From: John Woodgate
Subject: Re: output impedance
Date: Thu, 7 Nov 2002 20:18:16 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 7 Nov 2002 21:29:41 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Ban wrote
(in ) about 'output impedance', on
Thu, 7 Nov 2002:
>In a current source the internal resistance is in *parallel* to the ideal
>Io = (Uout/Rload)+(Uout/Ri)
>Rload is the resistance of the load, Uout is the voltage across the load, Ri
>is the inner resistance of the current source,
>If Ri is infinite, the output current is independent of the load resistance
>and that is what we expect from a current source.
True, but you are expecting the OP to understand what a current source
is, and he almost certainly doesn't. That's why he's asking.
>Ohm's law isn't it.
It comes in if you want to explain, as I think is essential, in terms of
a voltage source. You can easily buy (non-ideal) voltage sources -
batteries. You can't buy a current source at your local store, although
Agilent will probably sell you one for USD5000 or so.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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