[sdiy] LFSR digital noise source

Michael E Caloroso mec.forumreader at gmail.com
Wed Nov 13 01:13:36 CET 2019


The digital (non-cpu) noise source circuit gets consistent results and
eliminates component selection.

The analog noise source has discrete components and lower parts count,
thus is cheaper to build.  Due to selection of transistor or zener,
there's no guarantee of consistency.

Every circuit has its compromises.

MC

On 11/12/19, bbob <fluxmonk at gmail.com> wrote:
> Thanks to René Schmitz and Jay Schwichtenberg for answering the question I
> actually asked.  As it happens, i just found an ancient build attempt of
> the EN76 digital noise source that Jay referred to...  it didn't work at
> the time - it was in the (large) "pile of sad failed projects") - but
> that's the direction to go.
>
> cheers
> b
>
> On Tue, Nov 12, 2019 at 4:22 PM Richie Burnett
> <rburnett at richieburnett.co.uk>
> wrote:
>
>> You mean your white noise chips don't have IP connectivity, a firewall,
>> 256-bit encryption and patch storage in the cloud????
>>
>> Shame on you Tom ;-)
>>
>> -Richie,
>>
>> Sent from my Xperia SP on O2
>>
>> ---- Tom Wiltshire wrote ----
>>
>> >
>> >> On 12 Nov 2019, at 16:52, Gordonjcp <gordonjcp at gjcp.net> wrote:
>> >>
>> >> On Tue, Nov 12, 2019 at 03:14:47PM +0000, Tom Wiltshire wrote:
>> >>> ..because throwing a 32-bit chip at a job like this is a total waste?
>> Even the tiniest 8-bit PIC isn’t really breaking a sweat doing stuff like
>> this. You could do it on one of the little 6-pin SOT PIC10F chips.
>> >>>
>> >>
>> >> Right, but when an STM32F103 on a wee board is £2 and an off-brand
>> >> Arduino clone is £5, you may as well throw brute force at it.
>> >
>> >TWO POUNDS! TWO WHOLE POUNDS!! ;)
>> >
>> >I wouldn’t waste more than 50p on a chip to do this job!!
>> >
>> >I agree with most of Steve’s arguments - easier to program, quicker,
>> > etc.
>> Those are the reasons why I think a uP solution beats a pure hardware
>> one.
>> But it simply doesn’t need a 32-bit chip. Yeah, ok, you can write it in C
>> on a 32-bitter and probably get some tool to set the thing up for you.
>> And
>> it costs you £1. But I can write it in assembly on a chip that costs
>> £0.50p
>> just as quickly. Now, personally, I do that for my own satisfaction since
>> I
>> only need a few, but if I was producing ten million units, I’d have
>> powerful financial reasons for using an 8-bit chip. Volume helps, and
>> there
>> are such a vast number of little tiny jobs that an 8-bit chip can do that
>> the cost-sensitive/volume applications will always require them. Unless
>> us
>> human beings successfully manage to over-complicate everything…I admit
>> this
>> is a possibility when fridges have internet connections ;)
>> >
>> >
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