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From: "Phil Allison"
Subject: Re: Audio noise in diff amps
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Thu, 19 Dec 2002 21:19:45 +1100
NNTP-Posting-Date: Thu, 19 Dec 2002 21:07:54 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Don Pearce" wrote in message
> Oops - just seen that last phrase. There is no reason at all to
> suppose that the 2.4uV figure contains R - indeed if you do the maths,
> it can't. If it did, how would you then use R to calculate the power?
> No, that 2.4uV can only contain B, which is what I have assumed
** And that is your ** STUPID ERROR ** throughout.
Noise power does not vary with resistance value while noise voltage
> And of course if it did contain R, what value would you use? Phil told
> us 22000 ohms, but then used 600 ohms for his calculation (inherent in
> the adoption of 0.775 volts as a voltage level for 0dBm).
** I said no such thing ever. That is another of your delusions.
The famous formula is Vn (rms) = sq. rt. ( 4KTBR)
use 22000 ohms, 295 K and 16 kHz bandwidth and what do you get ??
You get 2.4uV rms. This is the open cct resistor noise voltage.
Why has this caused so much trouble for Mr Pierce ??????
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