🚀 go-pugleaf

A candidate for page protector immortality:

	$ Message-ID: <1308@neoucom.UUCP>     Date: 7 Aug 88 18:02:16 GMT
	$ From: wtm@neoucom.UUCP (Bill Mayhew)
	$ Subject: Capacitors and solving problems thereof

	$ ... One of the more important applications (outside tone control
	$ circuits) for capacitors in audio amplifiers is in
	$ miller-effect feedback bypass circuits.  Miller effect
	$ feedback involves placing a resistor in the emitter lead of
	$ a transistor to establish a certain DC operating characteristic
	$ effectively placing the transistor in a linear amplifying
	$ modality.  The capacitor is placed in parallel with the resistor
	$ to supply correct AC coupling of the transistor.  The problem
	$ is that the required AC and DC characteristics are often
	$ different, and thus the capacitor really is necessary.

	$ It possible to build a so-called direct coupled circuit that
	$ does not use any capacitors at all, but such a device tends
	$ to suffer markedly from temperature instibility, gain drift, etc.


In addition to being hopelessly befuddled about the Miller effect, the
article seems to insist that each amplifier *must* contain a certain
capacitor (it "really is necessary"), and that the entire body of
experience with DC-coupled amplifiers (including, of course, audio
power amplifiers and preamp line-stages) indicates that the DC-coupled
topology "suffers markedly" when compared to capacitor-coupled
amplifiers.
-- 
 -- Mark Johnson	
 	MIPS Computer Systems, 930 E. Arques, Sunnyvale, CA 94086
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