From: John Woodgate
Subject: Re: Amplifying stage with *negative* Voltage gain??
Date: Sat, 7 Dec 2002 18:27:51 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Sat, 7 Dec 2002 18:42:37 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Paul Burridge
wrote (in <9g64vuc5ue2mm59vc039t28opnlahbuj
firstname.lastname@example.org>) about 'Amplifying stage with *negative* Voltage gain??', on
Sat, 7 Dec 2002:
>On Fri, 06 Dec 2002 08:20:34 -0500, Mike Monett opined
>>This was tony's suggestion. He is always right.
>I'll bear that in mind in future. :-)
>>I can't figure out what you mean by "2.2 tenths of a volt".
>When using the 10X setting on the probe and the scope set on
>0.1v/div., the p-p waveform occupies just over 2 divisions. I guess
>that equates to 2.2v?
>>If you are taking p-p measurements from the scope, you need to account
>>for the trace width and the fuzz caused by scope noise.
>SFAICS, these are both negligible WRT the signal.
>What I *cannot* understand is why on the x1 probe, Vin is four times
>larger than Vout., whereas with X10., the signal levels are almost the
>same. It's a heck of a discrepancy. Can anyone enlighten me?
>BTW, your screen shots were very helpful. What simulation program do
What is very difficult to understand is that, AIUI, you measure 8 V
input with the probe on X1 setting but only 2.2 V out. If the probe has
100 pF capacitance, that suggests that your output coupling capacitor is
about 30 pF.
But then you measure 8 V in with the probe on X1 but 2.2 V with it on
X10. That seems utterly inexplicable.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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