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Jasen Betts[_2_] Jasen Betts[_2_] is offline
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Default "Random" Circuit Needed.

On 2015-04-01, Jim Thompson wrote:
On Thu, 02 Apr 2015 07:26:29 +1000, "David Eather"

On Thu, 02 Apr 2015 05:14:13 +1000, Jim Thompson

On Wed, 01 Apr 2015 15:07:54 -0400, Phil Hobbs

On 04/01/2015 02:00 PM, Jim Thompson wrote:
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

How random? You could use a 16-bit PRBS made from two HC299 and an
HC86. Feed back Q14 XOR Q13, and tap out four stages to a HC154 demux.
If you need better randomness, use four PRBSes of different length.


Phil Hobbs

I just need semi-random enough to test a fast AGC.

...Jim Thompson

there is a bias with the 8-bit just use the last 4 bit idea. With 255
'clocks' all states but 0000 will occur 16 times while 0000 will only
appear 15 - the cycle then repeats. The lack of the extra 0000 may cause
the bias point to continually drift high.

I was wondering about that myself... I'll see if there's a cure.

r=(75*r+74)%65537 visits 0-65535 with no gaps.

not that i'd want to build it using 74LS logic.

umop apisdn