[sdiy] reverse biased NPN vs Zener diode for noise...

[cheater cheater]

What if you use an op-amp to amplify the noise output of the silicon
diode? Will that introduce unwanted noise?

D.

On Mon, Nov 2, 2009 at 07:52, Oren Leavitt <obl64 at ix.netcom.com> wrote:
> Find old zeners from the 1960s, and about 8 volt or higher. You will likely
> find some really nice noise makers. Modern zeners are made with a different
> process that does not yield as much noise.
> The fun with "old" zeners is that each doide has its own individual
> character, color and grainy-ness. Don't be surprised if you find yourself
> giving your diodes names :-).
>
> - Oren
>
> nicolas wrote:
>>
>> I haven't done any comparative testing, but the advantage of the zener
>> diode is that you can order one off the shelf and it will have a known
>> voltage drop and fairly predictable noise character.  On the other hand
>> using a transistor you will have to experiment a bit, maybe adjust things to
>> suit the voltage drop you find or test several transistors to find one in
>> the right range.  My understanding is that if you do manage find a suitable
>> transistor it will give you a bit more noise at a somewhat lower voltage
>> drop than a zener.  With zeners, use the highest voltage you can accomodate
>> because below 10V they aren't so noisy.
>>
>> Cheers,
>> Nicolas
>>
>> --- On Fri, 30/10/09, Benjamin Budts <mailing at gigaspeeds.be> wrote:
>>
>>
>>> From: Benjamin Budts <mailing at gigaspeeds.be>
>>> Subject: [sdiy] reverse biased NPN vs Zener diode for noise...
>>> To: "synth-diy DIY" <synth-diy at dropmix.xs4all.nl>
>>> Received: Friday, 30 October, 2009, 3:13 AM
>>>
>>> Hi,
>>>
>>> I'm looking into building a noise module and I'm wondering
>>> what the audible difference is between
>>> reverse biased NPN based  vs Zener diode based... :-D
>>>
>>> Just wondering if there's somebody on the list who tested
>>> this...
>>>
>>> Thx
>>> Benjamin
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>>
>>
>>
>>
>>
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