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Tom Del Rosso[_7_] Tom Del Rosso[_7_] is offline
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Default "Random" Circuit Needed.

Jim Thompson
Wrote in message:
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.

It would be less than random because 0000 is still less likely.
Better to use a fast counter and latch it before the

Because it's not physical maybe you'd have to jiggle the fast
clock with a large resistor to one of the bits, if Spice would
have a tendency to make one clock an exact multiple of the other.