[sdiy] Simplest random source

[charlie lamm]

Perhaps stealing the noise generator + S/H of this circuit??

http://www.generalguitargadgets.com/fsh1asc.gif



On Sat, 16 Nov 2002, Seb Francis wrote:

> 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
>