[sdiy] Odd transistor connection, why???

[Walker Shurlds]

Base is direct connected to collector in npn current mirrors... but I
don't think that's what's going on in this case.

Walker

On Mon, 17 May 2010 17:23:50 -0600
"David Ingebretsen" <dingebre at 3dphysics.net> wrote:

> As I am digging into my Steiner resurrection, studying schematics, and
> trying to simulate some of these circuits, I am hitting a problem
> with the SPICE simulations. I have every confidence the schematics
> are correct, and the circuits work (at least the few I actually built
> in the 70's), but the simulations are not working.
> 
> The common link between the ones which don't work is a weird NPN
> transistor connection. Nyle connected the base to the emitter or
> collector and then uses the transistor as a two pin device, like this:
> 
> 
>              ______
>             |      |
>           __|__    |
>           /  \     |
>     _____/    >____|_____ 
> 
> What does this do to the transistor? What is the point of doing this?
> He does it in his VCO and in the EG. I am becoming convinced it is
> this weird connection which is giving SPICE problems. I can see when
> it the base is connected to the collector, it should be a diode, but
> then why connect it to the collector at all? I have no idea what it
> does when connected to the emitter. In all the EG schematics, the
> base goes to the emitter. In the two different VCO schematics I have,
> it goes to the collector.
> 
> The Synthacon schematics for the VCO and EG are here: 
> 
> http://www.xmission.com/~dingebre/page9.html
> 
> (since they are on the net in other places, I don't think I'm
> violating any copyright. If I'm wrong, let me know immediately).
> 
> David
> 
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