Posted by Wayne Parham [ 66.139.42.17 ] on June 03, 2004 at 02:37:07:
In Reply to: Re: Feedback posted by metasonix on June 02, 2004 at 23:44:44:
What amplifier topologies and feedback configurations do you like and which ones do you not like?
I often build amps that switch current to a load connected directly in series with the output device. That's a simple and effective configuration, one that is often used in transformer coupled tube stages. Another one I like is to use an unbypassed emitter (cathode) resistor, and sometimes use the voltage swing across it as the in-phase output. It doesn't give the full gain of the device going that way, but it is a simple configuration that is stable and works well. I can't think of any devices that don't work well in these modes, although they are only appropriate in certain situations.
What are some of your topological favorites? What are some you steer clear of? And what are those horrible feedback implementations you mentioned? I don't necessarily care to know names, but descriptions of ill-configured circuits would be interesting. Particularly if compared with others that were done right.
That may be a bit much for a messageboard post, but it would certainly make a good article. Or maybe a teaser with excerpts on the forum, followed by meat and potatoes in a printed article at a later date. I think everyone would like to know the why's and wherefor's so they'd know what to watch out for in future purchases, kits and homebrew projects.