and by coincidence i have found one. As we know its difficult
> to do a analog withe noise generator at low voltages by using 
> the typical PN junction, zener or diode couppled.
> 
> But i came by the korg Poly 800 and it uses a simple 
> NPN, open collector, emitter to +V, base negative biased
> to -5V, AC coupled to a simple inverter stage. It works verry
> well even at supply volatges of  +/-3,5. I use it with +/-5 volt
> and a non selected BC547 and a 2,2M ohm gain stage wich 
> gives several volts of uniform with noise.
> 
> Splendid!
> 
> Speaking of noise, theory says that white gaussian
> noise contains all frequencies but are theese steady
> tones or are they random in frequency?
> Or is it "one" wave with its frequency randomly?
> 
> KD 
>