[sdiy] Longish cables causing wierdish results

[Magnus Danielson]

From: "jhaible" <jhaible at debitel.net>
Subject: Re: [sdiy] Longish cables causing wierdish results
Date: Thu, 18 Sep 2003 00:59:11 +0200

> > > I don't know what's inside a Milton.
> >
> > "A small gray-coated gnat not half so big as a round little worm pricked
> > from the lazy finger of a maid."
> >
> > - Bill Shakespeare.  R and J, act 1.
> 
> Shakespeare rules!
> 
> It's a miracle how his words were so powerful that even the
> German translations sound good. (Which cannot be said of
> any of my favorite contemporary authors.)
> 
> Ooops - not much on topic.

Well, it does show what happends with the sources looking into a too long
cable... selfoscillation!

Op-amps may not be the best drive for a longer cable, but I agree... a series
resistor is what you might have to do in order to get into trouble. Too much
of capacitive loads on the output of a feedback system with much gain can be
quite dangerous, you easilly run into stability issues. For a digital signal
you better use a pair of transistors in a class-D setup.

Cheers,
Magnus