Post by thread:White noise generator

Speaking of pic sound code, does anyone have code/circuitry examples for generating white noise, etc. I was thinking of using a 12C509 and direct driving an element from an I/O pin with PWM. Then varying the duty cycle register with a random number generator. Do I have to vary the frequency too? I am new to this synthesis stuff. Thanks, Craig

At 09:43 28/05/99 -0600, you wrote: >Speaking of pic sound code, does anyone have code/circuitry examples >for generating white noise, etc. > >I was thinking of using a 12C509 and direct driving an element from >an I/O pin with PWM. Then varying the duty cycle register with a >random number generator. Do I have to vary the frequency too? You will find a PWM Sound generato example with UMPS, a project file called 84SNDPWM.PRJ show how it is possible to generate PWM sound. This can also be used to translate a recorded table directly as PWM output. UMPS will simulate that, record the waveform, resample it at 22KHz and resend it to your sound card if you have one. It will also create .WAV file that can be analysed after if necessary using a WAV viewer or other WAV tools. Give it a try: http://www.vmdesign.com Regards, Philippe.

>From time to time various shiftregister-feedback or other electonic randomizers appears. A quite simple way of generating a quite near white noice (well - pink) is to feed a zener diode with a high value resistor. The zener voltage should be around ¸ Vcc, and R about 1 Meg. Attach a 10 nF capacitor to the Zener, and the other end to an OP Amp - gain 1000 . You will find a rushing noice on the output pin. Depending on your needs, this could possibly be a way of very simply generationg a random noice. Sven Milton -----Ursprungligt meddelande----- FrŒn: Craig Lee <spam_OUTcleeTakeThisOuTATTCANADA.NET> Till: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU <PICLISTKILLspamMITVMA.MIT.EDU> Datum: den 28 maj 1999 17:48 €mne: White noise generator {Quote hidden}>Speaking of pic sound code, does anyone have code/circuitry examples >for generating white noise, etc. > >I was thinking of using a 12C509 and direct driving an element from >an I/O pin with PWM. Then varying the duty cycle register with a >random number generator. Do I have to vary the frequency too? > >I am new to this synthesis stuff. > >Thanks, > >Craig >

Thanks. I was looking more for simulated sounds, and examples of how to generate white noise, pink noise, buzzing, chirping, sirens, etc with a small cheapo pic. Precision isn't necessary, and direct drive with a square wave is fine. I am looking for noises that are annoying to animals, but are audible and tolerable to humans... perhaps a difficult task. Craig > {Original Message removed}

Craig Lee wrote: > I was looking more for simulated sounds, and examples of how to > generate white noise, pink noise, buzzing, chirping, sirens, etc with > a small cheapo pic. Precision isn't necessary, and direct drive with > a square wave is fine. White noise is the easiest insofar as feeding the bitstream from the PRBSG clocked at a frequency *much* beyond audio is *already* PWM. I have no suggestions on pink noise, and the others require little effort as far as "PWM" goes. > I am looking for noises that are annoying to animals, but are audible > and tolerable to humans... perhaps a difficult task. Oooh yes! I'm sure animals would by and large, ignore large amounts of white or pink noise entirely, and I cannot think of *any* possible sound that would annoy an animal that I wouldn't *hate*, inclusive of mating calls etc... Sven Milton (MILTON MEDICINTEKNIK KB) wrote: > A quite simple way of generating a quite near white noice (well - > pink) is to feed a zener diode with a high value resistor. The zener > voltage should be around ¸ Vcc, and R about 1 Meg. A popular component to use is the reverse-biassed E-B junction of a common signal transistor which typically breaks down at 5V (use a 12V supply). Note that the reverse-biassed E-C junction has a negative- resistance breakdown characteristic due to the transistor action. -- Cheers, Paul B.