[sdiy] 5mV of noise ...

[Seb Francis]

JH. wrote:

>I don't know how it was measured - it might just be the scope's own noise.
>Not uncommon even on expensive scopes, because of the wide bandwidth.
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especially digital scopes ..

also, if the typical signal level is 10V p.t.p then this amount of noise 
isn't bad at all ...

.. and another thing: you may get more noise when you breadboard 
(compared to PCB or even veroboard) because of all the extra tracks and 
long wires, etc.

seb


>----- Original Message ----- 
>From: "Magnus Danielson" <cfmd at bredband.net>
>To: <bert at percussa.com>
>Cc: <synth-diy at dropmix.xs4all.nl>
>Sent: Thursday, June 16, 2005 11:40 PM
>Subject: Re: [sdiy] 5mV of noise ...
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>>From: "Bert Schiettecatte" <bert at percussa.com>
>>Subject: [sdiy] 5mV of noise ...
>>Date: Thu, 16 Jun 2005 23:15:53 +0200
>>Message-ID: <004701c572b8$941266b0$4101a8c0 at laptop>
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>>>Hi all,
>>>
>>>I have a silly question so don't shoot me. I'm still learning on analog
>>>stuff.. I have been breadboarding some audio circuitry and I measured
>>>between 4mV and 5mV of noise. Exactly how bad is this? Of course I could
>>>convert this into dB I suppose but even then I'm not sure how bad this
>>>is once you start passing sound through it.
>>>      
>>>
>>If your referens level is 775 mV, a noise of 5 mV(RMS) equals -43.8 dBm.
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>This
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>>is bad. That's only 43.8 dB of dynamics. OK, let's say you have 6 dB of
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>head-
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>>room but that only gives you 50 dB of dynamics. OK, if you like the
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>dynamics
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>>of tape-recorders it may fit your needs, but you can do alot better.
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>>Cheers,
>>Magnus
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