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You could try using a couple of M-sequence generators. One to output to a DAC the other to control the update frequency. This will not be completely random but peudo-random as the generators will repeat the sequence. The frequency range of the white noise will of course depend on how fast you can update the DAC. A DSP may be better than a PIC.

 

If you want real white noise you could look at using a PN junction such as the be of a transistor. I have seen cotton wool soaked in silver nitrate inside a glass tube and a couple of silver wire used in a synthesizer. This was many years ago though.

 

Cheers

 

Reynard

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  • 2 weeks later...

Microcontrollers are great for many things, but making white noise isn't one of them, though maybe one of the dsPICs might be capable of it.

 

As Reynard suggests, you'll get a much better white noise source from a reverse-biased base-emitter junction. Here's an article and schematic for the Paia Gnome micro-synthesizer, which shows just such a noise generator. (I build one of these kits instead of studying for exams, one forgettable year long long ago. Good times...)

Edited by kenn
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Kenn,

 

You must go back along way then.

 

This is the synthesizer that I think used the cotton wool in a glass tube.

 

http://matrixsynth.blogspot.com/2008/03/pr...ynthesizer.html

 

My pile of Practical Electronic and Practical Wireless magazines of that era are long gone.

 

Cheers

 

Reynard

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Thanks for that link.

 

You must go back along way then.

 

Hey, it's my parents' fault! I was born prematurely... about 15 years too early ;)

 

I built that Gnome in the fall of - ahem - 1977. I still have it, and some other sundry PAiA modules like the analog sequencer, buried in the basement somewhere. I even have a small hoard of those now-rare CEM and SSM synth ICs.

 

That old stuff is cool... but I love today's stuff as well. With today's flash-memory microcontrollers, free or inexpensive compilers, cheap LCDs and modules for wifi, zigbee, ethernet, USB... linux single-board computers for under $100... the INTERNET! - it's never been easier or more interesting to be into electronics.

 

I hope to try to apply some of today's digital technology to yesterday's analog, such as using a microcontroller front-end to add MIDI control to an analog voltage-controlled oscillator bank.

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