Re: Barkhausen must be wrong.

On Oct 9, 8:58 pm, Jim Thompson <To-Email-Use-The-Envelope-I...@My-Web-
Site.com> wrote:
On Tue, 09 Oct 2007 20:46:12 -0700, The Phantom <phan...@xxxxxxx>
wrote:





On Tue, 09 Oct 2007 20:34:09 -0700, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Tue, 09 Oct 2007 19:10:03 -0700, The Phantom <phan...@xxxxxxx>
wrote:

At this site:

http://www.4qdtec.com/singen.html

there is a schematic titled "A Practical Twin-T Oscillator".

In the text under the schematic we find:

"Now hold on a minute: an emitter follower has no voltage gain and surely
you've been taught that an R-C oscillator must have voltage gain? Well this
one works and has no voltage gain (of course it does have current gain)."

The schematic does show two emitter followers closing the loop. One would
think this couldn't work, but the poster says it does.

Is Barkhausen wrong?

You can make an oscillator with just an emitter follower and some
r-c's... I did it accidentally ca 1975, and was surprised. The
impedances are such that you usually need a darlington to pull it off.

There are a couple of simple 2-terminal-plus-ground RC networks that
can have an AC voltage gain above 1.

But he says this one has no voltage gain. So how does this work?

John

POWER gain IS the requirement.

That's what I always thought. One doesn't, per se, care about "gain"
from the negative resistance viewpoint either.


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