zenier diode

[Fiver Campion]

Greetings,

What is meant by a 'noisy' zenier diode?

Thank you

 

[JeffM]

What is meant by a 'noisy' zenier diode?

Fiver Campion

In what context?

 

[UncleWobbly]

The most common use for the term "noisy Zener" would be defined thus:

When forward conducting, all silicon (any type of semi actually, but the
effect varies) junctions create "noise" - that is if you look at the signal
with a scope (AC coupled), you will see the output of the diode is not
totally clean and flat like the input might be but has a *very* small amount
of electrical noise super-imposed on the DC... this fuzz is random spikes
caused by the elctro-chemical bonding and splitting of electrons in the
silicon. Zeners are well documented for being noisy but it sometimes has a
real application... some types of particularly noisy zeners are manufactured
in small quantites purely as noise sources!

You can split it of by AC coupling through a small mylar capacitor, amplify
it and then flash sample it to give a true random number generator for your
PC... nice eh?

The noise from a zener when amplified and played throuh headphones is quite
nice sounding too - somehow different from the AF noise you get from a telly
between channels. Very relaxing.

 

[Fiver Campion]

I was looking for a source of switching a triac (as found in a typical
light dimmer circuit) on and off quickly in a random fashion to mimic
the light output of a flame.

I found the following explanation:

....the output of the diode is not totally clean and flat like the input
might be but has a *very* small amount of electrical noise super-imposed
on the DC... this fuzz is random spikes caused by the elctro-chemical
bonding and splitting of electrons in the silicon.
You can split it of by AC coupling through a small mylar capacitor,
amplify it and then flash sample it to give a true random number
generator...

I was hoping I might be able to get a 'how-to' on using the 'random
spikes' to achieve my goal.

 

[UncleWobbly]

remember that when you switch anything on, you get "inrush" current as the circuit beyond polarizes... if you are going to be switching AC mains then you need to put a "zero-crossing detect" circuit in so that you only turn the triac on when the voltage is tantamount to nothing otherwise you will put noise (at considerable levels) onto your mains as the current is applied to the bulb - this may well interfere with other stuff, like hi-fi, TV & pcs.
I was looking for a source of switching a triac (as found in a typical light dimmer circuit) on and off quickly in a random fashion to mimic the light output of a flame.
I found the following explanation:

...the output of the diode is not totally clean and flat like the input might be but has a *very* small amount of electrical noise super-imposed on the DC... this fuzz is random spikes caused by the elctro-chemical bonding and splitting of electrons in the silicon.
You can split it of by AC coupling through a small mylar capacitor, amplify it and then flash sample it to give a true random number generator...

I was hoping I might be able to get a 'how-to' on using the 'random spikes' to achieve my goal.