View Single Post
  #10   Report Post  
Posted to,alt.binaries.schematics.electronic,sci.electronics.basics
John Fields John Fields is offline
external usenet poster
Posts: 2,022
Default "Random" Circuit Needed.

On Wed, 01 Apr 2015 12:10:24 -0700, Jim Thompson

On Wed, 01 Apr 2015 11:53:10 -0700, Jim Thompson

On Wed, 01 Apr 2015 13:27:06 -0500, John Fields

On Wed, 01 Apr 2015 11:00:25 -0700, Jim Thompson

For a simulation situation I need a random number generator with a

What I need to simulate is a "random" selection of one-of-16 outputs.

Clock "speed" is 12.5kHz ;-)

Built of 74HCxx parts is preferred... I have a full ensemble of those
device in my PSpice library.

Thanks in advance.

...Jim Thompson

If you use something like an HC154 with an LFSR driving its address
inputs to generate random one-hots on its outputs, will that work
for you?


What are you saying... take the outputs of the LFSR broadside to drive
the address lines of the 'HC154?

I think that would do it.

Thanks also to Lasse for the same suggestion.

...Jim Thompson

I was puzzling over how to get 0000, but then it dawned... just use an
8-bit LFSR and use the last 4-bits.

...Jim Thompson

There's really nothing quite like that thrilling flash of discovery,
is there?

If you need 0000 out and you only want to use a 4 bit LFSR, then use
XNOR feedback to force the lockup state to 1111 instead of 0000 and
you'll magically jump over 1111 once per cycle.

If you need an LFSR with a maximal length of 2^n instead of 2^n-1,
then a pulse-stuffer is called for.

If there's any interest I'll post a schematic.