[sdiy] Simplest random source

[Seb Francis]

I'm not convinced sofware is the way to go.  It would be no problem to do it in software, but I have a couple of reasons for wanting to use analog:

- CPU cycles are a premium - this PIC is doing a *lot* and I don't want to waste more than 10 cycles or so getting a random number.

- I have a hunch that a simple random algorithm (such as what could be achieved in 10 cycles) would sound a whole lot different (not so nice) to the human brain than for example taking a sample via A->D of some white noise.

I've seen really simple noise generating circuits using just a diode or transistor plus a couple of opamps .. I guess I was hoping there might be a way to get analog noise using just a couple of transistors or something - the quality of the sound doesn't really matter, as long as it's random.

Seb



Paul Perry wrote:

> At 12:11 AM 16/11/02 +0000, Seb Francis wrote:
>
> >So what I'm looking for is the absolute simplest (minimum components - PCB
> space is scarce) way to make a 0->5V random source.  The PIC A/D has a 120pF
> hold cap, so I don't think a very HF source which averages to the same
> voltage is suitable.
> >
> Why yes..... the simplest solution, is ANOTHER PIC!
> I'm sure the code is out there..
>
> paul perry (not a programmer)

"J.D. McEachin" wrote:

> On Sat, 16 Nov 2002, Seb Francis wrote:
>
> > I've just finished routing the PCB for my MIDI2CV and I've realised
> > I've left off a vital part .. I need a random source for the digital
> > random LFOs.
>
> > So what I'm looking for is the absolute simplest (minimum components -
> >
> > Any suggestions?
>
> Software.  Use your brain and you should be able to generate a completely
> random number.   Look around the web if you have problems coming up w/ a
> suitable algorithm.
>
> JDM