From: Tom Libert <libert@citi.umich.edu>
Date: Sun, 31 Jan 93 09:49:00 PST
To: dsinclai@acs.ucalgary.ca
Subject: Re: randomness
Message-ID: <9301311748.AA08822@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


	Yes, I have heard of using diodes for white noise production.
	Hoewver, I am conserned as to the nature of this noise.  Is it
	some property of the silicon or is it just amplified radio
	noise that is bringing the diode above threshold??

Fundamental property of the switch.  If you bias a diode near the knee,
random events at the quantum mechanical level can cause readily
observable changes in the output potential.  Recall that the diode does
not conduct below the switch threshold, and conducts readily above it.
But what happens AT the threshold?  Thermal noise produces dramatic
changes in the output.  This approach has been used for years to
produce "white" (or "pink") noise.  I also believe (but am not certain)
that electronic poker and bingo games also use this technique.