Looking for white noise chip

[sj]

About 20 years ago Radio Shack sold an 8-pin chip which produced white noise
and was very simple to use. I have no idea what the part number was. Are
there any similar products available today?

Thanks

 

[William P.N. Smith]

sj <_jones57_@_swbell_._net> wrote:

About 20 years ago Radio Shack sold an 8-pin chip which produced white noise
and was very simple to use. I have no idea what the part number was. Are
there any similar products available today?

National MM5837, long since discontinued, AFAIK. I used it in a
random number generator for a "satellite telemetry" musical horn for
my car, and if I need to build any more of them I'll probably use a
PIC with software random number generator.

http://mohodisco.com/monopoly/pdf/mm5837.pdf

--
William Smith wpns@compusmiths.com N1JBJ@amsat.org
ComputerSmiths Consulting, Inc. www.compusmiths.com

 

[Michael Black]

sj (_jones57_@_swbell_._net) writes:

About 20 years ago Radio Shack sold an 8-pin chip which produced white noise
and was very simple to use. I have no idea what the part number was. Are
there any similar products available today?

Thanks

It was simply a lengthy shift register with feedback at the right points
so it would continuously cycle through a sequence. The shift register
was long enough so the sequence was long enough, so it provided a pseudo
random output. Clocked at a high enough frequency, the output comes out
like "white noise".

Don Lancaster has some stuff about this in his TTL and CMOS Cookbooks.
I gather the Art of Electronics has some about it too. There has
to plenty of other books that cover it too. Look for something like
"pseudorandom sequence generator".

Michael

 

[Dave VanHorn]

"sj" <_jones57_@_swbell_._net> wrote in message
news:c5X3b.306$hw6.298@newssvr23.news.prodigy.com...

About 20 years ago Radio Shack sold an 8-pin chip which produced white
noise
and was very simple to use. I have no idea what the part number was. Are
there any similar products available today?

Thanks

An Atmel AVR2343 could easily be programmed to do this.
8 pin DIP, with no external clock needed. +5V, ground, and noise out.

 

[Dave VanHorn]

"Lee Leduc" <leeleduc@netscape.com> wrote in message
news:ucj1lvof3ligua20e55apsb27tvesgjr4c@4ax.com...

Xilinx has an appnote for pseudorandom generators using shift
registers. It gives a table for the feedback taps for lengths up to
168 bits.

http://direct.xilinx.com/bvdocs/appnotes/xapp052.pdf

Boy that's tempting.
21 bytes of ram, a 16 element lookup table, and you get a PN generator
that's 371 million,million,million,million,million,million,million,million
bits long, and you only need four tap points taken from two adjacent bits of
two widely separated bytes.